TDA7461NDTR STMicroelectronics, TDA7461NDTR Datasheet - Page 28

• Manufacturer Part Number: TDA7461NDTR
• Description: IC PROCESSOR CAR RAD SGNL SO-28
• Manufacturer: STMicroelectronics
• Type: Car Signal Processorr

Specifications of TDA7461NDTR

• Applications: Automotive Systems
• Mounting Type: Surface Mount
• Package / Case: 28-SOIC (7.5mm Width)
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Stereo decoder part
4.5.6
4.5.7
4.5.8
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Fieldstrength control
The fieldstrength input is used to control the high cut and the stereo blend function. In
addition the signal can be also used to control the noise blanker thresholds.
Level input and gain
To suppress undesired high frequency modulation on the high cut and stereo blend function
the LEVEL signal is lowpass filtered firstly. The filter is a combination of a 1
lowpass at 53 kHz (working as anti-aliasing filter) and a 1storder switched capacitor lowpass
at 2.2 kHz. The second stage is a programmable gain stage to adapt the LEVEL signal
internally to different IF.
The gain is widely programmable in 16 steps from 0 dB to 10 dB (step = 0.67 dB). These 4
bits are located together with the Roll-Off bits in the “Stereo decoder Adjustment” byte to
simplify a possible adaptation during the production of the carradio.
Figure 22. Internal stereo blend characteristics
Stereo blend control
The stereo blend control block converts the internal LEVEL voltage (LEVEL INTERN) into
an demodulator compatible analog signal which is used to control the channel separation
between 0dB and the maximum separation. Internally this control range has a fixed upper
limit which is the internal reference voltage REF5V. The lower limit can be programmed to
be 33%, 42%, 50% or 58% of REF5V (see
To adjust the external LEVEL voltage to the internal range two values must be defined: the
LEVEL gain L
reached (VST) the LEVEL gain LG has to be defined. The following equation can be used to
estimate the gain:
The gain can be programmed through 4 bits in the "Stereo decoder-Adjustment" byte.
The MONO voltage VMO (0 dB channel separation) can be chosen selecting 33, 42, 50 or
58 % of REF5V.
G
and VSBL. To adjust the voltage where the full channel separation is
L
G
=
----------------------------------------------------------------------------------------------- -
Field strength voltage STEREO
Figure
REF5V
23).
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TDA7461