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| MAX629 Evaluation Kit _______________General Description The MAX629 evaluation kit (EV kit) contains two separate switching-regulator circuits. The first circuit converts a +0.8V to VOUT battery voltage to a +24V LCD backplane bias voltage for currents up to 20mA. The second circuit converts a +0.8V to +12V battery voltage to a -20V voltage for currents up to 20mA. The MAX629 requires a +2.7V to +5.5V supply at VCC, but the inductor can be powered from as low as 0.8V. Both output voltages can be adjusted by changing the feedback-resistor values. The MAX629 EV kit provides low quiescent current and high efficiency for maximum battery life. Operation up to 300kHz allows the use of a tiny surface-mount inductor. This EV kit is a fully assembled and tested surfacemount circuit board. ____________________________Features o Output Voltage: +24V Positive -20V Negative o Battery Input Voltage: +0.8V to VOUT (Positive Output) +0.8V to +15V (Negative Output) o +2.7V to +5.5V VCC Supply Range o Up to 20mA Output Current o Internal 28V N-Channel Switch o 1A (Max) IC Shutdown Current o Up to 300kHz Switching Frequency o Surface-Mount Components o Fully Assembled and Tested Evaluates: MAX629 ____________________Component List DESIGNATION QTY C1, C2, C10, C11 C3, C4, C8, C9 C5, C6 C7 D1, D2, D3 JU1-JU4 L1, L2 R1, R3 R2 R4 R5 U1, U2 None None 4 4 2 1 3 4 2 2 1 1 1 2 4 1 DESCRIPTION 10F, 35V tantalum capacitors AVX TPSD106M035R0300 or Sprague 593D106X0035D2W 0.1F ceramic capacitors 150pF ceramic capacitors 2.2F ceramic capacitor Marcon/United Chemi-Con THCR30E1225Z 40V, 0.5A Schottky diodes Motorola MBR0540LT3 3-pin headers 47H inductors Sumida CD54-470 576k, 1% resistors 31.6k, 1% resistor 35.7k, 1% resistor 2, 5% resistor MAX629ESA (SO-8) Shunts MAX629 PC board ______________Ordering Information PART MAX629EVKIT TEMP. RANGE 0C to +70C BOARD TYPE Surface Mount ______________Component Suppliers SUPPLIER* AVX Coilcraft Coiltronics Dale-Vishay Marcon/United Chemi-Con Motorola Sprague Sumida Vishay/Vitramon PHONE (803) 946-0690 (847) 639-6400 (561) 241-7876 (402) 564-3131 (847) 696-2000 (602) 303-5454 (603) 224-1961 (847) 956-0666 (203) 268-6261 FAX (803) 626-3123 (847) 639-1469 (561) 241-9339 (402) 563-6418 (847) 696-9278 (602) 994-6430 (603) 224-1430 (847) 956-0702 (203) 452-5670 * Please indicate that you are using the MAX629 when contacting these suppliers. ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800 MAX629 Evaluation Kit Evaluates: MAX629 _________________________Quick Start The MAX629 EV kit is fully assembled and tested. Follow these steps to verify board operation. VCC and VBATT are separated on each circuit to demonstrate operation of VBATT down to 0.8V. VCC and VBATT can be connected together and to a single supply from 2.7V to 5.5V. Do not turn on the power supply until all connections are completed. Positive Output: 1) Connect a +2.7V to +5.5V supply to the VCC pad, and a +0.8V to V OUT supply to the VBATT pad. Connect the grounds to the GND pad. 2) Connect a voltmeter and load, if any, to the VOUT pad. 3) Place the shunt on JU1 across pins 2 and 3. 4) Turn on the power supplies and verify that the output voltage is +24V. Negative Output: 1) Connect a +2.7V to +5.5V supply to the VCC pad, and a +0.8V to +15V supply to the VBATT pad. Connect the grounds to the GND pad. 2) Connect a voltmeter and load, if any, to the VOUT pad. 3) Place the shunt on JU3 across pins 2 and 3. 4) Turn on the power supplies and verify that the output voltage is -20V. For other output voltages, refer to the Setting the Output Voltage section in the MAX629 data sheet for instructions on selecting the feedback resistors. Shutdown Mode The MAX629 EV kit features a shutdown mode that reduces quiescent current to less than 1A to preserve battery life. The two-pin header JU1 selects shutdown mode for the positive output, and JU3 selects shutdown mode for the negative output. Tables 1 and 2 list the selectable jumper options. Current Limit The two-pin header JU2 selects the current limit for the positive output, and JU4 selects the current limit for the negative output. Table 3 lists the selectable jumper options. The MAX629 EV kit comes configured for a 500mA current limit. Table 1. Jumper JU1 Functions (Positive Output) SHUNT LOCATION 1 and 2 SHDN PIN MAX629 OUTPUT Shutdown mode, VOUT = VBATT - VDIODE MAX629 enabled, VOUT = +24V Connected to GND 2 and 3 Connected to VCC Table 2. Jumper JU3 Functions (Negative Output) SHUNT LOCATION 1 and 2 SHDN PIN MAX629 OUTPUT Shutdown mode, VOUT = 0V MAX629 enabled, VOUT = -20V _______________Detailed Description The MAX629 EV kit contains two separate switchingregulator circuits. The first circuit provides a +24V output for currents up to 20mA with 87% typical conversion efficiency. The second circuit provides a -20V output voltage for currents up to 20mA with 82% typical conversion efficiency. Both output voltages can be adjusted by changing the feedback-resistor values. Connected to GND 2 and 3 Connected to VCC Table 3. Jumper JU2 and JU4 Functions SHUNT LOCATION 1 and 2 2 and 3 ISET PIN Connected to GND Connected to VCC CURRENT LIMIT (mA) 250 500 2 _______________________________________________________________________________________ MAX629 Evaluation Kit Evaluates: MAX629 VBATT +0.8V TO VOUT VCC 2.7V TO 5.5V C3 0.1F C1 10F 35V VCC 3 SHDN JU1 2 1 VCC 3 2 1 JU2 2 POL VCC 8 L1 47H 7 D1 MBR0540L VOUT +24V C2 10F 35V R1 576k 1% C5 150pF 1 SHDN LX U1 MAX629 5 ISET FB 4 R2 31.6k 1% 6 GND REF 3 C4 0.1F REF (1.25V) Figure 1a. MAX629 EV Kit Schematic (Positive Output Voltage) VBATT +0.8V TO +15V VCC 2.7V TO 5.5V 2 3 SHDN JU3 2 1 VCC 3 JU4 2 1 REF REF (1.25V) R4 35.7k 1% 5 ISET 1 7 SHDN LX R5 2 C7 2.2F D3 MBR0540L R3 576k 1% C6 150pF POL VCC 8 L2 47H C8 0.1F C10 10F 35V D2 MBR0540L VOUT -20V C11 10F 35V U1 MAX629 FB 4 6 GND REF 3 C9 0.1F Figure 1b. MAX629 EV Kit Schematic (Negative Output Voltage) _______________________________________________________________________________________ 3 MAX629 Evaluation Kit Evaluates: MAX629 1.0" Figure 2. MAX629 EV Kit Component Placement Guide--Component Side 1.0" Figure 3. MAX629 EV Kit PC Board Layout--Component Side 1.0" Figure 4. MAX629 EV Kit PC Board Layout--Solder Side Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 4 ___________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600 (c) 1997 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. |
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