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MAX629 19-1219; Rev 1; 6/97 EVALUAATVIOANILKAIBTLMEANUAL 28V, Low-Power, High-Voltage, Boost or Inverting DC-DC Converter _______________General Description The MAX629 low-power DC-DC converter features an internal N-channel MOSFET switch and programmable current limiting. It is designed to supply positive or negative bias voltages up to ±28V from input voltages in the 0.8V to VOUT range, and can be configured for boost, flyback, and SEPIC topologies. The MAX629’s current-limited pulse-frequency-modulation (PFM) control scheme provides high efficiency over a wide range of load conditions. An internal, 0.5A Nchannel MOSFET switch reduces the total part count, and a high switching frequency (up to 300kHz) allows for tiny surface-mount magnetics. The MAX629’s combination of low supply current, logiccontrolled shutdown, small package, and tiny external components makes it an extremely compact and efficient high-voltage biasing solution that’s ideal for battery-powered applications. The MAX629 is available in an 8-pin SO package. ________________________Applications Positive or Negative LCD Bias Generators High-Efficiency DC-DC Boost Converters Varactor Tuning Diode Bias Palmtop Computers 2-Cell and 3-Cell Battery-Powered Applications ____________________________Features o Internal, 500mA, 28V N-Channel Switch (No External FET Required) o Generates Positive or Negative Output Voltages o 80µA Supply Current o 1µA Max Shutdown Current o Up to 300kHz Switching Frequency o Adjustable Current Limit Allows Use of Small, Inexpensive Inductors o 8-Pin SO Package ______________Ordering Information PART MAX629C/D MAX629ESA TEMP. RANGE 0°C to +70°C -40°C to +85°C PIN-PACKAGE Dice* 8 SO *Dice are tested at TA = +25°C, DC parameters only. Note: To order tape-and-reel shipping, add “-T” to the end of the part number. Pin Configuration appears at end of data sheet. ___________________________________________________Typical Operating Circuit VIN +2.7V TO +5.5V VCC SHDN LX ISET POL FB MAX629 REF GND VIN +2.7V TO +5.5V VOUT 28V VCC SHDN LX ISET POL MAX629 FB REF GND -VOUT -28V POSITIVE OUTPUT VOLTAGE NEGATIVE OUTPUT VOLTAGE ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800 MAX629 28V, Low-Power, High-Voltage, Boost or Inverting DC-DC Converter ABSOLUTE MAXIMUM RATINGS Supply Voltage (VCC to GND) ..................................-0.3V to +6V SHDN to GND...........................................................-0.3V to +6V ISET, REF, FB, POL to GND .......................-0.3V to (VCC + 0.3V) LX to GND ..............................................................-0.3V to +30V Continuous Power Dissipation (TA = +70°C) SO (derate 5.88mW/°C above +70°C) ..........................471mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +165°C Lead Temperature (soldering, 10sec) .............................+300°C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VCC = +5V, CREF = 0.1µF, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note1) PARAMETER VCC Input Voltage (Note 2) VCC Supply Current VCC Shutdown Current VCC Undervoltage Lockout Input Supply Voltage (Note 2) SHDN, POL, ISET Logic Levels Positive Output Voltage Negative Output Voltage LX Switch-Current Limit LX On-Resistance LX Leakage Current Maximum LX On-Time Minimum LX Off-Time FB Set Point FB Input Bias Current REF Output Voltage CONDITIONS VFB = 1.3V SHDN = GND 100mV hysteresis Voltage applied to L1 (VIN) VIH VIL Circuit of Figure 2 Circuit of Figure 3 ISET = VCC ISET = GND VCC = 5V VCC = 3.3V VLX = 28V, TA = +85°C POL = GND POL = VCC POL = GND, VFB < 1V POL = VCC, VFB > 0.25V POL = GND (positive output) POL = VCC (negative output) TA = 0°C to +85°C TA = -40°C to +85°C TA = 0°C to +85°C TA = -40°C to +85°C VCC = 2.7V to 5.5V, no load on REF TA = 0°C to +85°C TA = -40°C to +85°C MIN 2.7 2.3 0.8 2.4 -VIN 0.39 0.20 6.5 0.7 2.0 3.0 3.0 1.225 1.218 -15 -25 1.225 1.218 TYP 80 0.04 2.5 0.45 0.25 0.6 0.7 0.05 8.5 1.0 3.2 4.5 4.5 1.250 0 5 1.250 MAX 5.5 120 1 2.65 VOUT UNITS V µA µA V V V 0.4 28 V -28 V 0.51 A 0.33 1.2 Ω 1.4 2.5 µA 10.0 µs 1.3 3.8 µs 6.0 6.0 1.275 V 1.282 15 mV 25 50 nA 1.275 V 1.282 2 _______________________________________________________________________________________ 28V, Low-Power, High-Voltage, Boost or Inverting DC-DC Converter MAX629 ELECTRICAL CHARACTERISTICS (continued) (VCC = +5V, CREF = 0.1µF, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER REF Load Regulation Line Regulation Load Regulation Thermal Shutdown Threshold CONDITIONS MIN IREF = 0µA to 100µA, CREF = 0.47µF (Note 3) Circuit of Figure 2, VOUT = 24V, VCC = 3V to 5.5V, ILOAD = 5mA Circuit of Figure 2, VOUT = 24V, VCC = 5V, ILOAD = 0mA to 5mA Die temperature TYP 10 0.2 0.15 150 MAX 25 UNITS mV %/V % °C Note 1: Specifications to -40°C are guaranteed by design and not production tested. Note 2: The IC itself requires a supply voltage between +2.7V and +5.5V; however, the voltage that supplies power to the inductor can vary from 0.8V to 28V, depending on circuit operating conditions. Note 3: For reference currents less than 10µA, a 0.1µF reference-bypass capacitor is adequate. MAX629-03 __________________________________________Typical Operating Characteristics (SHDN = VCC , CREF = 0.1µF, TA = +25°C, unless otherwise noted.) EFFICIENCY (%) EFFICIENCY vs. LOAD CURRENT (VOUT = +24V) 100 VOUT = 24V 95 A: VIN = 12V, ISET = VCC B: VIN = 12V, ISET = GND 90 C: VIN = 5V, ISET = VCC A B 85 C 80 D 75 E, F 70 65 60 0.1 D: VIN = 5V, ISET = GND E: VIN = 3V, ISET = VCC F: VIN = 3V, ISET = GND 1 10 100 LOAD CURRENT (mA) MAX629-01 EFFICIENCY (%) EFFICIENCY vs. LOAD CURRENT (VOUT = +12V) 100 95 A 90 B 85 C 80 75 70 65 60 0.1 VOUT = 12V, ISET = VCC or GND A: VIN = 9V B: VIN = 5V C: VIN = 3V 1 10 100 LOAD CURRENT (mA) MAX629-02 MAXIMUM LOAD CURRENT (mA) MAXIMUM LOAD CURRENT vs. INPUT VOLTAGE (VOUT = +24V, +12V) 300 A: VOUT = 12V, ISET = VCC A 250 B: VOUT = 12V, ISET = GND 200 C: VOUT =24V, ISET = VCC D: VOUT = 24V, C 150 ISET = GND B 100 D 50 0 0 4 8 12 16 20 INPUT VOLTAGE (V) EFFICIENCY (%) EFFICIENCY vs. LOAD CURRENT (VOUT = -18V) 100 95 90 85 A 80 B C 75 D 70 65 60 55 50 0.1 A: VIN = 12V, ISET = VCC B: VIN = 12V, ISET = GND C: VIN = 5V, ISET = VCC or GND D: VIN = 3V, ISET = VCC or GND 1 10 100 LOAD CURRENT (mA) MAX629-04 EFFICIENCY (%) EFFICIENCY vs. LOAD CURRENT (VOUT = -12V) 100 95 90 85 80 A 75 B, C D 70 65 60 55 50 0.1 A = VIN = 5V, ISET = VCC B = VIN = 5V, ISET = GND C = VIN = 3V, ISET = VCC D = VIN = 3V, ISET = GND 1 10 100 LOAD CURRENT (mA) MAX629-05 MAXIMUM LOAD CURRENT (mA) MAXIMUM LOAD CURRENT vs. INPUT VOLTAGE (VOUT = -18V, -12V) 90 A 80 MAX629-06 70 60 B 50 A: VOUT = -12V, ISET = VCC B: VOUT = -18V, ISET = VCC 40 C: VOUT = -12V, ISET = GND 30 D: VOUT = -18V, ISET = GND C 20 D 10 0 0 4 8 12 16 20 INPUT VOLTAGE (V) _______________________________________________________________________________________ 3 MAX629 SUPPLY CURRENT (µA) 28V, Low-Power, High-Voltage, Boost or Inverting DC-DC Converter ____________________________Typical Operating Characteristics (continued) (SHDN = VCC , CREF = 0.1µF, TA = +25°C, unless otherwise noted.) MAX629-08 MAX629-07 REFERENCE VOLTAGE (V) SUPPLY CURRENT vs. INPUT VOLTAGE 700 VIN = VCC 600 500 IIN 400 IIN 300 REFERENCE VOLTAGE vs. REFERENCE LOAD CURRENT 1.255 1.250 VIN = VCC = 5V C4 = 0.47µF 1.245 1.240 200 ICC 100 1.235 0 0 1 2 3 4 5 INPUT VOLTAGE (V) 1.230 0 20 40 60 80 100 120 140 160 REFERENCE LOAD CURRENT (µA) OUTPUT VOLTAGE RIPPLE LOAD-TRANSIENT RESPONSE (ISET = VCC, ILIM = 500mA) LOAD-TRANSIENT RESPONSE (ISET = GND, ILIM = 250mA) MAX629-11 MAX629-09 MAX629-10 0mA 0mA A A A 5mA 5mA B B B 10µs/div VOUT = +24V, ILOAD = 5mA A: ISET = VCC, 20mV/div B: ISET = GND, 20mV/div 200µs/div VOUT = +24V, ISET = VCC A: LOAD CURRENT, 0mA TO 5mA, 2.5mA/div B: VOUT, AC-COUPLED, 10mV/div SHUTDOWN TRANSIENT (POSITIVE CONFIGURATION) 5V 5V SHDN SHDN 0V 0V MAX629-12 MAX629-13 100µs/div VOUT = +24V, ISET = GND A: LOAD CURRENT, 0mA TO 5mA, 2.5mA/div B: VOUT, AC-COUPLED, 10mV/div SHUTDOWN TRANSIENT (NEGATIVE CONFIGURATION) 24V 0V VOUT 0V VOUT -20V 50ms/div VCC = VIN = 5V, RL = 4kΩ 250ms/div SVTCACR=T-VUINP=D5EVL,ARYL, =VC4CkΩ= VIN = 5V, ILOAD = 5mA 4 _______________________________________________________________________________________ 28V, Low-Power, High-Voltage, Boost or Inverting DC-DC Converter MAX629 ______________________________________________________________Pin Description PIN NAME FUNCTION 1 SHDN Active-Low Shutdown Input. A logic low puts the MAX629 in shutdown mode and reduces supply current to 1µA. 2 POL Polarity Input. Changes polarity and threshold of FB to allow regulation of either positive or negative output voltages. Set POL = GND for positive output voltage, or set POL = VCC for negative output voltage. 3 REF 1.25V Reference Output. Bypass to GND with a 0.1µF capacitor for IREF ≤ 10µA. REF can source 100µA to drive external loads. For 10µA ≤ IREF ≤ 100µA, bypass REF with a 0.47µF capacitor. 4 FB Feedback Input for setting output voltage. Connect to an external voltage divider. See Setting the Output Voltage. 5 ISET Current-Limit Set Input. Connect to VCC for a 500mA LX current limit, or connect to GND for a 250mA LX current limit. See Setting the Current Limit. 6 GND Ground 7 LX Internal N-Channel DMOS Switch Drain 8 VCC Power-Supply Input _______________Detailed Description The MAX629 low-power, boost DC-DC converter provides either positive or negative output voltages up to ±28V from a wide range of input voltages. It is designed primarily for use in low-power, high-voltage applications such as LCD biasing and set-top box varactor tuning. The MAX629’s unique control scheme provides high efficiency and a wide range of output voltages with only 80µA quiescent supply current, making it ideal for battery-powered applications. The internal N-channel DMOS switch has a pin-programmable current limit (250mA and 500mA), allowing optimization of output current and component size. Figure 1 shows the MAX629 functional diagram. Control Scheme A combination of peak-current limiting and a pair of one-shots controls the MAX629 switching, determining the maximum on-time and constant off-time. During the on-cycle, the internal switch closes, and current through the inductor ramps up until either the fixed 10µs maximum on-time expires (at low input voltages) or the switch’s peak current limit is reached. The peak switch current limit is selectable to either 500mA (ISET = VCC) or 250mA (ISET = GND) (see Setting the Current Limit). After the on-cycle terminates, the switch turns off, charging the output capacitor through the diode. In normal operation, the minimum off-time is set to 1µs for positive output voltages and 3.5µs for negative output voltages. When the output is well below reg- ulation, however, the off-time is increased to 5µs to provide soft-start during start-up. The switching frequency, which depends upon the load, can be as high as 300kHz. Shutdown Mode When SHDN is low, the MAX629 enters shutdown mode. In this mode, the feedback and control circuit, reference, and internal biasing circuitry turn off. The shutdown current drops to less than 1µA. SHDN is a logic-level input; connect it to VCC for normal operation. The output voltage behavior in shutdown mode depends on the output voltage polarity. In the positive output voltage configuration (Figure 2), the output is directly connected to the input through the diode (D1) and the inductor (L1). When the device is in shutdown mode, the output voltage falls to one diode drop below the input voltage, and any load connected to the output may still conduct current. In the negative output voltage configuration (Figure 3), there is no DC connection between the input and the output, and in shutdown mode the output is pulled to GND. __________________Design Procedure Setting the Output Voltage For either positive or negative output voltage applications, set the MAX629’s output voltage using two external resistors, R1 and R2, as shown in Figures 2 and 3. Since the input bias current at FB has a 50nA maximum value, large resistors can be used in the feedback loop _______________________________________________________________________________________ 5 28V, Low-Power, High-Voltage, Boost or Inverting DC-DC Converter MAX629 POL REF 1.25V REF FB ERROR AMP MIN OFF-TIME GENERATOR POLARITY TRIG START-UP Q F/F S Q R MAX629 LX START-UP COMPARATOR ISET SHDN VCC 1V CONTROL TRIG MAX ON-TIME GENERATOR (10µs) Q GND Figure 1. Functional Diagram without a significant loss of accuracy. Begin by selecting R2 to be in the 10kΩ to 200kΩ range, and calculate R1 using the applicable equation from the following subsections. Positive Output Voltages For positive output voltages, use the typical boost configuration shown in Figure 2, connecting POL to GND. This sets the threshold voltage at FB to equal VREF. Choose the value of R2 and calculate R1 as follows: R1 = R2 x   VOUT VREF −  1 where VREF = 1.25V. Negative Output Voltages For negative output voltages, configure R1 and R2 as shown in Figure 3, connecting POL to VCC. This sets the FB threshold voltage to GND so that negative voltages can be regulated. Choose R2 and calculate R1 as follows: R1 = R2 x | VOUT | VREF where VREF = 1.25V. Figure 3 demonstrates generation of a negative output voltage by following the MAX629 with an inverting charge pump. This configuration limits VOUT to values between -VIN and -28V. If smaller negative output voltages are required, D2’s cathode can be connected to VIN. This alternative configuration permits output voltages smaller than -VIN, but cannot be used for output voltages more negative than -28V - VIN. It produces roughly one-half the output current as the standard configuration and is typically 5% less efficient. 6 _______________________________________________________________________________________ MAX629 28V, Low-Power, High-Voltage, Boost or Inverting DC-DC Converter Setting the Current Limit External current-limit selection provides added control over the MAX629’s output performance. A higher current limit increases the amount of energy stored in the inductor during each cycle, which provides a higher output current capability. For higher output current applications, choose the 500mA current-limit option by connecting ISET to VCC. When lower output current is required, the 250mA current limit can provide several advantages. First, a smaller inductor can be used, which saves board area and cost. Second, the smaller energy transfer per cycle reduces output ripple for a given capacitor, providing design flexibility between board area, cost, and output ripple by allowing cheaper, higher-ESR capacitors. Connect ISET to GND to select the 250mA current-limit option. Inductor Selection The MAX629’s high switching frequency allows for the use of a small inductor. The 47µH inductor shown in the Typical Operating Circuit is recommended for most applications. Larger inductances reduce the peak inductor current, but may limit output current capability at low input voltages and provide slower start-up times. Smaller inductances require less board space, but may cause greater peak current due to current-sense comparator propagation delay. If input voltages below 2V will be common, reducing the inductance to 22µH might improve performance; however, maximum load current and efficiency may decline. It is important to thoroughly test operation under all input and output conditions to ensure proper component selection. Inductors with a ferrite core or equivalent are recommended; powder iron cores are not recommended for use with high switching frequencies. The inductor’s incremental saturation rating must exceed the selected current limit. For highest efficiency, use an inductor with a low DC resistance (under 100mΩ). See Table 1 for a list of inductor suppliers. VIN +0.8V TO +24V VCC +2.7V * C1 10µF TO +5.5V 35V C3 0.1µF VCC SHDN LX ISET MAX629 FB POL C4 0.1µF REF GND L1 47µH D1 MBR0540L R1 576k 1% R2 31.6k 1% CF 150pF VOUT +24V C2 10µF 35V * FOR SINGLE-SUPPLY OPERATION *FOR SINGLE-SUPPLY OPERATION Figure 2. +24V for a Positive LCD Bias VIN +0.8V TO +15V VCC +2.7V TO +5.5V C1 * 10µF 35V C3 0.1µF VCC SHDN LX ISET POL MAX629 FB REF GND L1 47µH C5 R3 2.2µF 2Ω D1 = D2 = MBR0540L D2 R1 576k 1% D1 CF 150pF VOUT -20V C2 10µF 35V R2 35.7k 1% C4 0.1µF * FOR SINGLE-SUPPLY OPERATION *FOR SINGLE-SUPPLY OPERATION Figure 3. -20V for a Negative LCD Bias _______________________________________________________________________________________ 7 MAX629 28V, Low-Power, High-Voltage, Boost or Inverting DC-DC Converter Diode Selection The MAX629’s high switching frequency demands a high-speed rectifier. Schottky diodes, such as the 1N5819 or MBR0530L, are recommended. Make sure that the diode’s peak current rating exceeds the peak current set by ISET, and that its breakdown voltage exceeds the output voltage. Schottky diodes are preferred due to their low forward voltage. However, ultrahigh-speed silicon rectifiers are also acceptable. Table 1 lists Schottky diode suppliers. Capacitor Selection Output Filter Capacitor The primary criterion for selecting the output filter capacitor is low effective series resistance (ESR). The product of the peak inductor current and the output filter capacitor’s ESR determines the amplitude of the high-frequency ripple seen on the output voltage. These requirements can be balanced by appropriate selection of the current limit, as discussed in the Setting the Current Limit section. Table 1 lists some low-ESR capacitor suppliers. See the Output Voltage Ripple graph in the Typical Operating Characteristics section. Input Bypass Capacitor Although the output current of many MAX629 applications may be relatively small, the input must be designed to withstand current transients equal to the inductor current limit. The input bypass capacitor reduces the peak currents drawn from the voltage Table 1. Component Suppliers SUPPLIER CAPACITORS AVX: TPS series Matsuo: 267 series Sprague: 595D series DIODES Motorola: MBR0530L Nihon: EC11 FS1 series INDUCTORS Coilcraft: DO1608 and DT1608 series Murata-Erie: LQH4 series Sumida: CD43, CD54, and CDRH62B series TDK: NLC565050 series PHONE (803) 946-0690 (714) 969-2491 (603) 224-1961 (602) 303-5454 (805) 867-2555 (847) 639-6400 (814) 237-1431 (847) 956-0666 (847) 390-4373 FAX (803) 626-3123 (714) 960-6492 (603) 224-1430 (602) 994-6430 (805) 867-2698 (847) 639-1469 (814) 238-0490 (847) 956-0702 (847) 390-4428 source, and reduces noise caused by the MAX629’s switching action. The input source impedance determines the size of the capacitor required at the input (VIN). As with the output filter capacitor, a low-ESR capacitor is recommended. A 10µF, low-ESR capacitor is adequate for most applications, although smaller bypass capacitors may also be acceptable. Bypass the IC separately with a 0.1µF ceramic capacitor placed as close as possible to the VCC and GND pins. Reference Capacitor Bypass REF to GND with a 0.1µF ceramic capacitor for REF currents up to 10µA. REF can source up to 100µA of current for external loads. For 10µA ≤ IREF ≤ 100µA, bypass REF with a 0.47µF capacitor. Feed-Forward Capacitor Parallel a capacitor (CF) across R1 to compensate the feedback loop and ensure stability (Figures 2 and 3). Values up to 270pF are recommended for most applications. Choose the lowest capacitor value that ensures stability; high capacitance values may degrade line regulation. __________Applications Information Adjusting the Output Voltage Many biasing applications require an adjustable output voltage, which is easily obtained using the configuration in Figure 4. In this circuit, an external bias voltage (which may be generated by a potentiometer, a DAC, or other means) is coupled to FB through the resistor RB. The output voltage of this circuit is given by: VOUT = VINIT + R1 RB (VFB − VBIAS ) where VINIT is the fixed output voltage as calculated in the section Setting the Output Voltage, and VFB is equal to either VREF (1.25V) for the positive configuration or 0V for the negative configuration. Proper choice of RB provides a wide range of available output voltages using simple external components to generate VBIAS. Input Voltage Range Although, in many cases, the MAX629 and the inductor are powered from the same source, it is often advantageous in battery-powered applications to power the device from an available regulated supply and to power the inductor directly from a battery. The MAX629 requires a +2.7V to +5.5V supply at VCC, but the inductor can be powered from as low as +0.8V, significantly 8 _______________________________________________________________________________________ MAX629 28V, Low-Power, High-Voltage, Boost or Inverting DC-DC Converter VOUT R1 RB FB VBIAS MAX629 R2 GND (REF) ( ) ARE FOR NEGATIVE OUTPUT VOLTAGE CONFIGURATIONS. Figure 4. Adjustable Output Voltage increasing usable battery life. Using separate supplies for VCC and VIN also reduces noise injection onto VCC by isolating it from the switching transients, allowing a smaller, less-expensive input filter capacitor to be used in many applications. If input voltages below 2V will be common, reducing the inductor to 22µH may improve performance in this voltage range, at the potential cost of some decrease in maximum load current and efficiency. In the negative configuration shown in Figure 3, the inverting charge pump injects current into LX with each cycle. The amount of charge injected increases at higher VIN, and may prematurely trip the internal current- limit threshold. Resistor R3 increases the usable input voltage range by limiting the peak injected current. The 2Ω resistor shown provides a usable input voltage range beyond VIN = 15V. In applications with a different input voltage range, R3 may be increased or decreased as necessary, with a resulting efficiency change of roughly 0.5%/Ω. Layout Considerations Proper PC board layout is essential due to high current levels and fast switching waveforms that radiate noise. It is recommended that initial prototyping be performed using the MAX629 evaluation kit or equivalent PC board-based design. Breadboards or proto-boards should never be used when prototyping switching regulators. It is important to connect the GND pin, the input bypass-capacitor ground lead, and the output filtercapacitor ground lead to a single point (star ground configuration) to minimize ground noise and improve regulation. Also, minimize lead lengths to reduce stray capacitance, trace resistance, and radiated noise, with preference given to the feedback circuit, the ground circuit, and LX. Place R1 and R2 as close to the feedback pin as possible. Place the input bypass capacitor as close as possible to VCC and GND. Refer to the MAX629 evaluation kit data sheet for an example of proper board layout. _______________________________________________________________________________________ 9 MAX629 28V, Low-Power, High-Voltage, Boost or Inverting DC-DC Converter __________________Pin Configuration TOP VIEW ___________________Chip Information TRANSISTOR COUNT: 653 SUBSTRATE CONNECTED TO GND SHDN 1 POL 2 REF 3 FB 4 MAX629 8 VCC 7 LX 6 GND 5 ISET SO 10 ______________________________________________________________________________________ SOICN.EPS MAX629 28V, Low-Power, High-Voltage, Boost or Inverting DC-DC Converter ________________________________________________________Package Information ______________________________________________________________________________________ 11 MAX629 28V, Low-Power, High-Voltage, Boost or Inverting DC-DC Converter NOTES 12 ______________________________________________________________________________________

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