STV9553

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6

THEORY OF OPERATION

6.1

General

coupling mode).

In DC coupling mode, the application schematic is very simple and only a few external components are

needed to drive the cathodes. In particular, there is no need of the DC-restore circuitry which is used in

classical AC coupling applications.

The output voltage range is wide enough (Figure 2) to provide simultaneously :

– Cut-off adjustment (typ. 25V)

– Video contrast (typ. up to 40V),

– Brightness (with the remaining voltage range).

In normal operation, the output video signal must remain inside the linear region whatever the cut-off,

brightness and contrast adjustments are.

Figure 2. Output signal, level adjustments

(A) Top Non-Lin ear Region

GND

Blanking pulse

Video Signal

(B) Cut-off Adjust. (25V Typ.)

(C) Brightness Adjust. (10V Typ.)

(D) Contrast Adjust. (40V Typ.)

15V

17V

3