TDA7407 STMicroelectronics, TDA7407 Datasheet - Page 27

• Manufacturer Part Number: TDA7407
• Description: IC PROCESSOR CAR SIGNAL 44TQFP
• Manufacturer: STMicroelectronics
• Type: Car Signal Processorr

Specifications of TDA7407

• Applications: Automotive Audio
• Mounting Type: Surface Mount
• Package / Case: 44-LQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 497-3979

TDA7407
5.2.2
5.2.3
Figure 19. Signals during stereo decoder's softmute
Figure 20. Internal Stereoblend characteristics
If any other source than the stereo decoder is selected the decoder remains muted and the
MPX pin is connected to Vref to avoid any discharge of the coupling capacitor through
leakage currents.
Ingain + Infilter
The Ingain stage allows to adjust the MPX signal to a magnitude of about 1Vrms internally
which is the recommended value. The 4th order input filter has a corner frequency of 80KHz
and is used to attenuate spikes and nose and acts as an anti allasing filter for the following
switch capacitor filters.
Demodulator
In the demodulator block the left and the right channel are separated from the MPX signal.
In this stage also the 19 kHz pilot tone is cancelled. For reaching a high channel separation
the TDA7407 offers an I
compensate the lowpass behaviour of the tuner section. If the tuner attenuation at 38kHz is
in a range from 4.2% to 31.0% the TDA7407 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 channel separation and the fieldstrength control are trimmed.
CS [dB]
2
C bus programmable roll-off adjustment which is able to
-10
-15
-20
-25
-30
-35
-40
-45
-50
SOFTMUTE
-5
COMMAND
STD MUTE
0
0
V
O
1
LEVELINTERN [V]
2
3
D97AU638
4
t
t
t
5
Multipath detector
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