PCM2900CEVM-U: Need a mic input can use the Vin L and Vin R for mic in?

Dominick Iacovelli1

Part Number: PCM2900CEVM-U
Other Parts Discussed in Thread: PCM2900

HI,

Where's the mic input can i use Vin L(pin12) or Vin R (pin13) for MIC input? any other part in that family that has all requirements I need (USB, HID min 3 inputs, Left and Right head phone and one mic

Any suggestion on what part to use ?

11 months ago

0 Jeff McPherson 11 months ago

TI__Mastermind 30075 points

Hi Dominick,

Yes VINL and VINR can be used as mic inputs.

The parts you're describing can be found here. They all support the features you're asking for: https://www.ti.com/audio-ic/converters/usb/products.html

Best regards,
Jeff McPherson

0 Dominick Iacovelli1 11 months ago in reply to Jeff McPherson

Prodigy 50 points

Hi Jeff,

What about the bias voltage I have to generate my own? if I am using the PCM2900 also If I only use one mic input the other VIN can be left open?

Thank you ,

Dominick Iacovelli

0 Jeff McPherson 11 months ago in reply to Dominick Iacovelli1

TI__Mastermind 30075 points

Hi Dominick,

Yes you have to generate a bias on your own. These parts do not provide one.

If you are not using a VIN input we recommend you AC couple the input to GND using a 0.47uF or similarly sized capacitor

Best regards,

Jeff McPherson

0 Dominick Iacovelli1 11 months ago in reply to Jeff McPherson

Prodigy 50 points

Thanks a lot! couple more things can I use Vcom pin 14 for the bias voltage source with 1K series resistor to the output ?

Dominick

+1 Jeff McPherson 11 months ago in reply to Dominick Iacovelli1

TI__Mastermind 30075 points

Hi Dominick,

I would keep the AC coupling capacitor on VCOM to keep it stable. The resistor value depends on the impedance of the mic. Having it match the output impedance of the mic is the best practice. Otherwise, you can try using VCOM as the bias source.

Best regards,
Jeff McPherson

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PCM2900CEVM-U: Need a mic input can use the Vin L and Vin R for mic in?