TEA2128 데이터 시트보기 (PDF) - STMicroelectronics

부품명

상세내역

제조사

TEA2128

COLOR TV SCANNING AND POWER SUPPLY PROCESSOR

STMicroelectronics 

TEA2128

- High performance frame and line synchronization

with interlacing control.

- Supersandcastlegenerator

- Automatic 50Hz / 60Hz standard identification

- Frame saw-tooth generator

- Video identification circuit

- Very steady free running mode of the line and

frame oscillator in OSD mode. This allows on

screen display without phase Jitter in research

mode of the tuner

- Automatic VCR mode recognition for time con-

stant switching

- Switching mode regulated supply comprising er-

ror amplifier and phase modulator. This allowed a

secondary switch mode power regulation with a

master slave concept and provides active

standby facilities

- Line and S.M.P.S. start-up processor

- Frame safety input

WORKING DESCRIPTION

Synchronization Separator

Line synchronization separator is clamped to black

level of input video signal with synchronization

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 signal in noise conditions.

Frame Synchronization

Frame synchronization is fully integrated (no exter-

nal 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 (7.3ms wide window)

- Good noise immunity (0.4ms narrow window)

The internal generator starts the discharge of the

sawtooth generator capacitor, so that it is not dis-

turbed by line flyback effects.

Thanks to the logic control, the beginning of the

charge phase does not depend on any disturbing

effect of the line flyback. A 32µs timing is automat-

ically applied on standardized 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 PLL:

- The first one controls the frequency

- The second one controls the relative phase of the

synchronization and the line flyback signals.

The output pulse has a constant duration of 29µs,

independent of VCC and of any delay in switching-

off the scanning transistor.

Supersandcastle Generator

This output delivers a 3 level synchronization sig-

nal:

- Burst level

- Line blanking level

- Frame blanking level

In the event of vertical scanning failure, the frame

blanking level goes high to protect the tube.

Frame Scanning

The current to charge the frame sawtooth gener-

ator is automatically switched to 60Hz operation to

maintain constant amplitude.

Automatic VCR Mode Recognition for Time

Constant Switching

- A third phase comparator is used to detect VCR

signals and to switch the φ1 short time constant.

- A noise level measurement is realized on the

video synchronization pulse to inhibit the short

time constant if the noise level is superior to an

adjustable threshold.

- VCR signals are detected if peak to peak signal

on Pin 7 is superior to an internal threshold.

This threshold is depending on the noise level. So

with a no noisy video signal, the auto VCR switch

sensitivity is maximum, and it decreases when the

noise increases.

- The sensitivity of the noise gate and the auto VCR

switch is adjustable by external resistance.

- Long and short time constants can be selected

manually by Pin 5.

Video Identification

The horizontal synchronization signal is sampled

by a 2µs pulse within the synchronization pulse.

The signal is integrated by an external capacitor.

Identification Output

The identification function provides three different

levels :

- 0V : No video identification

- 6V : 60Hz video identification

- 12V : 50Hz video identification

6/8

Share Link: