SBAA600 October   2024 TAA5212 , TAC5111 , TAC5112 , TAC5211 , TAC5212

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Voice Activity Detection
    1. 2.1 VAD Configurations
      1. 2.1.1 User, Auto, Intermediate
      2. 2.1.2 VAD With ADC Recording
      3. 2.1.3 VAD Monitoring Channel
      4. 2.1.4 VAD Interrupt Pin
      5. 2.1.5 MICBIAS Enable During PDM Monitoring
      6. 2.1.6 VAD Clock Configurabilty
    2. 2.2 VAD Parameters
      1. 2.2.1 Initial Learning Period
      2. 2.2.2 Hold Over Counter
      3. 2.2.3 Wakeup Wait
      4. 2.2.4 Threshold
  6. 3VAD Performance Results
  7. 4Examples
  8. 5Summary
  9. 6References

2.1.1 User, Auto, Intermediate

VAD can be programmed by the user to be either in user mode, auto mode, or intermediate mode. Note that all VAD modes are only supported with an audio sample rate of 8kHz or 48kHz.

0d =User Initiated ADC power up and ADC power down: This is the user mode in which VAD monitoring is active and ADC power up and power down is initiated by the user.

1d = VAD interrupt based on ADC power up and ADC power down: This is the auto mode in which ADC is turned ON or OFF automatically based on the interrupt generated by the VAD algorithm.

2d = VAD interrupt based on ADC power up with user-initiated ADC power-down. This is an intermediate mode between user and auto modes. A voice triggered VAD interrupt powers on the ADC record path and the ADC continues recording until powered off through register write commands from the host. In this mode, the ADC must receive a register write to power on at the same time the VAD is powered on, but the VAD can keep the ADC powered down until voice is detected.

Table 2-2 shows the power benefits of using the VAD by comparing the current consumption on AVDD across the 3 modes.

Table 2-2 VAD Current Consumption
VAD Mode Voice Activity Detected? Typical Current (mA) Other Conditions
User Mode YES - ADC powered ON by host 6.899 AVDD = 3.3V; Fs = 8kHz, BCLK = 2.048MHz; TDM Format; CH1 enabled and monitored; MICBIAS Enabled
User Mode NO - ADC powered OFF by host 4.744
Auto Mode YES - ADC powered ON by VAD 6.799
Auto Mode NO - ADC powered OFF by VAD 4.571
Intermediate Mode YES - ADC powered ON by VAD 6.896
Intermediate Mode NO - ADC powered OFF by host 4.575

As Table 2-3 shows, VAD mode selection is done using the LPAD_MODE[1:0] bit of LPAD_CFG1[7:6] register (page = 0x01, address = 0x1E).

Table 2-3 VAD Mode Selection Using LPAD_CFG1 Register
Bit Field Type Reset Description
7-6 LPAD_MODE[1:0] R/W 00b Auto ADC power up and power down configuration selection.
0d = User initiated ADC power-up and ADC power down
1d = VAD interrupt based ADC power up and ADC power down
2d = VAD interrupt based ADC power up but user initiated ADC power down