Datasheet

3−19
TAS3103A, volume commands received for the other two monaural channels are not acted on until the active volume
transition completes. When the active volume transition does complete, the latest volume command received for the
three monaural channels during the previous soft volume transition time are serviced. LRCLK should not be stopped
during a volume transition.
Microprocessor
2048 Sample
Transition
4096 Sample
Transition
Soft Volume
Gain Control
Soft Volume
volume_setting
VSC
Subaddress 0xF1
= 1
VSC
Subaddress 0xF1
= 0
I
2
C Slave Mode
I
2
C Master Mode
I
2
C
Volume
Commands
GPIO
Volume
Commands
f (Volume)
Programmable
Biquad Filter
Channel-Processed
Audio
Loudness Compensation
Volume-Adjuste
d
Audio
Figure 3−16. Soft Volume and Loudness Compensation Block Diagram
Figure 3−15 is a more detailed block diagram of soft volume and loudness compensation, and includes the I
2
C
subaddress commands that control volume and loudness compensation. Volume control is accomplished using three
I
2
C subaddresses—volume control, mute/unmute control, and volume slew rate control.
Volume control in the TAS3103A applies a linear gain. The volume commands issued via I
2
C subaddresses 0xF2,
0xF3, and 0xF4 (monaural channels 1, 2, and 3, respectively) are signed 5.23-format numbers. These commands
are applied to mixers, whose other input port is the audio data stream. The mixer output is the product of the audio
data stream and the volume command. Examples of volume command settings follow.
Volume command = 0x3580 B07 = 0011 0.101 1000 0000 1011 0000 0111 = 6.6878365
Volume command = 0x01F0 000 = 0000 0.001 1111 0000 0000 0000 0000 = 0.2421875
Volume command = 0xCD6E FFE = 1100 1.101 0110 1110 1111 1111 1110 = −6.3208010