1

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FN1553.2

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CA3224E

Automatic Picture Tube Bias Control

Circuit

Description

The CA3224E is an automatic picture tube bias control cir-

cuit used in color TV receiver CRT drive circuits. It is used to

provide dynamic bias control of the grey scale both initially

and over the CRT operating life, compensating for CRT cut-

off changes.

The CA3224E provides automatic continuous control of the

cutoff current in each gun of a three-gun color CRT. From an

input pulse amplitude proportional to the difference between

the desired and the actual CRT cutoff, a gated sample/hold

circuit generates a DC correction voltage which correctly

biases the CRT driver circuit. The sample/hold bias

correction takes place each frame following the vertical

blanking. Figure 1 shows a block diagram of the CA3224E.

The functions include three identical servo loop

transconductance amplifiers with a sample/hold switch and

buffer amplifier plus control logic, internal bias and a mode.

Features

• Automatic Picture Tube Bias Cutoff Control

• Automatic Background Color Balance

• Eliminates Grey Scale Adjustments

• Compensates for Cathode-to-Heater Leakage

• Electrostatic Protection on All Pins

• Servo Loop Design

• Wide Dynamic Range

• Three-Gun Control

• Minimal External Components

Pinout

CA3224E

(PDIP)

TOP VIEW

Part Number Information

PART

NUMBER

TEMP. RANGE

PACKAGE

PKG. NO.

CA3224E

-40 to 85

22 Ld PDIP

E22.4

1

11

10

9

8

7

6

5

3

2

4

22

12

13

14

15

16

17

18

19

21

20

CHANNEL 1 INPUT

CHANNEL 1 FREQ COMPENSATION

CHANNEL 2 INPUT

CHANNEL 2 FREQ COMPENSATION

CHANNEL 3 INPUT

CHANNEL 3 FREQ COMPENSATION

GROUND

VERTICAL INPUT

HORIZONTAL INPUT

GRID PULSE OUTPUT

CHANNEL 1 HOLD CAP

CHANNEL 2 HOLD CAP

CHANNEL 2 OUTPUT

CHANNEL 3 HOLD CAP

CHANNEL 1 OUTPUT

CHANNEL 3 OUTPUT

AUTO BIAS LEVEL ADJUST

AUTO BIAS PULSE OUTPUT

PROGRAM PULSE OUTPUT

GROUND

Data Sheet

October 2002

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