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LC4.6U

Teletext/Closed Caption com a possibilidade de armazena-
mento diferente da página dependendo do tipo de Hercules.

No processador a uma ROM de 128 kB para 10 páginas de
Teletexto ou Closed Caption.

9.9.2 Diagrama em Blocos

O diagrama em bloco do Micro-controlador é mostrado a
seguir.

9.9.3 Especiﬁcações Básicas

O Micro controlador opera com as seguintes tensões de ali-

mentação:
•  +3.3 V_dc nos pinos 4, 88, 94 e 109.
•  +1.8 V_dc nos pinos 93, 96 e 117.
•  alimentação pull-up do I2C: +3.3 V_dc.

9.9.4 Conﬁguração dos pinos e funcionalidade

As portas do Micro-controlador podem ser conﬁguradas como

segue:

• Uma porta de entrada normal.

• Uma porta de entrada ADC.

• Uma porta de saída Open Drain.

• Uma porta de saída Push-Pull.

• Uma porta de saída PWM.

• Porta Entrada/Saída.

Figura 9-3 Diagrama em Blocos do Micro Controlador

A tabela a seguir mostra as portas usado para o controle L04:

A descrição da funcionalidade de cada pino é explicada abaixo:

•

LED.

Este sinal é usado para direcionar o LED para Standby,

Remoto e Indicador de Erro.

- Durante o modo de proteção, o LED pisca e o aparelho está

no modo Standby.

- Durante condições de erro em que pisca em uma taxa pré-

deﬁnida.

- Após recebimento do controle remoto válido ou comando de

teclado local, pisca uma vez.

- Para funções com indicação de mensagem de erro, o LED

pisca quando a mensagem é ativada e o aparelho esta no

modo Standby.

•

SCL.

Essa é a linha de clock do barramento I2C.

•

SDA.

Essa é a linha de dados do barramento I2C.

•

STANDBY.

O Hercules gera este sinal. Este ativa a alimen-

tação na operação normal e desativa durante Standby. Estará

“high” (3.3V) abaixo da operação normal e “low” (0V) durante

Standby.

•

IR.

Este pino de entrada é conectado a um receptor do con-

trole remoto RC5.

•

SEL-IF.

Este é um pino de saída para chavear o ﬁltro de Video

SAW entre o sistema M e outros sistemas.

- 0: NTSC M (defeito).

- 1: PAL B/G, DK, I, L.

•

NVM_WP.

A linha de proteção global é usada para ativar e

desativar a proteção de escrita do NVM. Quando a escrita do

NVM é solicitada, o pino 7 do NVM deve ser puxado para a

lógica “0” primeiro (através do pino Write_Protect do micro

controlador) antes da escrita ser executada. Se não o pino 7

do NVM deve sempre ser de lógica “1”.

- 0: Desativado.

- 1: Ativado (defeito).

•

SOUND_ENABLE.

Este pino é usado para MUTE do ampli-

ﬁcador de áudio. É conﬁgurado como push pull.

•

STATUS_1.

O sinal é usado para ler o status da entrada

SCART1 (somente para EU).

Circuit Descriptions, Abbreviation List, and IC Data Sheets

EN 76

LC4.6U

AP China can have a Multi-System and I/DK version. For
India, it might only be BG standard.

9.8.2

Functionality

The features available in the Hercules are as follows:

•

Treble and Bass Control.

•

Surround Sound Effect that includes:

–

Incredible Stereo.

–

Incredible Mono.

–

3D Sound (not for AV Stereo).

–

TruSurround (not for AV Stereo).

–

Virtual Dolby Surround, VDS422 (not for AV Stereo).

–

Virtual Dolby Surround, VDS423 (not for AV Stereo).

–

Dolby Pro-Logic (not for AV Stereo).

•

Bass Feature that includes:

–

Dynamic Ultra-Bass.

–

Dynamic Bass Enhancement.

–

BBE (not for AV Stereo).

•

Auto-Volume Leveller.

•

5 Band Equalizer.

•

Loudness Control.

All the features stated are available for the Full Stereo versions
and limited features for the AV Stereo.

9.8.3

Audio Amplifier Panel (diagram SA3)

Introduction

This panel contains the audio filters and amplifiers necessary
for driving the speakers.
The audio inputs come from the SSB (via connector 1739).
The PSU delivers the positive and negative supply voltage of
16 V

After being filtered and amplified, the signals go to the speaker
section, where the full range speakers are driven (load
impedance is 8 ohm).

Amplifier

The amplifier is an integrated class-D amplifier (TDA7490). It
combines a good performance with a high efficiency, resulting
in a big reduction in heat generation.

Principle

Audio-power-amplifier systems have traditionally used linear
amplifiers, which are well known for being inefficient. In fact, a
linear Class AB amplifier is designed to act as a variable
resistor network between the power supply and the load. The
transistors operate in their linear region, and the voltage that is
dropped across the transistors (in their role as variable
resistors) is lost as heat, particularly in the output transistors.
Class D amplifiers were developed as a way to increase the
efficiency of audio-power-amplifier systems.

The Class D amplifier works by varying the duty cycle of a
Pulse Width Modulated (PWM) signal.
By comparing the input voltage to a triangle wave, the amplifier
increases duty cycle to increase output voltage, and decreases
duty cycle to decrease output voltage.
The output transistors of a Class D amplifier switch from 'full off'
to 'full on' (saturated) and then back again, spending very little
time in the linear region in between. Therefore, very little power
is lost to heat. If the transistors have a low 'on' resistance
(RDS(ON)), little voltage is dropped across them, further
reducing losses.
A Low Pass Filter at the output passes only the average of the
output wave, which is an amplified version of the input signal.
In order to keep the distortion low, negative feedback is applied
(via R3723/3708).

The advantage of Class D is increased efficiency (= less heat
dissipation). Class D amplifiers can drive the same output
power as a Class AB amplifier using less supply current.
The disadvantage is the large output filter that drives up cost
and size. The main reason for this filter is that the switching

waveform results in maximum current flow. This causes more
loss in the load, which causes lower efficiency. An LC filter with
a cut-off frequency less than the Class D switching frequency,
allows the switching current to flow through the filter instead of
the load. The filter is less lossy than the speaker, which causes
less power dissipated at high output power and increases
efficiency in most cases.

Mute

A mute switch (item 7701) is provided at pin 6. This switch is
controlled by the SOUND_ENABLE line from the Hercules
(mute during operation).

Protections

Because of the symmetrical supply, a DC-blocking capacitor,
between the amplifier and the speaker, is not necessary.
However, it is still necessary to protect the speaker for DC
voltages. Therefore, the following protections are therefore
implemented:

•

Via R3765 and R3767, each stabilised supply voltage line
is checked on deviations.

•

Via R3718 and 3717, each amplifier output is checked for
DC-voltage.

9.8.4

Audio: Lip Sync

The chassis is not equipped with ”Lip Sync” (not for LCD).

9.9

Control

9.9.1

Hercules

The System Board has two main micro-controllers on board.
These are:

•

On-chip x86 micro-controller (OCM) from Genesis LCD TV/
Monitor Controller.

•

On-chip 80C51 micro-controller from Philips
Semiconductors UOCIII (Hercules) series.

Each micro-controller has it own I

C bus which host its own

internal devices.
The Hercules is integrated with the Video and Audio Processor.
For dynamic data storage, such as SMART PICTURE and
SMART SOUND settings, an external NVM IC is being used.
Another feature includes an optional Teletext/Closed Caption
decoder with the possibility of different page storage depending
on the Hercules type number.

The Micro Controller ranges in ROM from 128 kB with no TXT-
decoder to 128 kB with a 10 page Teletext or with Closed
Caption.

9.9.2

Block Diagram

The block diagram of the Micro Controller application is shown
below.

Figure 9-3 Micro Controller block diagram

HERCULES

SCALER

Tuner

ComPair

NVM

Sound

Amp