Unipolar stepper motor control

[frogdogbb]

Hey all I am trying to sort through data for controlling a unipolar stepper motor with a microcontroller. I have done this before but the hardware was already in place on a development board. What I need is a way to drive a 12V Unipolar stepper with a microcontroller. I have found a number of chips that may do what I need as far as switching and back EMF protection but not voltage conversion. I looked at a L6220 it says it can handle up to 50V on the output but the data sheet makes no mention of how this is accomplished. Maybe there is an easier way or maybe I am missing a part of the puzzle. Anyone have stepper motor experience?
Thanks
Ben

 

[light_bulb]

look like it does no voltage conversion, you need an external source, the center tap on the diodes stops emf. i'd use 4 mosfet here with built in diodes straight to the microcontroller and an add on power suppy, probably would be cheaper too.