SLAAED3A October   2023  – May 2024 TAA5212 , TAA5242 , TAC5111 , TAC5112 , TAC5142 , TAC5211 , TAC5212 , TAC5242

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Analog Input Configuration
    1. 2.1 Differential AC Coupled Configuration
    2. 2.2 Single Ended AC Coupled Configuration
    3. 2.3 Differential DC Coupled Configuration
    4. 2.4 Single Ended DC Coupled Configuration
    5. 2.5 Analog Input Mux Configuration
  6. 3Power Tune Mode and Analog Mixing Feature
    1. 3.1 Differential AC Coupled Power Tune Mode
    2. 3.2 Analog Mixing
  7. 4Summary
  8. 5References
  9. 6Revision History

1 Introduction

TAC5212 is a CODEC with dual-channel analog-to-digital converters whose input pins (IN1P/M and IN2P/M) are configurable as differential inputs, single-ended inputs or single-ended mux inputs in AC or DC coupling. The type of input is configured through ADC_CH1_INSRC, the input impedance is configured through ADC_CH1_IMP and the coupling and common-mode tolerance is configured through ADC_CH1_CM_TOL.

Table 1-1 Input Configuration Selection
Input Configuration SettingB0_P0_R80 (ADC_CH1_CFG0) [7:6]Input Channel Configuration
0ADC_CH1_INSRC=[00]Analog differential input
1ADC_CH1_INSRC=[01]Analog single-ended input
2ADC_CH1_INSRC=[10]Analog single-ended mux INP1 input

3

ADC_CH1_INSRC=[11]Analog single-ended mux INM1 input
Table 1-2 ADC Input Impedance Selection
Input Impedance SettingB0_P0_R80 (ADC_CH1_CFG0) [5:4]ADC Channel 1 Input Impedance
0ADC_CH1_IMP=[00]Typical 5-kΩ input impedance (For 4 Vrms case, is 10-kΩ)
1ADC_CH1_IMP=[01]Typical 10-kΩ input impedance
2ADC_CH1_IMP=[10]Typical 40-kΩ input impedance
3ADC_CH1_IMP=[11]Reserved

The common-mode tolerance is defined as the variation of the common mode signal of the differential amplifier, this is depicted in Figure 1-1.

Common-Mode ToleranceFigure 1-1 Common-Mode Tolerance

In AC-Coupling mode, this device family supports three common mode tolerances; differentially 100 mVpp, 1 Vpp and rail-to-rail (supply to ground) and in DC-Coupling mode, it supports differentially of 1 Vpp and rail-to-rail (supply to ground). This common mode tolerance needs to be selected based on the maximum expected common-mode variation. Since wider common-mode tolerance does degrade other performance parameters, the recommendation is to select the lowest tolerance mode possible.

Table 1-3 Common-Mode Tolerance Selection
Common-Mode Tolerance SettingB0_P0_R80 (ADC_CH1_CFG0) [3:2]Input Channel Common-Mode Tolerance
0ADC_CH1_CM_TOL=[00]AC-coupled input with common mode variance tolerance supported 50 mVpp for single ended and 100 mVpp for differential configuration
1ADC_CH1_CM_TOL=[01]AC-coupled / DC-coupled input with common mode variance tolerance supported 500 mVpp for single ended and 1 Vpp for differential configuration (Expected SNR degradation of 1-2 dB)
2ADC_CH1_CM_TOL=[10]AC-coupled / DC-coupled input with common mode variance tolerance supported rail to rail (supply to ground) (Expected SNR degradation of approximately 35 dB, High CMRR supported only in this case)
3ADC_CH1_CM_TOL=[11]Reserved

Note that it is important to keep in mind the full-scale range (Vswing) of the device in all modes. This is especially important for large common-mode signals as they will limit the effective input range. In Mode 1 DC-Couple for example, a 500 mVp common voltage variant from the device internal common mode voltage of 1.375 V will limit the Vswing to 3.75 Vpp single-ended or 7.5 Vpp (2.65 Vrms) differential. In mode 2, it can support a common-mode range of 0V to Supply, but there would be no room left for a differential signal to be applied to the input pins at either of these extremes.

Mode 1 Common-Mode ExampleFigure 1-2 Mode 1 Common-Mode Example
Mode 2 Common-Mode ExampleFigure 1-3 Mode 2 Common-Mode Example