TDA7407 Datasheet, PDF (20/30 Pages) STMicroelectronics – ADVANCED CAR SIGNAL PROCESSOR

TDA7407
AF Search Control
The TDA7407 is supplied with several functional-
ity to support AF-checks using the stereodecoder.
As mentioned already before the highohmic-mute
feature avoids any clicks during the jump condi-
tion. It is possible a the same time to evaluate the
noise- and multipath-content of the alternate fre-
quency by using the Quality detector output.
Therefore the multipath-detector is switched auto-
matically to a small time-constant.
One additional pin (AFS) is implemented in order
to separate the audioprocessor-mute and
stereodecoder AF-functions. In Figure 22 the
blockdiagram and control-functions of the com-
plete AFS-functionality is shown (please note that
the pins AFS and SM are active low as well as all
control-bits indicated by an overbar).
TEST MODE
During the test mode, which can be activated by
setting bit D0 of the testing byte and bit D5 of the
subaddress byte to "1", several internal signals
are available at the CASSR pin.
During this mode the input resistor of 100kOhm is
disconnected from the pin. The internal signals
available are shown in the software specification.
Figure 22. Mute Control Logic
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