Re: component overstress

Andy Ingraham (ingraham@wrksys.ENET.dec.com)
Tue, 12 Mar 96 08:32:39 EST

I understood George Stevens' comment about bus contention as meaning
that, if two or more drivers take the bus at the same time and in the
same direction (which sometimes is normal, i.e., in the case of an
open-collector/open-drain line), the magnitude and energy in the
overshoot/undershoot may be greater than anticipated, or greater than
you usually see when only one output drives at a time.

This might overstress the non-driving pin with enough current to cause
a latch-up condition.

As an example, on a PCI bus everything on the bus can drive SERR# low
simultaneously. SERR# is rarely asserted, but when it is, you don't
want it to toast something.

Regards,
Andy