SLASFD9 April 2025 TAC5301-Q1
PRODUCTION DATA
The TAC5301-Q1 consists of two pairs of analog input pins (INxP and INxM) that can be configured as either differential or single-ended inputs for the recording channel. The device supports recording of up to one analog channel and integrates an input swap feature (ADC_CH_SWAP (P0_R119_D[1])) to select the input pins for recording between the IN1x and IN2x using the low-power single-channel ADC. The input source for the analog pins can be either electret condenser analog microphones (ECM), microelectrical-mechanical system (MEMS) or line-in (auxiliary) inputs from the system board. Table 6-9 describes how to set the input configuration for the record channel.
| P0_R80_D[7:6] : ADC_CH1_INSRC[1:0] | INPUT CHANNEL 1 RECORD SOURCE SELECTION |
|---|---|
| 00 (default) | Analog differential input for channel 1 |
| 01 | Analog single-ended input for channel 1 |
| 10 or 11 | Reserved (do not use this setting) |
For the DC-coupled line input configuration, the DC common-mode difference (INxP – INxM) for the analog input pins must be within 3.4V to 6.0V to support the 2VRMS full-scale differential input in the default mode of operation. The DC differential common-mode voltage is later filtered out by the digital high-pass filter and the digital output full-scale corresponds to the 2VRMS AC signal in this case.
Figure 6-15 and Figure 6-16 show how to connect a DC-coupled microphone for a differential and single-ended input, respectively. The value of the external bias resistor, R1, must be appropriately chosen based upon the microphone impedance. For a differential input, the value of the external bias resistor is recommended to be used for half of the microphone impedance, whereas for a single-ended input, the external bias resistor is recommended to be the same as the microphone impedance.
In AC-coupled mode, the value of the coupling capacitor must be so chosen that the high-pass filter formed by the coupling capacitor and the input impedance do not affect the signal content. At power-up, before proper recording can begin, this coupling capacitor must be charged up to the common-mode voltage. For single-ended input configuration, the INxM pin must be grounded after the AC coupling capacitor in AC-coupled mode.
Figure 6-17 and Figure 6-18 show how to connect an AC-coupled microphone or line source for a differential and single-ended input, respectively. In AC-coupled mode, the device input pins INxP and INxM, must be biased appropriately for the DC common-mode value either using the on-chip MICBIAS output voltage along with external bias resistor, R0, or using an external bias generator circuit. The maximum value for resistor R0 depends upon the signal swing and the MICBIAS value programmed. See the TAC5xxx-Q1 AC Coupled External Resistor Calculator to calculate the R0 value for the desired system configuration.