TI TLV320AIC3104 

MICBIAS GENERATION

The TLV320AIC3104 includes a programmable microphone bias output voltage (MICBIAS), capable of providing output voltages of 2 V or 2.5 V (both derived from the on-chip band-gap voltage) with 4-mA output current drive.

In addition, the MICBIAS can be programmed to be connected to AVDD directly through an on-chip switch, or it can be powered down completely when not needed, for power savings. This function is controlled by register programming in page 0, register 25

CS-121064-DS-4 BC5MM Ext Data Sheet BC57E687C.pdf   page51

MIC_BIAS

The characteristics of the microphone bias include:

Power supply:

■ BlueCore5‑Multimedia External microphone supply is BAT_P

■ Minimum input voltage = Output voltage + drop-out voltage

■ Maximum input voltage is 4.4V

■ Typically the microphone bias is at the same level as VDD_AUDIO (1.5V)

Drop-out voltage:

■ 300mV minimum

■ Guaranteed for configuration of voltage or current output shown in Table 10.5 and Table 10.6

Output voltage:

■ 4-bit programmable between 1.7V to 3.6V

■ Tolerance 90 to 110%

Output current:

■ 4-bit programmable from 200μA to 1.230mA

■ Maximum current guaranteed to be >1mA

Load capacitance:

■ Unconditionally stable for 1μF ± 20% and 2.2μF ± 20% pure C

Powering microphones

http://www.epanorama.net/circuits/microphone_powering.html

Microphone Circuit

http://www.ece.ucsb.edu/yuegroup/Teaching/ECE2C/Lab/Lab1b.pdf

高品質可攜式音響設備設計實務

http://www.eettaiwan.com/STATIC/PDF/200808/20080801_OE_TI_TA_01.pdf?SOURCES=DOWNLOAD