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TAS6424E-Q1: Outputs Stuck on High Impedance With No Faults Reported

Tom G.
Prodigy 60 points
Part Number: TAS6424E-Q1
Other Parts Discussed in Thread: TAS6424

Hi there,
So I have a customer using our product which has the TAS6424 chip built in. They are reporting issues getting any audio to play to the speaker outputs. I inspected the system and found that the TAS chip outputs were stuck in high impedance and setting the CHANNEL_STATE_CONTROL register did not do anything to the CHANNEL_STATE_REPORT register and the outputs were stuck in Hi-Z. The commands are going through as I see the CHANNEL_STATE_CONTROL register being set. I know that this can happen if the chip has any faults on it however I checked the following registers and they all reported no faults:
  • ILIMIT_STATUS
  • CLIP_WARNING
  • CHANNEL_FAULT
  • GLOBAL_FAULT1
  • GLOBAL_FAULT2
  • WARNINGS
  • DC_LOAD_DIAGNOSTICS1_REPORT
  • DC_LOAD_DIAGNOSTICS2_REPORT
 
I’d like to get an idea of what failure modes may cause this and what I can try to fix this. Thanks.
Additional thing I'd like to note is that even after reportedly disconnecting the speaker and power cycling out device, the chip was giving no open load warnings.
I'm not sure if that is related but worth pointing out.
Thanks,
Yutong
  • 0
    TI__Mastermind 19880 points

    Hi Yutong,

    Please read 0x09 register to check if enable auto DC diag or not. If auto DC diag is enabled, device will auto run DC diag when channels leave Hi-Z. And device will not enter play mode if any load error.

    According to your description, I think DC diag failed when connected high impedance load.

    Regard,

    Derek 

  • 0 in reply to Yanming Gong
    Prodigy 60 points

    Hi Derek,

    Thank you for getting back to me. We're having the device shipped to our manufacturer now and they will be able to test it once they receive it. I will keep you updated once we investigate a bit more.

    Why might this failure mode not result in anything reported on the registers I mentioned? I would expect at least DC_LOAD_DIAGNOSTICS1_REPORT or DC_LOAD_DIAGNOSTICS2_REPORT to report something. Is it possible that something was shorted which might have damaged the chip?

    Thanks,

    Yutong

  • 0 in reply to Tom G.
    TI__Guru 52360 points

    Hi Yutong

        You are correct there should be failure reported normally. But according to your description, our customer may have some problem with the I2C communication, maybe our device doesn't been correctly initiated yet, not in the PLAY state. Let's test it first.