ZHCSPD7A April 2022 – September 2022 PCMD3140-Q1
PRODUCTION DATA
The device integrates a built-in, low-noise programmable microphone bias pin that can be used in the system for providing the supply to the MEMS digital microphone. The MICBIAS pin must be connected to an external 1-μF capacitor to analog ground (AVSS). The MICBIAS pin supports up to 5 mA of load current that can be used for multiple microphones. When using this MICBIAS pin for biasing or supplying to multiple microphones, avoid any common impedance on the board layout for the MICBIAS connection to minimize coupling across microphones. In the system, if the MICBIAS pin is used as a supply for digital microphones, then TI recommends using the MICBIAS configuration as AVDD, so that the digital microphone PDMCLKx and PDMDINx signals can be directly interface to the PCMD3140-Q1 without using any external level shifters. Table 7-9 shows the available microphone bias programmable options.
| P0_R59_D[6:4] : MBIAS_VAL[2:0] | P0_R59_D[1:0] : VREF_SEL[1:0] | MICBIAS OUTPUT VOLTAGE |
|---|---|---|
| 000 (default) | 00 (default) | 2.75 V (same as the VREF output) |
| 01 | 2.5 V (same as the VREF output) | |
| 10 | 1.375 V (same as the VREF output) | |
| 001 to 101 | XX | Reserved (do not use these settings) |
| 110 | XX | Same as AVDD |
| 111 | XX | Reserved (do not use this setting) |
The microphone bias output can be powered on or powered off (default) by configuring the MICBIAS_PDZ (P0_R117_D7) register bit. Additionally, the device provides an option to configure the GPIO1 or GPIx pin to directly control the microphone bias output powering on or off. This feature is useful to control the microphone directly without engaging the host for I2C communication. The MICBIAS_PDZ (P0_R117_D7) register bit value is ignored if the GPIO1 or GPIx pin is configured to set the microphone bias on or off.