On Thu, 15 Jan 1998, Matthew J. Bennett wrote:
> sampling time = 5us + 3.2us + 5us = 13.2us
>
> I noticed the crosstalk when the sampling time was 22us, so I tried a bunch
> of parts to see where the crosstalk stopped.  I had delays of 22, 43, 65,
> 105, 210, and 360 us, and the crosstalk was evident up to the 43 us
> sampling time, and not evident for the 65us and up sampling times.  I used
> a heat gun to warm up the 65us sampling PIC, and saw no degredation in the
> accuracy.  Thankfully I can afford to lose the extra clock cycles, but
> this is awfully frustrating.  Should I not trust the equations in the data
> sheet?  I have to resort to 4x the reccomended sampling time to make sure
> the conversion is correct.

This is pretty scary. I did something on a '74A that I will need to do
some checking of this, because I've been tracking down a mysterious
problem that may have its roots in this same thing. I thought I was safe
with 5 us extra, but really didn't test it.

Thanks for pointing this out.

-bob