TDA7404

Description of functionality

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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

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.

4.7

Bass

There are three parameters programmable in the bass stage:

4.7.1

Attenuation

Figure 10 shows the attenuation as a function of frequency at a center frequency of 80Hz.

Figure 10.

Time

SS Time

-1dB

-2dB

Vout

2dB

1dB

-15.0

-10.0

-5.0

0.0

5.0

10.0

15.0

10.0

100.0

1.0K

10.0K

dB

Hz