Re: Digest Number 373
Posted by
Walter McCarthy
on 2000-02-22 20:14:38 UTC
-Snip-
I'd like to know as well, as I was about to figure it out the hard
way. There is a 'not yet prototyped' design for a hefty MOSFET bridge
on www.dprg.org that is set up to emulate an L297. They use IRF540's
N-channel and IRF9540 p-channel devices. I have parts to try that,
but am also thinking of using a high-side driver chip (which is
overrated at several hundred volts) that lets one use N channel
devices everywhere. Of course given the voltage rating of that, and
that FET's are available in high voltages, it's tempting to try to
design a chopper drive that would run off 120 VAC with no transformer,
or only an isolation transformer...
-snip-
Suggestion
The Intersil HIP 4081A chip drives 4 N channel FETs in a H bridge configuration to 80 volts/ 10 amps to frequencies over 250 khz.
This can be wired to chop current with a comparator that senses the load. It has internal high side drivers for the high side fets.
It is available for about $7 each. It needs a translator chip to provide step and direction. Maybe the Ericcson 3517 chip would work
as a driver.
Perhaps this chip would simplify a new stepper driver design. - No P channel Fets.
Cheers
I'd like to know as well, as I was about to figure it out the hard
way. There is a 'not yet prototyped' design for a hefty MOSFET bridge
on www.dprg.org that is set up to emulate an L297. They use IRF540's
N-channel and IRF9540 p-channel devices. I have parts to try that,
but am also thinking of using a high-side driver chip (which is
overrated at several hundred volts) that lets one use N channel
devices everywhere. Of course given the voltage rating of that, and
that FET's are available in high voltages, it's tempting to try to
design a chopper drive that would run off 120 VAC with no transformer,
or only an isolation transformer...
-snip-
Suggestion
The Intersil HIP 4081A chip drives 4 N channel FETs in a H bridge configuration to 80 volts/ 10 amps to frequencies over 250 khz.
This can be wired to chop current with a comparator that senses the load. It has internal high side drivers for the high side fets.
It is available for about $7 each. It needs a translator chip to provide step and direction. Maybe the Ericcson 3517 chip would work
as a driver.
Perhaps this chip would simplify a new stepper driver design. - No P channel Fets.
Cheers