TLC320AD81C Datasheet, PDF (20/47 Pages) Texas Instruments – Stereo Audio Digital Equalizer DC

2.10 Volume Control Functions
The 0.5-dB steps are based on characterized data (SDOUT).
2.10.1 Soft Volume Update
The TLC320AD81C uses a soft volume update. This allows a smooth change from one volume level to the
next. The volume is represented in 4.16 format – 4 bits for the integer part and 16 bits for the fractional part.
The volume level is user adjustable (software downloadable) and has a total range of 18 dB to –70 dB plus
mute. There are 0.5-dB steps with a gain error of less than 0.12 dB over the entire range excluding mute.
Soft mute is the lowest setting (see section 2.10.2, Software Soft Mute and also see appendix A, Software
Interface).
2.10.2 Software Soft Mute
Soft mute may be implemented by inputting all 0s into the volume control register. This will cause the
TLC320AD81C to ramp the volume down to the lowest volume setting (mute) (see appendix A, Software
Interface).
2.10.3 Hardware Soft Mute
Alternatively, an external hardware control pin (smute), may be used to activated soft mute. This mutes the
output of the DAC only. This has no effect on the volume setting for the DSP in the volume control register.
2.10.4 Mixer Control
The TLC320AD81C is capable of mixing serial audio data. The mixing is controlled through two mixer control
registers. SDIN1 and SDIN2 can be mixed with a user selectable gain for each channel. The gain control
registers are represented in 4.20 format– 4 bits for the integer part and 20 bits for the fractional part. The
gain level has a total range of 18 dB to –70 dB plus mute. There are 0.5 dB steps from 18 dB to –70 dB (see
appendix A, Software Interface ). Mixer mute is implemented by inputting all 0s into the mixer 1 or mixer 2
control registers. The mixer controls are not intended to be dynamically updateable. Changes during
operation may cause audible artifacts.
2.10.5 Treble Control
The treble gain level may be adjusted within the range of 18 dB to –18 dB with 0.5 dB step resolution. The
level changes are accomplished by downloading treble codes shown in appendix A, Software Interface
section.
2.10.6 Bass Control
The bass gain level may be adjusted within the range of 18 dB to –18 dB with 0.5 dB step resolution. The
level changes are accomplished by downloading bass codes shown in appendix A, Software Interface.
2.10.7 De-Emphasis (DM)
De-emphasis is implemented in the DAC and is hardware pin controlled. De-emphasis is only valid at
44.1 kHz.
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