> > Wondering what factor(s) dictate the max spec of 250Hz? A minimum spec
> > would
> > be important to minimise flicker. Even so LED flicker can be noticeable
> > well above
> > 250Hz in some conditions. If there is no good reason why not then highe=
r
> > freq
> > would be better and your problem goes away.
> >
>=20
> I know that no text can ever be aligned properly, but here's a cut/paste
> from the data sheet.
> Parameter        Symbol  Min.  Typ.    Max.    Unit
> PWM frequency  fPWM  200  300     400        Hz
=20
That is curious. I still can't think of a good reason why there should be a=
 maximum=20
spec. Maybe higher freq square wave backlight current couples more easily i=
nto=20
LCD controller chip and causes problems. Or perhaps the LCD module has buil=
t in=20
PWM control of the LED backlight, maybe to effect constant current operatio=
n so=20
you don't need to add external series resistor, or there may even be a comm=
and so=20
you can control LED current? If so, very cool.

--=20
Brent Brown, Electronic Design Solutions
16 English Street, St Andrews,
Hamilton 3200, New Zealand
Ph: +64 7 849 0069
Fax: +64 7 849 0071
Cell: +64 27 433 4069
eMail:  brent.brown@clear.net.nz


--=20
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