CA3224E
November 1996
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 correc-
tion takes place each frame following the vertical blanking.
Figure 1 shows a block diagram of the CA3224E. The func-
tions include three identical servo loop transconductance
ampli鏗乪rs with a sample/hold switch and buffer ampli鏗乪r plus
control logic, internal bias and a mode switch.
Features
鈥?Automatic Picture Tube Bias Cutoff Control
鈥?Automatic Background Color Balance
鈥?Eliminates Grey Scale Adjustments
鈥?Compensates for Cathode-to-Heater Leakage
鈥?Electrostatic Protection on All Pins
鈥?Servo Loop Design
鈥?Wide Dynamic Range
鈥?Three-Gun Control
鈥?Minimal External Components
Ordering Information
PART NUMBER
CA3224E
TEMP.
RANGE (
o
C)
-40 to 85
PACKAGE
22 Ld PDIP
PKG.
NO.
E22.4
Pinout
CA3224E
(PDIP)
TOP VIEW
GROUND
CHANNEL 1 INPUT
CHANNEL 1 FREQ COMPENSATION
CHANNEL 2 INPUT
CHANNEL 2 FREQ COMPENSATION
CHANNEL 3 INPUT
CHANNEL 3 FREQ COMPENSATION
VERTICAL INPUT
GROUND
HORIZONTAL INPUT
GRID PULSE OUTPUT
1
2
3
4
5
6
7
8
9
10
11
22
21
20
19
18
17
16
15
14
13
12
V
CC
CHANNEL 1 HOLD CAP
CHANNEL 1 OUTPUT
CHANNEL 2 HOLD CAP
CHANNEL 2 OUTPUT
CHANNEL 3 HOLD CAP
CHANNEL 3 OUTPUT
V
REF
BYPASS
AUTO BIAS LEVEL ADJUST
AUTO BIAS PULSE OUTPUT
PROGRAM PULSE OUTPUT
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 321-724-7143 | Copyright 漏 Intersil Corporation 1999
File Number
1553.1
8-56
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