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TAS2770: No audio out on some board

Eric BUSI
Prodigy 90 points
Part Number: TAS2770


Hi Team,

We have a board with a TAS2770 amplifier in production for several months. On some cards (around 5%), we have a problem with the audio output which remains inactive.
When we change the IC it works correctly.

We continued our research to find the cause of this problem.

Currently the TAS2770 is configured with VSENSE and ISENSE powered down (register PWR_CTL with 1 in VSNS_PD and ISNS_PD).

On a faulty card whose output is always at 0V, when the configuration with ISNS is activated then the audio output is correct.

Is there a reason why certain amps do not work if ISENS is not activated?
Or is the amp damaged?

Thanks,

Eric

  • TI__Mastermind 21055 points

    Hi Eric,

    This is certainly not expected behavior. 

    Have you tested by re-placing a failing IC on a known working board? It would help to rule out an assembly/solder issue.

    When the amplifier shuts itself down it will usually be able to report an interrupt that describes the failure. Can you please read the registers book0 page 0 register 0x22-0x25? this will tell us if it is common failure like a short circuit.

    In addition I would ask that you share the related schematic for TAS2770. Since this is public forum I will add you as a friend and you can share it to me over direct message if you prefer

    Regards,

    Arthur

  • in reply to Arthur Brown
    Prodigy 90 points

    Hi Arthur,

    I replaced a falling IC on a know working board and i have the same issue. And on the no working board, when we replace the IC, there is no issue.

    It therefore seems that there is no assembly/solder issue.

    Read of registers book 0 page 0 0x20 to 0x25:

    FC B1 0 0 0 0

    I send the schematic page for TAS2770 over direct message.

    Thanks

    Eric

  • in reply to Eric BUSI
    TI__Mastermind 21055 points

    Hi Eric, 

    Do you mean that you read register 0x22-0x25? from what you shared it does seem that some interrupts are showing, but not all are cause for concern.

    I apologize to ask you to do the same test again, but can you provide me a register dump of all book0 page 0 registers for the three following conditions. 

    1) working device where ISNS is powered down and audio is playing back correctly

    2) Failing board where ISNS is powered down and audio is NOT playing back correctly

    3) Failing board where ISNS is powered UP and audio is playing back correctly.

    And remember that the latched interrupt registers are cleared when read, so if you get the system into the broken state, and read the registers more than once then the latch interrupt bits may not be saved, and i cant evaluate them 

    Also, I did not see the schematic in private messages.

    Regards,
    Arthur

  • in reply to Arthur Brown
    Prodigy 90 points

    Hi Arthur,

    I sent you an image instead of a pdf file. Did you receive it?

    I had read register 0x20 to 0x25 in my previous message.

    I will redo the tests as you want and I will only read the registers once so as not to erase the latched interrupt register. I am preparing a test program to have a dump of all the registers and I will send you the results.

    Thank you for your help.

    Regards,

    Eric

  • in reply to Eric BUSI
    TI__Mastermind 21055 points

    Hi Eric, 

    No I dont see it, you sent through E2E correct?

    Regards,
    Arthur

  • in reply to Eric BUSI
    TI__Mastermind 21055 points

    Hi Eric, 

    I received the schematic, Are C28 and C42 populated? we generally will not recommend decoupling directly on the output pins unless there is also a series inductive element before the caps. 

    Regards,
    Arthur

  • in reply to Arthur Brown
    Prodigy 90 points

    Hi Arthur,

    C28 and C42 are not populated.

    By doing other tests and checking the I2C bus, in the TAS2770 driver init I have a bug in the software reset command.

    There is a write on the I2C bus of 41 01 01 00, instead of sending 41 01 01 to do a software reset. there is a 0 byte too many. So I was on the wrong track with the ISENSE register.

    Here the dump files, register 0x2b to 0x2e and 0x78 are not documented. Is it still useful, and what do they indicate?

    Regards,

    Eric

    Fullscreen dump reg TAS2770 failling board audio KO witout software modif.txt Download 
    ad 00 = 0x00
ad 01 = 0x00
ad 02 = 0x0c
ad 03 = 0x14
ad 04 = 0x00
ad 05 = 0x06
ad 06 = 0x00
ad 07 = 0xc0
ad 08 = 0x00
ad 09 = 0x08
ad 0a = 0x06
ad 0b = 0x02
ad 0c = 0x30
ad 0d = 0x10
ad 0e = 0x00
ad 0f = 0x02
ad 10 = 0x00
ad 11 = 0x04
ad 12 = 0x06
ad 13 = 0x07
ad 14 = 0x08
ad 15 = 0x14
ad 16 = 0x76
ad 17 = 0x10
ad 18 = 0x6e
ad 19 = 0x1e
ad 1a = 0x58
ad 1b = 0x01
ad 1c = 0x14
ad 1d = 0x4e
ad 1e = 0x00
ad 1f = 0x00
ad 20 = 0xfc
ad 21 = 0xb1
ad 22 = 0x00
ad 23 = 0x00
ad 24 = 0x00
ad 25 = 0x00
ad 26 = 0x43
ad 27 = 0x00
ad 28 = 0x00
ad 29 = 0x00
ad 2a = 0x00
ad 2b = 0xa1
ad 2c = 0xe0
ad 2d = 0x9e
ad 2e = 0xe0
ad 2f = 0x02
ad 30 = 0x05
ad 31 = 0x00
ad 32 = 0x80
ad 33 = 0xc0
ad 34 = 0x00
ad 35 = 0x00
ad 36 = 0x00
ad 37 = 0x00
ad 38 = 0x00
ad 39 = 0x00
ad 3a = 0x00
ad 3b = 0x00
ad 3c = 0x08
ad 3d = 0x00
ad 3e = 0x2c
ad 3f = 0x00
ad 40 = 0x00
ad 41 = 0x00
ad 42 = 0x30
ad 43 = 0x00
ad 44 = 0x00
ad 45 = 0x00
ad 46 = 0x00
ad 47 = 0x00
ad 48 = 0x00
ad 49 = 0x00
ad 4a = 0x00
ad 4b = 0x00
ad 4c = 0x00
ad 4d = 0x00
ad 4e = 0x00
ad 4f = 0x00
ad 50 = 0x00
ad 51 = 0x00
ad 52 = 0x00
ad 53 = 0x00
ad 54 = 0x00
ad 55 = 0x00
ad 56 = 0x00
ad 57 = 0x00
ad 58 = 0x00
ad 59 = 0x00
ad 5a = 0x00
ad 5b = 0x00
ad 5c = 0x00
ad 5d = 0x00
ad 5e = 0x00
ad 5f = 0x00
ad 60 = 0x00
ad 61 = 0x00
ad 62 = 0x00
ad 63 = 0x00
ad 64 = 0x00
ad 65 = 0x00
ad 66 = 0x00
ad 67 = 0x00
ad 68 = 0x00
ad 69 = 0x00
ad 6a = 0x00
ad 6b = 0x00
ad 6c = 0x00
ad 6d = 0x00
ad 6e = 0x00
ad 6f = 0x00
ad 70 = 0x00
ad 71 = 0x00
ad 72 = 0x00
ad 73 = 0xff
ad 74 = 0x00
ad 75 = 0xff
ad 76 = 0x00
ad 77 = 0x13
ad 78 = 0x00
ad 79 = 0x00
ad 7a = 0x00
ad 7b = 0x00
ad 7c = 0x00
ad 7d = 0x10
ad 7e = 0x78
ad 7f = 0x00

    Fullscreen dump reg TAS2770 failling board audio OK with software modif.txt Download 
    ad 00 = 0x00
ad 01 = 0x00
ad 02 = 0x0c
ad 03 = 0x14
ad 04 = 0x00
ad 05 = 0x06
ad 06 = 0x00
ad 07 = 0xc0
ad 08 = 0x00
ad 09 = 0x08
ad 0a = 0x06
ad 0b = 0x02
ad 0c = 0x30
ad 0d = 0x10
ad 0e = 0x00
ad 0f = 0x02
ad 10 = 0x00
ad 11 = 0x04
ad 12 = 0x06
ad 13 = 0x07
ad 14 = 0x08
ad 15 = 0x14
ad 16 = 0x76
ad 17 = 0x10
ad 18 = 0x6e
ad 19 = 0x1e
ad 1a = 0x58
ad 1b = 0x01
ad 1c = 0x14
ad 1d = 0x4e
ad 1e = 0x00
ad 1f = 0x00
ad 20 = 0xfc
ad 21 = 0xb1
ad 22 = 0x00
ad 23 = 0x00
ad 24 = 0x00
ad 25 = 0x00
ad 26 = 0x5b
ad 27 = 0x8e
ad 28 = 0x10
ad 29 = 0x72
ad 2a = 0x90
ad 2b = 0xa2
ad 2c = 0xe0
ad 2d = 0xa0
ad 2e = 0x60
ad 2f = 0x02
ad 30 = 0x05
ad 31 = 0x00
ad 32 = 0x80
ad 33 = 0xc0
ad 34 = 0x00
ad 35 = 0x00
ad 36 = 0x00
ad 37 = 0x00
ad 38 = 0x00
ad 39 = 0x00
ad 3a = 0x00
ad 3b = 0x00
ad 3c = 0x08
ad 3d = 0x00
ad 3e = 0x2c
ad 3f = 0x00
ad 40 = 0x00
ad 41 = 0x00
ad 42 = 0x30
ad 43 = 0x00
ad 44 = 0x00
ad 45 = 0x00
ad 46 = 0x00
ad 47 = 0x00
ad 48 = 0x00
ad 49 = 0x00
ad 4a = 0x00
ad 4b = 0x00
ad 4c = 0x00
ad 4d = 0x00
ad 4e = 0x00
ad 4f = 0x00
ad 50 = 0x00
ad 51 = 0x00
ad 52 = 0x00
ad 53 = 0x00
ad 54 = 0x00
ad 55 = 0x00
ad 56 = 0x00
ad 57 = 0x00
ad 58 = 0x00
ad 59 = 0x00
ad 5a = 0x00
ad 5b = 0x00
ad 5c = 0x00
ad 5d = 0x00
ad 5e = 0x00
ad 5f = 0x00
ad 60 = 0x00
ad 61 = 0x00
ad 62 = 0x00
ad 63 = 0x00
ad 64 = 0x00
ad 65 = 0x00
ad 66 = 0x00
ad 67 = 0x00
ad 68 = 0x00
ad 69 = 0x00
ad 6a = 0x00
ad 6b = 0x00
ad 6c = 0x00
ad 6d = 0x00
ad 6e = 0x00
ad 6f = 0x00
ad 70 = 0x00
ad 71 = 0x00
ad 72 = 0x00
ad 73 = 0xff
ad 74 = 0x00
ad 75 = 0xff
ad 76 = 0x00
ad 77 = 0x13
ad 78 = 0x0c
ad 79 = 0x00
ad 7a = 0x00
ad 7b = 0x00
ad 7c = 0x00
ad 7d = 0x10
ad 7e = 0x78
ad 7f = 0x00

    Fullscreen dump reg TAS2770 working board audio OK without software modif.txt Download 
    ad 00 = 0x00
ad 01 = 0x00
ad 02 = 0x0c
ad 03 = 0x14
ad 04 = 0x00
ad 05 = 0x06
ad 06 = 0x00
ad 07 = 0xc0
ad 08 = 0x00
ad 09 = 0x08
ad 0a = 0x06
ad 0b = 0x02
ad 0c = 0x30
ad 0d = 0x10
ad 0e = 0x00
ad 0f = 0x02
ad 10 = 0x00
ad 11 = 0x04
ad 12 = 0x06
ad 13 = 0x07
ad 14 = 0x08
ad 15 = 0x14
ad 16 = 0x76
ad 17 = 0x10
ad 18 = 0x6e
ad 19 = 0x1e
ad 1a = 0x58
ad 1b = 0x01
ad 1c = 0x14
ad 1d = 0x4e
ad 1e = 0x00
ad 1f = 0x00
ad 20 = 0xfc
ad 21 = 0xb1
ad 22 = 0x00
ad 23 = 0x00
ad 24 = 0x80
ad 25 = 0x02
ad 26 = 0x5b
ad 27 = 0x8e
ad 28 = 0x00
ad 29 = 0x77
ad 2a = 0x10
ad 2b = 0xa2
ad 2c = 0xc0
ad 2d = 0xa2
ad 2e = 0xc0
ad 2f = 0x02
ad 30 = 0x05
ad 31 = 0x00
ad 32 = 0x80
ad 33 = 0x80
ad 34 = 0x00
ad 35 = 0x00
ad 36 = 0x00
ad 37 = 0x00
ad 38 = 0x00
ad 39 = 0x00
ad 3a = 0x00
ad 3b = 0x00
ad 3c = 0x08
ad 3d = 0x00
ad 3e = 0x2c
ad 3f = 0x00
ad 40 = 0x00
ad 41 = 0x00
ad 42 = 0x30
ad 43 = 0x00
ad 44 = 0x00
ad 45 = 0x00
ad 46 = 0x00
ad 47 = 0x00
ad 48 = 0x00
ad 49 = 0x00
ad 4a = 0x00
ad 4b = 0x00
ad 4c = 0x00
ad 4d = 0x00
ad 4e = 0x00
ad 4f = 0x00
ad 50 = 0x00
ad 51 = 0x00
ad 52 = 0x00
ad 53 = 0x00
ad 54 = 0x00
ad 55 = 0x00
ad 56 = 0x00
ad 57 = 0x00
ad 58 = 0x00
ad 59 = 0x00
ad 5a = 0x00
ad 5b = 0x00
ad 5c = 0x00
ad 5d = 0x00
ad 5e = 0x00
ad 5f = 0x00
ad 60 = 0x00
ad 61 = 0x00
ad 62 = 0x00
ad 63 = 0x00
ad 64 = 0x00
ad 65 = 0x00
ad 66 = 0x00
ad 67 = 0x00
ad 68 = 0x00
ad 69 = 0x00
ad 6a = 0x00
ad 6b = 0x00
ad 6c = 0x00
ad 6d = 0x00
ad 6e = 0x00
ad 6f = 0x00
ad 70 = 0x00
ad 71 = 0x00
ad 72 = 0x00
ad 73 = 0xff
ad 74 = 0x00
ad 75 = 0xff
ad 76 = 0x00
ad 77 = 0x13
ad 78 = 0x0c
ad 79 = 0x00
ad 7a = 0x00
ad 7b = 0x00
ad 7c = 0x00
ad 7d = 0x20
ad 7e = 0x78
ad 7f = 0x00

  • in reply to Eric BUSI
    TI__Mastermind 21055 points

    Hi Eric, 

    Apologies for the delay due to the US holiday, and thank you for this additional data. 

    I will check it and get back to you in <48Hrs

    Regards,
    Arthur

  • in reply to Eric BUSI
    TI__Mastermind 21055 points

    Hi Eric, 

    I notice a few things, 

    the failing device is RevA, not sure if the issue is related to this, 

    On both devices the VBAT conversion is enabled, but during the audio failing case the VBAT value is being recorded as 0V, can you check that all power rails are present? including AREG and DREG. 

    Also On the failing device there doesn't seem to be a reported interrupt that is relevant, but i can see that the Class-D is powered down. 

    Since you say that ISNS was not the reason for the working and not working condition, do you know what the difference in init was that cause the working audio condition?

    Regards,
    Arthur

  • Prodigy 90 points

    Hi Arthur,

    Yes, I found an error while checking the I2C connection to the oscilloscope during init.

    When sending the SW_RST command there was one byte too many sent. This therefore had to be written a byte at 0 in the following register which is PWR_CTRL Rage.

    I think you can close this topic.

    Thanks for your help.

    Eric

  • in reply to Eric BUSI
    TI__Mastermind 21055 points

    Sounds good eric, I'm glad it is all working!

    Best,

    Arthur