STV2112B datasheet(4/24 Pages) STMICROELECTRONICS

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3 - VIDEO CIRCUIT

- 2 RGB inputs : RGB (OSD) input has priority

against the RGBext. Maximum contrast on RGB

(OSD). -12dB range contrast control on RGBext.

Possibility to disable the RGBext insertion

through the bus.

- Oversize blanking capability on FB(OSD)(Pin15)

input. The RGB ouputs will be blanked when the

voltage on Pin 15 will exceed the second thresh-

old at 1.9V (blanking threshold) : the whole field

is blanked but not the inserted cut-off pulses. The

OSD insertion threshold is 0.7V.

- Automatic cut-off current loop : 2V cut-off range.

Sequential cut-off current measurement during

the three lines after the frame blanking signal.

Leakage current measurement during the frame

blanking, memorization on an internal capacitor.

- Warm up detector.

- Beam current limiter DC voltage input.

The beam current limiter control voltage will act

on contrast first, then the brightness will be de-

creased when contrast attenuationreaches -5dB.

- Bus control of the red, green and blue channel

gain (White point adjustment)

- Bus control of the red and green DC levels (black

point adjustment)

- PAL and SECAM matrix).

- Switch-off of the trap filter in SVHS mode.

- Bus controlled contrast on luminance (20dB range)

- Bus controlled saturation (50dB range)

- Bus controlled brightness : 40% range at maxi-

mum contrast.

- Bus controlled sharpness (peaking) ; sharpness

active in PAL standard only.

- Noise coring function on sharpness.

4 - CHROMA CIRCUIT

4.1 - PAL/SECAM Decoders

- SVHS inputs ; bus controlled SVHS mode.

- 30dB range ACC

- Use of an external base band delay line

(STV2180 recommended)

- Automatic standard identification, with possibility

to force the standard through the bus.

4.2 - PAL Decoder

- ACC done by peak detector on synchronous de-

modulation of the burst

- Fully integrated killer functions.

- VCO using crystal 4.43MHz

XTAL SPECIFICATION :

Frequency :

4.433619MHz (PAL/SECAM)

Vibration mode : Fondamental,series resonance

(no serial capacitor)

Motional capacity : 13fF

±3fF

Resonance resistance : < 70

Ω

Shunt capacitance : < 7pF

Spurious response : No resonance at 3*fo

±3kHz

-0

o and

±90o demodulation angles for PAL

4.3 - SECAM Decoder

- ACC

- Fully integrated killer

- Two integrated discriminators with two PLL

- Integrated deemphasis

4.4 - Standard Identification

- Sequential identification.

- 2 identification sequences :

PAL mode, SECAM mode

- PAL priority

- the SECAM mode is locked after two identified

SECAM sequences

- the SECAM mode can be selected in 50Hz only

- Blanking of the (R-Y) and B-Y) outputs during

color search mode.

5 - OTHER FUNCTIONS : IF CONTROLS

5.1 - Volume Control and Mute

The volume control voltage range on Pin 10 is from

0.5V to 5V.

A low voltage on Pin 10 (below 0.2V) will mute the

FM demodulator of the IF circuit STV8224.

It will put the volume at the minimum level and thus

there will be no soundeither in TV mode or SCART

mode.

The volume control voltage and the mute level are

controlled by the bus.

5.2 - IF Standard and TV/SCART Mode Selection

The selection of IF standard (positive or negative

vision modulation)and theTV/SCARTmode is con-

trolled by the bus. The selection is convertedin four

voltages on Pin 21.

The lowest voltage selects the TV mode and the

NEGATIVE vision modulation.

The highest voltage (open collector output with

internal pull-up resistor to VCC) selects the SCART

mode and the NEGATIVE vision modulation.

The two other intermediate voltages select either

TV mode and POSITIVE vision modulation or

SCART mode and POSITIVE vision modulation.

FUNCTIONAL DESCRIPTION (continued)

STV2112B

4/24

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