TDA7719 Datasheet, PDF (18/45 Pages) STMicroelectronics – 3 band car audio processor

Description
4.3.4
Flat mode
In flat mode the loudness stage works as a 0dB to -15dB attenuator.
TDA7719
4.4
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 8).
For timing purposes the Bit0 of the I²C-bus output register is set to 1 from the start of muting
until the end of demuting.
Figure 8. Softmute timing
1
EXT.
MUTE
Note:
4.5
4.6
+SIGNAL
REF
-SIGNAL
1
I²C BUS
OUT
D97AU634
Time
A started Mute action is always terminated and could not be interrupted by a change of the
mute signal
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 5ms or 10ms. The softstep control is described in detail in Chapter 4.10.
Bass
There are four parameters programmable in the bass stage:
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