As I/O moves from 5V to 3.3V in microprocessor systems, there is a need for power conversion from 3.3V to a lower core voltage such as 1.8V at appreciable current. Without a higher voltage available, this requires a controller that will operate on less than 3.3V and FETs that are specified at a sub-logic-level gate voltage.

The MAX1637 step-down controller (shown below) is guaranteed to operate with Vcc from 3.15V to 5.5V. The IRF7401 is specified with Vgs = 2.7V. In addition, the inductor is the tallest part at 4.5mm (max).


3.3V to 1.8V @ 4A