TDA7462 Datasheet, PDF (13/25 Pages) STMicroelectronics – DUAL AUDIOPROCESSOR WITH COMPANDER AND SUBWOOFER OUTPUT

TDA7462
Compander Stage
To achieve the desired compression charac-
teristic like shown below the volume has to be
decreased by 4dB.
Figure 17. Compander Characteristics
dB 0
-10
-20
-30
-40
-8dB
2:1
-38dB
15dB
-50
-60
0
-10
-20
-30
-40
-50
-60
Input Level
dB
When the compander is working a volume word
coming from this stage is added to the I²C bus
volume word and the volume is changed with a
soft slope between adjacent steps. As mentioned
in the description of this stage it is not recom-
mended to change the volume during this slope.
The compander-hold bit (Bit 7 in the subaddress-
byte) is present to implement the volume change
more easily. The recommended sequence for
changing the volume level when compander fea-
ture is on is the following:
1. Set the compander-hold bit
2. Wait the actual SoftStep time
3. Change the volume
4. Reset the compander-hold bit
The SoftStep times are (in compander ON condi-
tion) automatically adapted to the attach time of
the Compander. In the following table the related
SoftStep times are shown:
Attack-Time
6ms
12ms
24ms
48ms
SoftStep Time
0.16ms
0.32ms
0.64ms
1.28ms
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