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.

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