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TEA2029C

COLOR TV SCANNING AND POWER SUPPLY PROCESSOR

STMicroelectronics 

TEA2029C

GENERAL DESCRIPTION

This integrated circuit uses I2L bipolar technology

and combines analog signal processing with digital

processing.

Timing signals are obtained from a voltage-control-

led oscillator (VCO) operatingat 500KHz by means

of a cheap ceramic resonator. This avoids the

frequency adjustment normally required with line

and frame oscillators.

A chain of dividers and appropriate logic circuitry

produce very accurately defined sampling pulses

and the necessary timing signals.

The principal functions implemented are :

- Horizontal scanning processor.

- Frame scanning processor. Two applications are

possible :

- D Class : Power stage using an external

thyristor.

- B Class : Power stage using an external power

amplifier with fly-back generator

such as the TDA8170.

- Secondary switch mode power regulation.

The SMPS output synchronize a primary I.C.

(TEA2260/61) at the mains part.

This concept allows ACTIVE STANDBY facilities.

- Dual phase-locked loop horizontal scanning.

- High performance frame and line synchronization

with interlacing control.

- Video identification circuit.

- Super sandcastle.

- AGC key pulse output.

- Automatic 50-60Hz standard identification.

- VCR input for PLL time constant and frame syn-

chro switching.

- Frame saw-tooth generator and phase modula-

tor.

- Switching mode regulated power supply compris-

ing error amplifier and phase modulator.

- Security circuit and start-up processor.

- 500kHz VCO

The circuit is supplied in a 28 pin DIP case.

VCC = 12V.

Synchronization Separator

Line synchronization separator is clamped to

black level of input video signal with synchroniza-

tion pulse bottom level measurement.

The synchronization pulses are divided centrally

between the black level and the synchronization

pulse bottom level, to improve performance on

video signals in noise conditions.

Frame Synchronization

Frame synchronization is fully integrated (no ex-

ternal capacitor required).

The frame timing identification logic permits auto-

matic adaptation to 50 - 60Hz standards or non-in-

terlaced video.

An automatic synchronization window width sys-

tem provides :

- fast frame capture (6.7ms wide window),

- good noise immunity (0.4ms narrow window).

The internal generator starts the discharge of the

saw-tooth generator capacitor so that it is not dis-

turbed by line fly back effects.

Thanks to the logic control, the beginning of the

charge phase does not depend on any disturbing

effect of the line fly-back.

A 32µs timing is automatically applied on stan-

dardized transmissions, for perfect interlacing.

In VCR mode, the discharge time is controlled by

an internal monostable independent of the line

frequency and gives a direct frame synchroniza-

tion.

Horizontal Scanning

The horizontalscanning frequency is obtainedfrom

the 500kHz VCO.

The circuit uses two phase-locked loops (PLL) :

the first one controls the frequency, the second one

controls the relative phase of the synchronization

and line fly-back signals.

The frequency PLL has two switched time con-

stants to provide :

- capture with a short time constant,

- good noise immunity after capture with a long

time constant.

The output pulse has a constant duration of 26µs,

independent of VCC and any delay in switching off

the scanning transistor.

Video Identification

The horizontal synchronization signal is sampled

by a 2µs pulse within the synchronization pulse.

The signal is integrated by an external capacitor.

The identification function provides three different

levels :

- 0V : no video identification

- 6V : 60Hz video identification

- 12V : 50Hz video identification

This information may be used for timing research

in the case of frequency or voltage synthetizer type

receivers, and for audio muting.

Super Sandcastle with 3 levels : burst, line fly-

back, frame blanking

In the event of vertical scanning failure, the frame

blanking level goes high to protect the tube.

Frame blanking time (start with reset of Frame

divider) is 24 lines.

VCR Input

This provides for continuous use of the short time

constant of the first phase-locked loop (frequency).

In VCR mode, the frame synchronization window

3/9

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