MAXREFDES1168: 7V/200mA or 5V/100mA output, ISO-BUCK DC-DC power module

The MAXREFDES1168 is a high-efficiency, iso-buck DC-DC power module based on the MAX17681. It accepts an input voltage range from 17V to 32V and adjusts the output voltage through primary-side feedback. The reference design provides two output configurations: In one configuration, the output is set to 7V @ 200mA with a regulation accuracy of ±8%; in the second configuration, a post-regulator (MAX17651) is used to produce a 5V @ 100mA output with a stable output Pressure accuracy is within ±3%. This iso-buck isolated power module is available in the MAX17681 in a 10-pin (3mm x 2mm) TDFN package and the MAX17651 in a 6-pin TSOT package. The MAXREFDES1168's pin spacing complies with the Distributed Power Source Open Standards Alliance's (DOSA) open standard for DC/DC module power supplies. Two transformer options are provided, one is from Wurth; the other is from Chinese transformer manufacturer HanRun, which is convenient for users to choose. The reference design provides 1500V electrical isolation.

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Key Features

• +7V@200mA or +5V@100mA output

• 17V to 32V input voltage range

• EN/UVLO input

• 200kHz switching frequency

• 92.2% peak efficiency

• Overcurrent protection

• No optocoupler design

• Output power up to 1.4W

• Thermal Protection

• Proven PCB layout

• Primary and secondary output voltage short circuit protection

design resources

Design, build and test

This reference design introduces the MAXREFDES1168 hardware circuit design and provides detailed technical guidance for designing an iso-buck converter using Maxim's MAX17681A current-mode controller. The power supply has been built and tested.