TDA7404DTR Datasheet, PDF (17/35 Pages) STMicroelectronics – Car radio signal processor

TDA7404
Description of functionality
4.6
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 audiosignal. With the soft-step feature both kinds of clicks could be
reduced to a minimum and are no more audible. Four programmable soft step time from one
step to the next, are user selectable.
Figure 9. Soft-step timing
Vou t
2dB
1dB
-1dB
-2dB
SS Time
Time
4.7
4.7.1
1. For steps more than 1 dB the soft-step mode should be deactivated because it could generate a 1 dB error
during the blend-time.
Bass
There are three parameters programmable in the bass stage:
Attenuation
Figure 10 shows the attenuation as a function of frequency at a center frequency of 80Hz.
Figure 10. Bass control @ f_C = 80 Hz, Q = 1
15.0
10.0
5.0
dB
0.0
-5.0
-10.0
-15.0
10.0
100.0
Hz
1.0K
10.0K
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