TYPICAL APPLICATION

The STV5112 is composed of three independent

amplifiers, each of them including :

- A differential amplifier, the gain of which is fixed

by external feedback resistors,

- A voltage reference,

- A PMOS transistor providing a copy of the cathode

current,

- A protection diode against CRT arc discharges.

PC Board Layout

The best performances of the high voltage video

amplifier will be obtained only with a carefully desi-

gned PC board. Output to input capacitance is of

particular importance.

For a single amplifier, the input-output capacitance, in

parallel with the relatively high feedback resis-tance,

creates a pole in the closed-loop transfer function.

A low parasitic capacitance (0.3pF) feedback resis-

tor and HF isolated printed wires are necessary.

Furthermore, capacitive coupling from the output

of an amplifier toward the input of another one may

induce excessive cross-talk.

Power Dissipation

The power dissipation consists of a static part and

a dynamic part. The static dissipation is a function

tion of the static power can be calculated by the

following equation.

=

40k

+

The dynamic dissipation depends on the signal

- For a sine wave, dynamic dissipation is

capacitance (10pF), and amplifier output capaci-

2

V

REF

CATHODE 1

1k

Ω

33pF*

4.7k

Ω

V

CC

9V

100nF

100

µF

100nF

V

DD

220V

10

µF

510

Ω

V

DD

8

5

9

7

6

4

910

Ω

STV5112

CATHODE 2

V

DD

12

10

11

3

CATHODE 3

V

DD

15

13

14

1

CUT-OFF

SAMPLING

Figure 1 : Application Example

STV5112

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