I'm designing a circuit which has Voltage regulator(IC), current source(IC), resistor, capacitors, LED, reed switch and capacitor. It has to survive 10KV ESD event.

My question is: 1) What components should I protect with spark gap and TVS diode? 2) How can I achieve this? Use both(spark gap and TVS diode) or just one? 3) Any other things I should consider in my design for the protection?

Update: ESD standard/model to follow : IEC 61000-4-2

Circuit has to survive the ESD event at all the points in the circuit including at the connector where it receives the power.

Thanks in advance.

  • \$\begingroup\$ Does it need to survive ESD at any point in the circuit, or just at external connections? \$\endgroup\$ Aug 15, 2014 at 16:10
  • \$\begingroup\$ What model of ESD? \$\endgroup\$
    – Andy aka
    Aug 15, 2014 at 16:29
  • \$\begingroup\$ I updated the original post. Please let me know if I should clarify further. \$\endgroup\$
    – zust4you
    Aug 15, 2014 at 16:52
  • \$\begingroup\$ "ESD events at all point of the circuit ..." what does that mean? Every node inside the circuit? Put it in a metal box and then just worry about where it connects to the outside world. \$\endgroup\$ Aug 15, 2014 at 21:00
  • 1
    \$\begingroup\$ @GeorgeHerold - Yes, I meant at every node. I can't put it inside the metal box as the user needs access to the connectors, and other components all the time. \$\endgroup\$
    – zust4you
    Aug 18, 2014 at 13:48

2 Answers 2


Here is the general approach you should take.

Any connectors and contact points to the outside world should have protection. The outer perimeter of the board should have a guard ring running around it with protection on it. This is because people tend to handle the board by the edges. This guard ring should be the ground for the rest of the system with a another ring concentric just inside.

All other internal nodes probably can't be protected, in fact bare boards are never considered to be ESD proof for all possible scenarios.

You can encapsulate the board to provide a little more protection, depending upon the encapsulation it can be quite good. 32 um of parylene would really help but is expensive (this is a mil standard).

But ultimately, the whole board should be inside of an enclosure to prevent contact and discharge.

  • 2
    \$\begingroup\$ Can you please elaborate about the another ring beside the guard ring you had mentioned in the post above. Where should this ring be? And what is its purpose? \$\endgroup\$
    – zust4you
    Aug 18, 2014 at 20:38

I'll put this as an answer, though it's a comment also.
I would expect all the IC's and LED to be susceptible.
I don't see how it's practical to put TVS diodes everywhere.
If they must have access to the circuit, perhaps you can ask them to wear a ground strap?


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