Click here for production status of specific part numbers. Evaluates: MAX17681 for Isolated MAX17681EVKITF Evaluation Kit +24V Output Configuration General Description Quick Start The MAX17681EVKITF is a fully assembled and tested Recommended Equipment circuit board that demonstrates the performance of the One 15V to 60V DC, 0.5A power supply MAX17681 high-efficiency, iso-buck DC-DC Converter. One resistive load 100mA sink capacity The EV kit operates over a wide input-voltage range of 17V to 36V and uses primary-side feedback to regulate Two digital multimeters (DMM) the output voltage. The EV kit output is programmed to Caution: Do not turn on the power supply until all +24V at 100mA, with 8% output voltage regulation. connections are completed. The EV kit comes installed with the MAX17681 in a 10-pin Test Procedure (3mm x 2mm) TDFN package. The EV kit comes with the default output configuration Features programmed to +24V. 17V to 36V Input-Voltage Range 1) Verify that J1 is open. +24V, 100mA Continuous Current 2) Verify that R7 is not installed. EN/UVLO Input 3) Set the power supply output to 24V. Disable the power supply. 200kHz Switching Frequency 4) Connect the positive terminal of the power supply to Overcurrent Protection the VIN PCB pad and the negative terminal to the No Optocoupler nearest PGND PCB pad. Connect a 100mA resistive Delivers up to 2.4W Output Power load across the +24V PCB pad and the GND0 PCB pad. Overtemperature Protection 5) Connect a DMM configured in voltmeter mode across Proven PCB Layout the +24V PCB pad and the nearest GND0 PCB pad. 6) Enable the input power supply. 7) Verify that output voltage is at +24V (with allowable Ordering Information appears at end of data sheet. 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 voltage is at +24V (with allowable tolerance of 8%). 19-8438 Rev 2 5/18Evaluates: MAX17681 for Isolated MAX17681EVKITF Evaluation Kit +24V Output Configuration the primary output voltage, primary inductance selection, Detailed Description turns-ratio selection, output capacitor selection, output The MAX17681EVKITF evaluation kit (EV kit) is a fully diode selection, and external loop compensation are assembled and tested circuit board that demonstrates the given in the MAX17681 IC data sheet. performance of the MAX17681 high efficiency, iso-buck DC-DC converter designed to provide an isolated power Enable Control (J1) up to 2.4W. The EV kit generates +24V, 100mA from a The EN/UVLO pin on the device serves as an on/off 17V to 36V input supply. The EV kit features a forced control while also allowing the user to program the input PWM control scheme that provides constant switching- undervoltage-lockout (UVLO) threshold. J1 configures frequency of 200kHz operation at all load and line conditions. the EV kits output for turn-on/turn-off control. Install a The EV kit includes an EN/UVLO PCB pad to monitor and shunt across J1 pins 2-3 to disable VOUT. See Table 1 for program the EN/UVLO pin of the MAX17681. The V PRI proper J1 configurations. PCB pad helps measure the regulated primary output volt- NOTE 1: The secondary output diodes D1 is rated to age (V ). An additional RESET PCB pad is available for PRI carry short-circuit current only for a few 100s of ms and monitoring the health of the primary output voltage (V ). PRI is not rated to carry the continuous short-circuit current. RESET is pulled low if the FB voltage drops below 92.5% NOTE 2: The iso-buck converter typically needs 10% minimum of its set value. RESET goes high impedance 1024 clock load to regulate the output voltage. In this design when cycles after the FB voltage rises above 95.5% of its set the +24V rail is healthy, the U2 sinks the minimum load value. The programmable soft-start feature allows users current required to regulate the output voltages within 8% to reduce the input inrush current. regulation. The iso-buck is a synchronous-buck-converter-based topology, useful for generating isolated outputs at low power level without using an optocoupler. The detailed procedure for setting the soft-start time, ENABLE/UVLO divider, primary output voltage (V ) selection, adjusting PRI Table 1. Enable Control (EN/UVLO) (J1) Jumper Settings SHUNT POSITION EN/UVLO PIN VOUT J1 1-2 Connected to V Always Enabled IN 2-3 Connected to GND Always Disabled Open* Connected to midpoint of R1, R2 resistor-divider Enabled at V 15.5V IN *Default position. Maxim Integrated 2 www.maximintegrated.com