|Input Type||VIN (MIN)
The MAX17681/MAX17681A is a high-voltage, highefficiency, iso-buck DC-DC converter designed to provide isolated power up to 5W. The device operates over a wide 4.5V to 42V input and uses primary-side feedback to regulate the output voltage. The MAX17681/MAX17681A uses peak-current-mode control. Low-resistance, on-chip MOSFETs ensure high efficiency at full load while simplifying the PCB layout. The MAX17681/MAX17681A devices generate a well-regulated primary side voltage, which is then scaled by a suitable transformer turns ratio to derive isolated secondary output rails. While both the MAX17681 and MAX17681A support primary side overcurrent protection, the MAX17681A is an enhanced design that also supports robust secondary-side overcurrent protection. The MAX17681/MAX17681A is available in a compact 10-pin (3mm × 2mm) TDFN package.
This reference design describes the hardware shown in Figure 1. It provides a detailed systematic technical guide to design an iso-buck converter using Maxim’s MAX17681A current mode controller. The power supply has been built and tested, details of which follow later in this document.