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TPS22810: High resistance when at operating temperature

Scott Cabelli86
Prodigy 60 points
Part Number: TPS22810

We have 16 of the TPS22810DRVT ICs on our board. Recently 2 of the 16 are showing anomalous behavior. After a cold boot, they operated fine and supply the necessary current (at 12V) to their sub-system. However,. if the TPS22810DRVT is disabled after warm operation, then re-enabled (to reboot the associated subsystem), the voltage appears too low to reboot the subsystem. 

How does the thermal shutdown behave (binary = Ie 0V or 12V), or can the resistance rise due to the operating temperature. 

Has there been any observed operation of a similar kind?

  • 0
    TI__Genius 10855 points

    Hi Scott, 

    Thanks for reaching out on E2E! I have not seen this behavior before, and I was wondering if you could elaborate on a few questions to help me get a better understanding.

    To reiterate your application, you have 12Vin. Sometimes during warm operation, the ON pin is asserted high and you are don't read ~12V on the output? Is my understanding correct?

    A few questions:

    1. Can you elaborate on the "warm" environment? Do the devices only fail after undergoing the cold boot first, then the warm test?
    2. What load current are you using? What are your system conditions (CIN, load capacitance, load resistance, CT, etc.)
    3. What voltage does the output rise to?
    4. What voltage are you using to assert the ON pin?

    Could you also attach a schematic and scope shots of one device working and one device failing? 

    As a quick explanation, the thermal shutdown turns on whenever the junction temperature of the device exceeds ~160C. 

    Thanks,

    Arthur Huang

  • 0 in reply to Alpha H
    Prodigy 60 points

    Correct - 12Vin.

    Correct - Sometimes during warm operation, the ON pin is asserted high and you are don't read ~12V on the output.

    Devices work as expected after cold boot. Subsequent enable/disable of the TPS22810 IC fail to provide the necessary voltage to the sub-assembly. 

    Load current is ~2.1A.  

    We've not been able to measure the output voltage, however, the associated 12V fan initially spins, but stops and vibrates as if a low voltage is on it. 

    3.3V logic is used on the enable pin.

  • 0 in reply to Scott Cabelli86
    TI__Genius 10855 points

    Hi Scott,

    It would be great to get waveforms of the behavior to get a better understanding of what's going on. Are you able to test the TPS22810 without the downstream load attached, and seeing if you're able to replicate the behavior? 

    What temperatures are you running the cold / hot operation at?

    Thanks,

    Arthur Huang

  • 0 in reply to Alpha H
    Prodigy 60 points

    Hi Arthur

    The IC is working as expected without a load and generally working with the load as well, but do have some anomalous cases. 

    Should we expect the load switch to be completely off during thermal shutdown (or disabling), or is there a residual voltage?

    Thanks,

    Scott

  • 0 in reply to Scott Cabelli86
    TI__Genius 10855 points

    Hi Scott, 

    The load switch will be off during thermal shutdown, but the output discharge functionality will not be engaged. Therefore, an output load will not be discharged during thermal shutdown, and there could be residual voltage on the output.

    Thanks,

    Arthur Huang