TDA7402_07 Datasheet, PDF (48/71 Pages) STMicroelectronics – Car radio signal processor

Functional description of the multipath detector
TDA7402
8.2
Testmode
During the testmode, which can be activated by setting bit D₀ and bit D₁ of the stereo
decoder testing byte, several internal signals are available at the FD2R+ pin. During this
mode the input resistance of 100kOhm is disconnected from the pin. The internal signals
available are shown in the Data byte specification.
8.3
8.3.1
Dual MPX usage
Feature description
The A619 is able to support a twin tuner concept via the Dual MPX Mode. In this
configuration the MPX pin and the MD2G pin are acting as MPX1 and MPX2 inputs. The DC
voltage at the MD2 pin controls whether one or both MPX signals are used to decode the
stereo FM signal. It is designed as a window comparator with the characteristic shown in
Figure 3 (Please note that the thresholds have a hysteresis of 500mV).
In this mode the stereo decoder high ohmic-mute mutes both inputs in parallel.
Figure 36. Dual MPX input diagram
MPX/
MPX1
100K
MD2G/
MPX2
MD2/
CONTROL
100K
1
40K
40K
1
1
CONTROL
CIRCUITRY
INGAIN
3.5...11dB
step 2.5dB
D00AU1167
8.3.2
Configuration
The Dual MPX mode can be easily configured by setting bit 3 of subaddress 30 to LOW (see
Byte 30 description and application diagram of Figure 38).
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