MPQ4321C Synchronous Step-Down Converters Monolithic Power Systems (MPS) MPQ4321C Synchronous Step-Down Converters are integrated with internal high-side and low-side power MOSFETs. These converters feature a 3.3V to 36V input range with a 42V load dump tolerance and up to 1A continuous output current. The MPQ4321C step-down converters offer 350kHz to 2.5MHz configurable frequency range, and 1μA shutdown current (ISD) allows the converter to be used in battery-powered applications. The MPQ4321C step-down converters support frequency foldback that prevents inductor current (IL) runaway during start-up.