My PCB gets DC power from a connector, let's say the traces coming from the connector are VIN and RTN. I have a TVS (for ESD protection) between VIN and chassis ground. Should I put another TVS between RTN and chassis ground? RTN becomes board ground after it and VIN pass through a common mode choke. If a TVS is needed on RTN, what reverse working voltage should it have? As low as I can find?

Edit: I can make this question simpler. I know I should put ESD protection (like a TVS) on signal lines that exit the enclosure and even on power lines. But what about ground lines? I am using a bleeder circuit between 'ground' and 'chassis ground' so they are not the same. When they ESD gun the ground line, will it cause ripples on the board ground planes without a TVS?

  • \$\begingroup\$ No. Ask yourself under what conditions the TVS ever would conduct. How would a voltage develop that is large enough to trigger a TVS? \$\endgroup\$ – mkeith Dec 8 '16 at 7:31
  • \$\begingroup\$ @mkeith But why couldn't an ESD discharge happen on the RTN wire? Also, it says in this USB2 Littelfuse application note link that both VBUS and GND should have a TVS. \$\endgroup\$ – BenYL Dec 8 '16 at 17:20
  • \$\begingroup\$ Can you add a partial schematic showing VIN, RTN, chassis ground and board ground? Also, can you elaborate on what is connected to chassis ground? Is this a large device in a metal box, or is it a plastic box and is chassis ground physically large net or??? And how much total power (roughly) does your device use? 100mA, 500 mA, 1A, 5A?? \$\endgroup\$ – mkeith Dec 14 '16 at 18:08

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