Re: Stepper Drivers

stratton@... wrote:

> 3) I could use a pair of International Rectifier IR 2103 triple half
> bridge drivers ($11 each) [well, 4 chips gets 3 axis] and 8 power N
> channel mosfets per axis. The circuit looks simple, and it will
> handle any reasonable supply rail.

Highly recommended. I've used the IR2110 and the IR2113 in several
units, and they
have performed VERY well.

> 4) I could use a cheaper full bridge driver HIP4080 ($6) at moderately
>
> high supply rails (up to 80v) along with 8 N channel MOSFETS per axis.
>
> According to the data sheet, I would have to build extra circuit to
> prevent the bridges from shorting on power on. (Hm, tempting instead
> to put a relay latched "Motor Enable" button on the box to activate
> the motor supply rail - operater has to push after each power on,
> won't work until logic/bias power is good).

If you bug Harris enough, they will tell you that they have never gotten
the HIP4080
to work above 54 Volts, due to transients. I had some working at 59
volts, but
had problems with them failing. I finally replaced them with IR2113's
and a charge
pump for the continuous-on high-side drive, and they have done very
well.
What you want is to sequence the high voltage, so control power comes on
first,
and then when the E-stop condition is released, it turns on the HV.

>
> 5) I could just run the motors unipolar at about 2/3 the torque using
> very simple electronics. 4 N FET's and something to boost the gate
> drive voltage per channel... It's very tempting to build such a
> unipolar system to start! Is there a reason I don't want to do this?
>
> What kind of supply rails are people running anyway?

I'm running a circuit like this for a servo drive, using 4 IRF640 fets
and 2 IR2113S
drivers, with external charge pump to provide high side bias, at 69 V
DC. It has been
working fine for well over a year.

Jon