Vishay's latest TrenchFET power Mosfet comes in a chipscale package with a profile of just 0.59mm profile and a footprint area of 1.5x1mm.

Unusually, the Si8441DB specifies an on-resistance rating at 1.2V. So its on-resistance ranges from 0.600ohms at 1.2V VGS to 0.080ohms at 4.5V VGS, with a maximum gate-source voltage of +/-5 V.

The low on-resistance rating at 1.2 V can reduce the need for level-shift circuitry.

Also available in the same Micro Foot package is the 20V p-channel Si8451DB. Rated for a maximum gate-to-source voltage of 8V, on-resistance for the Si8451DB ranges from 0.200ohms at 1.5V to 0.080ohms at 4.5V.

See http://www.vishay.com