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Original question:

Connection between digital ground and chassis ground

Power Ground - Chassis Ground connection

Eby Jayan
Expert 2115 points

HI

If I'm using a TVS on the Power line should this be connected to the Power Ground or the Chassis Ground .

Whether the Power Ground and the Chassis Ground should be Shorted or connected by a resistor or capacitor ?

Adding to that if I'm Connecting this to My chassis Ground  which is my earth how can I Survive the Dielectric strength test since there might be leakage current for the TVS diode .

Regards

Eby Jayan

  • 0
    TI__Expert 4830 points

     Hi Eby,

    I am not sure about the specific application here, but I will do my best to advise generally.

    1) The TVS device should be connected to the chassis ground. This will ensure that the TVS diode will redirect any unwanted current away from the sensitive devices in your application.
    Please review this forum from a few years ago: e2e.ti.com/.../tpd4e1u06-chassis-ground-or-digital-ground-connection

    2) There are a lot of differing opinions on this topic, so you will have to make a decision based on your application. It is hard to say whether shorting the power and chassis ground directly will be more robust than adding a resistor or capacitor. If you wish, you can populate a resistor or capacitor into the design, and if later you don't want to add one you can always just have a 0ohm resistor there.

    3) A Hipot (High potential, also known as dielectric strength test) test will typically run a high DC voltage (~1kV) for around 1-2 seconds. TVS/ESD diodes are designed to take higher voltages (8kV-30kV) in much shorter bursts, no longer than a few milliseconds. Does the former test describe your testing environment? If so, you may look into finding a Zener diode as opposed to a TVS diode. Zener diodes are designed to protect from DC over-voltages that are closer in character to the former test (~1kV, 1-2 seconds in length).

    I hope this helps answer all of your questions! If not, please do not hesitate to reply here.

    Have a good day,
    Joshua Prushing