Evaluates: MAX17597 in a MAX17597 Evaluation Kit Flyback Configuration General Description Quick Start The MAX17597 evaluation kit (EV kit) is a fully assembled Recommended Equipment and tested circuit board that demonstrates an isolated One 18V to 36V DC, 2A power supply 20W flyback DC-DC converter. The circuit uses the Electronic load devices peak-current-mode controller in a 16-pin TQFN package with an exposed pad. The EV kit demonstrates Four digital multimeters (DMM) the ICs cycle-by-cycle current-limit, soft-start, and EN/ MAX17597-24V EVKITA UVLO features. Warning: The EV kit circuit output is configured for an isolated 24V Do not turn on the power supply until all connections and provides up to 833mA of output current. The EV kit is are completed. configured to operate at a 200kHz switching frequency. An optocoupler, along with the transformer, provides galvanic Wear protective eye gear at all times. isolation between input and output, up to 1500V . RMS Do not touch any part of the circuit with bare hands or conductive materials when powered up. Features Make sure all high-voltage capacitors are fully 18V to 36V Input Range discharged before handling. Allow 5 minutes after Isolated Output: 24V DC at 20W disconnecting the input power source before touching Cycle-by-Cycle Current Limit circuit parts. Resistor Programmable UVLO/OVI Threshold Equipment Setup and Test Procedure Low-Cost Flyback Design 1) Set the power supply to +24VDC. Disable the power- supply output. Galvanic Isolation Up to 1500V RMS 2) Connect the positive terminal of the power supply to the Proven PCB Layout VIN PCB pad and the negative terminal to the nearest Fully Assembled and Tested PGND PCB pad. Connect the positive terminal of the electronic load to the VOUT PCB pad and the negative terminal to the nearest GND0 PCB pad. 3) Set the electronic load to constant-current mode and Ordering Information appears at end of data sheet. disable the electronic load. 4) Connect a DMM configured in voltmeter mode across the VOUT PCB pad and the nearest GND0 PCB pad. 5) Connect another DMM configured in voltmeter mode across the VOUT PCB pad and the GND0 PCB pad. 6) Enable the power supply. 7) Enable the load and adjust the current to 833mA. 8) Verify that the output voltmeter displays 24V 9) If required, vary the input voltage from 18V to 36V, the load current from 0 to 833mA, and verify that the output voltage is 24V. 19-7726 Rev 0 7/15Evaluates: MAX17597 in a MAX17597 Evaluation Kit Flyback Configuration Note: The EV kit is shipped with the frequency dithering Detailed Description disabled and the DITHER/SYNC pin shorted to SGND by The MAX17597 EV kit provides a proven design to evaluate a 0 resistor. To set the desired frequency dither, replace the high-efficiency, DC-DC flyback converter in a space- resistor R23 with a capacitor of appropriate value, as saving 16-pin TQFN package. The EV kit is configured detailed in the MAX17595MAX17597 IC data sheet. The for a 24V output voltage that can supply up to 840mA of DITHER/SYNC PCB pad is available for monitoring the current. The EV kit features a 200kHz fixed switching signal at the DITHER/SYNC pin. frequency for optimum efficiency and component size. This EV kit uses the peak-current-mode, pulse-width- modulating (PWM) controller IC in a 16-pin TQFN package with an exposed pad. This PWM controller varies the duty cycle to compensate for the variation in input voltage (V ) and the output load to maintain a constant output IN voltage. The duty cycle determines the on/off duration of the MOSFET (Q1). The detailed description of flyback-design methodology, as well as the calculations for component value selection, are described in Application Note 5504, Designing Flyback Converters Using Peak-Current-Mode Controllers. The details of soft-start time programming, programming output voltage, peak-current limit setting, switching frequency setting, and the EN/UVLO, OVI settings are described in the MAX17595MAX17597 IC data sheet. Maxim Integrated 2 www.maximintegrated.com