TDA7406 datasheet(20/64 Pages) STMICROELECTRONICS

20 / 64 page

Description of the audioprocessor part

TDA7406

20/64

4.4

Soft Mute

The digitally controlled Soft Mute stage allows signal muting/demutingwith a programmable

slope. The Mute time is selectable among 4 values: 0.48, 0.96, 123 and 324ms. The mute

process can either be activated by the Soft Mute pin or via the I2C-bus. This slope is realized

in a special S-shaped curve to mute slow in the critical regions (see Figure 7).

For timing purposes the I2C-bus output register (Bit0 = SM read bit) is set to 1 from the start

of muting until the end of de-muting.

Figure 7.

Soft Mute-Timing

Note:

Please notice that a started Mute-action is always terminated and could not be interrupted

by a change of the mute -signal.

4.5

Volume Control

4.5.1

Gain/Attenuation Control

The volume control can range from a gain of 32dB up to an attenuation of 79dB; however it

is not recommended to use a gain higher than 20dB for performance reasons.

4.5.2

Soft Step Volume

When the speaker-level is changed, audible clicks could appear at the output. The root

cause of those clicks could either be a DC offset before the speaker-stage or the sudden

change of the envelope of the audio signal. With the SoftStep-feature both kinds of clicks

could be reduced to a minimum and are no more audible. The blend-time from one step to

the next is programmable with four different values: 320

μs, 1.28ms, 5.12ms and 20.4ms.

TDA7406 Arkusz danych(PDF) 20 Page - STMicroelectronics