[sdiy] MIDI and ESD protection

Julian elfenjunge at gmx.net
Wed Feb 5 22:47:40 CET 2020


I wonder how I should go about protecting a 3.3V MIDI out circuit
against 8kV contact ESD.
When I use a TVS with 5V working voltage, most of the time I still have
16-20V clamping voltage over the diode for 8kV contact pulses.
With the 3.3V setup I only have a 10Ohm resistor limiting the current to
my UART TX pin.
with a 74hc14 as driver/buffer I can sink +/-20mA, but with 16V at 10 ohm I
have much more to sink.
I can't find anything about MIDI and ESD in the official specs or other
sources.

I'm new to ESD. So do I miss something? Is the short pulse time not
enough to fry the internal clamping diodes of a 74HC chip?

Any insights are welcome!

Julian




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