Re: RE: PWM stepper driver external bridge

On 9 Jan, CAD_CAM_EDM_DRO@egroups.com wrote:

> Message: 9
> Date: Mon, 8 Jan 2001 16:51:40 -0800
> From: "Lawrence Glaister" <lg@...>
> Subject: RE: PWM stepper driver external bridge
>
> sorry folks, attachment was deleted from my last post. If you are
> interested, the cct for 1 of the 2 bridges required for each stepper drive
> is available in the files area at:

Clever. A couple of comments ..

1. Are you sure that with no drive present, the output FETs are in fact
off ?

2. The 1k resistor used for slow FET turnon may be needlessly high,
limiting your maximum step rate for no good purpose ( save to also limit
the dissipation of the bipolar drivers ). The A3955 may already supply
adequate delay.

3. Adding another transistor to the high side drive would allow you to
drive the bridge directly from a PIC ... <G>

Alan

--

Alan Rothenbush | The Spartans do not ask the number of the
Academic Computing Services | enemy, only where they are.
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