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TLV320DAC3100: About LRCK,BCK at power-down

Tao_2199
Genius 5660 points
Part Number: TLV320DAC3100
Other Parts Discussed in Thread: AM3352

Hello,

Regarding to LRCK,BCK on TLV320DAC3100, my customer has some question.

They use linux driver for TLV320AIC31XX.(Used DAC block.) and use AM3352 as MCU.

www.ti.com/.../TLV320AIC31XXSW-LINUX

TLV320DAC3100 is master and MCASP0(FSX ACLKX）in AM3352 is an input port.

 

(Question)

(1)When audio signal isn’t input to DAC from AM3352, PLL,DAC,HP DRIVE and Class-D AMP block in DAC3100 are power-down.

(They think this seems specification of linux driver.)

At that time, LRCK,BCK line between DAC3100 and AM3352 aren’t low level and this level is DC 0.8V.

Is there any problem on DAC3100 at level(DC 0.8V)? Or is it specification? (No pronlem)

When DAC3100 is power-down, are LRCK and BCK port in DAC3100 an input ?

(If so, the LRCK and BCK port of both DAC3100 and AM3352 are an input.)

 

(2)They want LRCK and BCK port are an output anytime in DAC3100.

Is it possible to modify to output anytime in linux driver by them?

 

(3) When PLL and DAC are on, HP DRIVER and Class-D DRIVER make power-down.

In this case, is there any problem on DAC3100?

 

Regards,

Tao_2199

  • 0
    TI__Guru* 95145 points

    Hi Tao,

    Let me comment on your questions below:

    1. As long as DAC device is shutdown or in Hardware Reset state, the level at the digital inputs should not be a problem. I would say the digital inputs are Hi-Z when device is not powered.
    2. What does anytime means? This includes hardware reset and default state? Does customer need to get signal outputs from DAC or only concerned of the status of the digital pins (sink/source current)?
    3. There should be no problem in this case. The output drivers can be disabled even with the PLL and DAC enabled.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators

  • 0 in reply to Ivan Salazar
    Genius 5660 points

    Hello Ivan,

     

    (2)(Answer)

    Currently, the DAC is active only during audio playback and within 5 seconds after playback is complete.

    Except when the hardware is reset, they want to set the output on the DAC side in other above states.

    Also, they are considering that whether the DAC is set the output at period from the reset release to the first audio playback.

    Is it possible to modify to output on above setting in linux driver by customer?

     

    As an additional question.(Just in case they have a question.)

    Is there any problem on AM3352 side when the DAC is power-down, LRCK,BCK are stopped?

     

    Regards,

    Tao_2199

  • 0 in reply to Tao_2199
    TI__Guru* 95145 points

    Hi Tao,

    Let me clarify on the I2S (BCLK and LRCK) status. This interface is not able to output signals until the device is configured through register settings. It cannot output signals by default.
    You may be able to use this sequence:

    • Power up device
    • Configure register settings
    • At this moment, the device can output signals into I2S interface
    • If playback is not needed, you can disable the outputs to the speaker, and keep PLL and I2S interface active to keep BCLK and LRCK signals active.

    I can't comment on AM3352 device, not sure what would happen if LRCK and BCLK signals are not present.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators