TDA7402_07 STMICROELECTRONICS [STMicroelectronics], TDA7402_07 Datasheet - Page 41

• Manufacturer Part Number: TDA7402_07
• Description: Car radio signal processor
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

TDA7402
6.2
6.3
Figure 29. Signals during stereo decoder's SoftMute
Figure 30. Signal control via SoftMute pin
InGain + infilter
The InGain stage allows adjustment of the MPX-signal to a magnitude of about 1V
internally, which is the recommended value. The 4th order input filter has a corner frequency
of 80kHz and is used to attenuate spikes and noise, and acts as an anti-aliasing filter for the
following switch capacitor filters.
Demodulator
In the demodulator block, the left and the right channels are separated from the MPX signal.
In this stage the 19kHz pilot tone is cancelled. To reach a high channel separation the A619
offers an I
lowpass behavior of the tuner section. If the tuner's attenuation at 38kHz is in a range from
7.2% to 31.0%, the A619 needs no external network in front of the MPX-pin. Within this
range, an adjustment to obtain at least 40dB channel separation is possible. The bits for this
adjustment are located together with the fieldstrength adjustment in one byte. This gives the
possibility to perform an optimization step during the production of the car radio, where the
2
C bus programmable roll-off adjustment which is able to compensate for the
SOFTMUTE
PIN
INFLUENCE
SOFTMUTE
IIC-BUS
INFLUENCE
SOFTMUTE
Functional description of stereo decoder
SOFTMUTE
INFLUENCE
STDHMUTE
INFLUENCE
PLL-HOLD
MUTED
MP-HOLD
PLL-HOLD
STDHMUTE
D00AU1165
rms
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