SLAS509G April 2006 – July 2021 TLV320AIC3106
PRODUCTION DATA
The audio DAC includes a digital volume control block which implements a programmable digital gain. The volume level can be varied from 0 dB to –63.5 dB in 0.5-dB steps, in addition to a mute bit, independently for each channel. The volume level of both channels can also be changed simultaneously by the master volume control. Gain changes are implemented with a soft-stepping algorithm, which only changes the actual volume by one step per input sample, either up or down, until the desired volume is reached. The rate of soft-stepping can be slowed to one step per two input samples through a register bit.
Because of soft-stepping, the host does not know when the DAC has been actually muted. This may be important if the host wishes to mute the DAC before making a significant change, such as changing sample rates. In order to help with this situation, the device provides a flag back to the host via a read-only register bit that alerts the host when the part has completed the soft-stepping and the actual volume has reached the desired volume level. The soft-stepping feature can be disabled through register programming. If soft-stepping is enabled, the MCLK signal should be kept applied to the device until the DAC power-down flag is set. When this flag is set, the internal soft-stepping process and power down sequence is complete, and the MCLK can then be stopped if desired.
The TLV320AIC3106 also includes functionality to detect when the user switches on or off the de-emphasis or digital audio processing functions, to first (1) soft-mute the DAC volume control, (2) change the operation of the digital effects processing, and (3) soft-unmute the part. This avoids any possible pop/clicks in the audio output due to instantaneous changes in the filtering. A similar algorithm is used when first powering up or down the DAC. The circuit begins operation at power up with the volume control muted, then soft-steps it up to the desired volume level. At power down, the logic first soft-steps the volume down to a mute level, then powers down the circuitry.