CA3224E_02 Datasheet, PDF (1/6 Pages) Intersil Corporation – Automatic Picture Tube Bias Control Circuit

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October 2002
CA3224E
FN1553.2
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
Part Number Information
PART
NUMBER
TEMP. RANGE
(^oC)
PACKAGE PKG. NO.
CA3224E
-40 to 85 22 Ld PDIP E22.4
Pinout
CA3224E
(PDIP)
TOP VIEW
GROUND 1
CHANNEL 1 INPUT 2
CHANNEL 1 FREQ COMPENSATION ₃
CHANNEL 2 INPUT ₄
CHANNEL 2 FREQ COMPENSATION ₅
CHANNEL 3 INPUT ₆
CHANNEL 3 FREQ COMPENSATION 7
VERTICAL INPUT 8
GROUND 9
HORIZONTAL INPUT 10
GRID PULSE OUTPUT 11
22 V_CC
21 CHANNEL 1 HOLD CAP
20 CHANNEL 1 OUTPUT
19 CHANNEL 2 HOLD CAP
18 CHANNEL 2 OUTPUT
17 CHANNEL 3 HOLD CAP
16 CHANNEL 3 OUTPUT
15 VREF BYPASS
14 AUTO BIAS LEVEL ADJUST
13 AUTO BIAS PULSE OUTPUT
12 PROGRAM PULSE OUTPUT
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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