DTMOSIV Series MOSFETs Toshiba DTMOSIV MOSFETs use the state-of-the-art single epitaxial process, which provides a 30% reduction in RDS(on), a figure of merit (FOM) for MOSFETs, compared to its predecessor, DTMOSIII. This reduction in the RDS(on) makes it possible to house lower RDS(on) chips in the same packages. This helps to improve efficiency and reduce the size of power supplies. Toshiba DTMOSIV MOSFETs are ideal for use with switching regulators.