TDA7402 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'TDA7402' PDF : 69 Pages View PDF
Audioprocessor part
TDA7402
3.5
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
bsolete Product(s) Note:
Obsolete Product(s) - O 3.6
1
EXT.
MUTE
+SIGNAL
REF
-SIGNAL
1
I2C BUS
OUT
D97AU634
Time
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
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 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
VOUT
1dB
0.5dB
Note:
-0.5dB
SS Time
Time
-1dB
D00AU1170
For steps more than 0.5dB the Soft Step mode should be deactivated because it could
generate a hard 1dB step during the blend time.
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