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TLV320AIC3256: Unipolar Configuration and MICBIAS of 2.5V

JDJ
Expert 3171 points
Part Number: TLV320AIC3256

We are having difficulties in achieving unipolar configuration for headset connection and associated MICBIAS of 2.5V

Below are the configurations we have done to set the MICBIAS:

Intended operation

Register/s Updated

Bit/s Updated in the register

Bit/s Value

Power-down MICBIAS

Page 1 / Register 51: MICBIAS Configuration Register

D6

0

Set MICBIAS to 2.5V

Page 1 / Register 10: Common Mode Control Register

D6

0

Page 1 / Register 51: MICBIAS Configuration Register

D5-D4-D3

1-0-1

Power-up MICBIAS

Page 1 / Register 51: MICBIAS Configuration Register

D6

1

 

We have set the following:  DRVdd_HP = 3.3V, AVdd = 1.8V, VNEG = GND

With the above configuration, we observed MICBIAS of 3.3V instead of the anticipated 2.5V.Then we tried to set MICBIAS to other possible values but observed that it is always equal to the source(AVdd or DRVdd_HP) selected to generate the MICBIAS i.e., either 1.8V or 3.3V.

For further detail, I have also attached details of all the other configurations that we have done. 

Thanks

TLV320AIC3256 CodecConfigurations.xlsx

 

  • 0
    TI__Expert 3171 points

    To further clarify, we are looking for next steps in order to debug the problem of setting MICBIAS, specifically in the scenario above when MICBIAS is 3.3V instead of 2.5V in unipolar configuration. 

    Thanks!

  • 0 in reply to JDJ
    TI__Guru**** 168485 points

    Hi Jack,

    We're looking into your query and will get back to you as soon as possible.  Will try to have some detail early next week.

  • 0 in reply to Tom Hendrick
    TI__Expert 6440 points

    Hi Jack,

    The register settings for MICBIAS register appear to be proper.

    When Page 1, Register 0x33 is set to 0x68 the MICBIAS voltage should be 2.5V for CM setting of 0.9V.

    To get 3.3V, the registers setting should be 0x78. But since you are getting 3.3V for a 0x68 setting, it could be a register programming error or some sort of a short on the board.

    Could you please remove R933 from the board and directly measure the voltage on Pin 23?

    If it is a programming error, please read back Page 1, Register 0x33 and verify that the register value is indeed 0x68.

    Best Regards.

  • 0 in reply to Diljith
    TI__Expert 6440 points

    Let us know if you need further assistance on the above. I shall close the thread. Responding will re-open the thread..

    Best Regards.