PA85 Datasheet, PDF (1/5 Pages) Cirrus Logic – HIGH VOLTAGE POWER OPERATIONAL AMPLIFIERS

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PA85PA•8P5 A• P8A58A5A
High Voltage Power Operational Amplifiers
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
DESCRIPTION
The PA85 is a high voltage, high power bandwidth MOSFET
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 cur-
rent 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.
EQUIVALENT SCHEMATIC
Q1
Q6
–IN
5
Q10A
Q13
Q2 ^Q4
Q7
+IN
4
Q10B
D2
3
D1
+V_S
D23
Q8 ^Q9
COMP
C_L
78
Q12
2
Q11
Q17
Q16
1
OUT
Q18
–V_S
6
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.
DC
R_IN1
FOCUS
X SWEEP
SAMPLE
z= x²+y²
R_IN2
Y SWEEP
SAMPLE
R_F
+225V
R_CL
PA85
TO
FOCUS
GRID
-225V
EXTERNAL CONNECTIONS
+Vs
3
CL R_CL
2
+IN ₄
1 OUT
TOP VIEW
–IN ⁵
COMP
8
6
7
C_C
–Vs
COMP
R_C
PHASE COMPENSATION
Gain
1
C_C
68pF
R_C
100Ω
20
10pF 330Ω
100
3.3pF
0Ω
C_C RATED FOR FULL
SUPPLY VOLTAGE
PA85_hU_{ttp://www.cirrus.com}
Copyright © Cirrus Logic, Inc. 2009
(All Rights Reserved)
MAY 2009₁
APEX − PA85UREVO