TDA7407 Datasheet, PDF (15/30 Pages) STMicroelectronics – ADVANCED CAR SIGNAL PROCESSOR

TDA7407
Figure 13. Treble Control @ fc = 17.5KHz
15.0
10.0
Figure 14. Treble Center Frequencies
@ Gain = 14dB
15.0
12.5
5.0
10.0
0.0
7.5
-5.0
-10.0
-15.0
10.0
100.0
1.0K
10.0K
structure and range like the Volume stage.
FUNCTIONAL DESCRIPTION OF STEREODE-
CODER
The stereodecoder part of the TDA7407 (see Fig.
15) contains all functions necessary to demodu-
late the MPX signal like pilot tone dependent
MONO/STEREO switching as well as
"stereoblend" and "highcut" functions.
Stereodecoder Mute
The TDA7407 has a fast and easy to control RDS
mute function which is a combination of the audio-
processor’s softmute and the high-ohmic mute of
the stereodecoder. If the stereodecoder is selected
and a softmute command is sent (or activated
Figure 15. Block Diagram of the Stereodecoder
5.0
2.5
0.0
10.0
100.0
1.0K
10.0K
through the SM pin) the stereodecoder will be set
automatically to the high-ohmic mute condition af-
ter the audio signal has been softmuted.
Hence a checking of alternate frequencies could
be performed. To release the system from the
mute condition simply the unmute command must
be sent: the stereodecoder is unmuted immedi-
ately and the audioprocessor is softly unmuted.
Fig. 16 shows the output signal VO as well as the
internal stereodecoder mute signal. This influ-
ence of Softmute on the stereodecoder mute can
be switched off by setting bit 3 of the Softmute
byte to "0". A stereodecoder mute command (bit
0, stereodecoder byte set to "1") will set the
stereodecoder in any case independently to the
high-ohmic mute state.
15/30