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LM49450: How is the analog line input mixed/activated/switched with the I2S digital input?

Georgy Chen
Prodigy 20 points
Part Number: LM49450
Other Parts Discussed in Thread: TLV320DAC3101, TLV320DAC3100, TAS2505

Hi,

We are designing a robot control board, and LM49450 seems a really good fit for our purpose. Understands from other posts that this pre-NS-chip is less supported without any demo board available. Still, we would like to know how is the analog line input mixed/activated/switched with the I2S digital input.

From figure 1 in datasheet (https://www.ti.com/lit/gpn/lm49450), it seems that there is a control line from i2c interface to control the I2S DAC and/or Analog Line inputs.

Are they mixed or switched? Or can be individually controlled volume-wise?

Any information is appreciated.

georgy

  • 0
    TI__Guru** 102045 points

    Hi Georgy,

    Welcome to e2e.

    Unfortunately as you say these legacy devices are hard to support. The documentation of this device does not explain how it should be configured although it suggest it can be done. Also the GUI suggest this same thing:

    I don't have access to an evaluation board of this device to verify what commands are sent with this control.
    If you might want to find it through trial and error I would try with register 0x00. Sorry for not being of more help in this issue.

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

  • 0 in reply to Ivan Salazar
    Prodigy 20 points

    Indeed it seems like the input source can be switched. Trial and error may work, but

    without further information, we can only look for other chips at this moment.

    Thank you for your prompt reply.

    - georgy

  • 0 in reply to Georgy Chen
    TI__Guru** 102045 points
    Georgy,

    Perhaps we can help on suggesting different parts?
    What are the customer requirements?
    TLV320DAC3101 has a stereo Class-D and stereo Headphone outputs. It also features digital and analog inputs that can be mixed or switched.
    If they need mono output they can look at TLV320DAC3100, TLV32DAC3120 or TAS2505.

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