Datasheet

ManualsBrandsANALOG DEVICES ManualsLinear ICsADAU1772BCPZ-R7

Data Sheet ADAU1772

Rev. B | Page 45 of 116

DSP BYPASS MODE

When DSP bypass mode is enabled, a direct path from the ADC

outputs to the DACs is set up to enable bypassing the core pro-

cessing to listen to environmental sounds. This is useful for

listening to someone speaking without having to remove the

noise cancelling headphones. The DSP bypass path is enabled

by setting an MPx pin low. Figure 84 shows the DSP bypass path

disabled, and Figure 85 shows the DSP bypass path enabled by

pressing the push-button switch. The DSP bypass feature works

for both analog and digital microphone inputs.

DSP bypass is enabled when a switch connected to an MPx pin

that is set to DSP bypass mode is closed and the MPx pin signal

is pulled low. Pressing and holding the switch closed enables the

DSP bypass signal path as defined in the TALKTHRU register

(Address 0x002A). The DAC volume control setting is switched

from the default gain setting to the new TALKTHRU_GAINx

is enabled only on ADC0 and ADC1. The DSP bypass signal path

is from the output of ADCx to the input of the DAC(s).

When DSP bypass is enabled, the current DAC volume setting

is ramped down to −95.625 dB and the DSP bypass volume

setting is ramped up to avoid pops when switching paths.

Figure 84. DSP Bypass Path Disabled

Figure 85. DSP Bypass Path Enabled

ADAU1772

PGA AND ADC

DAC AND HP

AMPLIFIER

NORMAL

SETTING

HPOUTxP

HPOUTxN

CORE

PROCESSING

10kΩ

MPx

AINxREF

AINx

10804-076