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TPA3001D1 and Short Circuit Protection

Other Parts Discussed in Thread: TPA3001D1, TPA3112D1

I have constructed the circuit in the datasheet with an LC filter circuit shown for 8 ohm speaker.  By-the-by, I am very pleased with the audio quality.  However, I'm experiencing a problem with the short circuit protection feature in the chip.  It intermittently activates.  As far as I can discern there is neither a short to either ground or power, certainly not constantly and I don't believe intermittently.  When I measure resistance at the output of the chip (more specifically at the cathode of the two Schottky diodes), I get readings above 2.275k (readings change slowly upward toward 5.60k as a cap charges up).  Playing time for this problem varies between a second to up to 75 seconds.  Cycling the "Shutdown" pin to ground and back to the pull up voltage (Vcc: +16vdc) will always bring the output back to life, even if only briefly.  Occasionally, very occasionally, it will start back up on its own without recycling the "Shutdown" pin.

Obviously, I am looking for the cause.  Right now I am leaning towards a malfunctioning TPA3001D1 chip.  Is that a possible failure mode?  Is there anyway to trouble shoot this problem sans replacing the chip?  Do you have any other ideas for my to investigate?

  • Hi Fred,

    Welcome to E2E, thanks for your interest in our products!

    Can you share your schematic? It would be helpful to know your output hardware configuration. If there is too much capacitance at the output it could be a reason for this behavior.
    By the way, the TPA3001D1 is a pretty old part, why don't you take a look at newer devices like TPA3112D1.

    Best regards,
    Iván Salazar
    Texas Instruments
  • Ivan,

    Thank you for your prompt response.  Your answer that this could happen under high capacitance on the output was exactly the type of scenario I was looking for - how I might have screwed up.  However, the schematic is exactly as in the data sheet with the LC filter on the output for 8ohm speaker with cut-off frequency of 27kHz.  So the only capacitance elements, other than the parasitic capacitance of the PCB, were the 0.1uF and the 1.0nF shown on the data sheet.

    In any case, I built up two more devices for test and they both work perfectly, so I don't think the circuit or the PCB was the problem.  Having two that worked, I tried to replace the chip on the initial device but buggered up the pin pads, so I guess we will never know if it was the problem.  I suspect that the chip may have been bad or I may have caused it to fail due to over heating during assembly.  In any case, I am very pleased with the results thus far of the other two examples.  Enough so to progress on to production.

    Regarding the newer products, whenever I require a stereo class "D" amplifier, I'll definitely look into one of your newer chips.

    Sincere thanks,
    Fred G. Phillips, Jr.
    Exhibit Control Engineering
    102 Waterview Circle
    Forest, VA 24551
    (434) 385-4144
    WEB: www.exhibit-control.net