I have a fault in my test equipment here centred around AD767 DACs. What
you need to know is that the AD767s latch an input with a short negative
pulse (as short as 40nS) on the /CS line. I'm not getting this action.
The pulse appears to come from a Pal. I sent the Pals to the
manufacturer who tried them in another unit and they worked all day.
I feel I am looking for a voltage level or timing problem.
I have a 20Mhz scope here and can't see the pulse, or trigger on it.
My thoughts turned to building a latch trap - some latch circuit that
would come up low and latch high if the pulse appeared. I could then
tack this onto the chip, and look for the pulse.
Such a latch could be made from a 74F<something>. Any thoughts on how to
check the level (e.g. does it go below 0.8V) or dwell (does it last
40+nS) with this or something similar?
--
With best Regards,
Declan Moriarty.
--
Author: Declan Moriarty
INET: [EMAIL PROTECTED]
Fat City Hosting, San Diego, California -- http://www.fatcity.com
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