Denny Esterline <desterline <at> gmail.com> writes:

>=20
> >
> > PWMing the direction pin (IN2) with the other pin held low means you ar=
e
> >
> reversing the voltage across the load on every PWM cycle (like a Class D
> > amp) rather than the more conventional method of keeping one side of th=
e
> > bridge in a static condition.
> >
>=20
> Not uncommon. It's called Locked Antiphase.
>=20
> > PWMing the 'enable' pin (IN1) with the other pin controlling direction
> > means
> > that in one direction you would be braking the motor during the high pa=
rt
> > of
> > the PWM, and in the other you would be letting it freewheel.
> >
>=20
> Various versions of this are also common, "fast decay" "slow decay" and
> "mixed decay" should be useful search terms.
>=20
> -Denny
>=20

Thanks for the correct name.  I was vaguely aware this was a possible mode
of operation (much like a Class D amp), but the automotive stuff I have
looked at has typically used a single ended drive.  Since the throttle moto=
r
operates against a pretty strong return spring, I wonder if a full H bridge
is even needed?

I still not convinced that driving this device with 4kHz PWM is appropriate
though.  One cycle at 4kHz is 250us, so the switching delay+switching speed
would remove a chunk of your possible PWM range.

Mike


--=20
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