TDA7402 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'TDA7402' PDF : 69 Pages View PDF
TDA7402
Functional description of stereo decoder
Figure 29. Signals during stereo decoder's Soft Mute
roduct(s) Figure 30. Signal control via Soft Mute pin
t(s) - Obsolete P SOFTMUTE
PIN
PLL-HOLD
INFLUENCE
SOFTMUTE
INFLUENCE
STDHMUTE
INFLUENCE
MP-HOLD
PLL-HOLD
STDHMUTE
SOFTMUTE
INFLUENCE
IIC-BUS
SOFTMUTE
MUTED
D00AU1165
Produc 5.2
InGain + infilter
leteThe InGain stage allows adjustment of the MPX-signal to a magnitude of about 1Vrms
internally, which is the recommended value. The 4th order input filter has a corner frequency
so of 80kHz and is used to attenuate spikes and noise, and acts as an anti-aliasing filter for the
Ob following switch capacitor filters.
5.3
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
TDA7402 offers an I2C bus programmable roll-off adjustment which is able to compensate
for the lowpass behavior of the tuner section. If the tuner's attenuation at 38kHz is in a range
from 7.2% to 31.0%, the TDA7402 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
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