Esd protection for pxi ttl lines

[rellutzu]

esd ttl

Hello all!
I'm working on a protection circuit for a pxi interface.
Basically I have to isolate the DUT from the command circuit through a pcb
that protects galvanic/ against Esd/ against UnderVolt-Overvoltage.

Now I've chosen an optocoupler for the galvanic isolation.
But I need to be protected also against Esd.
Where these diodes(zener is my choice) should be placed?

Right after input?
What if an Esd occurs at the output of my protesction circuit and it destroys my Dut?

Best regards!

 

[IanP]

ttl esd

Zener diodes (+ small resistor in series) should be added at "hazardous" side; the other side is protected by galvanicaly isolated optocoupler circuit .. see picture below ..

Regards,
IanP