Barry,
The bucket brigade solution is indeed a bit of overkill in my case.
Unfortunately a shift register plus flipflops too, however I like the
idea. The circuit I have right now only contains one comparator and a
couple of resistors/capacitors.

Dan,
You mean let the hysteresis of the input stage of the H-bridge driver
do the work? Might be a good idea, it deletes the comparator. However
I'll have to see how big the H-bridge driver's hysteresis is. If it's
too small, I will need to slow down the pulse edges too much, limiting
duty-cycle.

Thanks.

Daniel...


----- Original Message -----
From: Barry Gershenfeld <barry@ZMICRO.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Wednesday, August 29, 2001 20:11
Subject: Re: [EE]: Creating 1us pulse delay in hardware


> Overkill, yes, but a good idea.  The bucket brigade is made for
audio
> delay which means thousands of steps and analog.  Neither of which
> is needed.  But the digital equivalent would be a shift register
> and a clock.   With 1 MHz and two flip-flops you can get
> a delay that would be 1-2 us.  If you want more resolution
> just add more stages and up the clock, thus upping the "refresh"
> rate.
>
> >Porbably overkill for what you want to do but one device I remember
reading
> >about that does this sort of thing is a "bucket brigade" device. It
is used
> >in audio to create echos. TTYL
> >
>
> >> I was wondering if some of you guys happen to know a simple
circuit to
> >> create a 1us (approx.) delay for a 20kHz PWM signal coming out of
a
> >> PIC. I need this to create a death-time in order to avoid current
> >> shoot through in an H-bridge.
> >>
> >> The circuit I have right now consists of a small RC to slow down
the
> >> ramps of the pulse, followed by a comparator with significant
> >> hysteresis. The comparator hysteresis is set at 1/3 and 2/3 of
vdd.
> >> This circuit seems to work ok, but I was wondering if there were
other
> >> options too. Or is my current approach not so bad after all?
> >>
> >> Thanks!
> >>
> >> Daniel...
>
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