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TPS2595: TPS2595 does not trigger short circuit protection

zunuran nasrullah
Prodigy 240 points
Part Number: TPS2595
Other Parts Discussed in Thread: TPS5450

Tool/software:

We are using tps2595 for undervoltage, overvoltage and short circuit protection for our device. Undervoltage and overvoltage protections are working fine but the issue we are facing is with short circuit protection. When we shorted 5V and GND pins together then we observed that area around TPS5450DDAR buck converter got very hot, we had to remove the short circuit. We are suspecting that short circuit protection is not working in our system. Because if short circuit triggers then there should be complete power cut from the system and no component should get hot or damaged. Schema 2024-10-28.pdfI am attaching schematic for reference. Your help will be appreciated. 

  • 0
    Prodigy 240 points

    anyone here to respond? Thanks

  • 0 in reply to zunuran nasrullah
    TI__Mastermind 39315 points

    Hi Zunuran,

    How much current are you sensing when you are performing this short circuit test. Is eFuse performing auto-retry? Is TPS5450 performing thermal shutdown?

    From my understanding of your description, you are shorting at the output of boost and power switch is before the step down convertor. The convertor should have done overcurrent limiting.

    To confirm if the issue is due to eFuse, can you check Vin, Vout, and current through the eFuse.

    Best Regards,
    Arush

  • 0 in reply to Arush Gupta
    Prodigy 240 points

    sorry for late reply. i was busy with other things in testing. Since i have 9V, 1A power supply so I guess even if short circuit happens, current cant exceed 1A. but I did observe voltage behaviour. 

    10.27V Vin, 10.27 Vout when no short circuit.
    9.73V Vin, 6.31 Vout when THERE IS a short circuit.

    is it helpful to figure out where is the issue? It seems to me that no component gets damage during short circuit but TPS5450 is getting very hot.

    should i add fuse with 12V, 5V and 3.3V rails separately to overcome the issue?

  • 0 in reply to zunuran nasrullah
    TI__Mastermind 39315 points

    Hi Zunuran,

    zunuran nasrullah said:
    10.27V Vin, 10.27 Vout when no short circuit.
    9.73V Vin, 6.31 Vout when THERE IS a short circuit.

    I am assuming this measurement is near the pins of eFuse (TPS2595). Device won't do short circuit protection for 1A current. short circuit protection in this device needs much higher current.

    If you are getting 9.73V from the supply, that means the supply is still not providing 1A current otherwise it would have gone into constant current mode and dropped the voltage. (assuming your power supply is capable of only 9V/1A) that means most likely, you are performing overcurrent test and not the short circuit test and the device is limiting the current and this is resulting in higher power dissipation at the device resulting in the heating up and then I am expecting the device to go into thermal shutdown.

    Please check all your results. Also, for TPS5450 device, if you have any specific question, please create another question with correct part number so that team specialized in that part can check your question.

    Best Regards,
    Arush