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TAS5731EVM Sound Output Issue

Jim Eastman
Prodigy 30 points
Other Parts Discussed in Thread: TAS5731M, TAS5731

Hi there, I have a TAS5731EVM that I've been having ongoing issues with.


I'm following all of the instructions I've found to set up for 2.1 output.

I have the jumpers (JP4 and JP5) set up to use the analog inputs.

All of the I2C jumpers (JP6 through JP10) are set correctly, and I've verified that I2S signals are present.

I'm able to power up the board, connect to it using the TAS57X1 GDE software. I can set up the registers appropriately (set X05 to 84, X07 to 30) and I should be getting sound out.

I see some DC voltages on the amp output pins but that's it.

I've gotten this unit to produce sound output on occasion, but only after fiddling for a while (lots of power cycling, sometimes fiddling with the PBTL jumper? sometimes other jumpers), but it's not worked consistently, especially recently.

This is quite urgent and any help would be appreciated. Thanks!

  • 0
    TI__Guru 57800 points

    Hi, Jim,

    Welcome to E2E, Thanks for your interest in our products!.

    This behavior seems strange,if the DC voltage that you see is about half the power supply, then the amplifier output stage is working. Can you please try a different audio source just to discard any issue in the ADC from MC57xxPSIA?. Also, can you please include the detailed steps you follow to connect and configure the amplifier with GUI in 2.1 configuration?.

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    Prodigy 30 points
    Hi Diego,

    Thanks for the reply!

    I've got it partially resolved, but it's still exhibiting some quirky behavior.

    The DC voltage on the SE pins (with speaker connected) after trying to start up and play audio is about 1.82V (half should be about 6V; running on a 12V supply).

    The curious behavior happens here:
    If I disconnect the two SE speakers from the amp, it starts behaving normally: sound starts coming out of the CD BTL channel. I can then reconnect the SE speakers to the amp and they will play audio normally as well.

    No clue why it works this way, but it at least provides me with a temporary fix.

    To your questions:
    My setup is such:
    I wire everything up (attach amp board to MC57 board, attach leads for 5V and 12V supplies to the MC57 board, attach speakers to SE A, SE B, and BTL CD pin pairs, analog RCA inputs wired to analog audio source).
    I power on 5v, then 12v, then attach the USB cable to my laptop.
    Using the I2C utility in the GDE software, I then set:
    X1B 00
    X21 00 00 42 03
    X05 84
    X07 30

    No sound comes out of the speakers until I disconnect the SE A and SE B speakers. Then sound starts coming out of the third speaker. I'm able to reconnect the SE speakers and they play sound normally at this point.
  • 0 in reply to Jim Eastman
    TI__Guru 57800 points

    Hi, Jim,

    Thanks for the detailed information, I was able to replicate the behavior you mention. It is caused because the TAS5731M has a Pin to Pin short circuit protection feature (PPSC) that monitors the power stage looking for a short or DC offset in the outputs. In 2.1 mode, a small voltage is coupling through the load to the SE output pins from split caps, this small voltage is detected by the amp as DC offset, so the PPSC protection puts the amplifier into shutdown. 

    Once you disconnect and connect again the loads, the amp will start normal operation because this feature works only during startup. A power cycle on PVDD will also fix the issue. 

    This EVM was designed for the TAS5731, this part doesn't have the PPSC feature. In order to use the TAS5731M and avoid PPSC to shutdown the amplifier, you need to change resistors R20, R21, R22 and R23 from 4.99K to 100K ohm.

    Also, I would like to mention that you need to configure the output MUX register to setup correctly the output channels in 2.1 mode. So, the basic code required to configure the amplifier in 2.1 mode will be:

    X1B 00
    X21 00 00 42 03
    X25 00 01 32 45
    X05 84
    X07 30

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    Prodigy 30 points
    Thanks! I finally had a chance to replace those resistors (they were not easy to get to!), and that solved my issue.