• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Subscribers 30 subscribers
  • Views 722 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TAS2781: No sound output

Ian Costabile
Prodigy 40 points
Part Number: TAS2781


Hi, I designed a PCB with TAS2781 and although communication seems fine when writing the registers, there is no audio signal in the outputs. I'm connecting it to a Teensy 4.1 and can see the TDM signals are working correctly.

My connections are:

AVDD > 1.8V
PVDDH > 20V
PVDDL > NC (I'm not using batteries)
IOVDD > 3.3V

ADDR > GND (to select the first address, 0x70)

SCL > to MCU and 2.2K pullup to 3.3V
SDA > to MCU and 2.2K pullup to 3.3V
NC_SCLK > GND (I2C mode)
NC_SDO > GND (I2C mode)

SBLCK > TDM clock from MCU
SDIN > TDM data from MCU
FSYNC > TDM frame from MCU
(all TDM signals were tested with an oscilloscope and are OK)

SDZ > MCU digital pin (I'm setting it to HIGH for the I2C communication)
IRQZ > 20K pullup to 3.3V (IOVDD)
MODE > GND
PWM_CTRL > 1K pullup to 3.3V (IOVDD)
DREG > 1uF to GND





For the code, I'm sending the power-up initialisation sequence, followed by the pwr_mode0 sequence as per sections 10.1 and 10.2 of the datasheet.

I2C comm works fine when writing to the registers. Am I missing something?


Any help will be very much appreciated.

Thanks,
Ian

  • +1
    TI__Mastermind 21185 points

    Hi Ian,

    the issue here is likely that you are using PWR_MODE0 without PVDDL present. I would expect the device to have some issue. 

    if you do not want to provide an external PVDDL that is OK, but you will need to use PWR_MODE2 so that the device will generate PVDDL itself from an internal LDO. 

    When using PWR_MODE2 make sure to remove the 10uF decoupling capacitor from PVDDL. if this 10uF is not removed the LDO will not come up completely and it will get stuck. 

    Regards,
    Arthur

  • 0 in reply to Arthur Brown
    Prodigy 40 points

    Hi Arthur,

    Thank you so much, that did the trick!

    I want to explore DSP now as I'd like to do some equalizing on the signal. What route would you recommend? I can't find much documentation about this in the datasheet.

    Thank you,
    Ian

  • 0 in reply to Ian Costabile
    TI__Mastermind 21185 points

    Hi Ian,

    We have a few relevant app notes. the smart amp tuning guide gives a better description on how to do the actual tuning

    TAS2781 Audio enhancements https://www.ti.com/lit/an/sloa329/sloa329.pdf?

    Smart Amplifier tuning guide https://www.ti.com/lit/an/slaa751/slaa751.pdf?

    A few notes;

    -to get the best performance you will need to have a model of the speakers Thiele Small parameters. this will rarely be provided by speaker vendors, so you may need to measure it yourself. it can be done with the Smart amp learning board 2 https://www.ti.com/tool/PP-SALB2-EVM. (but we are phasing this out and are developing characterization that can be done with only the EVM itself) if you need characterization You can ship me the speakers and I can do it for you.

    -set the devices channel gain to match your supply voltage. (I mean the AMP_LVL register field) for example if your supply voltage is 12V, set the AMP_LVL such that 0dBFS = 12Vp out of the device.

    -first tune the EQ with low volume (30/100 windows volume for example) do this first with a microphone to objectively flatten the response, then listen to music you know and tweak it to the sound you like. it is always a good idea to not use 'boost' EQ(EQ with positive gain) the audio clarity will be better if you only cut away frequencies and then compensate with positive volume control.

    -then tune with higher volume the Dynamic range compressor DRC. you will need to use this to maintain the sound balance as the volume increases. likely you will need to compress more in mid and high bands. generally it will sound better to use low compression ratios. <2:1

    Regards,
    Arthur

  • 0 in reply to Arthur Brown
    Prodigy 40 points

    Thanks Arthur,

    All this looks good! We have requested access to PPC3 so hopefully we will be able to test it soon.

    Regards,
    Ian