TDA7405_04 STMICROELECTRONICS [STMicroelectronics], TDA7405_04 Datasheet - Page 37

• Manufacturer Part Number: TDA7405_04
• Description: EQUALIZER CARRADIO SIGNAL PROCESSOR
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

11.6 Dual-MPX Mode
The TDA7405 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 36 (Please note that the thresholds have a hysteresis of 500mV). In this mode
the stereodecoder highohmic-mute mutes both inputs in parallel.
Figure 37. Blockdiagram Dual MPX
Table 10. Pin-Configuration DMPX-/WSM-Mode
11.7 Weak-Signal Mute
For use with front-ends which do not support a weak-signal-mute function the TDA7405 offers this feature as
well. If this mode is enabled the pins 29 and 30 are used as an AC-coupling behind the Mute-Stage (see block-
diagram). In parallel pin 12 (AMIF) is switched internally to realize a mute time-constant with fast attack- and
slow decay-time.
Dual MPX
off
off
on
on
Weak-Signal
Mute
off
on
off
on
AMIF(12)
WSM-TC
WSM-TC
AMIF-In
AMIF-In
DMPXC(25)
DMPC-Cntrl
not used
WSM-In
WSM-In
MPX2(26)
WSM-Out
WSM-Out
not used
MPX2
DMPC-Cntrl
MD2(43)
MD2-In
MD2-In
MD2-In
MD2G(44)
MD2-Gnd
MD2-Gnd
MD2-Gnd
TDA7405
MPX2
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