Evaluates: MAX17681 for Isolated 7V MAX17681 Evaluation Kit or 5V Output Configuration General Description Quick Start The MAX17681EVKITB is a fully assembled and tested Recommended Equipment circuit board that demonstrates the performance of the One 15V60V DC, 0.5A power supply MAX17681 high-efficiency, iso-buck DC-DC converter. Two resistive loads of 50mA to 100mA sink capacity The EV kit operates over a wide input-voltage range of 17V to 36V and uses primary-side feedback to regulate Four digital multimeters (DMM) the output voltage. The EV kit has two output configurations. Caution: Do not turn on the power supply until all connections In configuration one the output is programmed to are completed. 7V 100mA, with 8% output voltage regulation. The second configuration uses a post regulator, MAX17651 to Procedure produce 5V 50mA with < 3% regulation. The EV kit comes with the default output configuration programmed to 7V. The EV kit comes installed with the MAX17681 in a 10-pin (3mm x 2mm) TDFN package and MAX17651 in a 6-lead Test Procedure for 7V Output TSOT package. 1) Verify that the J1 is open. Features 2) Verify that the R17, R18, and R19 are not installed. 17V to 36V Input Voltage Range 3) Set the power supply output to 24V. Disable the power supply. 7V, 100mA or 5V, 50mA Continuous Current 4) Connect the positive terminal of the power supply EN/UVLO Input to the V PCB pad and the negative terminal to IN 200kHz Switching Frequency the nearest PGND PCB pad. Connect a 100mA 87.5% Peak Efficiency resistive load across the +7V PCB and GND0 PCB pads. Connect another 100mA resistive load across Overcurrent Protection the GND0 PCB and -7VPCB pads. No Optocoupler 5) Connect a DMM, configured in voltmeter mode, Delivers up to 1.4W Output Power across the +7V PCB pad and the nearest GND0 PCB Overtemperature Protection pad. Connect another DMM configured in voltmeter mode across the -7V PCB pad and the nearest GND0 Proven PCB Layout PCB pad. Ordering Information appears at end of data sheet. 6) Enable the input power supply. 7) Verify that output voltages are at 7V (with allowable tolerance of 8%) with respect to GND0. 8) If required, vary the input voltage from 17V to 36V, the load current from 0mA to 100mA, and verify that output voltages are 7V (with allowable tolerance of 8%). 19-8443 Rev 1 5/16Evaluates: MAX17681 for Isolated 7V MAX17681 Evaluation Kit or 5V Output Configuration The iso-buck is a synchronous-buck-converter-based Test Procedure for 5V Output topology, useful for generating isolated outputs at low 1) Verify that J1 is open power level without using an optocoupler. The detailed 2) Remove R16 and R10. Place 0 resistors in R18 procedure for setting the soft-start time, ENABLE/ and R19. UVLO divider, primary output voltage (V ) selection, PRI 3) Set the input power supply output to 24V. Disable the adjusting the primary output voltage, primary inductance power supply. selection, turns-ratio selection, output capacitor selection, output diode selection and external loop compensation 4) Connect the positive terminal of the power supply are given in the MAX17681 IC data sheet. The post to the V PCB pad and the negative terminal to the IN regulator, MAX17651 output voltage setting and the nearest PGND PCB pad. Connect a 50mA resistive related additional information are detailed in MAX17651 load across the +5V PCB pad and the GND0 PCB IC data sheet. pad. Connect another 50mA resistive load across the GND0 PCB pad and the -5VPCB pad. Enable Control (J1) 5) Connect a DMM, configured in voltmeter mode, The EN/UVLO pin on the device serves as an on/ across the +5V PCB pad and the nearest GND0 off control while also allowing the user to program the PCB pad. Connect another DMM, configured in input undervoltage-lockout (UVLO) threshold. Jumper J1 voltmeter mode, across the -5V PCB pad and the configures the EV kits output for turn-on/turn-off control. nearest GND0 PCB pad. Install a shunt across J1 pins 2-3 to disable V See OUT. 6) Enable the input power supply. Table 1 for proper J1 configurations. 7) Verify that output voltages are at 5V (with allowable Table 1. Enable Control (EN/UVLO) (J1) tolerance of 3%) with respect to GND0. Jumper Settings 8) If required, vary the input voltage from 17V to 36V, the load current from 0mA to 50mA, and verify that output SHUNT voltages are 5V (with allowable tolerance of 3%). EN/UVLO PIN VOUT OUTPUT POSITION Detailed Description J1 The MAX17681EVKITB EV kit is a fully assembled and 1-2 Connected to VIN Always Enabled tested circuit board that demonstrates the performance 2-3 Connected to GND Always Disabled of the MAX17681 high-efficiency, iso-buck, DC-DC Connected to converter designed to provide an isolated power up Enabled at V IN Open* midpoint of R1, R2 to 1.4W. The EV kit generates either 7V, 100mA 15.5V resistor-divider or 5V, 50mA output, from a 17V to 36V input supply. The EV kit features a forced PWM control scheme *Default position. that provides constant switching-frequency of 200kHz NOTE 1: The secondary output diodes D1, D2 are rated to carry operation at all load and line conditions. short-circuit current only for a few hundredths of a millisecond and are not rated to carry the continuous short-circuit current. The EV kit includes an EN/UVLO PCB pad to monitor and program the EN/UVLO pin of the MAX17681. The NOTE 2: The iso-buck converter typically needs 10% minimum V PCB pad helps measure the regulated primary PRI load to regulate the output voltage. In this design, when both output voltage (V ). An additional RESET PCB pad is PRI +7V and -7V rails are healthy, the U4 sinks the minimum load available for monitoring the health of primary output current required to regulate the output voltages within 8% regulation. When a short is applied on any one of the output voltage (V ). RESET is pulled low if the FB voltage PRI rails with no-load on other healthy rail, the healthy rail voltage drops below 92.5% of its set value. RESET goes high can be as high as 16V. 1024 clock cycles after the FB voltage rises above 95.5% of its set value. The programmable soft-start feature allows users to reduce the input inrush current. Maxim Integrated 2 www.maximintegrated.com