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AOZ1010 EZBuck™ 2A Simple Regulator General Description The AOZ1010 is a high efficiency, simple to use, 2A buck regulator. The AOZ1010 works from a 4.5V to 16V input voltage range, and provides up to 2A of continuous output current with an output voltage adjustable down to 0.8V. The AOZ1010 comes in an SO-8 package and is rated over a -40°C to +85°C ambient temperature range. Features ● 4.5V to 16V operating input voltage range ● 130mΩ internal PFET switch for high efficiency: up to 95% ● Internal Schottky diode ● Internal soft start ● Output voltage adjustable to 0.8V ● 2A continuous output current ● Fixed 500kHz PWM operation ● Cycle-by-cycle current limit ● Short-circuit protection ● Thermal shutdown ● Small size SO-8 package Applications ● Point of load DC/DC conversion ● PCIe graphics cards ● Set top boxes ● DVD drives and HDD ● LCD panels ● Cable modems ● Telecom/networking/datacom equipment Typical Application C1 Cd 22µF Ceramic VIN L1 3.3µH EN VOUT AOZ1010 LX COMP R1 RC FB C2, C3 22µF Ceramic CC AGND PGND R2 Rev. 1.0 November 2006 Figure 1. 3.3V/2A Buck Regulator www.aosmd.com Page 1 of 14 AOZ1010 Ordering Information Part Number Ambient Temperature Range Package Environmental AOZ1010AI -40°C to +85°C SO-8 RoHS All AOS Products are offering in packaging with Pb-free plating and compliant to RoHS standards. RCooHmSpliant Please visit wwww.aosmd.com/web/rohs_compliant.jsp for additional information. Pin Configuration PGND 1 VIN 2 AGND 3 FB 4 SO-8 (Top View) 8 LX 7 LX 6 EN 5 COMP Pin Description Pin Number Pin Name 1 PGND 2 VIN 3 AGND 4 FB 5 COMP 6 EN 7, 8 LX Pin Function Power ground. Electrically needs to be connected to AGND. Supply voltage input. When VIN rises above the UVLO threshold the device starts up. Reference connection for controller section. Also used as thermal connection for controller section. Electrically needs to be connected to PGND. The FB pin is used to determine the output voltage via a resistor divider between the output and GND. External loop compensation pin. The enable pin is active high. Connect EN pin to VIN if not used. Do not leave the EN pin floating. PWM output connection to inductor. Thermal connection for output stage. Block Diagram VIN EN UVLO 5V LDO Internal OTP & POR Regulator +5V Reference & Bias Softstart 0.8V FB + EAmp – + – PWM Comp + ILimit PWM Control Logic + ISen – Level Shifter + FET Driver COMP Rev. 1.0 November 2006 500kHz Oscillator AGND www.aosmd.com Q1 LX LX D1 PGND Page 2 of 14 11 2 Absolute Maximum Ratings Exceeding the Absolute Maximum ratings may damage the device. Parameter Rating Supply Voltage (VIN) LX to AGND EN to AGND FB to AGND COMP to AGND PGND to AGND Junction Temperature (TJ) Storage Temperature (TS) 18V -0.7V to VIN+0.3V -0.3V to VIN+0.3V -0.3V to 6V -0.3V to 6V -0.3V to +0.3V +150°C -65°C to +150°C µ AOZ1010 Recommend Operating Ratings The device is not guaranteed to operate beyond the Maximum Operating Ratings. Parameter Rating Supply Voltage (VIN) Output Voltage Range 4.5V to 16V 0.8V to VIN Ambient Temperature (TA) -40°C to +85°C Package Thermal Resistance SO-8 (ΘJA)(1) 87°C/W Note: 1. The value of ΘJA is measured with the device mounted on 1-in2 FR-4 board with 2oz. Copper, in a still air environment with TA = 25°C. The value in any given application depends on the user's specific board design. Electrical Characteristics TA = 25°C, VIN = VEN = 12V, VOUT = 3.3V unless otherwise specified(2) Symbol Parameter Conditions Min. Typ. Max. Units VIN VUVLO IIN IOFF VFB Supply Voltage Input Under-Voltage Lockout Threshold Supply Current (Quiescent) Shutdown Supply Current Feedback Voltage Load Regulation VIN Rising VIN Falling IOUT = 0, VFB = 1.2V, VEN > 1.2V VEN = 0V 4.5 0.782 4.00 3.70 2 3 0.8 0.5 16 3 20 0.818 Line Regulation 1 IFB Feedback Voltage Input Current VEN EN Input Threshold Off Threshold On Threshold 200 0.6 2.0 VHYS EN Input Hysteresis 100 MODULATOR fO DMAX DMIN Frequency Maximum Duty Cycle Minimum Duty Cycle Error Amplifier Voltage Gain 350 500 600 100 6 500 Error Amplifier Transconductance 200 PROTECTION ILIM Current Limit Over-Temperature Shutdown Limit tSS Soft Start Interval OUTPUT STAGE TJ Rising TJ Falling 2.5 3.6 145 100 4 High-Side Switch On-Resistance VIN = 12V VIN = 5V 97 130 166 200 Note: 2. Specification in BOLD indicate an ambient temperature range of -40°C to +85°C. These specifications are guaranteed by design. V V mA µA V % % nA V mV kHz % % V/ V µA / V A °C ms mΩ Rev. 1.0 November 2006 www.aosmd.com Page 3 of 14 AOZ1010 Typical Performance Characteristics Circuit of Figure 1. TA = 25°C, VIN = VEN = 12V, VOUT = 3.3V unless otherwise specified. Light Load (DCM) Operation Vin ripple 0.1V/div Vo ripple 20mV/div IL 1A/div Full Load (CCM) Operation VLX 10V/div 1µs/div 1µs/div Startup to Full Load Vin 5V/div Vo 1V/div Full Load to Turnoff Iin 0.5A/div 1ms/div 50% to 100% Load Transient 1ms/div Light Load to Turnoff Vin ripple 0.1V/div Vo ripple 20mV/div IL 1A/div VLX 10V/div Vin 5V/div Vo 1V/div Iin 0.5A/div 100µs/div Vo Ripple 50mV/div Io 1A/div 1s/div Vin 5V/div Vo 1V/div Iin 0.5A/div Rev. 1.0 November 2006 www.aosmd.com Page 4 of 14 Typical Performance Characteristics (Continued) Circuit of Figure 1. TA = 25°C, VIN = VEN = 12V, VOUT = 3.3V unless otherwise specified. Short Circuit Protection Short Circuit Recovery Vo 2V/div IL 1A/div AOZ1010 Vo 2V/div IL 1A/div 100µs/div 1ms/div Efficieny (%) AOZ1010AI Efficiency Efficiency (VIN = 12V) vs. Load Current 100 8.0V OUTPUT 95 90 5.0V OUTPUT 3.3V OUTPUT 85 80 75 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Load Current (A) Thermal de-rating curves for SO-8 package part under typical input and output condition based on the evaluation board. 25°C ambient temperature and natural convection (air speed < 50LFM) unless otherwise specified. Derating Curve at 5V Input Derating Curve at 12V Input 2.5 2.5 3.3V, 5.0V OUTPUT 8.0V OUTPUT 2.0 2.0 1.8V OUTPUT 5.0V OUTPUT 1.5 1.5 3.3V OUTPUT 1.8V OUTPUT 1.0 1.0 0.5 0.5 0 25 35 45 55 65 75 85 Ambient Temperature (TA) 0 25 35 45 55 65 75 85 Ambient Temperature (TA) Rev. 1.0 November 2006 www.aosmd.com Page 5 of 14 Output Current (IO) Output Current (IO) AOZ1010 Detailed Description The AOZ1010 is a current-mode step down regulator with integrated high side PMOS switch and a low side freewheeling Schottky diode. It operates from a 4.5V to 16V input voltage range and supplies up to 2A of load current. The duty cycle can be adjusted from 6% to 100% allowing a wide range of output voltage. Features include enable control, Power-On Reset, input under voltage lockout, fixed internal soft-start and thermal shut down. The AOZ1010 is available in SO-8 package. Enable and Soft Start The AOZ1010 has internal soft start feature to limit in-rush current and ensure the output voltage ramps up smoothly to regulation voltage. A soft start process begins when the input voltage rises to 4.0V and voltage on EN pin is HIGH. In soft start process, the output voltage is ramped to regulation voltage in typically 4ms. The 4ms soft start time is set internally. The EN pin of the AOZ1010 is active high. Connect the EN pin to VIN if enable function is not used. Pulling EN to ground will disable the AOZ1010. Do not leave it open. The voltage on EN pin must be above 2.0V to enable the AOZ1010. When voltage on EN pin falls below 0.6V, the AOZ1010 is disabled. If an application circuit requires the AOZ1010 to be disabled, an open drain or open collector circuit should be used to interface to EN pin. Steady-State Operation Under steady-state conditions, the converter operates in fixed frequency and Continuous-Conduction Mode (CCM). The AOZ1010 integrates an internal P-MOSFET as the high-side switch. Inductor current is sensed by amplifying the voltage drop across the drain to source of the high side power MOSFET. Output voltage is divided down by the external voltage divider at the FB pin. The difference of the FB pin voltage and reference is amplified by the internal transconductance error amplifier. The error voltage, which shows on the COMP pin, is compared against the current signal, which is sum of inductor current signal and ramp compensation signal, at PWM comparator input. If the current signal is less than the error voltage, the internal high-side switch is on. The inductor current flows from the input through the inductor to the output. When the current signal exceeds the error voltage, the high-side switch is off. The inductor current is freewheeling through the internal Schottky diode to output. The AOZ1010 uses a P-Channel MOSFET as the high side switch. It saves the bootstrap capacitor normally seen in a circuit which is using an NMOS switch. It allows 100% turn-on of the upper switch to achieve linear regulation mode of operation. The minimum voltage drop from VIN to VO is the load current times DC resistance of MOSFET plus DC resistance of buck inductor. It can be calculated by equation below: V O_MAX = V IN – I O × (R DS(ON ) + R inductor ) where; VO_MAX is the maximum output voltage, VIN is the input voltage from 4.5V to 16V, IO is the output current from 0A to 2A, RDS(ON) is the on resistance of internal MOSFET, the value is between 97mΩ and 200mΩ depending on input voltage and junction temperature, and Rinductor is the inductor DC resistance. Switching Frequency The AOZ1010 switching frequency is fixed and set by an internal oscillator. The actual switching frequency could range from 350kHz to 600kHz due to device variation. Output Voltage Programming Output voltage can be set by feeding back the output to the FB pin with a resistor divider network. In the application circuit shown in Figure 1. The resistor divider network includes R2 and R3. Usually, a design is started by picking a fixed R3 value and calculating the required R2 with equation below: VO = 0.8 ×  1 + -R----1--  R2 Some standard values of R1 and R2 for the most commonly used output voltage values are listed in Table 1. Table 1. VO (V) 0.8 1.2 1.5 1.8 2.5 3.3 5.0 R1 (kΩ) 1.0 4.99 10 12.7 21.5 31.6 52.3 R2 (kΩ) Open 10 11.5 10.2 10 10 10 Rev. 1.0 November 2006 www.aosmd.com Page 6 of 14 AOZ1010 The combination of R1 and R2 should be large enough to avoid drawing excessive current from the output, which will cause power loss. Since the switch duty cycle can be as high as 100%, the maximum output voltage can be set as high as the input voltage minus the voltage drop on upper PMOS and inductor. Protection Features The AOZ1010 has multiple protection features to prevent system circuit damage under abnormal conditions. Over Current Protection (OCP) The sensed inductor current signal is also used for over current protection. Since the AOZ1010 employs peak current mode control, the COMP pin voltage is proportional to the peak inductor current. The COMP pin voltage is limited to be between 0.4V and 2.5V internally. The peak inductor current is automatically limited cycle by cycle. The cycle by cycle current limit threshold is set between 2.5A and 3.6A. When the load current reaches the current limit threshold, the cycle by cycle current limit circuit turns off the high side switch immediately to terminate the current duty cycle. The inductor current stops rising. The cycle by cycle current limit protection directly limits inductor peak current. The average inductor current is also limited due to the limitation on peak inductor current. When the cycle by cycle current limit circuit is triggered, the output voltage drops as the duty cycle is decreasing. The AOZ1010 has internal short circuit protection to protect itself from catastrophic failure under output short circuit conditions. The FB pin voltage is proportional to the output voltage. Whenever FB pin voltage is below 0.2V, the short circuit protection circuit is triggered. As a result, the converter is shut down and hiccups at a frequency equal to 1/8 of normal switching frequency. The converter will start up via a soft start once the short circuit condition disappears. In short circuit protection mode, the inductor average current is greatly reduced because of the low hiccup frequency. Power-On Reset (POR) A power-on reset circuit monitors the input voltage. When the input voltage exceeds 4V, the converter starts operation. When input voltage falls below 3.7V, the converter will stop switching. Thermal Protection An internal temperature sensor monitors the junction temperature. It shuts down the internal control circuit and high side PMOS if the junction temperature exceeds 145°C. The regulator will restart automatically under the control of soft-start circuit when the junction temperature decreases to 100°C. Application Information The basic AOZ1010 application circuit is shown in Figure 1. Component selection is explained below. Input Capacitor The input capacitor (C1 in Figure 1), must be connected to the VIN pin and PGND pin of the AOZ1010 to maintain steady input voltage and filter out the pulsing input current. A small decoupling capacitor (Cd in Figure 1), usually 1µF, should be connected to the VIN pin and AGND pin for stable operation of the AOZ1010. The voltage rating of input capacitor must be greater than maximum input voltage plus ripple voltage. The input ripple voltage can be approximated by the equation below: ∆V IN = -f---×---I--OC-----I--N-- ×  1  – -V-----O---- V IN × -V-----O---V IN Since the input current is discontinuous in a buck converter, the current stress on the input capacitor is another concern when selecting the capacitor. For a buck circuit, the RMS value of input capacitor current can be calculated by: I CIN _RMS = I O × -V-----O----  1 – -V-----O---- V IN  V IN If let m equal the conversion ratio: -V-----O---- = m V IN The relationship between the input capacitor RMS cur- rent and voltage conversion ratio is calculated and shown in Figure 2 on the next page. It can be seen that when VO is half of VIN, CIN is under the worst current stress. The worst current stress on CIN is 0.5 x IO. Rev. 1.0 November 2006 www.aosmd.com Page 7 of 14 AOZ1010 0.5 0.4 ICIN_RMS(m) 0.3 IO 0.2 0.1 0 0 0.5 1 m Figure 2. ICIN vs. Voltage Conversion Ratio For reliable operation and best performance, the input capacitors must have current rating higher than ICIN_RMS at the worst operating conditions. Ceramic capacitors are preferred for input capacitors because of their low ESR and high ripple current rating. Depending on the application circuits, other low ESR tantalum capacitors or aluminum electrolytic capacitors may also be used. When selecting ceramic capacitors, X5R or X7R type dielectric ceramic capacitors are preferred for their better temperature and voltage characteristics. Note that the ripple current rating from capacitor manufacturers is based on certain amount of life time. Further de-rating may be necessary for practical design requirement. Inductor The inductor is used to supply constant current to the output when it is driven by a switching voltage. For a given input and output voltage, inductance and switching frequency together decide the inductor ripple current, which is: ∆IL = --V-----O---f ×L ×  1  – -V-----O---- V IN The peak inductor current is: ILpeak = IO + ∆-----I--L2 High inductance gives low inductor ripple current but requires a larger size inductor to avoid saturation. Low ripple current reduces inductor core losses. Low ripple current also reduces RMS current through the inductor and switches, which results in less conduction loss. When selecting the inductor, make sure it is able to handle the peak current at the highest operating temperature without saturation. The inductor takes the highest current in a buck circuit. The conduction loss on the inductor needs to be checked for thermal and efficiency requirements. Surface mount inductors in different shape and styles are available from Coilcraft, Elytone and Murata. Shielded inductors are small and radiate less EMI noise, but they cost more than unshielded inductors. The choice depends on EMI requirement, price and size. Table 2 lists some inductors for typical output voltage design. Table 2. Typical Inductors VOUT 5.0V 3.3V 1.8V L1 Unshielded, 4.7µH, LQH55DN4R7M03 Shielded, 4.7µH, LQH66SN4R7M03 Shielded, 5.8µH, ET553-5R8 Unshielded, 6.7µH, DO3316P-682MLD Unshielded, 4.7µH, LQH55DN3R3M03 Shielded, 4.7µH, LQH66SN3R3M03 Shielded, 3.3µH, ET553-3R3 Unshielded, 4.7µH, DO3316P-472MLD Unshielded, 4.7µH, DO1813P-472HC Unshielded, 2.2µH, LQH55DN1R5M03 Shielded, 2.2µH, LQH66SN1R5M03 Shielded, 2.2µH, ET553-2R2 Unshielded, 2.2µH, DO3316P-222MLD Unshielded, 2.2µH, DO1813P-222HC Manufacture MURATA MURATA ELYTONE Coilcraft MURATA MURATA ELYTONE Coilcraft Coilcraft MURATA MURATA ELYTONE Coilcraft Coilcraft Rev. 1.0 November 2006 www.aosmd.com Page 8 of 14 AOZ1010 Output Capacitor The output capacitor is selected based on the DC output voltage rating, output ripple voltage specification, and ripple current rating. The selected output capacitor must have a higher rated voltage specification than the maximum desired output voltage including ripple. De-rating needs to be considered for long term reliability. Output ripple voltage specification is another important factor for selecting the output capacitor. In a buck converter circuit, output ripple voltage is determined by inductor value, switching frequency, output capacitor value and ESR. It can be calculated by the equation below: ∆V O = ∆I L ×   ES R C O + 8-----×-----f---1-×-----C-----O-- where, CO is output capacitor value, and ESRCO is the equivalent series resistance of the output capacitor. When low ESR ceramic capacitor is used as output capacitor, the impedance of the capacitor at the switching frequency dominates. Output ripple is mainly caused by capacitor value and inductor ripple current. The output ripple voltage calculation can be simplified to: ∆V O = ∆I L × 1 8-----×-----f----×-----C-----O-- If the impedance of ESR at switching frequency dominates, the output ripple voltage is mainly decided by capacitor ESR and inductor ripple current. The output ripple voltage calculation can be further simplified to: ∆V O = ∆IL × ESRCO For lower output ripple voltage across the entire operating temperature range, X5R or X7R dielectric type of ceramic, or other low ESR tantalum capacitor or aluminum electrolytic capacitor may also be used as output capacitors. In a buck converter, output capacitor current is continuous. The RMS current of output capacitor is decided by the peak to peak inductor ripple current. It can be calculated by: I CO_RMS = -∆----I---L-12 Usually, the ripple current rating of the output capacitor is a smaller issue because of the low current stress. When the buck inductor is selected to be very small and inductor ripple current is high, output capacitor could be overstressed. Loop Compensation The AOZ1010 employs peak current mode control for easy use and fast transient response. Peak current mode control eliminates the double pole effect of the output L&C filter. It greatly simplifies the compensation loop design. With peak current mode control, the buck power stage can be simplified to be a one-pole and one-zero system in frequency domain. The pole is dominant pole and can be calculated by: f P1 = 1 -2---π-----×-----C-----O-----×-----R-----L- The zero is a ESR zero due to output capacitor and its ESR. It is can be calculated by: fZ1 = 1 -2---π-----×-----C-----O-----×-----E----S-----R-----C----O-- where; CO is the output filter capacitor, RL is load resistor value, and ESRCO is the equivalent series resistance of output capacitor. The compensation design is actually to shape the converter close loop transfer function to get desired gain and phase. Several different types of compensation networks can be used for AOZ1010. For most cases, a series capacitor and resistor network connected to the COMP pin sets the pole-zero and is adequate for a stable high-bandwidth control loop. In the AOZ1010, FB pin and COMP pin are the inverting input and the output of internal transconductance error amplifier. A series R and C compensation network connected to COMP provides one pole and one zero. The pole is: f P 2 = -2---π-----×-----C--G---C--E---×-A----G-----V---E----A-- where; GEA is the error amplifier transconductance, which is 200 x 10-6 A/V, GVEA is the error amplifier voltage gain, which is 500 V/V, and CC is compensation capacitor. Rev. 1.0 November 2006 www.aosmd.com Page 9 of 14 AOZ1010 The zero given by the external compensation network, capacitor CC (C5 in Figure 1), and resistor RC (R1 in Figure 1), is located at: fZ2 = 1 -----------------------------------2π × CC × RC To design the compensation circuit, a target crossover frequency fC for close loop must be selected. The system crossover frequency is where control loop has unity gain. The crossover frequency is also called the converter bandwidth. Generally a higher bandwidth means faster response to load transient. However, the bandwidth should not be too high because of system stability concerns. When designing the compensation loop, converter stability under all line and load condition must be considered. Usually, it is recommended to set the bandwidth to be less than 1/10 of switching frequency. The AOZ1010 operates at a fixed switching frequency range from 350kHz to 600kHz. The recommended crossover frequency is less than 30kHz. f C = 30kHz The strategy for choosing RC and CC is to set the cross over frequency with RC and set the compensator zero with CC. Using selected crossover frequency, fC, to calculate RC: RC = f C × --V-----O---V FB × G-----2-E--π-A----×-×----C-G----O-C----S- where; fC is the desired crossover frequency, VFB is 0.8V, GEA is the error amplifier transconductance, which is 200 x 10-6 A/V, and GCS is the current sense circuit transconductance, which is 5.64 A/V. The compensation capacitor CC and resistor RC together make a zero. This zero is put somewhere close to the dominate pole, fP1, but lower than 1/5 of the selected crossover frequency. CC can is selected by: CC = 1.5 -2---π-----×-----R-----C-----×-----f---P---1-- The previous equation can also be simplified to: CC = C-----O------×-----R-----LRC An easy-to-use application software which helps to design and simulate the compensation loop can be found at www.aosmd.com. Table 3 lists the values for a typical output voltage design when output is 44µF ceramics capacitor. Table 3. VOUT 1.8V 3.3V 5V 8V L1 2.2µH 3.3µH 4.7µH 10µH RC 20kΩ 31.6kΩ 49.9kΩ 80.6kΩ CC 1.5nF 1.0nF 1.0nF 0.82nF Thermal Management and Layout Consideration In the AOZ1010 buck regulator circuit, high pulsing current flows through two circuit loops. The first loop starts from the input capacitors, to the VIN pin, to the LX pins, to the filter inductor, to the output capacitor and load, and then returns to the input capacitor through ground. Current flows in the first loop when the high side switch is on. The second loop starts from the inductor, to the output capacitors and load, to the PGND pin of the AOZ1010, and to the LX pins of the AZO1010. Current flows in the second loop when the low side diode is on. In PCB layout, minimizing the two loops area reduces the noise of this circuit and improves efficiency. A ground plane is recommended to connect input capacitor, output capacitor, and PGND pin of the AOZ1010. In the AOZ1010 buck regulator circuit, the two major power dissipating components are the AOZ1010 and output inductor. The total power dissipation of converter circuit can be measured by input power minus output power. P total _loss = V IN × I IN – V O × I O The power dissipation of inductor can be approximately calculated by output current and DCR of inductor. P inductor _loss = IO2 × R inductor × 1.1 Rev. 1.0 November 2006 www.aosmd.com Page 10 of 14 AOZ1010 The junction to ambient temperature can be got from power dissipation in the AOZ1010 and thermal impedance from junction to ambient. T (jun-amb) = (Ptotalloss–Pinductorloss) × ΘJA The maximum junction temperature of AOZ1010 is 145°C, which limits the maximum load current capability. Please see the thermal de-rating curves for the maximum load current of the AOZ1010 under different ambient temperatures. The thermal performance of the AOZ1010 is strongly affected by the PCB layout. Extra care should be taken by users during the design process to ensure that the IC will operate under the recommended environmental conditions. Several layout tips are listed below for the best electric and thermal performance. Figure 3 below illustrates a single layer PCB layout example as a reference. 1. Do not use thermal relief connection to the VIN and the PGND pin. Pour a maximized copper area to the PGND pin and the VIN pin to help thermal dissipation. 2. Input capacitor should be connected to the VIN pin and the PGND pin as close as possible. 3. A ground plane is preferred. If a ground plane is not used, separate PGND from AGND and connect them only at one point to avoid the PGND pin noise coupling to the AGND pin. In this case, a decoupling capacitor should be connected between VIN pin and AGND pin. 4. Make the current trace from LX pins to L to Co to the PGND as short as possible. 5. Pour copper plane on all unused board area and connect it to stable DC nodes, like VIN, GND, or VOUT. 6. The two LX pins are connected to the internal PFET drain. They are low resistance thermal conduction path and most noisy switching node. Connect a copper plane to the LX pin to help thermal dissipation. This copper plane should not be too large otherwise switching noise may be coupled to other parts of the circuit. 7. Keep sensitive signal traces such as trace connecting FB pin and COMP pin away from the LX pins. Cin PGND 1 8 VIN 2 SO-8 7 Cd AGND 3 6 R2 FB 4 5 R1 Cc Rc LX Cout LX L EN COMP Figure 3. AOZ1010 PCB Layout Rev. 1.0 November 2006 www.aosmd.com Page 11 of 14 Package Dimensions, SO-8L D e 8 E E1 1 7° (4x) 0.1 b A2 A A1 AOZ1010 Gauge Plane Seating Plane 0.25 L h x 45° C θ 2.20 1.27 Unit: mm 5.74 0.80 Dimensions in millimeters Symbols A A1 A2 b c D E1 e E h L θ Min. Nom. Max. 1.35 1.65 1.75 0.10 — 0.25 1.25 1.50 1.65 0.31 — 0.51 0.17 — 0.25 4.80 4.90 5.00 3.80 3.90 4.00 1.27 BSC 5.80 6.00 6.20 0.25 — 0.50 0.40 — 1.27 0° — 8° Dimensions in inches Symbols A A1 A2 b c D E1 e E h L θ Min. Nom. Max. 0.053 0.065 0.069 0.004 — 0.010 0.049 0.059 0.065 0.012 — 0.020 0.007 — 0.010 0.189 0.193 0.197 0.150 0.154 0.157 0.050 BSC 0.228 0.236 0.244 0.010 — 0.020 0.016 — 0.050 0° — 8° Notes: 1. All dimensions are in millimeters. 2. Dimensions are inclusive of plating 3. Package body sizes exclude mold flash and gate burrs. Mold flash at the non-lead sides should be less than 6 mils. 4. Dimension L is measured in gauge plane. 5. Controlling dimension is millimeter, converted inch dimensions are not necessarily exact. Rev. 1.0 November 2006 www.aosmd.com Page 12 of 14 Tape and Reel Dimensions SO-8 Carrier Tape D1 T See Note 5 P1 P2 See Note 3 E1 E2 E K0 Unit: mm Package SO-8 (12mm) A0 6.40 ±0.10 B0 B0 5.20 ±0.10 K0 2.10 ±0.10 D0 1.60 ±0.10 A0 D1 1.50 ±0.10 D0 P0 E E1 12.00 1.75 ±0.10 ±0.10 E2 5.50 ±0.10 P0 8.00 ±0.10 See Note 3 Feeding Direction P1 4.00 ±0.10 P2 2.00 ±0.10 T 0.25 ±0.10 SO-8 Reel W1 G M N V S K R H W Tape Size Reel Size M N W W1 H K S G R V 12mm ø330 ø330.00 ø97.00 13.00 17.40 ø13.00 10.60 2.00 — — — ±0.50 ±0.10 ±0.30 ±1.00 +0.50/-0.20 ±0.50 SO-8 Tape Leader/Trailer & Orientation Trailer Tape 300mm min. or 75 empty pockets Components Tape Orientation in Pocket Leader Tape 500mm min. or 125 empty pockets AOZ1010 Rev. 1.0 November 2006 www.aosmd.com Page 13 of 14 AOZ1010 Package Marking AOZ1010 Z1010AI FAYWLT Part Number Code Fab & Assembly Location Assembly Lot Code Year & Week Code Rev. 1.0 November 2006 www.aosmd.com Page 14 of 14

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