How can I have a pulse of 30V at .7A for 30ms then a holding current of 3V at 50mA for as long as I want?
If your load is something like a 40 ohm coil you can do something like this: 







simulate this circuit &ndash; Schematic created using CircuitLab

The top schematic is a dual high side driver that will run cool, but has a lot of parts. The second schematic is a much simpler low-side driver that burns a bunch of power in the 560 ohm resistor (should be rated for 2W) during hold.