Zenith D52WLCD Series Service Manual page 20

1.3 MSP3440G :
Sound Processor
(1) Introduction
The MSP 3440G family of single-chip Multistandard Sound
Processors covers the sound processing of all analog TV-
Standards worldwide. The full TV sound processing, starting
with analog sound IF signal-in, down to pro-cessed analog
AF-out, is performed on a single chip.
Figure shows a simplified functional block diagram of the
MSP 3440G.
Surround sound can be reproduced to a certain extent with
two loudspeakers.
These TV sound processing ICs include versions for process-
ing the multichannel television sound (MTS) signal conform-
ing to the standard recommended by the Broadcast
Television Systems Committee (BTSC).
The DBX noise reduction, or alternatively, MICRONAS Noise
Reduction (MNR) is performed alignment free.
The MSP 3440G has built-in automatic functions: The IC is
able to detect the actual sound standard automat-ically
(Automatic Standard Detection). Furthermore, pilot levels and
identification signals can be evaluated internally with subse-
quent switching between mono/stereo/bilingual; no I
action is necessary (Auto-matic Sound Selection).
(Fig Simplified functional block diagram of the MSP 3440G)
(2) Sound IF Processing
1) Analog Sound IF Input
The input pins ANA_IN1+, ANA_IN2+, and ANA_IN-offer
the possibility to connect two different sound IF(SIF)
sources to the MSP 3440G. The analog-to-digital conver-
sion of the preselected sound IF signal is done by an A/D-
converter. An analog automatic gain circuit(AGC) allows a
wide range of input levels. The high-pass filters formed by
the coupling capacitors at pins ANA_IN1+ and ANA_IN2+.
2) Demodulator: Standards and Features
The MSP 3440G is able to demodulate all TV-sound stan-
dards worldwide including the digital NICAM system.
DESCRIPTION OF CIRCUITS
2 C inter-
Very high deviation FM-Mono: Detection and robust demodu-
lation of one FM carrier with a maximum devi-ation of 540 kHz.
BTSC-Stereo: Detection and FM demodulation of the aural car-
rier resulting in the MTS/MPX signal. Detec-tion and evaluation
of the pilot carrier, AM demodula-tion of the (L-R)-carrier and
detection of the SAP sub-carrier.
Processing of DBX noise reduction or MICRONAS Noise
Reduction (MNR).
BTSC-Mono + SAP: Detection and FM demodulation of the
aural carrier resulting in the MTS/MPX signal.
Detection and evaluation of the pilot carrier, detection and FM
demodulation of the SAP subcarrier. Process-ing of DBX noise
reduction or MICRONAS Noise Reduction (MNR).
[ [ Application Note:
All ground pins should be connected to one low-resis-tive
ground plane. All supply pins should be connected separately
with short and low-resistive lines to the power supply.
Decoupling capacitors from DVSUP to DVSS, AVSUP to
AVSS, and AHVSUP to AHVSS are recommended as closely
as possible to these pins.
Decoupling of DVSUP and DVSS is most important.
We recommend using more than one capacitor. By choosing
different values, the frequency range of active decoupling can
be extended. In our application boards we use: 220 pF, 470
pF, 1.5 nF, and 10 mF. T he capacitor with the lowest value
should be placed near-est to the DVSUP and DVSS pins.
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