MAX629 Evaluation Kit ____________________Component List DESIGNATION QTY ____________________________Features ♦ Output Voltage: +24V Positive -20V Negative ♦ Battery Input Voltage: +0.8V to VOUT (Positive Output) +0.8V to +15V (Negative Output) ♦ +2.7V to +5.5V VCC Supply Range ♦ Up to 20mA Output Current ♦ Internal 28V N-Channel Switch ♦ 1µA (Max) IC Shutdown Current ♦ Up to 300kHz Switching Frequency ♦ Surface-Mount Components ♦ Fully Assembled and Tested DESCRIPTION C1, C2, C10, C11 4 10µF, 35V tantalum capacitors AVX TPSD106M035R0300 or Sprague 593D106X0035D2W C3, C4, C8, C9 4 0.1µF ceramic capacitors C5, C6 2 150pF ceramic capacitors C7 1 2.2µF ceramic capacitor Marcon/United Chemi-Con THCR30E1225Z D1, D2, D3 3 40V, 0.5A Schottky diodes Motorola MBR0540LT3 PHONE FAX JU1–JU4 4 3-pin headers AVX (803) 946-0690 (803) 626-3123 L1, L2 2 47µH inductors Sumida CD54-470 Coilcraft (847) 639-6400 (847) 639-1469 Coiltronics (561) 241-7876 (561) 241-9339 ______________Ordering Information PART MAX629EVKIT TEMP. RANGE 0°C to +70°C BOARD TYPE Surface Mount ______________Component Suppliers SUPPLIER* R1, R3 2 576kΩ, 1% resistors Dale-Vishay (402) 564-3131 (402) 563-6418 R2 1 31.6kΩ, 1% resistor R4 1 35.7kΩ, 1% resistor Marcon/United Chemi-Con (847) 696-2000 (847) 696-9278 R5 1 2Ω, 5% resistor Motorola (602) 303-5454 (602) 994-6430 U1, U2 2 MAX629ESA (SO-8) Sprague (603) 224-1961 (603) 224-1430 None 4 Shunts Sumida (847) 956-0666 (847) 956-0702 None 1 MAX629 PC board Vishay/Vitramon (203) 268-6261 (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 Evaluates: MAX629 _______________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. Evaluates: MAX629 MAX629 Evaluation Kit _________________________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. _______________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. Shutdown Mode The MAX629 EV kit features a shutdown mode that reduces quiescent current to less than 1µA 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 SHDN PIN MAX629 OUTPUT 1 and 2 Connected to GND Shutdown mode, VOUT = VBATT - VDIODE 2 and 3 Connected to VCC MAX629 enabled, VOUT = +24V Table 2. Jumper JU3 Functions (Negative Output) SHUNT LOCATION SHDN PIN 1 and 2 Connected to GND Shutdown mode, VOUT = 0V 2 and 3 Connected to VCC MAX629 enabled, VOUT = -20V MAX629 OUTPUT Table 3. Jumper JU2 and JU4 Functions 2 SHUNT LOCATION ISET PIN CURRENT LIMIT (mA) 1 and 2 Connected to GND 250 2 and 3 Connected to VCC 500 _______________________________________________________________________________________ MAX629 Evaluation Kit Evaluates: MAX629 VBATT +0.8V TO VOUT VCC 2.7V TO 5.5V C1 10µF 35V C3 0.1µF VCC 2 POL VCC 8 L1 47µH 3 JU1 SHDN 1 2 SHDN LX D1 MBR0540L 7 VOUT +24V C2 10µF 35V 1 U1 VCC C5 150pF MAX629 3 JU2 2 R1 576k 1% 5 ISET FB 4 1 R2 31.6k 1% 6 GND REF 3 REF (1.25V) C4 0.1µF Figure 1a. MAX629 EV Kit Schematic (Positive Output Voltage) VBATT +0.8V TO +15V VCC 2.7V TO 5.5V C8 0.1µF 2 VCC POL C10 10µF 35V 8 L2 47µH D2 MBR0540L 3 1 JU3 SHDN 2 VOUT -20V 7 LX SHDN R5 2Ω 1 U1 VCC C7 2.2µF D3 MBR0540L R3 576k 1% C6 150pF C11 10µF 35V MAX629 3 JU4 5 2 ISET FB 4 1 REF 6 GND REF 3 REF (1.25V) R4 35.7k 1% C9 0.1µF Figure 1b. MAX629 EV Kit Schematic (Negative Output Voltage) _______________________________________________________________________________________ 3 Evaluates: MAX629 MAX629 Evaluation Kit 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 © 1997 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.