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

· QPSK demodulator, PCM decoder, digital filters, D/A

converters, and operational amplifiers integrated on a
single chip.

· 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.

· CPU interface using an I

C bus

· Interface circuits for CORTEC and SkyPort

descramblers

Functions

· QPSK demodulation
· Bit timing clock recovery
· Differential decoding conversion and parallel-to-serial

conversion

· Frame synchronization (forward protection: 8 cycles,

back protection: 3 cycles): Frame synchronized/not
synchronized detection flag output provided.

· Tenth-order M-series descrambling
· Deinterleaving
· BCH (63, 56) error correction and dual error detection:

Single error detected flag output provided.

· Support for both interpolation and previous data hold

when a dual error is detected.
Control bit majority judgment protection every 16
frames

· Register data previous value hold when dual errors are

detected using BCH(7,3)

· Ten to 14 bit expansion of audio data during A mode

broadcasts.

· Data protection using majority control for the upper bits

of the audio data during B mode broadcasts

· Full complement of muting functions

-- Audio suppression provided (bit 16 of the post-

majority decision control bits)

-- Non-audio signal suppression (bits 2 to 5 of the post-

majority decision control bits)

-- Forced muting
-- Muting when not synchronized
-- Muting when large numbers of errors are detected

(modifiable conditions)

-- Channel switching
-- Charged (pay-per-view) program flag muting
-- Mute detection output provided.

· General-purpose ports (2 input ports and 8 output ports)
· EIAJ digital audio interface output
· 8

oversampling digital filters

· Multi-bit D/A converter (with built-in output operational

amplifiers)

· 5 V single-voltage power supply
· QFP (QIP) 64E package

Package Dimensions

unit: mm

3195-QFP64E

CMOS LSI

Ordering number : EN5691

83097HA(OT) No. 5691-1/9

[LC7851E]

SANYO Electric Co.,Ltd. Semiconductor Bussiness Headquarters

TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110 JAPAN

QPSK Demodulation and Audio Signal-Processing IC

for Satellite Broadcast Reception

LC7851E

SANYO: QIP64E

Block Diagram

No. 5691-2/9

LC7851E

Differential conversion

parallel-to-serial

converter

QPSK

demodulator

Scramble interface 1

Sync detection

and sync protection

Descrambler

Control bit extraction

CPU interface

Deinterleaving

Scramble interface 2

10 to 14 bits expansion

Data

interpolation and previous value hold

oversampling digital filters

Digital de-emphasis

filter

D/A converter

Audio signal

buffer amplifier

Audio switching

Digital audio interface

output

Upper bit majority

protection

Range bit error

correction

For-fee flag detection

General-purpose ports

Error detection and correction

Bit timing clock

recovery

Pin Assignment

No. 5691-3/9

LC7851E

Pin Functions

Pin No.

I/O

Function

BSTRI

Bit stream input

BSTRO

Bit stream output

General-purpose output port

CK5M

Filter adjustment clock output (5.7272 MHz)

Digital system power supply

TSL

Output control for the state when reset by the PHCNT pin (Low: high-impedance, high: 50% duty pulse output)

Internal A/D converter ground

QPSKI

QPSK modulated signal input

Internal A/D converter power supply

VRM

Internal A/D converter reference (center) output

Internal A/D converter ground

VRB

Internal A/D converter reference (low) output

VCADJ

Connection for internal VCO adjustment external resistor

VCIN

Internal VCO control input

Continued on next page.

No. 5691-4/9

LC7851E

Continued from preceding page.

Pin No.

I/O

Function

Internal VCO ground

Internal VCO power supply

(N.C)

Phase comparator power supply

PHCNT

Phase comparator output

Phase comparator ground

(N.C)

Oscillator circuit power supply

XI1

Crystal oscillator (22.909088 MHz) input

XO1

Crystal oscillator (22.909088 MHz) output

Oscillator circuit ground

Digital system ground

DADO

Digital audio interface output

(N.C)

TEST1

Test pin

TEST2

Test pin

Digital system power supply

Internal D/A converter ground

AOUTL

Left channel audio data output

REFL

Internal D/A converter reference voltage: low

REFH

Internal D/A converter reference voltage: high

AOUTR

Right channel audio data output

Internal D/A converter power supply

RST

Reset input

MUTI

Forced muting input

MUTO

Mute detection output (When muting detected: high)

MOD

Audio mode detection output (A mode: low, B mode: high)

LOIN

Frame synchronization detection output (When synchronized: low)

ERR

Error detection output (Error detected: high)

REQ

Host CPU readout request signal

SDA

I/O

C bus data I/O

SCL

C bus clock input

Digital system ground

DSTRI2

Data stream input 2/general-purpose I/O port

DSTRI1

Data stream input 1/general-purpose I/O port

DSTRO

Data stream output (post-error correction data)

DASL

Descrambler interface switching

FRM

Frame synchronization signal

CK2M

Bit stream clock (2.048 MHz)

Caution: All NC pins must be left open.

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