Using two Mic Bias for four electret microphones with ADAU 1787
Hello together,
I would like to connect four electret microphones to the analog inputs of the ADAU 1787. I am using the evaluation board. My question is, if it possible (and a good/bad idea) to use the two microphone bias that the ADAU 1787 offers to supply four electret microphones?
The way I would do that is shown in the following image:
MICBIAS0 would be used for AIN0 and AIN1 via the Jumpers J11 and J14.
MICBIAS1 would be hardwired to AIN2 and AIN3 as illustrated below.
Thank you in advance for your opinion.
Best regards
Stefan
Hello Stefan,
My first thought is the current requirements for the microphones. The most you can source from the Micbias pins is 2ma total from both pins. 1ma from each pin if you have each pin drive two microphones. The 2ma specification is for the bias voltage generator and not the pins themselves. There is only one bias generator that can drive two pins.
So look at the datasheet for the microphone you will be using and see what the current requirements are. They very a great deal and some will require more current than is available from the bias generator. Also, the voltage is low so be certain the microphone can operate on the low voltages that is available.
I think it will work. It is certainly worth trying.
Dave T
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