TDA7718N datasheet(17/40 Pages) STMICROELECTRONICS

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TDA7718N

Description of the audioprocessor

Doc ID 16502 Rev 1

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4.3

SoftMute

The digitally controlled SoftMute stage allows muting/demuting the signal with a I2C bus

programmable slope. The mute process can either be activated by the SoftMute pin or by

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 bit 0 of the I2C bus output register is set to 1 from the start of muting

until the end of demuting.

Figure 7.

SoftMute timing

Note:

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

by a change of the mute –signal.

4.4

SoftStep volume

When the volume-level is changed audible clicks could appear at the output. The root cause

of those clicks could either be a DC-offset before the volume-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 as 5 ms or 10 ms. The SoftStep control is described in detail in Chapter 4.9.

EXT.

MUTE

+SIGNAL

REF

-SIGNAL

2C BUS

OUT

Time

D97AU634

TDA7718N Datasheet(PDF) 17 Page - STMicroelectronics