Q
Typically the ESD has the following characteristics (signal applied at
amplifier input) :
* 20 to 800 mA peak to peak
* period of 200 nano sec
* total duration of 1 micro sec
Is the "proprietary ESD protection circuitry" of OP07 sufficient to protect the
amplifier against such ESD ?
If not, what can we fear ?
A
This is a very high peak current and is likely to permanently damage the OP07
so you should think about adding some external protection circuitry. I have
included some general notes on ESD protection which ought to be of use to you.
If you have further questions, please let me know.
Most ICs are protected against ESD hits of between 1kV and 3kV based on the
human body model.
From the point of view of the end manufacturer or OEM, equipment must pass the
CE-mark which means meeting IEC1000-4-2 for ESD protection, and IEC1000-4-4
for Electrical Fast Transient (EFT) Immunity.
These standards apply only to inputs and outputs which are directly accessible
by the end user. The IEC ESD protection standard normally requires equipment to
pass level 3 (8kV air discharge, 6kV contact discharge). It is the
responsibility of the end manufacturer to ensure that their equipment passes
these tests.
We don't have any standard recommendation on how to protect circuits from ESD
damage as most manufacturers develop their own standard methods. Basically you
have to ensure that the energy from an electrostatic discharge is dissipated
long before it ever reaches the sensitive electronics. There are a number of
ways of doing this. Some methods include, a diode clamping circuit, tranzorbs,
sparkgaps on the PCB, capacitors to earth ground, a current limiting resistor,
and combinations of the above.
The final chapter in all our seminar books is dedicated to hardware design
techniques and deals with such issues as grounding, decoupling, parasitic
thermocouples and good PCB design.
