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FEATURES
• HIGH VOLTAGE — 450V (±225V)
• HIGH SLEW RATE — 1000V/μS
• HIGH OUTPUT CURRENT — 200mA
APPLICATIONS
•
•
•
•
HIGH VOLTAGE INSTRUMENTATION
PIEZO TRANSDUCER EXCITATION
PROGRAMMABLE POWER SUPPLIES UP TO 430V
ELECTROSTATIC TRANSDUCERS & DEFLECTION
PATENTED
8-PIN TO-3
PACKAGE STYLE CE
TYPICAL APPLICATION
Dynamic focusing is the active correction of focusing voltage
as a beam traverses the face of a CRT. This is necessary in
high resolution flat face monitors since the distance between
cathode and screen varies as the beam moves from the center
of the screen to the edges. PA85 lends itself well to this function
since it can be connected as a summing amplifier with inputs
from the nominal focus potential and the dynamic correction.
The nominal might be derived from a potentiometer, or per-
haps automatic focusing circuitry might be used to generate
this potential. The dynamic correction is generated from the
sweep voltages by calculating the distance of the beam from
the center of the display.
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DESCRIPTION
The PA85 is a high voltage, high power bandwidth MOS-
FET operational amplifier designed for output currents up to
200mA. Output voltages can swing up to ±215V with a dual
supply and up to +440 volts with a single supply. The safe
operating area (SOA) has no second breakdown limitations
and can be observed with all types of loads by choosing an
appropriate current limiting resistor. High accuracy is achieved
with a cascode input circuit configuration. All internal biasing is
referenced to a bootstrapped zener-MOSFET current source.
As a result, the PA85 features an unprecedented supply range
and excellent supply rejection. The MOSFET output stage is
biased on for linear operation. External compensation provides
user flexibility.
This hybrid circuit utilizes thick film (cermet) resistors, ceramic
capacitors and silicon semiconductor chips to maximize reli-
ability, minimize size and give top performance. Ultrasonically
bonded aluminum wires provide reliable interconnections at all
operating temperatures. The 8-pin TO-3 package is hermeti-
cally sealed and electrically isolated. The use of compressible
isolation washers voids the warranty.
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EQUIVALENT SCHEMATIC
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EXTERNAL CONNECTIONS
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PHASE COMPENSATION
R
C
Gain
C
C
1
68pF
100Ω
20
10pF
330Ω
100
3.3pF
0Ω
C
C
RATED FOR FULL
SUPPLY VOLTAGE
APEX MICROTECHNOLOGY CORPORATION • TELEPHONE (520) 690-8600 • FAX (520) 888-3329 • ORDERS (520) 690-8601 • EMAIL prodlit@apexmicrotech.com
1
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