Y'know, I'm going a little OT, but I had fun once hot plugging a PC
peripheral card.  It was a simple 8 bit A/D card I designed to go in a
product, and pulling it out to change something required shutting down and
rebooting into my program that I was writing.  And being impatient, I didn't
want to wait.  So I started hot unplugging and plugging that A/D card I was
working on. It was such a simple card, I figured what harm?   I got away
with it about six times, but on the last try, smoke rose from the IDE hard
drive card.  I got real lucky, replaced the drive card and moved on with no
other damage.

Chris Eddy, Pioneer Microsystems

Andrew Mayo wrote:

> [snip]
> > > > No, in fact we often plug them into a powered-up circuit without a
> > problem.
> >
> You are very lucky. If two pins other than power or ground make contact
> first, current will flow through those pins, probably through protective
> diodes to the substrate. If the power source has a low impedance,
> sufficient current could flow through this path to destroy or damage the
> chip before proper power connections are made. I definitely would not do
> this.