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LM4674: Output Short Protection

Roy Hsu
Genius 9300 points
Part Number: LM4674
Other Parts Discussed in Thread: TPA2012D2,

Hi Team,

In the datasheet, there is a short description about output short protection but details are not included.

I'd like to know about the mechanism of it. Does it monitor the current on the FETs of the H-bridges? Or does it monitor physical short between the output pins and the other pins like PVDD and GND? 

Thanks!

Roy

  • 0
    TI__Guru* 99815 points

    Hi Roy,

    Output short circuit protection is most likely current monitored.

    Unfortunately there is not much detail on these old legacy devices.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators

  • 0 in reply to Ivan Salazar
    TI__Genius 9300 points

    Hi Ivan,

    Do you have the test SOP of the output short protection? If that's not available for this device, you may also use any other device similar to this part as alternative.

    Thanks!

    Roy

  • 0 in reply to Roy Hsu
    TI__Guru* 99815 points

    Roy,

    Similar device is TPA2012D2. Typical over-current limit is 1.5A.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators

  • 0 in reply to Ivan Salazar
    TI__Genius 9300 points

    Hi Ivan,

    1. Can you check if its short-circuit protection functions the same way the LM4674 does?

    2. What does it mean by "goes to low duty cycle"? I guess it means that the FETs still conduct even when short-circuit happens, is that correct? Does it limit the output current at 1.5 A when short-circuit happens?

    Thanks!
    Roy

  • 0 in reply to Roy Hsu
    TI__Guru* 99815 points

    Roy,

    Actually the description is a bit confusing, but what happens when short-circuit protection is triggered is that output is shutdown. The output is not switching or conducting. The device can be set back to active mode by power cycling VDD or pulling down and then pulling up the SDx pin.

    This protection is most likely the same on LM4674, I'll try LM4674 protection over the next week to confirm if it could be the same as TPA2012D2.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators