TDA7406T Datasheet, PDF (33/49 Pages) STMicroelectronics – CAR RADIO SIGNAL PROCESSOR

TDA7406T
Highcut through the multipath detector
Selecting the “internal influence” in the configuration byte the Stereo-Blend and/or the Highcut is automatically
invoked during a multipath condition according to the voltage appearing at the MP_OUT-pin.
Figure 28. Block diagram of the Multipath-Detector
7 QUALITY DETECTOR
The TDA7406T offers a quality detector output which gives a voltage representing the FM-reception conditions.
To calculate this voltage the MPX-noise and the multipath-detector output are summed according to the follow-
ing formula:
V_Qual = 1.6 (V_Noise-0.8 V)+ a (REF5V-V_Mpout).
The noise-signal is the PEAK-signal without additional influences (see noiseblanker description). The factor 'a'
can by programmed from 0.7 to 1.15. The output is a low impedance output able to drive external circuitry as
well as simply fed to an AD-converter for RDS applications.
8 TESTMODE
During the Testmode, which can be activated by setting bit I2 of the subaddress byte and bit D1 of the stereo-
decoder testing-byte, several internal signals are available at the FD2R+ pin. During this mode the input resis-
tance of 100kOhm is disconnected from the pin. The internal signals available are shown in the Data-byte
specification
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