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TPA2005D1 shutdown

Gerald Cooper
Prodigy 220 points
Other Parts Discussed in Thread: TPA2005D1

I'm working with a customer who has encountered several instances where the TPA2005D1 amplifier entered shutdown mode for an undetermined reason. 

Symptoms and observations:

1) Once shutdown begins, it persists until the power supply voltage is removed and then restored

2) While shutdown is underway, the outputs are static

3) The SHUTDOWN signal is strapped to the non-shutdown state

4) The package being used is the 8-pin MSOP

5) An examination of one PCB exhibiting the problem revealed proper soldering of the pad on the bottom of the package

Question #1: Are there any known mechanisms other than thermal overload and improper loads that will produce the shutdown state?

Question #2: Is it normal for the shutdown state to persist until the supply voltage is removed/restored? (Alternately, does the shutdown state behave the same way for thermal vs. improper load shutdowns?)

gerald

  • 0
    TI__Guru** 110745 points
    Hi Gerald,

    This device has short-circuit and thermal protection; the short-circuit protection can be triggered due to low impedance load, too much capacitance to GND at the outputs, or load, VDD, GND shorts.
    When does the device enter to shutdown mode? is it at startup? or is it working and then enters to shutdown mode?
    The device should exit shutdown mode due to protection (if the fault is removed) by driving low the shutdown pin and then driving it high again, have you tried this? or are you driving high the shutdown pin all the time?

    Best regards,
    Iván Salazar
    Texas Instruments
  • 0 in reply to Ivan Salazar
    Prodigy 220 points

    Ivan,

    The device works fine at startup, and the shutdown incidents have been very infrequent. We have not been able to correlate them to any particular event. Only a few finished products are exhibiting this symptom, and then only rarely.

    We don't have the option to exit the shutdown mode because the shutdown control pin is tied high continuously.  

    So, do both types of shutdown leave the device in continuous shutdown until either the power or the shutdown control pin is cycled?

  • 0 in reply to Gerald Cooper
    TI__Guru** 110745 points
    Hi Gerald,

    That's right, the protection circuit will set the device to shutdown mode until shutdown pin or power is cycled.
    Perhaps there's an over-current event that is triggering the protection and thus the device is set to shutdown mode.
    Have you tried reducing the input voltage level?

    Regards,
    Iván Salazar
    Texas Instruments
  • 0 in reply to Ivan Salazar
    Prodigy 220 points

    Ivan,

    The amp is driven by a op-amp stage, and I have driven that stage into clipping without being able to reproduce the shutdown.

    The failure occurs so infrequently that it is tough to correlate a test modification (such as lowering the input voltage)  to the failure rate.

     Gerald