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TPS1H200A-Q1: Fault pin Functionality Issue

Tejas P R
Prodigy 40 points
Part Number: TPS1H200A-Q1

Hi All, 

We are using the overload protection IC TPS1H200AQDGNRQ1 in our design, We have designed in such a way that Fault pin is Pulled High with 10K 3.3V and when IN pin is enabled we are getting proper output (High) and status of the Faut pin is Low which is not right as per the Datasheet, One more point we have pulled up the Delay pin with 100k 5V which will work in auto retry mode, could you please give clarity on Fault pin misbehaving functionality.

Thanks and regards

Tejas

  • 0
    TI__Mastermind 28385 points

    Tejas,

    The TPS1H200A-Q1 has a limited set of conditions where the device pulls the fault pin low:

    A couple of questions/notes here-

    • Do you have a graph of what the current is? For start-up, the most likely culprit is inrush current from some sort of capacitance on the load. Could you comment on what exactly is on the load?
    • I noticed the rail is 24V. Is this an automotive application or something else? If it is automotive- do note that this device is designed for 12V automotive rails and would not be able to handle ISO pulses such as load dump for 24V applications.

    Best Regards,
    Tim

  • 0 in reply to Timothy Logan
    Prodigy 40 points

    Hi Tim,

    Responses for your query.

      • For now we have not connected any Load for this Output, About the inrush current I don't think it will affect the FAULT Pin status.

      • Yes You are right The Input voltage is 24V, and this IC is used to protect from short circuit protection, and +24V is proper DC voltage and it is not automotive application.

    Our requirement is whenever the output short is open then the IC should work normally so we connected DELAY Pin to Pull up of 5V (as it is work in auto retry mode).

    I would like to hear from you for my responses.

    Thanks and Regards

    Tejas

  • +1 in reply to Tejas P R
    TI__Mastermind 28385 points

    Tejas,

    For this device- we only test/guarantee the short-circuit protection to work for the AEC-Q100-012 short circuit conditions for 12V automotive systems as described in the application note below:

    https://www.ti.com/lit/pdf/slva709

    For a 24V system- we do not test the short circuit capabilities and would not be able to comment on the durability/survivability of the device in one of these instances.

    If there is no load on the output, then probably what is happening is the open load detection is triggering and causing the fault pin to go low. If there is very low load current on the device:

    What happens is the device detects the open load and pulls low the fault pin. Could you put something like a 100ohm resistor on the output and see if you are still seeing this behavior?

    Best Regards,
    Tim

  • 0 in reply to Timothy Logan
    Prodigy 40 points

    Hi Tim, 

    You are right, in no load condition at the output the open load detection is triggering and causing the fault pin to go low.

    As per your suggestion we tested by adding Electronic load on the output, exactly for 10mA Load the Fulat pin is having 2.289V, for 11mA load, Fault pin status is exactly High i.e., +3.3V.

    So our issue got solved from your valuable suggestion, Thank you so much for the reply.

    Regards

    Tejas

  • 0 in reply to Tejas P R
    TI__Mastermind 28385 points

    Tejas,

    No problem- side note, but be careful when testing with an eLoad:

    https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1021866/faq-why-does-my-e-load-cause-my-high-side-switch-to-shut-down

    It is recommended to put it in CR mode to avoid erroneously triggering the current limit.

    Best Regards,
    Tim