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Original question:

Non Use Pin Connection for TLV320AIC3263

TLV320AIC3263: Non Use Analog I/O Pin Connection

Jorge Brenes
Prodigy 20 points
Part Number: TLV320AIC3263


Dear Sir/Madame,

On my customer schematic, I don't use the inputs signals IN1L/Aux1, IN1R/Aux2, IN3L, IN3R, IN4L and IN4R.

No problem if all pins are left floating? I'm not sure if they can be totally disabled by software. Or do you recommend connecting a pull-down to them to avoid possible interference?

For the output pins, I don't use speaker outputs (RECP, RECM, SPKP and SPKM), do you recommend connecting them to resistor of equal value to the corresponding speaker resistor (8Ω and 32Ω respectively)?

In case LOL and LOR or HPL and HPR are not going to be used, what do you recommend me to connect them? Floating left or pull-down?

Best Regards,

Jorge Brenes.

  • +1
    TI__Mastermind 47945 points

    Hi Jorge,

    For input pins we recommend AC coupling unused inputs to GND with 0.47uF caps. The inputs can be disabled in software, but to improve noise performance they are AC coupled to GND.

    All output pins can be left floating. No load is necessary. Those outputs can also be disconnected in software.

    Best regards,
    Jeff McPherson

  • 0 in reply to Jeff McPherson
    Prodigy 20 points

    Thank you for your response, Jeff!

    Regarding the MICBIAS pin, is it necessary to connect it to the input I am using?

    Who sets the voltage of the codec inputs and outputs would be IOVDD, am I right? Example: if I supply the IOVDD pin with a level of 3.3 V, my analog input signal should be 3.3 V and my output would be 3.3 V.

    Best regards, 

    Jorge Brenes.

  • +1 in reply to Jorge Brenes
    TI__Mastermind 47945 points

    Hi Jorge,

    MICBIAS is only necessary if you are using an electret-condenser mic or some other mic that requires a supply voltage. If you are using line sources then it's not necessary.

    IOVDD sets the digital logic level for the device. It does not have any impact on the analog input or outputs. Section 2.11 in the Applications Reference Guide describes what each power supply is responsible for.

    Best regards,
    Jeff McPherson

  • 0 in reply to Jeff McPherson
    Prodigy 20 points

    Hi Jeff, 

    I assume that my analog inputs and outputs should have a level of 1.8 V because the recommended analog supply voltage is 1.8 V (just to confirm).

    Can I assume that these impedance values are the output impedances that I need to couple with my microphone and speaker?

    If you can recommend me an approach for MCLK I would be grateful. I know that the ASI configuration suggests a combination of crystal + oscillator, but I don't understand the implementation done in the EVM.

    Is there a register where I can see the TLV320AIC3263 status?

    Best regards, 

    Jorge Brenes.

  • +1 in reply to Jorge Brenes
    TI__Mastermind 47945 points

    Hi Jorge,

    Analog inputs and outputs do not have a "level" per say, but a full scale voltage, which is the max voltage allowed by the ADC/DAC. Those full scale values are found in the electrical characteristics table for a select few configurations. 

    The impedances you shared are load impedances for the speaker/headphone/line outputs. They aren't relevant to the microphone inputs.

    The EVM has a convoluted approach to MCLK since it has to support USB interfacing and sample rate conversion. I wouldn't use it as an example to start with. Simply, you just need a low jitter clock source. This can be from a crystal/oscillator like you said, or can come from a host controller/ whatever the master of the system is.

    Best regards,
    Jeff McPherson