1 Introduction

The TAC5x1x and TAC5x1x-Q1 family of audio codecs have separate signal chains for recording (through analog and or digital microphones) and for playback (through DAC) of audio signals.

Each channel of the recording path follows the signal chain shown in Figure 1-1. The mixers described in Recording Path Mixers mixes up to four signals which can be selected from two ADC channels and four PDM microphone channels through a 6-to-4 mux.

Figure 1-1 Recording Path Signal Chain

Similarly each channel of the playback path follows the signal chain shown in Figure 1-2. The mixers described in Playback Path Mixers mix up to eight digital input signals from the main Audio Serial Interface (ASI) path along with two digital signals from the auxiliary ASI path, which is further processed down the signal chain.

When the Sample Rate Converter (SRC) is bypassed in the device, the Main ASI refers to the Primary ASI (PASI), and the Auxiliary ASI refers to the Secondary ASI (SASI) bus. When the SRC is active, the Main ASI refers to the ASI bus which is at the faster sampling rate. For more details on the sampling rate converter, see TAx5x1x Synchronous Sample Rate Conversion.

Figure 1-2 Playback Path Signal Chain

This application note describes how to configure the different mixers to get the desired signal output, and also describes the following key applications:

1. ADC Channel summation, which can be used to improve the dynamic range by 3dB, described in Application: ADC Channel Summation to Improve TAC5212 Dynamic Range.
2. Mixing the analog input signal of the TAC5412-Q1 with the digital input signal and play the resulting signal on the analog outputs, described in Application: Analog Input to Analog Output Signal Flow in TAC5412-Q1.