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tvp5158 overvoltage protection

Enrique Romay
Prodigy 20 points

Other Parts Discussed in Thread: TVP5158

Hi all,

we are using a tvp5158 in a design for an automotive application and our schematic is derived from the evaluation module's, analog input ground is not isolated from the rest of the board (there's just one ground plane).

Now we are interested in adding overvoltage protection to the analog inputs to try and survive shortcircuit to battery (16v) tests, but we have no idea where to start, we are new to this protection of analog inputs.

Are there any guidelines or reference designs for making analog video inputs robust to overvoltage? thank you for any help.

 

  • 0
    TI__Mastermind 43875 points

    Automotive protection is a huge topic and there is not really anything specific to the TVP5158.

    I would suggest searching the web for some guidance on "automotive circuit protection" where you will find lots of information.

    To help protect the TVP analog video inputs though you can simply add generic ESD protection diodes to the input connectors. Input signal levels are in the 2V range and fairly low frequency (<10MHz) so special protection is not really necessary.

    The TVP inputs are AC coupled through low value capacitors so the probability of input ESD or short circuit damage is extremely low at the system level. A short directly to the TVP5158 input pin though will damage the device but I assume this is not the situation you are trying to protect.

    BR,

    Steve

  • 0 in reply to Steve Clynes
    Prodigy 20 points

    Hi steve! thank you for your fast answer,

    automotive normatives specify electric tests that include shortcircuit to battery Vcc in every input and output pin, that's why we were wondering if anyone could help us with a protection circuit to avoid frying the TVP (I think it specifies 2V5 max input voltage).

    ESD protection has been included, AC coupling is copied from the reference design, main voltage regulators are designed to absorb 80v peaks, and we have seen a device that has a separate ground plane for the analog input before something like an opamp

    anyone has any experience protecting analog inputs against overvoltage?

  • 0 in reply to Enrique Romay
    TI__Mastermind 43875 points

    Unfortunately I don't have anything more specific, sorry.

    BR,

    Steve