Hi David,
In general, I would have to know the geometry of the equipment to
answer the question. In general, voltage is not so important as
current and it can be in the several tens of amperes. And...current is
not so important as di/dt for upset effects on equipment. The result
is that low voltage discharges can be worst than high voltage ones.
You should not be using ESD drain pins. The connection to the pin can
have voltage drops of hundreds of volts/inch and even a small fraction
induced into nearby circuits can cause upset. Charge dissipation
should happen as the board in inserted (if at all) to the frame, not
ever to a pin of the circuit pack. There is no such thing as a
"chassis ground" pin. Everything is tightly coupled. Take a look at:
http://emcesd.com/tt2002/tt050102.htm
for an example of this.
To adequately treat this subject would require a day of typing so this
reply is just a general overview.
Doug
David Heald wrote:
All,
Does anyone know of a sample waveform or general characteristics for worst
case V&I on an ESD drain pin when a circuit pack is inserted into an
equipment shelf? This is an odd question I know, but my management asked
for the info and I really have no idea (and it "shouldn't" happen anyway ;o)
I guess even a typical maximum charge that can be expected to be on a
circuit pack would be sufficient information.
Thanks in advance!
Dave Heald
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