Re: Stepper motor driver with less noise?

On Jul 11, 2:22 pm, Joerg <notthisjoerg...@xxxxxxxxxxxxxxxxxxxxx>
wrote:
Mika Lindblad wrote:
OTOH those driver chips are not cheap so a roll-your-own session brings
about a nice BOM cost reduction.

I't doesn't lower the total cost so much.. Relatively cheap stepper motor
controller costs only ~3e (4$) in reasonable quantitys. For example, the
cheapest ones in New Japan Radio NJM377x-series.

Yes, but the problem is that the noise pollution it is spewing around is
so bad for this circuit that we must abandon it. If they would contain a
proper PWM, meaning not much jitter, I'd agree.

And to do it in discrete components, you'd need.. Components for 2
H-bridges, their drivers, logic, switch mode current limit, etc. And the
cost of pcb space and installing all those discrete components. Not to
mention the designing cost.

You can use cheap gate drivers for H-bridges but I have suggested to
that client to consider unipolar steppers. Then all you need is a bunch
of <10c FETs or a cheap ULN driver. The rest is going to be inside
programmable logic.

As long as cheap controllers are suitable for the job, they seem to be the
easiest and cheapest way to go. I know, there are much more advanced and a
lot more axpensive chips around. And applications where cheaper controllers
just aren't good enough.

And applications where even the "good" controllers aren't good enough.
That is kind of my domain, where standard stuff doesn't cut it and a
roll-your-own solution with better performance is required. IOW that's
when my phone rings ;-)

However, as a hobby project, discrete stepper motor controller/driver would
be great.

Not just for hobby. In production there is a huge incentive to live with
standard discretes. It greatly reduces the chance of a line stop if for
some reason the fancy chip slips in delivery schedule.

--
Regards, Joerg

http://www.analogconsultants.com


I've used the NJP 3961/3770 's driving bipolar stepper motors in
industrial printers (32 microsteps / fullstep) in production for years
and the Allegro A3979SLP-T recently in the same application. No
problems with FCC class A radiated or conducted. Allegro's are low
cost, run cool, tiny, low parts count.

Just my 2 cents....

Bruce


.

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