1 Introduction

The TAX5XXX are TI audio devices where a new Analog Digital Converter (ADC) architecture is introduced without the Programmable Gain Amplification (PGA). This new ADC architecture integrates the PGA into the ADC module, thus removing the PGA block which normally used for additional amplification. This integration allows us to increase the performance of the signal chain as if the PGA is present. When additional gain or attenuation is needed, the device has DVOL register that provides gain from -80dB to 47dB with a 0.5dB step. This new architecture gives a dynamic range of 118dB in the AC-Coupled differential input configuration with 2 Vrms full-scale input. Normally in an audio application, the front-end connection of the audio converter is a microphone or line input. Microphone such as the Electret Condenser Microphone (ECM) or the HD-Series Microphone has Signal Noise Ratio (SNR) in the 50dB-70dB range and the maximum input level (AOP) is much lower than the converter full range input. Thus, amplification is added to increase the input level into the converter full-scale level. We can look at some examples of interfacing these microphones to these converters in this appliation note.