sorted... Why have Darlingtons?

Magician:
I was referring to P-channel , when I need high side switch in low voltage (< 3.3V) design.

What, switch 3.3V @ ~3A high side using a PNP darlington? Even if you did have a high current 3.3V device, the Vce(sat) of the darlington would render it pretty much useless at that supply voltage.