Description of functionality TDA7404
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4.4.3 Low and high frequency boost
Figure 7 shows the different Loudness-shapes in low & high frequency boost.
Figure 7. Loudness attenuation, f
C
= 2.4 kHz
4.5 Soft-mute
The digitally controlled soft-mute stage allows muting/demuting the signal with a I
2
C bus
programmable slope. The mute process can either be activated by the Mute pin or by the
I
2
C bus. This slope is realized in a special S-shaped curve to mute slow in the critical
regions (seeFigure 6).
For timing purposes the Bit 0 of the I
2
C bus output register is set to 1 from the start of muting
until the end of de-muting.
Figure 8. Soft-mute timing
1. Please notice that a started Mute-action is always terminated and could not be interrupted by a change of
the mute -signal.
-20
-15
-10
-5
0
5
10
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1K
10K
