SDAA293 February   2026 TAC5111-Q1 , TAC5112-Q1 , TAC5311-Q1 , TAC5312-Q1 , TAC5412-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Detailed Description
    1. 2.1 Analog Input Hardware Design
      1. 2.1.1 Selection of External Bias Resistor
      2. 2.1.2 Selection of Coupling Capacitor
    2. 2.2 Analog Output Hardware Design
      1. 2.2.1 Selection of Output Coupling Capacitor
      2. 2.2.2 Output Capacitor Summary
      3. 2.2.3 How to Select ESD for Audio Ports
    3. 2.3 AC-Coupled and DC-Coupled
      1. 2.3.1 AC-Coupled Systems
      2. 2.3.2 DC-Coupled Systems
    4. 2.4 TAC5212 and TAC5112-Q1 Headset Detection Design
      1. 2.4.1 How to Implement Headset Detection
        1. 2.4.1.1 Headset Detection in AC-Coupled Output Mode
        2. 2.4.1.2 Headset Detection in DC-Coupled Output Mode
      2. 2.4.2 Debounce and Detection Real-Time Performance of Headset Detection
      3. 2.4.3 TAC5X1X-Q1 Family Other Advanced Features
  6. 3Summary
    1. 3.1 Configuration Example
  7. 4References

2.1.1 Selection of External Bias Resistor

For the selection of external components, it is recommended to choose the value of external bias resistor R1 according to the microphone impedance. For single-ended input, it is recommended that the external bias resistor matches the microphone impedance. If it is a standard headset interface, the MIC impedance is typically 2.2kΩ, so R1 should be selected as 2.2kΩ. For differential input, it is recommended that the external bias resistor value be half of the microphone impedance. If it is a headset MIC, R1 can be selected as 1.1kΩ.

AC-Coupled Single-Ended Mic Input Hardware Design: TAC5212 & TAC5112-Q1 Figure 2-1 AC-Coupled Single-Ended Mic Input Hardware Design: TAC5212 & TAC5112-Q1
AC-Coupled Single-Ended Mic Input Hardware Design: TAC5412-Q1 & TAC5312-Q1 Figure 2-2 AC-Coupled Single-Ended Mic Input Hardware Design: TAC5412-Q1 & TAC5312-Q1
DC-Coupled Differential Mic Input Hardware Design: TAC5212 & TAC5112-Q1 Figure 2-3 DC-Coupled Differential Mic Input Hardware Design: TAC5212 & TAC5112-Q1
DC-Coupled Differential Mic Input Hardware Design: TAC5412-Q1 & TAC5312-Q1 Figure 2-4 DC-Coupled Differential Mic Input Hardware Design: TAC5412-Q1 & TAC5312-Q1

TAC5212 & TAC5112-Q1 bias the ADC through an internal pull-up circuit, which means its MICBIAS pin is only used to power the microphone. The TAC5(3/4)12-Q1 operates differently: the device requires the voltage common-mode to be set externally. This can be done with the integrated MICBIAS or driven by the signal source. In the AC-coupled input configuration, reference Figure 2-1 and Figure 2-2, the MICBIAS pin of the TAC5(3/4)12-Q1 must be connected to the side of the AC-coupling capacitor close to the chip to achieve ADC biasing; in this case, the microphone must be powered by another power supply. Therefore, in terms of input mode compatibility, DC-coupling is the optimal choice for the TAC5(3/4)12-Q1 — in this mode, the MICBIAS can both power the microphone and provide proper biasing for the ADC input. The main advantage for DC-coupling the input signal is to use the input fault diagnostics, with more information found in TAx5xxx-Q1 Fault Diagnostic Features.

Since the performance of the devices changes with the input configuration, it is recommended to use the lowest common-mode setting possible that still satisfies the tolerance required by the system. For best performance in TAC5212 & TAC5112-Q1, AC-coupling is recommended.