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TLV320AIC1110: Loopback function of TLV320AIC1110

Conor
Guru 10020 points
Part Number: TLV320AIC1110
Other Parts Discussed in Thread: TAC5111

Hi,

I'm working on verifying a custom board with TLV320AIC1110, but the loopback function isn't working as expected.
So, could you please tell me the following?

Q1
Is it correct to understand that the PCM loopback set by the 5th bit of the Mode Control Register outputs the PCMIN data from PCMOUT?
If there is an input from MIC, it is added, converted, and output from PCMOUT.
　
Q2
Is it correct to understand that even if loopback is enabled, the PCMIN audio data will be converted and output from EAR1O (EAR2O)?


-Additional notes below-
Currently, analog input is being input to board A, and analog output is being output from board B via communication.
If you enable board B's loopback from this state, nothing will be output from board B's EAR1OP-N.

Also, when I enabled loopback on board A, which is receiving analog input from MIC1P-N, a waveform similar to the input waveform is output from board A's EAR1OP-N. From these, it appears that the analog side is being looped back rather than the PCM side.

Thanks,

Conor

  • 0
    TI__Mastermind 34370 points

    Hi Conor,

    I believe what you're seeing is intended. The loopback directs PCMO to PCMI. On Board B, there is no PCMO so the PCMI is overriden to 0 and so no output is played as a result.

    So the answer to your first question is yes, you're describing it correctly.

    For Q2, PCMIN should not be receiving any additional data on the pin in loopback mode. The two signals will not add correctly. 

    Also just for your awareness, we are releasing a part later this year which is supposed to replace the AIC1110: TAC5111 (the AIC1110 is not planned to be obsolete, just not recommended for new designs). I understand if your design schedule doesn't allow for it but I wanted to make you aware, since our support will be much better for our more modern devices.

    Best regards,
    Jeff McPherson

  • 0 in reply to Jeff McPherson
    Guru 10020 points

    Hi Jeff,

    Jeff McPherson said:
    Also just for your awareness, we are releasing a part later this year which is supposed to replace the AIC1110: TAC5111 (the AIC1110 is not planned to be obsolete, just not recommended for new designs). I understand if your design schedule doesn't allow for it but I wanted to make you aware, since our support will be much better for our more modern devices.

    I'm considering converting the audio band to U-law. Is it possible to achieve the above with TAC5111? As far as I know, there are no other ICs that can convert to PCM.

    I also have an additional question.

    - Is it correct to understand that the PCM loopback set by the 5th bit of the Mode Control Register is a function that outputs PCMIN data to PCMOUT? If there is an input from MIC, will it be added, converted, and output from PCMOUT?

    - Even if loopback is enabled, am I correct in understanding that the PCMIN audio data will be converted and output from EAR1O (EAR2O)?

    - Regarding TLV320AIC1110, is the analog reference voltage 0V (VSS)? Or is it the Vref listed in Figure 12? Also, could you please tell me about the voltage value of Vref?

    Thanks,

    Conor

  • 0 in reply to Conor
    TI__Mastermind 34370 points

    Hi Conor,

    - I think the internal conversion to u law or a law has fallen out of date. All of our modern parts including the TAC5111 just output linear PCM aka uncompressed.

    - The loopback function will not add to PCMIN. The PCMOUT data from the MIC will replace the data input to the DAC side, essentially disconnecting PCMIN. I don't have a device to check this on at the moment but I would expect the PCMOUT data to appear on the PCMIN pin, meaning that adding another PCMIN source would not be possible. The data would be corrupted.

    - Similar answer as above, the PCMIN data that is used when loopback is OFF while not be regarded once loopback is ON.

    - The reference voltage of the device is VSS. This is equivalent to ground. VREF is an internally generated voltage that is the source that powers the MICBIAS generation.

    Best regards,
    Jeff McPherson