LM2202 datasheet(4/17 Pages) NSC

4 / 17 page

Typical Performance Characteristics (V

CC = 12V, TA = 25˚C unless otherwise specified)

Circuit Description

Figure 2 shows a block diagram of the LM2202 video ampli-

fier along with contrast and brightness (black level) control.

Contrast control is a DC-operated attenuator which varies

the AC gain of the amplifier. Signal attenuation (contrast) is

achieved by varying the base drive to a differential pair and

thereby unbalancing the current through the differential pair.

As shown in

Figure 2, pin 20 provides a 5.3V bias voltage for

the positive input of the attenuator (pin 1). Pin 3 provides a

control voltage for the negative input (pin 2) of the attenuator.

The voltage at pin 3 varies as the voltage at the contrast con-

trol input (pin 8) varies thus providing signal attenuation. The

gain is maximum (0 dB attenuation) if the voltage at pin 8 is

4V and is minimum (maximum attenuation) if the voltage at

pin 8 is 0V. The 0V to 4V DC-operated drive control at pin 9

Quiescent Supply Current

vs Supply Voltage

DS012591-3

Attenuation vs Drive Voltage

DS012591-4

Contrast vs Frequency

DS012591-5

Drive vs Frequency

DS012591-6

Attenuation vs

Contrast Voltage

DS012591-7

LM2202 Fiches technique(PDF) 4 Page - National Semiconductor (TI)