Audio codec selection: Supports 12 PDM digital MICs, and includes a DAC to connect to an audio amplifier for speaker output.

Question

Hello, 
 Requirements:

Support for 12 digital microphone inputs (PDM interface).

DAC functionality is required to connect to an audio amplifier for driving a speaker.

Operating temperature range: -40&deg;C to +85&deg;C.

Questions:

Can two ADAU1787 chips be cascaded to meet these requirements? Can time synchronization be achieved via TDM?

Are there any better component recommendations for the above requirements?

Thank you.

DaveThib · Accepted Answer

Hello zeng1, 
 You mentioned needing to drive a speaker. How much power is required and what impedance is the speaker? 
 The ADAU1787 is designed to drive earphone speakers. So the power output is very low. 
 Yes, you can cascade two of the ADAU1787 chips to obtain 12 channels of DMICs. You will use the serial ports to exchange data which means you will have to compensate for the few sample periods to transfer some of the channels if the phase requirements of your application is critical for the 12 mics. But, that is easily done in the SigmaDSP. You will need to use some GPIO pins for four of the mics, (two pins) 
 Then it has a small BGA package that can be a problem or an advantage based on your application. 
 
 There are other choices. 
 You could use the ADAU7118 to collect eight DMICs and then transmit it to an ADAU1452 which can also accept four mics giving you the 12 you need. The only problem is there is no DAC so you would have to go to an external amp but this opens up the possibilities for greater power output. 
 Dave T)

SLA Status	Assignee	Support Status
SLA Closed. Met after 12 hours	galvinpjg Toshita_Khandare	Closed

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Audio codec selection: Supports 12 PDM digital MICs, and includes a DAC to connect to an audio amplifier for speaker output.

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