TDA7416_11 Datasheet, PDF (17/37 Pages) STMicroelectronics – Car radio signal processor

TDA7416
Description of the audio processor part
4.5
Soft-mute
The digitally controlled soft-mute stage allows muting/demuting the signal with a I²C bus
programmable slope. The mute process can either be activated by the soft-mute 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 Bit0 of the I²C bus output register is set to 1 from the start of muting
until the end of de-muting.
Figure 7. Soft-mute timing
4.6
'!0'03
1. Please notice that a started Mute-action is always terminated and could not be interrupted by a change of
the mute -signal.
Soft-step volume and speaker
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 soft-step 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 in four steps.
Figure 8. Soft-step timing for volume
D"
D"
D"
334IME
D"
'!0'03
1. For steps more than 0.5dB (Volume) or 1dB (Speaker) the soft-step mode should be deactivated because
it could generate a hard 1dB step during blending.
Doc ID 9837 Rev 2
17/37