STV9212 datasheet(9/34 Pages) STMICROELECTRONICS

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STV9212

Functional Description

The screen can also be blanked by permanently keeping the On-Screen Display FBLK input signal

at high level. In this case, only the video contents of the three video channels are replaced by “black

level” OSD content insertion (signals on pins OSD1 through OSD3 permanently at low level). Refer

to Section 2.5: OSD Insertion on page 11.

2.3

Contrast Control Stage and Automatic Beam Limiter

The contrast stages are simultaneously controlled on all three RGB channels with high attenuation

matching precision. Refer to electrical specifications for values. See Figure 7: Contrast Control and

Table 4: I²C-Bus Register Map.

The Automatic Beam Limiter (ABL) is an attenuator controlled through the ABL input, independent

of contrast stage attenuation. The operating range is about 2 V (from 3 V to 1 V). A typical

characteristic is shown in Figure 8. Refer to Section 4: Electrical Specifications for specific values.

When not used, the ABL pin is to be connected to VCCA.

Figure 7: Contrast Control

Figure 8: ABL Characteristics

Before contrast stage

After contrast stage

VRef

Note: CRST I²C-bus field acts equally on all 3 video channels

Video Black Level

CRST=max

CRST=mid

CRST=min

-2

-4

-6

-8

-10

-12

-14

-16

Attenuation (dB)

VABL (V)

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