Stepper Drivers

> Does anyone know of replacements I could recommend? The essential specs
> are that it should take step, direction & enable, and be able to drive
> bipolar motors, supply 2A at up to 24 volts. They're running inside an
> instrument, so OEM modules are fine and dandy.

I'm sure Geckodrive (.com) has something suitable. They have a huge following in the homebrew CNC community[*].

If Ben's suggestion doesn't pan out and it's urgent give Allegro a call. Their app engineers and sales guys should know which of their customers sell similar modules. Allegro makes tons of motor driver chips. I am not all that fond of them because of noise issues but that's another story.

parts:

That driver is based on the Allegro A3977:

If he wants, he could easily design his own PCB's for that driver chip with a few current sense resistors and capacitors. If not, xylotex makes a driver using the A3977 as well:

Make Geico ads? ;-)

Cheers! Rich

Is there a size constraint? I could easily do that with a 68HC11, some FETs and a suitable power supply; so could you.

Jerry

But they probably need some Monday next week ;-)

Precisely. We're buying time to market by putting things together from modules as much as possible. At some point in the future we may decide on doing something like that as a cost reduction -- for now, being able to lash it all together from parts while we concentrate on the really unique parts of the system is driving us to purchase things at the highest level of integration that we can.

I'm not sure you could achieve nice microstepping with a 68HC11, but one could certainly do it with some of the more modern chips with richer PWM resources.

parts:

That looks like a very good candidate -- I'll dig into their data sheet soon.

Check out

Good Luck george

Speaking of datasheets -- has anybody yet figured out how to find datasheets on Allegro's website?

robert

If it's like in the med devices biz the trick is to create some universally useful blocks, along with tested avenues for rapid prototyping. But that takes time and resources to set up.

Looks more like an FPGA job. If noise isn't an issue the Allegro chips do a fine job. I can't really use them though because the T-off times flop around like crazy.

What problems do you have? This would be the datasheet for the discussed chip:

Yes.

Will I tell you?

Maybe I will.

Go to the individual product page and on the top right of the page there is a column titled "Related links". The datasheet is usually the top one in that list.