Ordering number : EN5691
CMOS LSI
LC7851E
QPSK Demodulation and Audio Signal-Processing IC
for Satellite Broadcast Reception
Overview
The LC7851E demodulates the QPSK (quadrature phase
shift keying) modulated audio data broadcast by the
Japanese BS and CS broadcast satellites and converts that
data to an analog audio signal. This IC integrates on a
single chip the audio system signal processing required for
BS and CS receivers from QPSK demodulation to analog
audio reproduction. The main functions provided by the
LC7851E include QPSK demodulation, differential
decoding conversion, descrambling, deinterleaving, and
error correction. It also generates a PCM audio signal. The
PCM audio signal is converted to an analog audio signal
by on-chip digital filters and A/D converters.
Features
鈥?QPSK demodulator, PCM decoder, digital filters, D/A
converters, and operational amplifiers integrated on a
single chip.
鈥?The number of required external components has been
reduced and adjustment-free operation achieved in the
QPSK demodulator by implementing that block as a
digital circuit on a single chip.
鈥?CPU interface using an I
2
C bus
鈥?Interface circuits for CORTEC and SkyPort
descramblers
鈥?Ten to 14 bit expansion of audio data during A mode
broadcasts.
鈥?Data protection using majority control for the upper bits
of the audio data during B mode broadcasts
鈥?Full complement of muting functions
鈥?Audio suppression provided (bit 16 of the post-
majority decision control bits)
鈥?Non-audio signal suppression (bits 2 to 5 of the post-
majority decision control bits)
鈥?Forced muting
鈥?Muting when not synchronized
鈥?Muting when large numbers of errors are detected
(modifiable conditions)
鈥?Channel switching
鈥?Charged (pay-per-view) program flag muting
鈥?Mute detection output provided.
鈥?General-purpose ports (2 input ports and 8 output ports)
鈥?EIAJ digital audio interface output
鈥?8脳 oversampling digital filters
鈥?Multi-bit D/A converter (with built-in output operational
amplifiers)
鈥?5 V single-voltage power supply
鈥?QFP (QIP) 64E package
Package Dimensions
unit: mm
3195-QFP64E
[LC7851E]
Functions
鈥?QPSK demodulation
鈥?Bit timing clock recovery
鈥?Differential decoding conversion and parallel-to-serial
conversion
鈥?Frame synchronization (forward protection: 8 cycles,
back protection: 3 cycles): Frame synchronized/not
synchronized detection flag output provided.
鈥?Tenth-order M-series descrambling
鈥?Deinterleaving
鈥?BCH (63, 56) error correction and dual error detection:
Single error detected flag output provided.
鈥?Support for both interpolation and previous data hold
when a dual error is detected.
Control bit majority judgment protection every 16
frames
鈥?Register data previous value hold when dual errors are
detected using BCH(7,3)
SANYO: QIP64E
SANYO Electric Co.,Ltd. Semiconductor Bussiness Headquarters
TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110 JAPAN
83097HA(OT) No. 5691-1/9
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