TDA7402_07 STMICROELECTRONICS [STMicroelectronics], TDA7402_07 Datasheet - Page 27

• Manufacturer Part Number: TDA7402_07
• Description: Car radio signal processor
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

TDA7402
4.10.2
4.10.3
volume with the same value in order to get the desired output-level. In clipping situation the
open collector current generates a voltage drop at the rectifier input, which forces the
compander to decrease the gain until the clipping disappears.
It is even possible to run the compression mode and the anti-clipping mode in parallel. In
this case the maximum compander gain should be set to 29dB.
Characteristic
To achieve the desired compression characteristic like shown below the volume has to be
decreased by 4dB.
Figure 18. Compander characteristic
I²C bus timing
While the compander is working, a volume word coming from this stage is added to the I
bus volume word, and the volume is changed with a soft slope between adjacent steps
(softstep stage). As mentioned in the description of this stage, it is not recommended to
change the volume during this slope. To avoid this while the compander is working and the
volume has to be changed, the compander hold-bit is implemented (Bit 7 in the subaddress
byte). The recommended timing for changing the volume during compander ON is the
following:
1.
2.
3.
4.
The softstep-times are in compander ON condition automatically adapted to the attack time
of the compander. In the following table the related SoftStep-times are shown:
Table 6.
Set the compander hold bit
Wait the actual softstep time
Change the volume
Reset the compander hold bit
Attack times vs soft-step times
Attack time
Output Level
12ms
24ms
48ms
6ms
dB
-10
-20
-30
-40
-50
-60
0
0
-10
-8dB
-20
Input Level
2:1
-30
-40
-38dB
15dB
SoftStep time
-50
0.16ms
0.32ms
0.64ms
1.28ms
dB
Audioprocessor part
-60
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