UDN2987A as a H-bridge

Forum 2005-2010 (read only) Hardware Interfacing
1

help
I have a bunch of these line drivers (20 odd) but I can't see how to build a H-bridge to drive my 2 phase (bi-polar) stepper motor.

Driver data sheet http://www.datasheetdir.com/ALLEGROMICRO-UDN2987A+Power-Drivers
Motor data sheet http://www.active-robots.com/products/motorsandwheels/stepper-motors.shtml model 103H7123-0440

I have a drive cct working but it uses 8 TIP121s and these are bulky and difficult to mount.

Any help gratefully received.

Chewie Baker

2

That's only half of what you need for a H bridge. You need also some sink driving like the ULN2803.
Then you need attach one source to one sink for half a drive, then turn one pair on and the other off. So you need 4 lines to control 1 H bridge.
Watch out though if you turn both top and bottom on at the same time you have a short and things start to melt.

3

OK so its back to dedicated motor drive chips. I'll keep the line drivers for flashy LED displays.

Cheers

Chewie