STV5730A datasheet(15/20 Pages) STMICROELECTRONICS

15 / 20 page

FUNCTIONAL DESCRIPTION (continued)

9 - VIDEO FULL PAGE MODE

In addition to the normal full page mode in which a

uniformely colored screen background is gener-

ated, the STV5730A is able to perform a ”video full

page mode”.

Normal and video full page mode are selected by

the control bit C11 (respectively set high and low).

By using the video full page mode the channel

capture operation can be easily monitored on the

screen since the signal at the VIDEO IN input is

displayed, unlocked, in the screen background

area ; the text being stable and colored, with or

without colored background.

Presence detection is permanently active to keep

the microcontroller informed of the input signal

quality. The information is delivered by the MUTE

pin.

This information can be used by the microcontroller

to force the STV5730A into the mixed mode (set

C0 low) when the input signal becomes good

enough.

In the video full page mode, it can be usefull to set

the M11 (mode register) bit high, so that the mute

signal is not synchronized on the vertical sync, thus

accelerating the VIDEO IN presence detection.

10 - S-VHS APPLICATION (see Figure 5)

The STV5730Acan be used in S-VHS applications

easily.

The Y signal must be delivered to the VIDEO IN

input. The VIDEO OUT1 output then delivers a

Y + text signal, whilst the VIDEO OUT2 delivers the

Y input signal, provided that the CIN input is con-

nected to a bias DC level.

An external switch must be used to select the C

signal in mixed mode or the COUT output signal in

full page mode.

In mixed mode the chroma signal (C) can be exter-

nally attenuated (multistandard translucent opera-

tion) or killed (PAL/NTSC opaque operation only)

during the character gate controlled by the fast

blanking signal.

Table 1

FULL PAGE

PAL/NTSC

MIXED MODE

TRANSLUCENT PAL/NTSC/SECAM

OPAQUE PAL/NTSC

VIDEO OUT1

CVBS (OSD)

VIDEO IN or Text

VIDEO OUT2

High impedance

VIDEO IN

High Impedance

CVBS

(OSD)

VIDEO IN or

R2 x Text

+ R1 x VIDEO IN

+ R2

VIDEO IN

or Text

CHARACTER

GATED

ATTENUATOR

EXTERNAL

S WITCH

CIN

Mixed Mode (MM)

Full Pa ge Mode (FP)

COUT

S TV5730A

VIDEO IN

VIDEO OUT1

VIDEO OUT2

INTERNAL BIAS

OP TIONAL

FILTER

YOSD

Yor Te xt

Yor

Full pa ge mode

Opa que mixed mode

Tra ns luce nt mixed mode

R 2

R 1

R 2 * Text R 1 * Y

R 2

Figure 5 :

S-VHS Input/Output Configuration

STV5730A

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