STV9212 datasheet(11/34 Pages) STMICROELECTRONICS

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STV9212

Functional Description

2.5

OSD Insertion

The On-Screen Display (OSD) is inserted with a high level on the FBLK input (TTL). The device

acts as follows:

The three RGB video input signals (IN1, IN2, IN3) are internally blanked, i.e. put at the black

level.

Binary levels (TTL) on inputs OSD1, OSD2 and OSD3, after processing in the OSD contrast

stage, are added to the corresponding blanked video channels.

In this way, the OSD contents replace the video contents where the FBLK input is high. See

Figure 2 and Figure 10.

The OSD is inserted after the PictureBooST

™ block and before the Drive block. As a consequence,

OSD insertion overlaps all video contents, including the PictureBooST

™-ed zones. Color

temperature adjustments by means of the I²C-bus Drive registers act in the OSD insets.

The OSD contrast stage allows the adjustment of the level of OSD insets simultaneously on the

three OSD channels and independently of the video contrast adjustment. Refer to

Section 4: Electrical Specifications for values.

2.6

Drive Stage

The Drive stage is a set of three attenuators separately controlled via three I²C-bus registers,

DRIVE1, DRIVE2 and DRIVE3. It affects all signals, ordinary video, PictureBooST

™ processed

video and OSD insets. It is designed to compensate for differences in gain of the three CRT

cathodes. See Figure 11 and for values, refer to Section 4: Electrical Specifications.

Figure 10: OSD Insertion

OSD insertion

FBLK

OSD1(2,3)

min.

max

Video Black Level

mid

VOSD

Video before

OSDCRST

OSD insertion

Video after

VRef

Video Black Level

VRef

Note: The OSDCRST I²C-bus field acts equally on all 3 OSD channels.

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