Analog Devices ADAU1772 User Manual page 10

UG-177
Figure 32. Mic Bias Enable and Gain
Stereo Line Input
The stereo input jack, J22, accepts a standard stereo TRS 1/8-inch
mini-plug (tip=left, ring=right) with two channels of audio.
Digital Microphones
PDM digital microphones can be connected to standard 0.100"
Headers J6 and J7. For example, the Analog Devices ADMP521
digital microphone on the
ADMP521Z
plug directly into the header.
To utilize the digital microphone headers on the EVAL-
ADAU1772Z board, first make sure that the proper settings
have been made in SigmaStudio. Navigate to the PIN/PAD
Control tab in the Hardware Configuration/ADAU1772
Register Control section. Change the value of the MP6 drop
down menu to "Clock Output" (See Figure 33).
Figure 33. MP6, Clock Output
To set the value of BCLK, go to the PLL & Clock Control tab
and change the value of the Output Clock drop down menu to
the desired division on MCLK (See Figure 34).
evaluation board will
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Evaluation Board User Guide
Figure 34. Clock Output Enabled/Divided
Now, set the input of the ADAU1772 to be the digital
microphones instead of the ADCs by toggling the appropriate
Decimator Source settings. Navigate to the PGA/ADC tab to
find and set the following switches (See Figure 35).
Figure 35. Decimator Source
You are now able to route the digital microphones via the
appropriate inputs on the Audio Input cell.
Headphone Output
The headphone output, J23, connects to any standard 1/8-inch
mini-plug stereo headphones. The output pins can be driven by
either a line output driver or a headphone driver by setting the
HP_EN_L and HP_EN_R bits in the headphone line output
select register (Address 0x0043). Headphones can be driven
either single ended or differentially, and there are bits to disable
the LN and RN pins if single ended.
Line Outputs
The analog output pins, J19 and J21, can be used to drive
differential loads. In their default settings, these pins can drive
line loads of 10 Ohms or greater.
To use an external speaker, wires can be soldered to
unpopulated header pads J13 and J16 (See Figure 36).