Path: utzoo!news-server.csri.toronto.edu!rutgers!psuvax1!wuarchive!usc!apple!portal!cup.portal.com!CPS
From: CPS@cup.portal.com (CHRIS PATRIC SMOLINSKI)
Newsgroups: sci.electronics
Subject: Help with 74192!
Message-ID: <40157@cup.portal.com>
Date: 15 Mar 91 01:01:26 GMT
Distribution: usa
Organization: The Portal System (TM)
Lines: 14

Help!  I'm trying to use 5 74192 BCD counters in a PLL freq synth
circuit.  The problem I'm having is that as I increase the input
frequency, I begin to "lose" chips.  Let me explain.  At a frequency of
say 1 mhz, everything is fine.  As I increase the frequency, first the
highest counter fails to assert the borrow output (I am preloading the
counters with an initial value (the frequency I want) and counting down).
As I increase the frequency, the "failure" occurs earlier in the counter
chain.  However, the "failed" counter is still counting itself (the four
outputs still show the chip is counting).  And, if I replace the chips
with 74193s (4 bit counters), everything is fine.
 
Any dieas?
     ^ideas
- CHRIS