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TAS5822M: TAS5822M : Over-temperature shutdown at no load

takashi furuya
Prodigy 60 points
Part Number: TAS5822M

Tool/software:

Hello, TI Team

I am not sure if I can communicate well because my English is not good enough, but thank you in advance.

When the speaker is not connected and white noise is sent via I2S, if the POWER_STATE register (offset = 68h) is set to Play state, OTSD_I in the GLOBAL_FAULT2 register (offset = 72h) will be set to '1'.

If OTSD_I is not set to '1', OTSD_I remains '0' no matter how many minutes of playback are performed.

This happens after power-on.

When OTSD_I is set to '1', the device instantly becomes hot.
Even if I reset the OTSD_I flag in software, OTSD_I is set to '1' again immediately.

Are there any possible causes?

  • 0
    TI__Mastermind 20431 points

    hi, takashi

    the brd you use is our evm or your own designed brd?

    can you kindly help clear below several points for deep analysis:

    1.pvdd, load resistance

    2.inductor Isat current

    3.amp configuration: pbtl or btl ? bd or 1spw, Fsw, BW?

    as otsd be 1 means amp is too heat, if the heat cannot decrease, the amp cannot recover to work.

    you can use 0x78 which clear all fault, but if the heat is still there, the fault still can be reported.

    thanks

    jesse

  • 0 in reply to Jesse Ji
    Prodigy 60 points

    hi, Jesse san

    I created the circuit with reference to the EVM board.

    1.pvdd, load resistance

    8-ohm speaker. Tests were conducted with no load.

    2.inductor Isat current

    6.2A(Max.) / 8.2A(Typ.)　MURATA:1274AS-H-100M=P3

    3.amp configuration: pbtl or btl ? bd or 1spw, Fsw, BW?

    BTL, BD

    Settings remain default.

    Thank you.

    Schematic.

  • 0 in reply to takashi furuya
    TI__Genius 9195 points

    Hi Takashi,

    Can you send a screenshot of the PCB layout for the device?

    Regards,

    Ramsey

  • 0 in reply to Ramsey Foote
    Prodigy 60 points

    Hi Ramsey

    There are four AMP circuits and an I2C multiplexer.
    TAS5822M is mounted on the solder side.

  • 0 in reply to takashi furuya
    TI__Genius 9195 points

    Hi Takashi,

    Is the fault on one of the amps or all 4? 

    Regards,

    Ramsey

  • 0 in reply to Ramsey Foote
    Prodigy 60 points

    Hi Ramsey

    I have made 18 boards and 3 of them have abnormal heat generation in 2 AMP locations.
    I thought the soldering of the GND pad was bad, so I checked with the mounting manufacturer, and they replied that there was no problem with the soldering.

    If no error occurs, no abnormal heat generation occurs even if speakers are connected and playback is performed for a long time.
    If the error occurs with the same AMP, the error occurs immediately after playback.

    I will check the I2S signal for noise, overshoot and undershoot.

    Thank you.

  • +1 in reply to takashi furuya
    TI__Genius 9195 points

    Hi Takashi,

    If the device is giving you an OTE fault, then it is unable to get heat out of the device. The schematic you sent looks fine, so unless there is something shorting the pins through enough resistance to not cause an over current event but enough to draw a lot of current, the it means the device's thermal pad is not connected to enough copper to dissipate the heat. From the layout, the three devices on the right (mostly the center two) are a bit restricted thermally which may be contributing to the problem. However, given that it is only on a few of the boards, I suspect you are correct that the devices are not making good contact on the thermal pad. 

    Regards,

    Ramsey

  • 0 in reply to Ramsey Foote
    Prodigy 60 points

    Hi Ramsey

    Thanks for the advice
    I'll try to re-mount the IC on the board that was NG.

    Regards