OptiMOS™ low-voltage power MOSFET 60 V in PQFN 3.3x3.3 Source-Down DSC package with industry leading RDS(on) and superior thermal performance OptiMOS™5 60 V PQFN 3.3x3.3 Source-Down: offering a flipped silicon die, which is positioned upside down inside of the components. This adjustment allows the source potential (instead of the drain potential) to be connected to the PCB over the thermal pad. Therefore, it offers several advantages, such as increased thermal capability, advanced power density or improved layout possibilities.