Evaluates: MAX629 MAX629 Evaluation Kit General Description Features The MAX629 evaluation kit (EV kit) contains two sepa- Output Voltage: rate switching-regulator circuits. The first circuit con- +24V Positive verts a +0.8V to V battery voltage to a +24V LCD OUT -20V Negative backplane bias voltage for currents up to 20mA. The Battery Input Voltage: second circuit converts a +0.8V to +12V battery voltage to a -20V voltage for currents up to 20mA. The MAX629 +0.8V to V (Positive Output) OUT requires a +2.7V to +5.5V supply at VCC, but the +0.8V to +15V (Negative Output) inductor can be powered from as low as 0.8V. Both out- +2.7V to +5.5V V Supply Range CC put voltages can be adjusted by changing the feed- back-resistor values. Up to 20mA Output Current The MAX629 EV kit provides low quiescent current and Internal 28V N-Channel Switch high efficiency for maximum battery life. Operation up 1A (Max) IC Shutdown Current to 300kHz allows the use of a tiny surface-mount induc- tor. This EV kit is a fully assembled and tested surface- Up to 300kHz Switching Frequency mount circuit board. Surface-Mount Components Fully Assembled and Tested Component List DESIGNATION QTY DESCRIPTION 10F, 35V tantalum capacitors C1, C2, C10, Ordering Information 4 AVX TPSD106M035R0300 or C11 Sprague 593D106X0035D2W PART TEMP. RANGE BOARD TYPE C3, C4, C8, C9 4 0.1F ceramic capacitors MAX629EVKIT 0C to +70C Surface Mount C5, C6 2 150pF ceramic capacitors 2.2F ceramic capacitor C7 1 Marcon/United Chemi-Con THCR30E1225Z Component Suppliers 40V, 0.5A Schottky diodes D1, D2, D3 3 Motorola MBR0540LT3 SUPPLIER* PHONE FAX JU1JU4 4 3-pin headers AVX (803) 946-0690 (803) 626-3123 47H inductors Coilcraft (847) 639-6400 (847) 639-1469 L1, L2 2 Sumida CD54-470 Coiltronics (561) 241-7876 (561) 241-9339 R1, R3 2 576k, 1% resistors Dale-Vishay (402) 564-3131 (402) 563-6418 R2 1 31.6k, 1% resistor Marcon/United (847) 696-2000 (847) 696-9278 R4 1 35.7k, 1% resistor Chemi-Con R5 1 2, 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 contact- ing these suppliers. Maxim Integrated Products 1 For free samples & the latest literature: MAX629 Evaluation Kit Shutdown Mode Quick Start The MAX629 EV kit features a shutdown mode that The MAX629 EV kit is fully assembled and tested. reduces quiescent current to less than 1A to preserve Follow these steps to verify board operation. V and CC battery life. The two-pin header JU1 selects shutdown V are separated on each circuit to demonstrate BATT mode for the positive output, and JU3 selects shut- operation of V down to 0.8V. V and V can BATT CC BATT down mode for the negative output. Tables 1 and 2 list be connected together and to a single supply from the selectable jumper options. 2.7V to 5.5V. Do not turn on the power supply until all connections are completed. Current Limit The two-pin header JU2 selects the current limit for the Positive Output: positive output, and JU4 selects the current limit for the 1) Connect a +2.7V to +5.5V supply to the VCC pad, negative output. Table 3 lists the selectable jumper and a +0.8V to V supply to the VBATT pad. OUT options. The MAX629 EV kit comes configured for a Connect the grounds to the GND pad. 500mA current limit. 2) Connect a voltmeter and load, if any, to the VOUT pad. Table 1. Jumper JU1 Functions 3) Place the shunt on JU1 across pins 2 and 3. (Positive Output) 4) Turn on the power supplies and verify that the out- put voltage is +24V. SHUNT SHDN PIN MAX629 OUTPUT LOCATION Negative Output: 1) Connect a +2.7V to +5.5V supply to the VCC pad, Shutdown mode, 1 and 2 Connected to GND and a +0.8V to +15V supply to the VBATT pad. V = V - V OUT BATT DIODE Connect the grounds to the GND pad. MAX629 enabled, 2) Connect a voltmeter and load, if any, to the VOUT 2 and 3 Connected to VCC V = +24V pad. OUT 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. Table 2. Jumper JU3 Functions For other output voltages, refer to the Setting the (Negative Output) Output Voltage section in the MAX629 data sheet for SHUNT instructions on selecting the feedback resistors. SHDN PIN MAX629 OUTPUT LOCATION Detailed Description Shutdown mode, The MAX629 EV kit contains two separate switching- 1 and 2 Connected to GND V = 0V OUT regulator circuits. The first circuit provides a +24V out- put for currents up to 20mA with 87% typical conver- MAX629 enabled, 2 and 3 Connected to VCC sion efficiency. The second circuit provides a -20V out- V = -20V OUT put voltage for currents up to 20mA with 82% typical conversion efficiency. Both output voltages can be adjusted by changing the feedback-resistor values. Table 3. Jumper JU2 and JU4 Functions SHUNT CURRENT LIMIT ISET PIN LOCATION (mA) 1 and 2 Connected to GND 250 2 and 3 Connected to VCC 500 2 Evaluates: MAX629