RE: [CAD_CAM_EDM_DRO] Re: L297/L298 And a "correction"

The LM298 style of driver requires a sensing resistor for each leg.
Normally 0.01 to 0.05 ohms it should also be a low inductance resistor. One
quarter watt 0.01 ohm will do but with a 3.5 amp current that's only 35mV.
Your reference voltage used by the comparator will have to be very stable
and the circuit layout clean and noise free running close to wide traces
with 3.5A running through them.

As Mariss stated about his high side drivers, an optimum circuit isn't
always cost effective. I've done both L298 circuits and LM18245 and the
LM18245 is way easier to use. Unless I was building thousands I'd take the
easier route.

John Dammeyer



Wireless CAN with the CANRF module now available.
http://www.autoartisans.com/products
Automation Artisans Inc.
Ph. 1 250 544 4950

> -----Original Message-----
> From: CAD_CAM_EDM_DRO@yahoogroups.com
> [mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of Wayne
> C. Gramlich
> Sent: Wednesday, August 09, 2006 10:01 AM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: [CAD_CAM_EDM_DRO] Re: L297/L298 And a "correction"
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "ballendo"
> <ballendo@...> wrote:
> >
> > >In CCED, "Wayne C. Gramlich" <Wayne@> wrote:
> > >This was written about 2 years ago, so it is possible that
> some new
> > ><$10/axis integrated MOSFET solution has been deployed. I
> certainly
> > >am not aware of any, but I haven't beeen looking recently.
> >
> > Wayne,
> >
> > The Sanken Chips sold by Allegro are under your price point, and
> > perform very nicely. The "problem" is that Sanken has been of
> > a "unipolar" mindset for many years.
> >
> > I only wish Sanken and STS could run into each other (Reeses like)
> > saying,"Hey! you got microstepping in MY bipolar?!?
> >
> > "Yeah?, Well you got bipolar in MY microstepping"
> >
> > The STS L6208 with Sanken's uStep translator would be a nice chip
> > IMO. (or an SLA7078 with bipolar outputs; even better!)
> >
> > Until then, the choice seems to be two LMD18245's or the
> Sanken chips
> > for 3amp drives...
>
> Ballendo:
>
> The LM18245's are pretty expensive. By breaking out
> the DAC's and comparators, it is possible to use
> a L298 instead of an LM18245. The L298 can be configured
> to tie both internal H-bridges together to form a single
> H-bridge rated at 3.5 Amps I saw one person out there that
> built such a critter (I can't remember the URL tho'). It
> would only be rated for 48V instead of 55V tho'.
>
> -Wayne
>
>
>
>
>
>
>
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