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Original question:

[FAQ] How to design the COMP pin components for TPS923655 / TPS923654 / TPS923653 / TPS923652?

TPS923652：TPS923652(BOOST) short circuit protection function

HSU HUNG YUAN
Prodigy 20 points
Other Parts Discussed in Thread: TPS923652

Tool/software:

Use TPS923652 to build a BOOST architecture LED DRIVER. When the LED terminal is short-circuited, there seems to be no protection function? Only the FAULT PIN will be pulled low? (Vin=24Vdc, Iout=0.7A@39~42V (LED voltage)

  • 0
    TI__Mastermind 23190 points

    Hi HSU HUNG,

    There will be protection function. Please refer to Table 8-3 from the datasheet.

    Best Regards,

    Steven

  • 0 in reply to Steven Li
    Prodigy 20 points

    When the output LED is short-circuited, stop the FET switching. Looking at the overall circuit, it mean that the input is short-circuited? This is also the case in my actual test. Is there something wrong with my test method or parameter adjustment? There is no LED short circuit (BOOST) test waveform in the datasheet.

  • 0 in reply to HSU HUNG YUAN
    TI__Mastermind 23190 points

    Hi HSU HUNG,

    HSU HUNG YUAN said:
    When the output LED is short-circuited, stop the FET switching. Looking at the overall circuit, it mean that the input is short-circuited?

    Yes, you are correct. When LED is short-circuited in boost configuration, the VIN is actually short to GND through inductor, Schottky diode and current sense resistor. TPS923652 can only protect itself at this condition, but it cannot protect other system components. If you want to protect other components, you should design some protection mechanism in your system, like adding a power line FET to cut off the input power when such short circuit happens.

    HSU HUNG YUAN said:
    There is no LED short circuit (BOOST) test waveform in the datasheet.

    We do not provide this waveform since when we did this test, our bench supply limited the input power immediately when short circuit happened and the results were not representative.

    Best Regards,

    Steven