This reference design presents a synchronous buck converter using the UCC38C43 BiCMOS low-power current-mode PWM controller, the TPS2838 synchronous buck MOSFET driver with drive regulator, and the INA138 high-side measurement current shunt monitor. The input voltage for this converter is from a 3.3-Vdc rail which draws the bias voltage for the devices from an available 12-Vdc bus. The converter is designed to operate at a switching frequency of 400 kHz and supports a non-isolated 1.8-Vdc, 17-A output. The complete schematic, board layout, circuit description, list of materials, and circuit performance curves are included.