• State
  • Locked Locked
  • Replies 8 replies
  • Subscribers 31 subscribers
  • Views 1213 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TAS5727 Spontaneously Shutting Down

Alex Fink
Prodigy 70 points
Other Parts Discussed in Thread: TAS5727

Hi,

We are using two TAS5727 digital amps in a product, and we are observing that one of the amps (the same one each time and only that one) sporadically shuts down. When this happens, many register values change and the amplifier stops outputting sound (unsurprising in this aspect given the register changes). We have observed this numerous times, and in each case, the error register in the "bad" amp does not report an error. This occurs during normal operation of our product with sound playing and with no clear cause. We are monitoring the I^2C lines and observe nothing on them when the problem occurs.


Is there any known or speculated cause for this type of behavior? I've included some of the values of the changed registers below, for reference, in case that is useful.

Register Address Original Value Changed Value
0x00 0x74 0x6C
0x03 0x80 0xA0
0x05 0x02 0x40
0x07 0x0020 0x03FF

Thanks for continued support via this forum--it is very helpful.

- Alex

  • 0
    TI__Guru 57800 points

    Hi, Alex,

    Thanks for your post. This is not an expected behavior, it looks like the amplifier is resetting itself, I would like to ask you a couple questions so I will have a better understanding of the issue. Can you please read back register 0x1B and let us know what is the value after the issue appears?. Also, can you please monitor the /RESET signal of the amp with the problem?.If my understanding is correct, this issue happens after Audio is being played correctly, right?. Is this issue happening in different boards or just in one prototype?.

    Thanks and Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    Prodigy 70 points
    Hi Diego,

    Register 0x1B has a value of 0x82 after this problem occurs. (The value is 0xC0 prior)

    I'll let you know once we set up a scope to monitor /RESET when the problem occurs.

    Yes, the problem is occurring after audio is being played. We have only observed this problem in one prototype, but this prototype is the only "complete" prototype we have at the moment, with all other components and peripherals, so it is the only one currently being tested.

    I agree that it looks like the amp is resetting. It is suspicious because a second TAS5727 amp on our unit is not resetting, and the two amps share a trace for /RESET, though I suppose a PCB-related problem is not out of the question. I will be certain to update you with our findings.

    Thanks for your prompt reply.

    - Alex
  • 0 in reply to Diego Melendez
    Prodigy 70 points
    Hi Diego,


    Today, we were able to monitor the /RESET signal of the amp. When this problem occurs, the voltage at /RESET is holding steady at ~3.3V.
  • 0 in reply to Alex Fink
    TI__Guru 57800 points

    Hi, Alex,

    Thanks for checking this. Can you please monitor DVDD power supply as well?. If the DVDD power supply has a power loss, the amplifier will be reset. Have you tried changing the IC in the board and see if the issue appears in a different amplifier?.

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    Prodigy 40 points
    Hi Diego,

    The board has 2 TAS5727 devices. They share control signals and power supplies. Only one amplifier shuts down. The 2 amplifiers are located within about 5cm of each other. I don't see how the power supply could have a problem that would only affect one amplifier.
    Furthermore, the data sheet seems to indicate that the amplifier should recover automatically from any conditions that cause it to shutdown.
    The amplifier never recovers from this condition.

    Richard Bryan
    Associate Hardware Engineer
  • 0 in reply to Diego Melendez
    Prodigy 40 points
    Hi Diego,

    We have confirmed that this problem occurs in at least 3 boards. So it is not an isolated case of one failed part.

    Richard Bryan
  • 0 in reply to RICHARD BRYAN
    Prodigy 40 points
    Hi Diego,

    I forgot to mention that we did also replace the chip on one board, but the shutdown still happens with the new part.

    Richard Bryan
  • 0 in reply to RICHARD BRYAN
    TI__Guru 57800 points

    Hi, Richard,

    Thanks for the complementary information. The amplifier will not return to normal operation if DVDD is removed as all the registers will be reset. Then the problem could be related to the layout of the amplifier as the issue follows the board. Can you please send me the schematics and layout so I can take a look and check for a possible cause? diego.melendez@ti.com. 

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer