What do you do when your design is wimmpy?

     1)  Read "Noise Reduction Techniques in Electrical Systems"  Henry W.
     Ott, John Wiley and Sons, ISBN 0-471-85068-3

     2)  Read it again.

     3)  If you have $1000 to invest in your education (the best damn $1000
     you'll ever spend...), look up the Univerisy of Missouri-Rolla,
     Electrical Engineering department, EMC lab, (say Prof. Tom Van Doren).
     Then sign up for one of their classes on EMC.

     4)  Buy a Schaffner NSG 435 ESD gun (the best damn $8500 you'll ever
     spend).  Don't be a affraid to crank it to 16KV and hit everything a
     hundred times.

     5)  Pay extra attention to the "loop areas" in your PC layout.  Reduce
     them as close to zero as possible.  That means putting caps of the
     correct value in the correct place.  On two layer boards everything
     becomes "close pairs of signal and return lines."

     6)  Partition your loop areas.  Keep the dirty loops from the clean
     loops, or the outside world loops from the inside world loops, or the
     Hit-by-ESD loops from the not-hit-by-ESD loops.

     7)  Use resistors, diodes, and caps to stear any ESD energy around
     your circuit let it return on it's return line (i.e. minimize the ESD
     loop areas).

     8)  Trust nothing.  Every line into your processor is a line that can
     corrupt you.  Put resistors on them all.  Limit all unneeded bandwidth
     on every line with RC filters.

     In the end you may add $1.50 to your design but I'll be worth it.

     If you need more info email me directly.




     Jon Bertrand
     jonb@cirris.com