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    C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. Noise Suppression by EMIFIL® Application Guide Cat.No.C35E-2 Application Manual Murata Manufacturing Co., Ltd. C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. Introduction To make effective noise suppression in electronic equipment it is necessary for design engineers to have a good understanding of the various types of EMI suppression filters available and the characteristics so that they can use suitable components. Because filtering characteristics of EMI suppression filters depend significantly on the construction, a wide variety of products are available in the market, it is difficult to understand all of them. This brochure provides an overview of EMI suppression filters by classifying them into several groups and describing the characteristics of each group along with a brief summary for the engineers. This publication is intended to help readers to make correct selection of EMI suppression filters for their applications. Definition DC EMI suppression filters : EMI filters to be used in the secondary side DC circuits such as digital circuits, audio and video circuits. * EMIFIL® and EMIGUARD® are the registered trademarks of Murata Manufacturing Co., Ltd. C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 1 Example of Noise Suppression in Desktop PCs ŠŠŠ2 Noise Emission Status ...................................................................02 Noise Suppression Content in Personal Computers ................... 03 Improving Shielding ......................................................................04 Installing EMI filters on Interface Cable Ports ...............................04 Example of effects produced when improving the GND and installing EMI filters on the cable connector port.. 5 Improving the GND on Extension Boards ....................................06 Installing EMI filters on the Clock Lines.........................................06 Installing EMI filters on Bus Lines..................................................06 2 Example of Noise Suppression in Notebook PCsŠŠ7 Noise Emission Status ...................................................................07 Noise Suppression Content in Notebook Personal Computers.......08 Improving the Case Shielding and GND Connection ...................09 Improving the External Card GND ................................................09 EMI Filter at LVDS Cable Connection............................................09 Noise Suppression in LCD ............................................................ 10 Installing EMI filters on Interface Cable Ports ............................... 10 Installing EMI Filters on the DC Power Supply Input..................... 10 3 Example of Noise Suppression for USB'sŠŠŠŠŠŠ 11 Noise Suppression Content for USB ............................................. 12 Examples of transmission signal waveforms and noise suppressing effects in HS mode .. 13 4 Example of Noise Suppression in CD-ROM DrivesŠŠ14 Noise Emission Status ................................................................... 14 Noise Suppression Content in CD-ROM Drives............................ 15 Installing EMI Filters on the Headphone Output Port.................... 16 Installing EMI filters on the Clock Line ..........................................16 Installing EMI filters on Bus Lines..................................................16 Example of effects produced when installing the Chip Ferrite Bead on the bus lines 17 Installing EMI filters on Interface Cable Ports ............................... 18 5 Example of Noise Suppression in DVD PlayersŠŠ 19 Noise Emission Status ................................................................... 19 Noise Suppression Content in DVD Players ................................. 20 Improving the Shielding ................................................................21 Installing EMI filters on Interface Cable Ports ............................... 21 Installing EMI filters on the Clock Line ..........................................21 Installing EMI Filters on Bus Lines.................................................22 Installing EMI Filters on High-speed Bus Lines.............................22 6 Example of Noise Suppression in PrintersŠŠŠŠŠ 23 Noise Emission Status ................................................................... 23 Noise Suppression Content in Printers......................................... 24 Improving the GND .......................................................................25 Installing EMI filters on Motor Control Lines ..................................25 Installing EMI filters on the Parallel Interface ................................25 Installing EMI filters on the DC Power Supply Input and Lines ..... 25 Installing EMI filters on the Clock Line ..........................................26 Example of effects produced when installing EMI filters on the Clock lines . 26 Installing EMI filters on Bus Lines..................................................27 7 Example of Noise Suppression in Fax Machines Š 28 Noise Emission Status ................................................................... 28 Noise Suppression Content in Fax Machines............................... 29 Installing EMI filters on Interface Cable Ports ............................... 30 Installing EMI filters on the DC Power Supply Input and Lines ..... 30 Installing EMI filters on Signal Lines to the Handset ..................... 30 Installing EMI filters on the Clock Line ..........................................30 Example of effects produced when installing EMI filters on the Clock lines . 31 Installing EMI filters on Bus Lines..................................................31 8 Example of Noise Suppression for Car Navigators Š 32 Noise Emission Status ................................................................... 32 Noise Suppression Content in Car Navigators............................. 33 Improving the Shielding ................................................................34 Installing EMI filters on Interface Cable Ports ............................... 34 Example of effects produced when installing EMI filters on Interface Cable Ports . 35 Installing EMI filters on the Clock Lines.........................................36 Installing EMI filters on Bus Lines..................................................36 9 Example of Noise Suppression in AC Power Supplies Š 37 Noise Emission Status for Switching Power Supplies ................ 37 Noise Suppression Model for Ordinary Switching Power Supplies.... 38 Differential Mode Noise and Common Mode Noise......................39 Functions of Respective Noise Filters ...........................................40 Noise Tendencies in Switching Power Supplies............................41 Examples of Suppression against Strong Differential Mode Noise ... 42 Reasons Why Common Mode Choke Coils Contain Mode Inductance... 43 Effective Suppression Methods against Differential Mode Noise using Hybrid Choke Coils ... 44 Examples of Confirming the Effectiveness of Hybrid Choke Coils... 45 10 Example of Noise Suppression in Mobile PhonesŠ46 Noise Emission Status ................................................................... 46 Noise Suppression content in Mobile Phones.............................. 47 Installing EMI filters on LCD line....................................................48 Installing EMI filters on DC Power Supply .....................................48 Installing EMI filters on Data Line ..................................................48 Installing EMI filters on interface section.......................................49 Improving the Shielding ................................................................49 CONTENTS 1 Example of Noise Suppression in Desktop PCs 2 Example of Noise Suppression in Notebook PCs 3 Example of Noise Suppression for USB's 4 Example of Noise Suppression in CD-ROM Drives 5 Example of Noise Suppression in DVD Players 6 Example of Noise Suppression in Printers 7 Example of Noise Suppression in Fax Machines 8 Example of Noise Suppression for Car Navigators 9 Example of Noise Suppression in AC Power Supplies 10 Example of Noise Suppression in Mobile Phones C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 1 Example of Noise Suppression in Desktop PCs Noise Emission Status : Noise is emitted from the cables connected to a personal computer. When using a computer case that does not have efficient shielding, radiated noise from the computer body may 1 sometimes cause problems. Power supply USB Mouse Keyboard Display cable Extension card Back side of PC Conducted noise Radiated noise 2 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. Example of Noise Suppression in Desktop PCs 1 Noise Suppression Content in Personal Computers A PC contains many sources of noise inside and out, with many connected cables. Therefore, it is necessary to use EMI filters on the interface cables, in addition to 1 shielding and improving GND connections. The PCB incorporates many signal lines that contain high-level noise. The EMI filters should also be mounted on potential noise sources such as the clock line, bus line and DC power supply line, to suppress noise conduction to the cable. EMI filters on PC power supply line Chip Ferrite Bead BLMP Series Chip EMIFIL® for DC power supply circuits NFM21P Series EMI filters on the clock line Chip EMIFIL® for signal lines NFW31S Series NFR21G Series Chip Ferrite Bead BLM Series EMI filters on bus line Chip Ferrite Bead BLM Series Chip EMIFIL® NFM21C Series NFR21G Series Shielding Metal case shielding CD-ROM CPU Power Supply Gate Array Driver Driver Driver USB Chip Set RAM ROM Improving shielding Upper and lower covers of metal case are connected together with fingers or gaskets. EMI filters on interface ports Chip Ferrite Bead BLM Series Chip EMIFIL® NFM21C Series Mouse Keyboard Display USB Improved GND PCB GND and metal case are screwed together. Improved GND on extension board connector Extension board's GND and metal case are connected together with metal fittings. Chip EMIFIL® for signal lines NFW31S Series EMI filters on USB line Chip Ferrite Bead BLM15BB121SN1 Chip Common Mode Choke Coil DLP11SN900HL2 Chip Ferrite Bead for DC power supply circuits BLM15PG Series 3 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 1 Example of Noise Suppression in Desktop PCs Improving Shielding Parts of the metal case make contact with each other by surface contact, where fingers and gaskets are used where necessary to minimize the impedance of contact 1 points at high frequencies. Overlaps should be provided for each edge of upper and lower covers to eliminate any gaps between the covers. Upper cover Overlap margin An overlap is created on each edge of the upper and lower covers so that no gap exists between them. Lower cover Installing EMI filters on Interface Cable Ports On the interface cable connection, three terminal capacitor NFM21C series, and Chip Ferrite Bead BLM series are used together to achieve better noise suppression. In some cases, the EMIFIL® for signal lines is used. It is important to design the circuitry to minimize the high frequency impedance between the EMI filter's GND (of circuit board) and the metal case. Fingers The fingers are installed so that the upper and lower covers maintain good contact with each other. Chip Ferrite Bead BLM18AG601SN1 (600Ω at 100MHz) Interface Cable Chip EMIFIL® NFM21CC102R1H3 (1000pF) Board Metal case 4 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. Example of Noise Suppression in Desktop PCs 1 Example of effects produced when improving the GND and installing EMI filters on the cable connector port In the data above the GND is improved by increasing the number of connection points between the board and chassis, and then an EMI filter, NFM21CC222R1H3 is 1 installed on the cable. This suppresses the noise level by 10dB. Noise Level (dBμV/m) Noise Level (dBμV/m) Before improving the GND 60 50 40 30 20 10 30 100 300 500 700 Frequency (MHz) 900 1000 After improving the GND 60 50 40 30 20 10 30 100 300 500 700 Frequency (MHz) 900 1000 Installing an EMI filter on the cable connector port 60 50 40 30 20 10 30 100 300 500 700 Frequency (MHz) 900 1000 Before improving the GND After improving the GND Chip EMIFIL® for signal lines NFM21CC222R1H3 (2200pF) To mouse To keyboard Installing an EMI filter on the cable connector port Noise Level (dBμV/m) 5 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 1 Example of Noise Suppression in Desktop PCs Improving the GND on Extension Boards In case of installing an extension board with a cable, noise may conduct to the cable when GND noise level is high. This results in high-level noise radiation from the 1 cable. Therefore, the board's GND must be stabilized by connecting the GND with the metal fitting (which is connected to the metal case of the personal computer) with screws so that high frequency impedance is low. In addition, EMI filters are installed on the cable connector port. PC's metal case Metal fitting Chip Ferrite Bead BLM Series Chip EMIFIL® NFM21C Series GND pattern Board Through hole Screwed to GND on extension board Extension board Installing EMI filters on the Clock Lines High frequency clock signals generate high frequency noise. Noise and signal frequencies may be close to each other. Therefore, an EMI filter with high and steep attenuation is used such as the NFW31S series (Chip EMIFIL® for signal lines), or the BLM˘˘B series (Chip Ferrite Bead for high-speed signal lines). Noise caused by transient currents is also generated on the power supply line. Therefore, a chip ferrite bead is installed, as well as a by-pass capacitor, to suppress noise on the power supply line. Installing EMI filters on Bus Lines Bus lines contain many lines that switch on and off simultaneously. Especially on data and address bus lines, an instantaneous large current flows into the GND and power supply lines. Therefore, it is necessary to suppress the current flow on the signal lines. The BLM series (Chip Ferrite Bead) is generally used for this purpose. On the control bus line, especially at high operating speeds and high noise levels, a filter with resistance components is used, such as the NFR21G series (Chip EMIFIL®). Chip Ferrite Bead BLM21PG300SN1 (30Ω at 100MHz) Vcc Chip Ferrite Bead BLM18BB220SN1 (22Ω at 100MHz) Gate Array Chip Ferrite Bead BLM18PG600SN1 (60Ω at 100MHz) Vcc CPU Chip Ferrite Bead BLM18BB220SN1 (22Ω at 100MHz) Address Bus Chip Ferrite Bead BLM18BB220SN1 (22Ω at 100MHz) Data Bus Chip EMIFIL® for signal lines NFR21GD1002202 (10pF, 22Ω) Control Bus 6 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 2 Example of Noise Suppression in Notebook PCs Noise Emission Status : Noise emission from PC body, LCD, connection cables, and connection cable between PC body and LCD. In notebook PCs, PCBs incorporate many signal lines which also emit noise. with high-level noise. Generally, notebook PCs use a In most cases, transmission signals to the LCD are resin case with conductive plating, which provides a LVDSs (Low Voltage Differential Signals). Since the lower shielding effect than the metal case of desktop LVDSs are high-speed signals containing high level PCs, causing high level noise to be emitted from the PC body. Furthermore, they use many connection cables, noise, the connection cable between the PC body and LCD also emits high level noise. 2 Connection cable between PC body and LCD LCD Panel Connectors Body Conducted noise Radiated noise AC adapter Interface cables 7 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 2 Example of Noise Suppression in Notebook PCs Noise Suppression Content in Notebook Personal Computers Notebook PC components are mounted in a limited space. Therefore, it is important to intensify the shielding condition as much as possible to suppress noise emission, before mounting noise-suppressing components. As shielding measures, the resin case is 2 provided with conductive plating, and metal plates are provided above and below the PCB to intensify the shielding condition. For cable connectors, the PCB GND is connected with the metal plates to intensify the GND condition, and additionally, noise suppressing components are mounted. Transmission signals to the LCD are mainly LVDSs (Low Voltage Differential Signals), which also emit high-level noise. Therefore, the DLP series common mode choke coils should be mounted to the signal lines. In some cases, it is also necessary to shield the cables. The LCD incorporates many signal lines that are connected from the graphic control IC to the LCD driver. Because these signal lines may emit noise, chip ferrite beads (e.g. BLM series) should be mounted to the signal lines to suppress noise emission. The card slot for connecting an external card, such as PCMCIA card, must be designed to reduce the high frequency impedance between the PCB GND and the card. Also, the card slot must be shielded. Noise suppression in LCD panel Installing EMI filters on Bus lines Chip Ferrite Bead BLM Series Chip EMIFIL® NFM21C Series Chip EMIFIL® for signal lines F NFW31S Series LVDS Receiver Connector Graphic Controller Shielding EMI filters at LVDS Cable Connection Chip Common Mode Choke Coil DLP31S/D EMI filters on Interface Cable Ports Chip Ferrite Bead BLM Series Chip EMIFIL® NFM21C Series Chip EMIFIL® for signal lines F NFW31S Series EMI filters on DC power supply line Chip Ferrite Bead BLMP Series Shielding Shielding by plating inside of plastic case EMI filters on Bus Lines Chip Ferrite Bead BLM Series Chip EMIFIL® NFM21C Series Chip EMIFIL® for signal lines NFR21G Series to Display Graphic IC IVRAN Gate Array to keyboard/mouse to USB to Serial port to Parallel Port CPU PCMCIA Card Power Supply HDD FDD Audio IC CD-ROM to Audio Improved GND PCB GND and metal case are screwed together. EMI filters on USB line Chip Ferrite Bead BLM15BB121SN1 Chip Common Mode Choke Coil DLP11SN900HL2 Chip Ferrite Bead for DC power supply circuits BLM15PG Series EMI filters on DC power supply input Chip Common Mode Choke Coil DLW5B Series Chip Ferrite Bead BLMP Series Improved GND on external card. 8 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. Example of Noise Suppression in Notebook PCs 2 Improving the Case Shielding and GND Connection Since plastic is usually used to encase a notebook PC, conductive plating is applied to the inside of the case. However, conductive plating alone is not sufficient for shielding. Therefore, to improve the GND, metal plates are also installed above and below the PCB. These plates are screwed together so they maintain contact with the PCB's GND and the conductive plating. Case (Apply conductive plating to inside of case.) PC Board Connectors Metal plate Connectors Metal plate 2 Improving the External Card GND When an external card with a cable is connected, noise is emitted not only from the card itself but also from the notebook PC, conducted through the cable. When the high frequency impedance between the card's GND and PC's GND is high, the card's GND becomes unstable. This makes noise suppression difficult. Therefore, the slot fingers in contact with the card's GND are screwed to the PCB's GND and metal plate, minimizing the high frequency impedance between them. If the PC's noise affects the card, radiated noise cannot be suppressed, even if the card contains a noise suppressor. In this case, the slot is shielded with a metal plate. When the ground connection relies on physical contact, such as when an external card makes contact with the slot, the level of radiated noise varies widely depending on the status of the contact. When taking measures to suppress noise or measure the noise level, care must be taken. EMI Filter at LVDS Cable Connection The connection cable between the PC body and LCD raises problems on noise emission due to signal harmonics to the LCD, and from the surrounding circuits other than the signal line. Because LVDSs (Low Voltage Differential Signals) are transmitted at a high-speed of several hundred MHz, common mode choke coils should be used to prevent rounding of the signal waveform. LVDSs are based on the differential transmission method, which cancels magnetic flux generated by a current, resulting in noise suppression. However, the current may be unbalanced by signal reflection. In this case, the common mode choke coil serves as a transformer to balance the current, thus enabling the noise caused by the unbalanced current to be suppressed. External card Metal case Slot for external card PC Board Metal plate Metal case is screwed to board's GND and metal plate. LVDS Receiver Connector Chip Common Mode Choke Coil DLP31D Cable Shielding LCD Panel Chip Common Mode Choke Coil DLP31D LVDS (Low Voltage Differential Signal) Line 9 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 2 Example of Noise Suppression in Notebook PCs Noise Suppression in LCD The connection between the graphic controller and LCD driver contains many lines that switch on and off simultaneously. This switching creates instantaneous large current flows into the GND and power supply line. Therefore, it is necessary to suppress the current flow from the signal lines. The BLM series (Chip Ferrite Bead) is typically used for this purpose. On the clock 2 line, especially at high operating speeds and high noise levels, a filter with high and steep attenuation is used, such as the NFW31S series (Chip EMIFIL® for signal lines). LVDS Receiver Chip Ferrite Bead BLM18PG600SN1 (60Ω at 100MHz) Chip Ferrite Bead BLM18BD421SN1 (420Ω at 100MHz) Graphic To LCD driver Controller 10Ω Clock Chip EMIFIL® for signal lines NFW31SP207X1E4 (Cut-off frequency : 200MHz) LCD Panel Installing EMI filters on Interface Cable Ports On the lines to the interface cable, three terminal capacitor the NFM21C series and Chip Ferrite Bead BLM series are generally installed in combination. In some cases, the EMIFIL® for signal lines is used. It is important to design the circuitry to minimize the high frequency impedance between the EMI filter's GND and the metal plate. Chip Ferrite Bead BLM18AG601SN1 (600Ω at 100MHz) Interface Cable Chip EMIFIL® NFM21CC102R1H3 (1000pF) PC Board Metal Plate Installing EMI Filters on the DC Power Supply Input Since noise is radiated from the DC power supply cable of the AC adapter, some noise suppression is necessary at input to DC power supply of personal computer. The DC power supply line contains both differential mode noise and common mode noise. Both mode noises need to be suppressed. The GND and metal plate are first connected together. The NFM31K series (Chip EMIFIL®) and the BLM ˘˘ P series (Chip Ferrite Bead) are used for differential mode noise suppression. The DLW5BS/AH series (Chip Common Mode Choke Coil) is used for common mode noise suppression. Chip Common Mode Choke Coil DLW5BSM351SQ2 (350Ω at 100MHz, Rated current : 2A) Chip Ferrite Bead BLM41PG600SN1 (60Ω at 100MHz, Rated current : 6A) Connector To AC adapter Chip EMIFIL® NFM31KC104R1H3 (0.1μF, Rated current : 6A) 10 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 3 Example of Noise Suppression for USB's The USB (Universal Serial Bus) was devised as an external bus to connect a PC (host) and its peripherals (functions). Because of easiness to use, the USB is expected to rapidly become widespread in the future. The major noise problem with USB's is noise radiation from the cables. However, common mode noise from other circuits does tend to be stronger than generated by USB signal because USB used differential data transmission. PC Host/Root hub Hub/Function 3 Hub Hub/Function Function Function Function Function Function 11 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 3 Example of Noise Suppression for USB's Noise Suppression Content for USB USB's support three types of transmission modes, depending on the function of the connected device: LS (Low Speed: 1.5Mbps), FS (Full Speed: 12Mbps) and HS (High Speed: 480Mbps). In order to suppress noise emission without deforming the signal waveform, it is necessary to take noise suppressing measures suitable for individual transmission modes. For noise suppression in the LS/FS mode, chip ferrite bead BLM18BB121SN1 or common mode choke coil 3 DLP11SN900HL2 should be mounted on the signal line, and the BLM--PG series chip ferrite bead should be mounted on the power supply and GND lines. In the LS/FS mode, using the EMI filters raises the problem of signal waveform deformation. In this case, influence of the EMI filters on EOP (End of Packet) signal must also be watched. In the high speed transmission mode such as the HS mode, using the ferrite bead results in signal waveform deformation. To prevent this problem, common mode choke coil DLW21SN900SQ2 should be used, instead of the ferrite bead to suppress noise emission. VDD Line BLM21PG221SN1 (220Ω 2A) VDD VDD/GND Line VDD BLM21PG221SN1 (220Ω 2A) USB Controller VDD D+ DGND LS/FS Chip Ferrite Bead BLM18BB121SN1 D+/D- Line HS Common Mode Choke Coil DLW21SN900SQ2 Common Mode Choke Coil DLP11SN900HL2 12 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. Example of Noise Suppression for USB's 3 Examples of transmission signal waveforms and noise suppressing effects in HS mode An example of noise suppressing measures for the HS mode is described here. For the HS mode, quality of the signal waveform is checked with eye patterns. Common mode choke coil DLW21SN900SQ2 has little influence on the eye patterns. With the choke coil, noise emission can be reduced by approx. 5dB max. No Filter Differential signal, V Eye pattern 0.5 0.4 0.3 0.2 0.1 0 -0.1 -0.2 -0.3 -0.4 -0.5 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Time, ns Level (dBμV/m) Level Noise 60 3 50 40 30 20 10 0 100 200 300 400 500 600 700 800 900 1000 Frequency (MHz) Common Mode Choke Coil DLW21SN900SQ2 Differential signal, V 0.5 0.4 0.3 0.2 0.1 0 -0.1 -0.2 -0.3 -0.4 -0.5 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Time, ns Level (dBμV/m) 60 50 40 30 20 10 0 100 200 300 400 500 600 700 800 900 1000 Frequency (MHz) 13 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 4 Example of Noise Suppression in CD-ROM Drives Noise Emission Status : Noise from both the CD-ROM drive and computer are conducted through the headphone cable and radiated. Since an internal CD-ROM drive is shielded with a metal case, radiated noise from the CD-ROM drive rarely causes a problem. However, in some cases, radiated noise from the headphone cable can cause problems. Computer 4 CD-ROM Conducted noise Radiated noise Headphone 14 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. Example of Noise Suppression in CD-ROM Drives 4 Noise Suppression Content in CD-ROM Drives Noise conducted to the headphone cable comes from the both the CD-ROM drive and the PC. Initially, noise from the headphone cable needs to be suppressed. The PCB's GND is first connected to the metal case, and then EMI filters are installed. If radiated noise cannot be suppressed using these methods, additional measures must be taken. If the problem appears to be noise generated from the CD-ROM drive, the source of the noise must be suppressed. The first potential noise sources are the clock and bus lines. Note that noise generated around the oscillator frequently can also cause problems. When noise generated around the D-A converter causes a problem, the point where the analog and digital GNDs are connected must be carefully considered. In many cases, improving this connection often suppresses the noise. If noise generated from the PC is causing a problem, EMI filters need to be installed on the cable between the PC and CD-ROM drive. Note that the CD-ROM drive may not operate on some computers if large capacitance or large inductance EMI filters are used. 4 EMI filters on the clock line Chip EMIFIL® for signal lines NFW31S Series Chip EMIFIL® for signal lines NFR21G Series Chip Ferrite Bead BLM Series EMI filters on the DC power supply input and line Chip Ferrite Bead BLMP Series Chip EMIFIL® for DC power supply circuits NFM41P Series EMI filters on interface cable ports Chip Ferrite Bead BLM Series Chip EMIFIL® NFM21C Series EMIFIL® for signal lines NFW31S Series Shielding Metal case shielding to Pick Up Unit +5V Analog +5V Digital ConDv-ertAor AUmpp. Power Supply Line Interface +5V +12V +5V +5V CPU Resonator +5V +5V +12V Audio Signal Processor DMriotvoerr Resonator DRAM DRAM to Motor Audio Out EMI filters on Bus lines Chip Ferrite Bead BLM Series Chip EMIFIL® NFM21C Series Chip EMIFIL® NFR21G Series Volume pHh teooande-s Improved GND PCB GND and metal case are screwed together. EMI filters on headphone output Chip Ferrite Bead BLM Series Chip EMIFIL® NFM21C Series GND connection considerations Connection of analog GND digital GND, etc. EMI filters on oscillator output Chip Ferrite Bead BLM Series 15 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 4 Example of Noise Suppression in CD-ROM Drives Installing EMI Filters on the Headphone Output Port To suppress noise in the headphone output port, it is important to minimize the GND's noise level of the port. The PCB's GND and metal case are screwed together to make a low impedance connection at high frequency. The NFM21C series (Chip EMIFIL®) capacitor is then installed on the headphone lines. More effective noise suppression can be achieved by also installing BLM series (Chip Ferrite Bead) on the lines. Shield case PC Board Chip EMIFIL® NFM21CC102R1H3 (1000pF) Screwed Chip Ferrite Bead BLM18AG221SN1 (220Ω at 100MHz) 4 Headphone cable Installing EMI filters on the Clock Line High-speed clock signals generate high frequency noise and in these conditions, the noise frequency may be sometimes quite close to the signal frequency. Therefore, an EMI filter with high suppression ability and steep attenuation characteristics is used such as the NFW31S series (Chip EMIFIL® for signal lines), or the BLM˘˘B series (Chip Ferrite Bead for high speed signal lines). Noise caused by transient current is also generated on the power supply line. Therefore, a chip ferrite bead is installed, as well as a by-pass capacitor to suppress the noise on the power supply line. Installing EMI filters on Bus Lines Data bus/Address bus lines contain many lines that switch on and off simultaneously. An instantaneous large current flows into the GND and power supply lines. Therefore, it is necessary to suppress the current flow to the signal lines. The BLM series (Chip Ferrite Bead) is generally used for this purpose. On the control bus line, especially at high operating speeds and high noise levels, a filter with resistance components is used such as the NFR21G series (Chip EMIFIL®). Chip Ferrite Bead BLM18PG300SN1 (30Ω at 100MHz) Vcc EMIFIL® for signal lines NFW31SP506X1E4 (Cut-off 50MHz) Gate 50Ω Array Chip Ferrite Bead BLM18PG600SN1 (60Ω at 100MHz) Vcc (+5V) CPU Chip Ferrite Bead BLM18AG601SN1 (600Ω at 100MHz) Address Bus Chip Ferrite Bead BLM18AG601SN1 (600Ω at 100MHz) Data Bus EMIFIL® for signal lines NFR21GD4701012 (47pF, 100Ω) Control Bus 16 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. Example of Noise Suppression in CD-ROM Drives 4 Example of effects produced when installing the Chip Ferrite Bead on the bus lines Noise suppression effects produced when installing the BLM series on the data bus lines. Noise Level (dBμV/m) 60 50 40 30 20 10 30 50 Before measure 100 150 200 250 300 Frequency (MHz) After installing the Chip Ferrite Bead on the bus lines 60 50 Noise Level (dBμV/m) 40 30 20 10 30 50 100 150 200 250 300 Frequency (MHz) CPU DRAM Before measure 4 Chip Ferrite Bead Inductor BLM18AG601SN1 600Ω at 100MHz Bus line (8MHz) After installing the Chip Ferrite Bead on the bus lines 17 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 4 Example of Noise Suppression in CD-ROM Drives Installing EMI filters on Interface Cable Ports Minimizing the GND's noise level of PCB is important in the interface cable port. The PCB's GND and metal case are screwed together to form a low impedance connection at high frequency. EMI filters are installed in the interface cable connection. Note that the CD-ROM drive may not operate on some computers if large capacitance or large inductance EMI filters are used. 4 Screwed Interface cable Screwed Chip Ferrite Bead BLM15AG700SN1 (70Ω at 100MHz) Board Shield case 18 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 5 Example of Noise Suppression in DVD Players Noise Emission Status : Noise generated in the DVD player is radiated from the audio and video signal cables. In addition, although the player body is shielded with a metal case, radiated noise is emitted from the connector port openings. A DVD player processes image signals using the MPEG2 method. Since image Processing requires highspeed signal processing, signals are transmitted at a very high speed. Therefore, high frequency noise around 1GHz, may be radiated. DVD player body Opening Video signal cable 5 Audio signal cable Metal case Conducted noise Radiated noise AC power supply cable 19 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 5 Example of Noise Suppression in DVD Players Noise Suppression Content in DVD Players High frequency noise radiates from the player body and cables. Therefore, the noise is suppressed by shielding the body and by installing noise filters in the cable port. However, it is necessary to carefully select noise filters noise filters because images or sounds could be deteriorated, If a high capacitance or high inductance filter is installed in the video or audio signal cable connection. In case that noise suppression in the cable port is not enough, it is necessary to make noise suppression of the PCB by improving the GND, and by installing noise filters at noise sources. The high-speed data bus between the MPEG2 and SDRAM chips generates especially high-level noise. This noise can be suppressed by installing a BLM series (Chip Ferrite Bead) applicable for high-speed signal lines. EMI filters on DC power supply line Chip Ferrite Bead BLM Series EMI filters on EMI filters on EMI filters on AC power supply input GND connection audio signal video signal Chip EMIFIL® for DC power considerations output line output line 5 Chip Common Mode Choke Coil PLA10 Series supply circuits NFM41P Series Connection of analog GND, Chip Ferrite Bead BLM Series Chip Ferrite Bead BLM Series digital GND, etc. Shielding Metal case shielding To AC100V Power Supply +3V +3.3V +3.3V To PICKUP Unit +3.3V D/A +3.3V Audio IC +3.3V MIC MPU D/A +3.3V Video IC +3.3V+3.3V MPEG2 +3V+3.3V +3.3V ROM RAM +3.3V SD RAM Noise Suppression for Synchronous DRAM EMI filters on clock line Chip EMIFIL® for signal lines NFW31S Series Chip EMIFIL® for signal lines NFR21G Series Chip Ferrite Bead BLM Series EMI filters on oscillator output Chip Ferrite Bead BLM Series Improved GND PCB GND and metal case are screwed together. EMI filters on DC power supply input and power supply line Chip Ferrite Bead BLM Series Chip EMIFIL® for DC power supply circuits NFM41P Series EMI filters on bus lines Chip Ferrite Bead BLMP Series Chip EMIFIL® NFM21C Series Chip EMIFIL® for signal lines NFR21G Series EMI filters on high speed Bus lines Chip Ferrite Bead for high speed signal lines BLMBSN1 Series 20 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. Example of Noise Suppression in DVD Players 5 Improving the Shielding The size of the opening in the metal case affects the shielding effects. As the opening becomes larger, the shielding effect decreases. It is best if larger openings are divided into multiple smaller openings, making each opening as small as possible, with the objective of making the longest part of the opening as small as possible. Opening Connectors Poor example : Opening is large Opening Opening Connectors Good example : Opening is small Installing EMI filters on Interface Cable Ports 5 When noise is conducted to the cable, the cable will radiate high noise levels. To suppress this noise, EMI filters are installed at the cable connection. In some cases, the installed EMI filters may affect or deteriorate images or sounds. It is necessary to pay Chip Ferrite Bead BLMB Series careful attention is selecting noise filters. Audio signal lines Video signal lines Installing EMI filters on the Clock Line High frequency clock signals generate high frequency noise. Noise and signal frequencies may be close to each other. Therefore, an EMI filter with high and steep attenuation is used such as the NFW31S series (Chip EMIFIL® for signal lines), or the BLM˘˘B series (Chip Ferrite Bead for high-speed signal lines). Noise caused by transient currents is also generated on the power supply line. Therefore, a chip ferrite bead is installed, as well as a by-pass capacitor, to suppress noise on the power supply line. Chip Ferrite Bead BLM18PG300SN1 (30Ω at 100MHz) Chip Ferrite Bead BLM18PG300SN1 (30Ω at 100MHz) Vcc Vcc EMIFIL® for signal lines NFW31SP107X1E4 (Cut-off frequency: 100MHz) Video IC 22Ω MPEG2 21 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 5 Example of Noise Suppression in DVD Players Installing EMI Filters on Bus Lines Data bus/Address bus lines contain many lines that switch on and off simultaneously. An instantaneous large current flows into the GND and power supply lines. Therefore, it is necessary to suppress the current flow to the signal lines. The BLM series (Chip Ferrite Bead) is generally used for this purpose. On the control bus line, especially at high operating speeds and high noise levels, a filter with resistance components is used such as the NFR21G series (Chip EMIFIL®). Chip Ferrite Bead BLM18PG300SN1 (30Ω at 100MHz) Vcc (+5V) CPU Chip Ferrite Bead BLM18AG471SN1 (470Ω at 100MHz) Address Bus Chip Ferrite Bead BLM18AG471SN1 (470Ω at 100MHz) Data Bus EMIFIL® for signal lines NFR21GD4701012 (47pF, 100Ω) Control Bus Installing EMI Filters on High-speed Bus Lines Since very high speed signals are transmitted on the bus lines between the MPEG2 and SDRAM chips, high 5 levels of high frequency noise are generated. In these cases, the BLM˘˘BB ˘˘˘ SN1 series (Chip Ferrite Bead for high-speed signal lines) is used. Featuring a sharp impedance rise at the specified frequency, this filter is used to minimize distortion of the signal waveform. Chip Ferrite Bead BLM18PG300SN1 (30Ω at 100MHz) Vcc Chip Ferrite Bead BLM18PG300SN1 (30Ω at 100MHz) Vcc Chip Ferrite Bead BLM18BB220SN1 (22Ω at 100MHz) MPEG2 SDRAM 22 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 6 Example of Noise Suppression in Printers Noise Emission Status : Noise generated from the main printer board and from the drive motor are radiated from the printer cable. In printers, noise generated from the main board is conducted to the printer cable and AC power supply cable, where they act as antennas. Noise generated while the motor is operating may sometimes cause a problem. In addition, friction between paper sheets generates static electricity, causing a malfunction. Printer body (Plastic housing) Main board AC power supply cable 6 Metal plate Printer cable To personal computer Conducted noise 23 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 6 Example of Noise Suppression in Printers Noise Suppression Content in Printers In printers, the GND is improved to suppress noise from the main board and prevent static electricity from causing a malfunction. A GND plate (metal plate) is installed onto the rear face of the main board and connected to the main board GND. To suppress noise conduction from the main board to the printer cable, EMI filters are installed on the printer cable port (parallel interface). To suppress noise conduction to the AC power supply cable, EMI filters are installed on the DC power supply input and DC power supply line. To suppress noise caused by the motor, EMI filters are installed on the motor control signal lines. When noise radiated from the board itself is combined with noise from the surrounding cables, ferrite beads are installed on the clock and bus lines. EMI filters on parallel interface Chip Ferrite Bead BLM Series Chip EMIFIL® NFR21G Series EMI filters on bus lines Chip Ferrite Bead BLM Series Chip EMIFIL® NFM21C Series Chip EMIFIL® NFR21G Series EMI filters on oscillator output line Chip Ferrite Bead BLM Series 6 EMI filters on USB line Chip Ferrite Bead BLM15BB121SN1 Chip Common Mode Choke Coil DLP11SN900HL2 Chip Ferrite Bead for DC power supply circuits BLM15PG Series 5V RAM 5V Gate Array ROM CPU Motordriver Motordriver To Motor 12V Signal 5V processing To Motor EMI filters on Clock line Chip EMIFIL® for signal lines NFW31S Series Chip EMIFIL® NFR21G Series Chip Ferrite Bead BLM Series To power supply EMI filters on DC power supply input and lines Chip Ferrite Bead BLMP Series Chip EMIFIL® for DC power supply circuits NFMP Series To print head Improved GND PCB GND and metal case are screwed together. EMI filters on DC power supply input and lines Chip Ferrite Bead BLM Series Chip EMIFIL® NFM21C Series 24 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. Example of Noise Suppression in Printers 6 Improving the GND To reduce the level of noise from the main board, a GND plate (metal plate) is installed onto the rear face of the main board to improve the GND. The main board GND and GND plate are connected at several points. However, if the connection points are inappropriate, the noise level may increase. Therefore, great care must be given when selecting the connection points. Connections should not be made at points where the noise level is especially strong, such as the oscillator circuit GND. Improving the GND is also intended to prevent static electricity from causing a malfunction. Improving the GND suppresses any potential difference between the GND generated when current from static electricity flows into the board. Installing EMI filters on Motor Control Lines Noise generated by the motor is conducted to the main board and other cables via the motor cable and radiated. EMI filters are installed near the motor to suppress the noise. In case that EMI filters cannot be installed near the motor, NFM21C series (Chip EMIFIL®) are installed on cable connections to the motor. However, the noise suppression effect may not be as much as that obtained by installing EMI filters near the motor. Installing EMI filters on the Parallel Interface If noise is conducted to the printer cable, high levels of noise are radiated. Therefore, EMI filters are installed on the cable port (parallel interface) to suppress noise. Note that installing a filter with a large impedance value may sometimes hinder communication between the printer and personal computer. Using a BLA31 series (Array type) decreases the mounting surface area. The main board and metal plate are connected at several points using screws Main board GND plate (Metal plate) Chip EMIFIL® 6 NFM21C Series Motor control lines Chip Ferrite Bead BLMB Series Installing EMI filters on the DC Power Supply Input and Lines Noise is conducted from the DC power supply and GND lines to the switching power supply and radiated from the AC power supply cable. To suppress the noise, the BLM ˘˘P series (Chip Ferrite Bead) is inserted onto each power supply line (including the GND line). If the noise level is high, the NFM˘˘P series (Chip Solid EMIFIL® for DC power supply circuits) is installed in addition to the chip ferrite bead to achieve more noise suppression effect. Switching power supply Chip EMIFIL® for DC power supply circuits NFMP Series Chip Ferrite Bead BLMP Series GND line Power supply line 2 Power supply line 1 25 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 6 Example of Noise Suppression in Printers Installing EMI filters on the Clock Line Clock signals generate high frequency noise. Noise and signal frequencies may be close to each other. Therefore, an EMI filter with high and steep attenuation is used, such as the NFW31S series (Chip EMIFIL® for signal lines) or the BLM˘˘B series (Chip Ferrite Bead For high-speed signal lines). Noise caused by transient currents is also generated on the power supply line. Therefore, a chip ferrite bead is installed, as well as a by-pass capacitor, to suppress noise on the power supply line. Chip Ferrite Bead BLM18PG300SN1 (30Ω at 100MHz) Chip Ferrite Bead BLM18PG300SN1 (30Ω at 100MHz) Vcc Vcc Chip EMIFIL® for signal lines NFW31SP506X1E4 (Cut-off frequency: 50MHz) Gate Array 32Ω Signal processing IC Example of effects produced when installing EMI filters on the Clock lines Noise suppression effects produced when installing the EMI filter on the data clock lines. Before measure 60 50 Noise Level (dBμV/m) 40 6 30 20 10 30 84 138 192 246 300 Frequency (MHz) Before measure Noise Level (dBμV/m) When the EMI filter for signal line is mounted to a clock line, and the chip ferrite bead inductor is mounted to a DC power supply line 60 50 40 30 20 10 30 84 138 192 246 300 Frequency (MHz) Chip Ferrite Bead BLM18BD102SN1 (1000Ω at 100MHz) Chip EMIFIL® for signal lines NFW31SP107X1E4 (Cut-off frequency : 100MHz) 22Ω 37MHz Clock CPU When the EMI filter for signal line is mounted to a clock line, and the chip ferrite bead inductor is mounted to a DC power supply line 26 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. Example of Noise Suppression in Printers 6 Installing EMI filters on Bus Lines Bus lines contain many lines that switch on and off simultaneously. This causes instantaneous large currents to flow into the GND and power supply lines through the data and address. Therefore, it is necessary to suppress the current flow on the signal lines. The BLM series (Chip Ferrite Bead) is generally used for this purpose. On the control bus line, especially at high operating speeds, the BLM˘˘B series (Chip Ferrite Bead for high-speed signal lines that features a steep impedance rising) is used. On bus lines with high-level noise, the NFM21G series (Chip EMIFIL®) is sometimes used. The radiation spectrum of noise generated from bus lines resembles that of noise generated from the motor. It is important to check which of the motor or bus lines is the source of the noise and then install EMI filters. Chip Ferrite Bead BLM18PG300SN1 (30Ω at 100MHz) Vcc Gate Array Chip Ferrite Bead BLM18AG121SN1 (120Ω at 100MHz) Address Bus Chip Ferrite Bead BLM18AG121SN1 (120Ω at 100MHz) Data Bus Chip EMIFIL® for signal lines NFR21GD4701012 (47pF, 100Ω) Control Bus 6 27 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 7 Example of Noise Suppression in Fax Machines Noise Emission Status : Digital noise generated from the main board of the facsimile machine is conducted to the handset cable, sensor signal input cable, and power supply cable. The noise is then radiated using the cables as antennas. With a facsimile machine, the main board is not shielded by a case or similar protection. Therefore, it is important to decrease the noise level from the board itself. Since many kinds of cables are connected to the board, Handset an EMI filter is installed on each cable. Telecommunication Line Radiated noise 7 28 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. Example of Noise Suppression in Fax Machines 7 Noise Suppression Content in Fax Machines The example above is a noise suppression model of a fax machine. As shown, there are many cables inside the facsimile which are notorious for generating EMI noise. In most cases, the cables are placed close to the main board. In this condition, the cables are coupled to the main board, causing the noise from the main board to be emitted through the cable like an antenna. It is necessary to install EMI filters on the cable ports in addition to improving GND connections. It is also necessary to install EMI filters on the main board's digital circuits. EMI filters on sensor signal input Chip Ferrite Bead BLM Series Chip EMIFIL® NFR21G Series Chip EMIFIL® for signal lines NFW31S Series EMI filters on cable ports Chip Ferrite Bead BLM Series Chip EMIFIL® NFM21C Series Sensor signal input Improved GND PCB GND and metal case are screwed together. To operation panel Signal processing IC Signal processing IC Signal processing IC EMI filters on oscillator output line Chip Ferrite Bead Gate BLM Series Motor drive IC Array CPU 7 Signal processing IC Relay Motor drive IC RAM ROM Signal processing IC Relay To telecommunication line Handset EMI filters on bus Lines Chip Ferrite Bead BLM Series Chip EMIFIL® for signal lines NFW31S Series Chip EMIFIL® NFR21G Series To power supply EMI filters on DC power supply input and lines Chip Ferrite Bead BLMP Series Chip EMIFIL® for DC power supply circuits NFMP Series EMI filters on signal lines to handset Chip Ferrite Bead BLM Series Common Mode Choke Coil DLW5 Series EMI filters on telecommunication line Common Mode Choke Coil PLT09HN2003R0P1 29 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 7 Example of Noise Suppression in Fax Machines Installing EMI filters on Interface Cable Ports When noise is conducted to the cable, strong noise is radiated from the cable. Therefore, the BLM series (Chip Ferrite Bead) is installed on the cable connection. Since sensor input signals for detecting the presence or absence of paper are of a low speed and temporary, an EMI filter whose impedance value is as large as possible should be used. In case that the noise level is high, a capacitor chip EMIFIL® NFM series is used additionally to achieve more noise suppression effect. Installing EMI filters on the DC Power Supply Input and Lines Noise is conducted from the DC power supply and GND lines to the switching power supply and radiated out using the AC power supply cable as an antenna. To suppress the noise, the BLM˘˘P series (Chip Ferrite Bead) and NFM˘˘P series (Chip EMIFIL® for DC power supply circuits) are installed close to the power supply connector. A filter whose rated current is sufficiently larger than the power supply current should be selected. 7 Installing EMI filters on Signal Lines to the Handset Noise from the digital circuit is conducted to the handset cable and radiated from the cable. Since the noise is common mode noise, the BLM series (Chip Ferrite Bead) or DLW5BS/AH series (Common Mode Choke Coil) is installed on all four lines to suppress the noise. Installing EMI filters on the Clock Line Clock signals contain noise covering the high frequency range, and in some cases, the clock signal frequency is close to the noise frequency. Therefore, an EMI filter that effectively eliminates noise in high frequency range and provides sharp cutoff, the NFW31S series EMIFIL® for signal lines and the BLM˘˘B series chip ferrite beads for high-speed signal lines, should be used. In combination with a resistor, the NFW31S series EMIFIL® can suppress overshoot and undershoot in the signal waveform, providing further improved noise suppressing effect. Because power supply lines, as well as signal lines, conduct a transient current that causes noise emission, the BLM˘˘P series chip ferrite bead together with a bypass capacitor should be mounted to suppress noise conduction through the power supply lines. 30 Chip Ferrite Bead BLM Series Sensor signal Input lines Switching power supply Chip EMIFIL® for DC power supply circuits NFMP Series Chip Ferrite Bead BLMP Series GND line Power supply line 2 Power supply line 1 Chip Ferrite Bead BLM Series Signal lines to handset Chip Ferrite Bead BLM18PG300SN1 (30Ω at 100MHz) Chip Ferrite Bead BLM18PG300SN1 (30Ω at 100MHz) Vcc Vcc Chip EMIFIL® for signal lines NFW31SP107X1E4 (Cut-off frequency: 100MHz) Video IC 32Ω MPEG2 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. Example of Noise Suppression in Fax Machines 7 Example of effects produced when installing EMI filters on the Clock lines Noise suppression effects produced when installing the EMI filter on the data clock lines. Noise Level (dBμV/m) 60 50 40 30 20 10 30 Before measure 84 138 192 246 300 Frequency (MHz) Before measure Noise Level (dBμV/m) When the EMI filter for signal line is mounted to a clock line, and the chip ferrite bead inductor is mounted to a DC power supply line 60 50 40 30 20 10 30 84 138 192 246 300 Frequency (MHz) Installing EMI filters on Bus Lines The Data and Address bus contain many lines that switch on and off simultaneously. This constant switching causes instantaneous large currents to flow through the GND and power supply lines resulting in unwanted noise. Therefore, it is necessary to suppress the current flow on the signal line. The BLM series (Chip Ferrite Bead) is generally used for this purpose. On the control bus line, especially at high operating speeds, the BLM˘˘ B series (Chip Ferrite Bead for high-speed signal lines that features a steep impedance rising) is used. On bus lines with high-level noise, the NFR21G series (Chip EMIFIL®) may be effective. The radiation spectrum of noise generated from bus lines resembles that of noise generated from the motor. It is important to check which of the motor or bus lines is the source of the noise and then install EMI filters. Chip Ferrite Bead BLM18BD102SN1 (1000Ω typ. at 100MHz) Chip EMIFIL® for signal lines NFW31SP107X1E4 (Cut-off frequency : 100MHz) 7 22Ω 37MHz Clock CPU When the EMI filter for signal line is mounted to a clock line, and the chip ferrite bead inductor is mounted to a DC power supply line Chip Ferrite Bead BLM18PG300SN1 (30Ω at 100MHz) Vcc Chip Ferrite Bead BLM18PG300SN1 (30Ω at 100MHz) Vcc Chip Ferrite Bead BLM18AG221SN1 (220Ω at 100MHz) Gate array ROM or RAM Chip EMIFIL® for signal lines NFR21GD4701012 (47pF 100Ω) 31 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 8 Example of Noise Suppression for Car Navigators Noise Emission Status : Noise from a car navigator radiates from the interface cable. Noise also radiates from the connector port openings in the metal case. As car navigation system is located near car radio/TV, which is interfered by noise easily. The noise emission from the car navigation system should be suppressed much lower than regulation level by CISPR etc. It is possible for the system to have function error/ damage by strong noise from igniter. Car navigator housing Connectors Interface cable Therefore, car navigation system should have noise suppression and noise protection. GPS antenna Metal case Conducted noise Radiated noise 8 32 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. Example of Noise Suppression for Car Navigators 8 Noise Suppression Content in Car Navigators The car navigator is shielded with a metal case to prevent noise radiation from the body, as well as noise entering into the system. EMI filters are installed on all lines of each interface cable to suppress noise conduction through the cable. The noise suppression effects obtained by a capacitor type EMI filter installed in the cable connector port varies depending on the GND condition. Therefore, it is necessary to pay much attention to the GND condition. Improve the GND connection between the PCB and metal case, and design the circuitry to minimize the impedance at high frequencies between the metal case and the GND of the capacitor type EMI filter. Noise radiated from the car navigator can be most effectively suppressed by also installing EMI filters on the clock line, bus lines, and power supply line. Driver Driver Gyro ROM Vcc Chip Ferrite Bead BLM Series Chip EMIFIL® NFM21C Series EMI filters on cable connector port Chip EMIFIL® for signal lines F NFW31S Series Chip EMIFIL® for DC power supply circuits NFM41P Series T-type Chip EMIFIL® NFE31P Series Shielding Metal case shielding Improved GND PCB GND and metal case are screwed together. PoIwntererfSaucpeply To CD-ROM Gate array Video IC Audio IC AudiOo/UViTdeo Improved shielding Area of openings is reduced RAM RAM Vcc GPS Antenna GPS 8 CPU Resonator EMI filters on clock lines Chip EMIFIL® for F signal lines NFW31S Series Chip EMIFIL® NFR21G Series Chip Ferrite Bead BLM Series EMI filters on bus Lines Chip Ferrite Bead BLM Series Chip EMIFIL® NFM21C Series Chip EMIFIL® NFR21G Series EMI filters on DC power supply lines Chip Ferrite Bead BLMP Series Chip EMIFIL® for DC power supply circuits NFM41P Series 33 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 8 Example of Noise Suppression for Car Navigators Improving the Shielding Increasing the size of the opening in the metal case causes the shielding effect to decrease. As the opening gets larger, the shielding effect decreases. Large openings should be divided into multiple smaller openings to decrease the length of each opening, making each opening as small as possible. Opening Connectors 1 Connectors 2 Poor example : Opening is large Opening Opening Connectors 1 Connectors 2 Good example : Opening is small Installing EMI filters on Interface Cable Ports For noise suppression in a cable connector, a combination of the NFM series chip EMIFIL® and the BLM series chip ferrite bead provides an enhanced noise suppressing effect. To make full use of the chip EMIFIL®'s noise suppressing effect, reduce the high frequency impedance between the filter GND and the shield case, and intensify the GND condition by screw- mounting the PCB GND to the shield case and connecting them with fingers, and by adding through holes for the filter GND. 8 If the GND pattern is distant from a connector, noise conduction occurs, resulting in noise emission from a cable. To prevent this problem, mount the filters near the connector terminals. Connector Chip Ferrite Bead BLM Series Chip EMIFIL® NFM21C Series Through hole GND pattern (Poor example) Shield case Each EMI filter is placed far away from a connector terminal. (Impedance at high frequencies between filter's GND and case is high.) Connection with metal case is improved Through hole are added (Good example) Shield case Each EMI filter is placed close to a connector terminal. (Impedance at high frequencies between filter's GND and case is low.) 34 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. Example of Noise Suppression for Car Navigators 8 Example of effects produced when installing EMI filters on Interface Cable Ports Noise suppression effects produced when installing the EMI filter on interface cable port. Noise Level (dBμV/m) Before measure -60 -70 -80 -90 -100 -110 70 95 120 Frequency (MHz) After installing the Chip Ferrite Bead on the bus lines -60 -70 Noise Level (dBμV/m) -80 -90 -100 -110 70 95 120 Frequency (MHz) Before measure Chip Ferrite Bead Inductor BLM18AG121SN1 (120Ω typ. at 100MHz) Chip EMIFIL® NFM21CC222R1H3 (2200pF) 8 After installing the Chip Ferrite Bead on the bus lines 35 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 8 Example of Noise Suppression for Car Navigators Installing EMI filters on the Clock Lines High frequency clock signals generate high frequency noise. Noise and signal frequencies may be close to each other. Therefore, an EMI filter with high and steep attenuation is used, such as the NFW31S series (Chip EMIFIL® for signal lines) or the BLM˘˘B series (Chip Ferrite Bead for high-speed signal lines). Noise caused by transient currents is also generated on the power supply line. Therefore, a chip ferrite bead is installed, as well as a by-pass capacitor, to suppress noise on the power supply line. Installing EMI filters on Bus Lines Bus lines contain many lines that switch on and off simultaneously. Especially on data and address bus lines, an instantaneous large current flows into the GND and power supply lines. Therefore, it is necessary to suppress the current flow on the signal lines. The BLM Series (Chip Ferrite Bead) is generally used for this purpose. On the control bus line, especially at high operating speeds, the BLM˘˘B series (Chip Ferrite Bead) is used, featuring a sharp impedance rise at the specified frequency. For high noise levels, in some cases NFW31S series (Chip EMIFIL® for signal lines) is used. Chip Ferrite Bead BLM21PG300SN1 (30Ω at 100MHz) Vcc Chip EMIFIL® for signal lines NFW31SP107X1E4 (Cut-off frequency: 100MHz) CPU 30Ω Chip Ferrite Bead BLM21PG300SN1 (30Ω at 100MHz) Vcc CPU Chip Ferrite Bead BLM18AG601SN1 (600Ω at 100MHz) Address Bus Chip Ferrite Bead BLM18AG601SN1 (600Ω at 100MHz) Data Bus Chip Ferrite Bead Control Bus BLM18BD221SN1 (220Ω at 100MHz) 8 36 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 9 Example of Noise Suppression in AC Power Supplies Noise Emission Status for Switching Power Supplies In switching power supplies, noise is generated by the switching. This noise is conducted to the AC power supply cable. The cause of this noise does not meet as Mains Terminal Interference Voltage. Therefore, noise suppression is required for switching power supplies. ˙Noise from Switching Power Supplies Switching power supply Conducted noise ˙Example of Measured Noise in Switching Power Supplies Conducted Disturbance (dBμV) 120 110 100 Conducted Disturbance 90 80 70 60 50 40 30 20 0.1 1 10 100 Frequency (MHz) 9 37 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 9 Example of Noise Suppression in AC Power Supplies Noise Suppression Model for Ordinary Switching Power Supplies In switching power supplies, noise filters are installed as shown below to suppress noise conducting to the AC power supply cable. The capacitors are used as a bypass for noise, and the coils suppress noise conduction to the cable by increasing line impedance. ˙ Noise Suppression model for Switching Power Supplies Common Mode Chock Coil Hybrid Chock Coil PLA10 PLH10 L1 CL PLY10 CB1 Switching power supply CB2 Symbol L1 Name Common mode choke coil Function Suppresses common mode noise Across the line capacitor CL (X-capacitor) Suppresses differential mode noise CB1 Line bypass capacitor Suppresses common mode noise CB2 (Y-capacitor) and differential mode noise 9 38 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. Example of Noise Suppression in AC Power Supplies 9 Differential Mode Noise and Common Mode Noise Noise is classified into two types: differential mode noise and common mode noise. Differential mode noise is conducted on the two power supply lines in opposite directions to each other, as shown in Fig. (a). Common mode noise is conducted on all lines in the same direction, as shown in Fig. (b). Differential mode noise Switching power supply Power supply cable Differential mode Common mode Common mode noise Reference ground surface Switching power supply Signal source N Noise source (a) Normal mode noise (Differential mode noise) Switching power supply Signal source Noise source N Stray capacitance 9 Stray capacitance (e.x.) Reference ground surface (b) Common mode noise 39 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 9 Example of Noise Suppression in AC Power Supplies Functions of Respective Noise Filters The figures above show examples of the functions of respective noise filters used in a switching power supply. To confirm these functions, changes in the Mains Terminal Interference Voltage are broken down into differential mode and common mode noise. Figure (a) shows data obtained when no noise fitter is used. This figure reveals that both the differential mode and common mode noise are high. Figure (b) shows data obtained when an X-capacitor is used. This figure reveals that the differential mode noise is decreased. Figure (c) shows data obtained when both an X-capacitor and Y-capacitor are used. This figure reveals that both the common mode and differential mode noise are decreased. Figure (d) shows data obtained when an X-capacitor, Y-capacitor, and common mode choke coil are all used. This figure reveals that the differential mode noise is further decreased as well as the common mode one. This is because an actual common mode choke coil contains a certain amount of differential mode inductance. ˙Examples of confirming the Functions of Respective Noise Filters Conducted Disturbance (dBμV) 120 110 100 90 80 70 60 50 40 30 20 0.1 Conducted Disturbance Differential mode Component Common mode Component 1 10 100 Frequency (MHz) Conducted Disturbance (dBμV) 120 110 100 90 80 70 60 50 40 30 20 0.1 Conducted Disturbance Differential mode Component Common mode Component 1 10 100 Frequency (MHz) Conducted Disturbance (dBμV) 120 110 Conducted Disturbance Differential mode Component 100 Common mode Component 90 80 70 60 9 50 40 30 20 0.1 1 10 100 Frequency (MHz) Conducted Disturbance (dBμV) 120 110 100 90 80 70 60 50 40 30 20 0.1 Conducted Disturbance 1 10 100 Frequency (MHz) (a) No filter used (b) X-capacitor used (c) Both X-and Y-capacitor used (d) X-capacitor, Y-capacitor, and common mode choke coil all used 40 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. Example of Noise Suppression in AC Power Supplies 9 Noise Tendencies in Switching Power Supplies Newer switching power supplies tend to have a high switching frequency that generates high levels of noise. Noise is especially strong in the several hundred kHz frequency range, close to the switching frequency. The figure below shows an example of measured Mains Terminal Interference Voltage. In this example, noise of 500kHz or less frequency is strongly generated. When this noise is broken down into common mode and differential mode components, it is found that the noise consists mainly of differential mode components. Newer switching power supplies tend to strongly generate low frequency differential mode noise. Therefore, more effective methods of suppressing differential mode noise are required. ˙ Example of Resolving Noise into Differential Mode and Common Mode Components Conducted Disturbance (dBμV) 120 110 100 90 80 70 60 50 40 30 20 0.1 Conducted Disturbance Differential mode Component Common mode Component 1 10 100 Frequency (MHz) 9 41 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 9 Example of Noise Suppression in AC Power Supplies Examples of Suppression against Strong Differential Mode Noise The figures below show examples of noise suppression noise. However, increasing the X-capacitor's capacitance in inverter power supplies for lighting equipment. Since causes a problem of increased reactive current. In low frequency differential mode node is high, noise addition, increasing the Y-capacitor's capacitance causes filters are installed as shown in figures (b), (c), and (d). a problem of increased leakage current. For these Differential mode inductance is increased by adding reasons, a capacitor with very large capacitance cannot more differential mode choke coils in figure (b), adding be used. Therefore, when differential mode noise is another common mode choke coil in figure (c), and strong, it is necessary to increase differential mode increasing the size of the common mode choke coil in inductance as shown in figures (b), (c), and (d). However, figure (d). The reason why a common mode choke coil using the suppression methods shown above causes contains differential mode inductance is that magnetic problems with the increased number of components, flux caused by differential mode current does not with the mounting area, and with the cost. To solve entirely cancel out because it produces leakage flux. these problems, a choke coil with unchanged common One would think that a capacitor with a larger constant mode inductance and increased differential mode should be used for suppression against differential mode inductance is in demand. ˙Examples of Differential Mode Noise Suppression by Adding Choke Coils or Increasing Its Size (a) Noise suppression of ordinary switching power supply (b) More differential mode choke coils are installed 9 (c) Another common mode choke coil is installed (d) Size of common mode choke coil is increased 42 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. Example of Noise Suppression in AC Power Supplies 9 Reasons Why Common Mode Choke Coils Contain Mode Inductance With an ideal common mode choke coil, magnetic flux caused by common mode current is accumulated inside ˙Ideal Common Mode Choke Coil the ferrite core. Therefore, the common mode choke coil works as an inductor against common mode current. On Magnetic flux caused by common mode current is accumulated, producing impedance. the other hand, magnetic flux caused by differential mode current cancels out. Therefore, a common mode choke coil does not affect differential mode current. Common mode current Differential mode current However, since an actual common choke coil produces leakage flux, magnetic flux caused by differential mode current does not entirely cancel out. In other words, an actual common mode choke coil contains differential mode inductance as well as common mode inductance. Since magnetic flux caused by differential mode current cancels out, impedance is not produced. ˙Actual Common Mode Choke Coil Leakage flux Differential mode Since leakage flux is produced, magnetic flux caused by differential mode current does not entirely cancel out. Therefore, differential mode inductance is produced. 9 43 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 9 Example of Noise Suppression in AC Power Supplies Effective Suppression Methods against Differential Mode Noise using Hybrid Choke Coils The hybrid choke coil is available as a common mode choke coil with increased differential mode inductance. ˙PLY10 Series Hybrid Choke Coil The appearance and equivalent circuit for the PLY10 series hybrid choke coil are shown above. The devised Appearance Equivalent circuit structure allows the hybrid choke coils to have increased differential mode inductance. For example, the PLY10 series hybrid choke coil contains 3 to 5 times larger differential mode inductance as the previous common mode choke coil of the same size, while the hybrid choke coil contains common mode inductance equivalent to that of the previous common mode choke. In other words, differential mode noise can effectively be suppressed as well as common mode noise, simply by replacing the previously used common mode choke coil with the PLY10 series. This cuts the number of components and mounting area in half, compared to adding another differential mode choke coil or common mode choke coil on the circuit. ˙Advantage of Using Hybrid Choke Coils for Noise Suppression 9 44 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. Example of Noise Suppression in AC Power Supplies 9 Examples of Confirming the Effectiveness of Hybrid Choke Coils An example to confirm the effects obtained by using the PLY10 series hybrid choke coil is shown above in Fig. 1. Compared with adding an additional differential mode choke coil, using the PLY10 series suppresses Mains Terminal Interference Voltage with a smaller circuit and decreases the mounting area. (Although this example uses lighting equipment as a suppression model, the same suppression methods can be used for switching power supplies.) ˙Example of Using the PLY10 Series Hybrid Choke Coil Noise filter Active filter Inverter Fluorescent light Common Mode Choke Coil 7mH (18×16mm) Differential Mode Choke Coil 330μH (20×10mm) Hybrid choke coil PLY10AN8720R7D Fluorescent light Common 8.7mH Differential 500μH (18×16mm) Noise Level (dBμV) Noise Level (dBμV) 0.22μF (23×5mm) 0.22μF (23×5mm) 0.22μF (23×5mm) 120 110 100 90 80 70 60 50 40 30 20 0.01 0.1 1 Frequency (MHz) 10 50 0.22μF (23×5mm) (The mounting area is reduced approx. by half.) (The number of components is reduced by half or more.) 120 110 9 100 90 80 70 60 50 40 30 20 0.01 0.1 1 10 50 Frequency (MHz) 45 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 10 Example of Noise Suppression in Mobile Phones Noise Emission Status : When noise from the base band section flows into RF section, sensitivity suppression occurs, resulting in BER (Bit Error Rate) deterioration. Mobile phone base band section, typically the base band IC, controls various signals such as voice signal and LCD signal. The base band IC is a significant noise Base Band IC ANT LCD Panel TCXO source, because it operates at a high-speed and connects many data lines. If such noise flows into the RF section through the data line or power/GND line, sensitivity suppression occurs, resulting in BER (Bit Error Rate) deterioration. RF Chip Set RF Section Base Band Section 10 46 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. Example of Noise Suppression in Mobile Phones 10 Noise Suppression content in Mobile Phones To improve BER (Bit Error Rate) deterioration, it is necessary to suppress noise conduction from the base band section to the RF section. For this purpose, the EMI filter should be mounted to the noise conduction route between the base band section and the RF section. Recently, as the base band section's noise level has become higher, shielding the base band section is now also important. The following pages provide detailed description on noise suppression models for the above five items. 10 Installing EMI filters on LCD line Chip Ferrite Beads Arrays BLA31 Series Chip EMIFIL® NFA31G Series EMC Absorbers EA Series Installing EMI filters on interface section Chip Ferrite Beads BLM15 Series GHz Noise Suppression Chip Ferrite Beads BLM18HG/HD Series Common Mode Choke Coil DLP0N/11 Series or DLW21 Series Improving the Shielding Intensify the case connections, or attach the EA series EMC absorber Speaker RF Chip Set Installing EMI filters on DC Power Supply Chip Ferrite Beads BLM15 Series Chip EMIFIL® for DC Power Supply NFM21P Series ANT LCD Panel TCXO Charge IC Base Band IC DC-DC Converter Microphone Installing EMI filters on Data line Chip Ferrite Beads BLM15 Series GHz Noise Suppression Chip Ferrite Beads BLM18HG/HD Series 10 47 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. 10 Example of Noise Suppression in Mobile Phones Installing EMI filters on LCD line Because LCD's data bus and address bus are comprised of many lines that simultaneously turn on or off, a large current flows into the power/CND line instantaneously. Therefore, it is necessary to take measures for suppressing the current flow into the signal line. Typically, the BLA31 series chip ferrite bead array, and the NFA31G series chip EMIFIL® with resistance can be used for this purpose. If these components cannot be inserted, the EA series EMC absorber should be attached to the flexible cable for the LCD, to suppress noise conduction through the flexible cable. Installing EMI filters on DC Power Supply To suppress noise conduction from the base band section to the RF section through a DC power supply line, the BLM15 series chip ferrite bead should be mounted to the DC power supply line. A combination of the ferrite bead and the NFM21P series chip EMIFIL® for DC power supply lines provides an enhanced noise suppressing effect. The NFM21 P series chip EMIFIL® is a three terminal capacitor, which provides better high frequency characteristics than a two terminal capacitor. When a bypass capacitor is comprised of several two terminal capacitors with different constants, they can be replaced with a single chip EMIFIL®, which provides an advantage in mounting space. Installing EMI filters on Data Line The base band section contains many data lines. As a typical example, a SIMM data line is described here. A chip ferrite bead BLM15AG601SN1 is mounted to the SIMM data line to suppress noise conduction. Since the SIMM data line operates at a relatively low speed, a chip ferrite bead with large impedance can be used. However, if a chip ferrite bead with large impedance is 10 used for a high-speed data transmission line, it will adversely affect the transmission signal waveform, resulting in waveform deformation, rounding or operation failure. To prevent these problems, the BLM15BB/BD series ferrite bead for signal lines, which has little influence on the signal waveform, should be used for high-speed signal lines. TCXO Chip Ferrite Bead Arrays BLA31BD221SN4 (220Ω at 100MHz) LCD Panel LCD Driver IC RF Chip Set Base Band IC Base Band IC DC-DC Converter Vcc Chip EMIFIL® NFM21PC104R1E3 (0.1μF) Chip Ferrite Bead BLM15AG121SN1 (120Ω at 100MHz) Base Band IC SIMM Connector Chip Ferrite Bead BLM15AG601SN1 (600Ω at 100MHz) 48 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering. Example of Noise Suppression in Mobile Phones 10 Installing EMI filters on interface section If noise flows through an interface cable, noise emitted from the cable is diffracted and flows into the antenna, causing BER deterioration. To suppress noise conduction through the interface cable, the BLM15 series chip ferrite bead should be mounted between the base band IC and the cable connector. For mobile phones with high communication frequency (e.g. PDC1.5, DCS, PCS), using the DLP0N/11 or DLW21 series common mode choke coil, which provides high impedance in this frequency range, offers more excellent noise suppressing effect. For noise suppression in interfaces, immunity test and transmission wave diffraction preventive measures are required. Therefore, it is necessary to select the optimum EMI filters according to the intended purpose and frequency band. Improving the Shielding Generally, the mobile phone resin case is shielded by conductive plating. As mobile phones have become more functional, the noise level from the base band section has been increased. Therefore, it is important to shield the base band Section, as well as the RF section. Mobile phones should be designed to make the contact surface of the case as large as possible, and to reduce high frequency impedance. Shielding the base band section partially with a metal case or attaching the EMC absorber to the shield contact surface can also intensify the shielding condition. Base Band IC Chip Ferrite Bead BLM15AG601SN1 (600Ω at 100MHz) LCD Panel Base Band IC RF Chip Set Resin Case Conductive Plating Apply conductive plating to the case so that the contact surface between the upper and lower parts of the case becomes as large as possible. If this is impossible, shield the PCB partially with a metal case, or attach the EMC absorber to the contact surface of the case. EMC Absorbers EA2100A050 10 49 C35E.pdf September.5,2013 Note • Please read rating and CAUTION (for storage and operating, rating, soldering and mounting, handling) in this catalog to prevent smoking and/or burning, etc. • This catalog has only typical specifications. Therefore, please approve our product specifications or transact the approval sheet for product specifications before ordering.

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