Best way to toast TTL

Tony Duell ard at p850ug1.demon.co.uk
Sun Sep 2 16:14:00 CDT 2007


> What I'm wondering is if anyone knows how I can prematurely kill a 
> TTL device or simulate static failure.  I'd like to try to test how 
> thoroughly the programmer tests the chips.  It can't tell the 
> difference between a 7410 and 7412, but that isn't too important for 
> knowing the chip works (mostly)

IIRC, the 7410 is a triple 3-input NAND gate (totem pole outputs), the 
7412 is the open-collector version. If it can't tell those apart, how can 
it reject a 7410 where one or more of the 'top' transsitors in the totem 
pole output have failed? And yes, I've had that failure mode (actually in 
74H series devices).

FOr that matter can it tell if 3-state outputs are working correctly 
(rather than, say, being stuck high when they should be disabled)?

If you twant to simulate simple failures, how about wiring the IC to a 
DIL header with one or more pins open-circuited (and maybe tying pins 
that should be outputs to ground rather than to the output pin of the chip).

-tony




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