Hot-plugging damage what?

[davyzhu]

Hello all,

I heard that when a pc Card hot-plugged into its host socket, the host processor maybe damaged.

But why cause the damage? The current through the bypass capacities or the current through I/O, or something else?

And what are damaged? VCC-GND pair or I/O or control signal pins?

And can you give me some reference on this topic?

Regards,

Davy Zhu

 

[pixel]

Chip can be damaged by electrostatical discharge process (ESD).
Also if you have continually higher voltage than Vdd at the input.
You can avoid theese problems, by mechhanical construction of the card, when pins for gnd and Vdd are llonger than others, and because of that you can be shure that they will discharge electricity, before input pins are connected. Usually are killed input protection diodes by high current.
You can find some things on this topic in the book The Art of Electronic by Horowitz.

 

[Hai_Men]

Some IC/chips designed not to accept any input, any output or to sink any current before it reachs the operating voltage. Some with protection circuit that only operational at operating voltage. Almost all PC cards designed as cold insert (except pcmcia).

addition to pixel ... if you hot insert the card, the operating voltage not immediately achieved (eventhough it take only a few microsecond). Therefore risk of damaging the card is higher.

On processor side, hot insert may produce glitches to power and signalling system. The extend of damage greatly depend on the design of the board, some with greater tolerence and some without any tolerence.