there is now the requirement to protect electronics against ESD+EMC interference.
The ugliest of all requirements is IEC 1000-4-5 (surge). This is 500V up to 200V and up to 500A peak(!!!)
For mains supply lines it makes sense and for this purpose VDRs, spark gaps etc. are fine.
But how to protect these:
- differential input lines for sub-microvolt-resolution & accuracy (bridge measurement)
- 4...20mA output signal
- +/-10V outputs
- For this task there is a need for a electronic fuse / bidirectionional low voltage current limit in a small package with minimal extra components. Working voltage 3,3V...30V; 80V peak rating, holding currents <200mA. Also response time have to be < 1µs. Voltage drop across should be << 100mV. I didn't find anything suitable on the market.
- "electronic" TVS-Diodes that have near zero dynamic resistance, even negativ dynamic resistance would be fine. So clamp voltage is just a little higher than rated voltage. Peak current handling capacity should be > 25A @10/1000µs.
And I am surely not the only one that have to meet surge requirements. So I am astonished that there are no good solutions
for space constrained embedded electronics available.