TDA7460ND STMicroelectronics, TDA7460ND Datasheet - Page 28

• Manufacturer Part Number: TDA7460ND
• Description: IC PROCESSOR CAR RAD SGNL SO-20
• Manufacturer: STMicroelectronics
• Type: Car Signal Processorr

Specifications of TDA7460ND

• Applications: Automotive Systems
• Mounting Type: Surface Mount
• Package / Case: 20-SOIC (7.5mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Stereo decoder part
5.5.2
5.5.3
5.5.4
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Input stages
The In gain stage allows to adjust the MPX signal to a magnitude of about 1Vrms internally
which is the recommended value. The 4.th 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 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 TDA7460ND offers an I
compensate the lowpass behavior of the tuner section. If the tuner attenuation at 38kHz is in
a range from 20.2% to 31% the TDA7460ND needs no external network before the MPX pin.
Within this range an adjustment to obtain at least 40d B 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.
Figure 22. Signals during stereo decoder's soft mute
De-emphasis and high cut
The lowpass filter for the de-emphasis allows to choose between a time constant of 50ms
and 75ms (bit D7, Stereo decoder byte).
The high cut control range will be in both cases t
range (between VHCH and VHCL) the LEVEL signal is converted into a 5 bit word which
controls the lowpass time constant between t
remain always 5 bits independently of the absolute voltage range between the VHCH and
VHCL values.
The high cut function can be switched off by I
SOFTMUTE
COMMAND
STD MUTE
2
C bus programmable roll-off adjustment which is able to
V
O
Deemp
2
C bus (bit D7, Fieldstrength byte set to "0").
HC
...3 · t
= 2 · t
Deemp
D97AU638
Deemp
. There by the resolution will
. Inside the high cut control
t
t
t
TDA7460ND