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TAS2505: TAS2505: Sound stops above a limit level and never returns

Coelho Jérémy
Prodigy 15 points
Part Number: TAS2505


Hello,

We are using a TAS2505 chip on a 4.14.78 Linux kernel.
The driver port and the device-tree configuration have been made so we can play some sound on the device.
The speaker is a 8 ohms / 0.7 W.
The issue we are facing is a sound cut when the level is over a limit level (Speaker amplifier / Speaker Driver / PCM).
Even if the sound level is reduced, the speaker doesn't emit any sound until platform reboot.

We first tough it could be the over-current protection.
But the 'HP Over Current Protection Configuration (0x01/0x0B)' register's value is 0x10.
So, refering to the TAS2505 Applicatin Reference Guide:
- 'the Output current will be limited if over current condition is detected'
- 'No debounce is used for Over Current detection'
So it should not mute the speaker.

Does a DAC overflow can mute the speaker, even after level has been reduced ?

Is there another protection of the chip which could explain this behavior ?

Thanks for helping,

Regards,

Olivier

  • 0
    TI__Guru** 110745 points

    Hi Olivier,

    Are you using the HP or Speaker driver?
    There is no dedicated flag for Speaker (Class-D) output overcurrent, instead it automatically disables the amplifier at bit 1 from register 45 on page 1. There is more information on this thread: https://e2e.ti.com/support/audio-group/audio/f/audio-forum/832843/faq-tas2505-protection-flags-and-interrupts
    You may try disconnecting the load and leave the outputs floating, this should help identify if there is overcurrent event or something else.

    Best regards,
    -Ivan Salazar
    Applications Engineer

  • 0 in reply to Ivan Salazar
    Prodigy 15 points

    Hello, thanks for you answer, I'm trying your solution right now.

    Regards

  • 0 in reply to Ivan Salazar
    Prodigy 15 points

    Hello,

    We are using a small speaker driver.
    In each steps of the tests explained bellow, we have printed content of each registers describe here to try to understand the observed behaviour (so, registers 42/43/44/46/48/49 of page 0, and registers 11/45 of page 1 are printed).

    About the content of the specified registers, here is what we observe :
    * Before playing anything, bit 1 from register 45 of page 1 is set to '0', all other registers are set to '0' (except register 11 of page 1 which is set to 0x10).
    * When the output sound level is set to a 50 (a level which apparently works all the time) and we play a sound, the speaker plays all the sound correctly, bit 1 from register 45 of page 1 is set to '1', all other registers are set to '0' (except register 11 of page 1 which is set to 0x10).
    * When we stop playing the sound, eventually, bit 1 from register 45 of page 1 is set back to '0', all other registers are set to '0' (except register 11 of page 1 which is set to 0x10).
    * When the output sound level is set to a 100 (a level which apparently never works) and we play a sound, the speaker does play the sound for less than a second then stops playing, bit 1 from register 45 of page 1 is set to '0', all other registers are set to '0' (except register 11 of page 1 which is set to 0x10).

    We tried disconnecting the speaker and observe the same behaviour (bit 1 from register 45 of page 1 is set to '0' when playing at at too high volume).

    What does that mean ? Is there another speaker protection at work here ?

    Best Regards,

    Jonathan Aillet.

  • 0 in reply to Coelho Jérémy
    TI__Mastermind 47905 points

    Hi Jonathan,

    Ivan is out this week and will be returning Monday.

    Thank you for your patience,

    Jeff

  • 0 in reply to Coelho Jérémy
    TI__Guru** 110745 points

    Hi Jonathan,

    Do you have a schematic you can share? You may send it over private e2e message if don't want to post it on the forum.

    It would seem like overcurrent event is resetting the Class-D control bit (page 1 register 45). Since you also tried without the speaker connected, I wonder if you have some capacitor as part of an output filter that could be causing current peaks and potentially triggering OCP.

    Best regards,
    -Ivan Salazar
    Application Engineer

  • 0 in reply to Ivan Salazar
    Prodigy 15 points

    Dear Ivan,

    We sent you the relevant information through e2e message.

    Regards,

  • 0 in reply to Coelho Jérémy
    TI__Guru** 110745 points

    Hi, I'm following up over the private message.

    Best regards,
    -Ivan Salazar
    Application Engineer