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TPS61299-Q1: TPS61299-Q1 Stress Testing

Benjamin Werner
Prodigy 10 points
Part Number: TPS61299-Q1

Tool/software:

Working with the TPS61299-Q1.  I'm converter 2xAAA batteries (series) to a 5V output.  The part powers up fine.  It's loaded by 10uF DCAP, and similarly has 10uF DCAP on the input. Inductor is an LQH5BPN1R0NT0L 1uH 3.1A part.  VSEL resistor is 7.87k(1%).

I'm stress testing it now by powering up the unit and then, while powered, (1) shorting the output to ground or (2) adding in a large load cap (eg. 1mF).  Both of these tests cause the part to fail and required replacement.  Confused why this is failing.  Datasheet seems to outline several failure-mode protections including Short-Circuit protection, thermal shutdown, and input current limiting.

  • 0
    TI__Genius 13315 points

    Hi 

    Firstl of all , have you checked that the device was shot, like SW to GND short , internal power fet short

    (1) and (2) are the same, are you trying to start up the device with short circuit ?The short circuit protection means when Vout drops, the device will limit the input current then no much power dissipation to damage the device. Could you provide some waveforms of the behavior?

    Like Vin, Vout, SW and inductor current?

  • 0 in reply to Nini Zhong
    Prodigy 10 points

    Hi.

    Thank you for your response.  Here are some answers to your questions:

    • No, i'm not starting up the device with the short. Device powers up properly and reads 5V, then I apply the short.
    • Testing an unloaded already-damaged converter with a 3V power supply at the input, my drawn current pushes 3A+, so it does seem there is a short happening inside the converter
    • I don't have an SMU. If I measure the resistance with a multimeter, it appears that the damaged converters might have a short between SW and ground. I'm measuring about 1.5 ohms.  I no longer have functional devices I can probe for reference.
    • I unfortunately don't have instrumentation or a test-bench set up to capture waveforms.
  • 0 in reply to Benjamin Werner
    TI__Genius 13315 points

    Hi 3A will definitely short the device. Could you check the waveforms of Vout, inductor current and SW , Vin ,when you are doing the short test 

  • 0 in reply to Nini Zhong
    Prodigy 10 points

    Thank you again for your response here.  I unfortunately don't have the resources or the test bench set up to further evaluate this failure experimentally.  I'm really just trying to understand if this type of failure is to-be-expected given the component's specifications and how i'm testing the device.

  • 0 in reply to Benjamin Werner
    TI__Genius 13315 points

    Although the short circuit protection is active it doesn't mean the device won't damage under all the short conditions, depending on the load, short wire, short speed. Hope this is helpful to application.