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TDA955X

TV signal processor-Teletext decoder with embedded µ-Controller

Philips Electronics 

Philips Semiconductors

TV signal processor-Teletext decoder

with embedded µ-Controller

Tentative Device Specification

TDA955X/6X/8X PS/N1 series

GENERAL DESCRIPTION

The various versions of the TDA955X/6X/8X PS/N1 series

combine the functions of a video processor together with a

µ-Controller and US Closed Caption decoder. Several

versions have a Teletext decoder on board. The Teletext

decoder has an internal RAM memory for 1or 10 page text.

The ICs are intended to be used in economy television

receivers with 90° and 110° picture tubes.

The ICs have supply voltages of 8 V and 3.3 V and they

are mounted in an S-DIP 64 envelope.

The features are given in the following feature list. The

differences between the various ICs are given in the table

on page 4.

FEATURES

TV-signal processor

• Multi-standard vision IF circuit with alignment-free PLL

demodulator

• Internal (switchable) time-constant for the IF-AGC circuit

• A choice can be made between versions with mono

intercarrier sound FM demodulator and versions with

QSS IF amplifier. In the QSS versions without

East-West output an AM/FM mode can be activated. In

that case both the QSS amplifier (for AM demodulation)

and the FM demodulator are available.

• The mono intercarrier sound circuit has a selective

FM-PLL demodulator which can be switched to the

different FM sound frequencies (4.5/5.5/6.0/6.5 MHz).

The quality of this system is such that the external

band-pass filters can be omitted.

• The FM-PLL demodulator can be set to centre

frequencies of 4.74/5.74 MHz so that a second sound

channel can be demodulated. In such an application it is

necessary that an external bandpass filter is inserted.

• The QSS amplifier and mono intercarrier sound circuit of

some versions can be used for the demodulation of FM

radio signals

• Source selection between the ‘internal’ CVBS and one

external CVBS or Y/C signal

• Integrated chrominance trap circuit

• Integrated luminance delay line with adjustable delay

time

• Picture improvement features with peaking (with

switchable centre frequency, depeaking, variable

positive/negative overshoot ratio and video dependent

coring) and blue- and black stretching

• Integrated chroma band-pass filter with switchable

centre frequency

• Only one reference (12 MHz) crystal required for the

µ-Controller, Teletext- and the colour decoder

• PAL/NTSC or multi-standard colour decoder with

automatic search system

• Internal base-band delay line

• Indication of the Signal-to-Noise ratio of the incoming

CVBS signal

• RGB control circuit with ‘Continuous Cathode

Calibration’, white point and black level off-set

adjustment so that the colour temperature of the dark

and the light parts of the screen can be chosen

independently.

• A linear RGB/YUV/YPBPR input with fast blanking for

external RGB/YUV sources. The synchronisation circuit

can be connected to the incoming Y signal. The

Text/OSD signals are internally supplied from the

µ-Controller/Teletext decoder.

• Contrast reduction possibility during mixed-mode of

OSD and Text signals

• Adjustable ‘wide blanking’ of the RGB outputs

• Horizontal synchronization with two control loops and

alignment-free horizontal oscillator

• Vertical count-down circuit

• Vertical driver optimized for DC-coupled vertical output

stages

• Horizontal and vertical geometry processing

• Horizontal and vertical zoom function for 16 : 9

applications

• Horizontal parallelogram and bow correction for large

screen picture tubes

• Low-power start-up of the horizontal drive circuit

2000 Jun 22

2

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