Stepper Drivers

Aug 13, 2007 10 Replies

I've got a client in a bind. He's designed in these parts:

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but the vendor is out of stock.



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.



Thanks.


Tim Wescott Control systems and communications consulting http://www.wescottdesign.com Need to learn how to apply control theory in your embedded system? "Applied Control Theory for Embedded Systems" by Tim Wescott Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html

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

[*] I'm not sure what your customer will do with all the free magnetic geckos they'll get.
Ben Jackson AD7GD http://www.ben.com/

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.

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1-508-853-5000
Regards, Joerg http://www.analogconsultants.com

parts:

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but the vendor is

That driver is based on the Allegro A3977:

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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:

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

Jerry

Engineering is the art of making what you want from things you can get. ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

But they probably need some Monday next week ;-)

Regards, Joerg http://www.analogconsultants.com

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.

Tim Wescott Control systems and communications consulting http://www.wescottdesign.com Need to learn how to apply control theory in your embedded system? "Applied Control Theory for Embedded Systems" by Tim Wescott Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html

parts:

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but the vendor is

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

Tim Wescott Control systems and communications consulting http://www.wescottdesign.com Need to learn how to apply control theory in your embedded system? "Applied Control Theory for Embedded Systems" by Tim Wescott Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html

Check out

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Intelligent Motion Systems.

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.

Regards, Joerg http://www.analogconsultants.com

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