Functional description

STV9211

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2.9

ABL Control

The STV9211 includes an ABL (automatic beam limitation) input to attenuate the RGB Video

signals depending on the beam intensity.

The operating range is 2 V (from 3 V to 1 V). A typical 15 dB maximum attenuation is applied to the

output signal whatever the contrast adjustment is. (See

When not used, the ABL input (Pin 2) must be connected to a 5 V supply voltage.

2.10

OSD

Principle

The STV9211 allows to mix the OSD signals into the RGB main picture. The four pins dedicated to

this function are the following:

q

Three TTL RGB inputs (Pins 8, 9, 10) connected to the three outputs of the corresponding

OSD processor.

q

One TTL fast blanking input (Pin 11) also connected to the FBLK output of the OSD processor.

When a high level is present on the FBLK, the IC acts as follows:

q

The three main picture RGB input signals (IN1, IN2, IN3) are internally switched to an internal

clamp reference voltage.

q

The three output signals (OUT1, OUT2, OUT3) are set to the voltage corresponding to the

three OSD input logic states (0 or 1). (See

Output level

If the OSD input is set to 0, the output is set to the black level (see

The same variation is applied simultaneously to the three channels providing the OSD contrast.

Figure 9: ABL attenuation range

5

0

-2

-4

-6

-8

-10

-12

-14

-16

Attenuation (dB)

0

V

4

3

2

1