鈥?/div>
PIEZOELECTRIC POSITIONING
HIGH VOLTAGE INSTRUMENTATION
ELECTROSTATIC TRANSDUCERS
PROGRAMMABLE POWER SUPPLIES UP TO 440V
TYPICAL APPLICATION
R
F
DESCRIPTION
The PA88 is a high voltage, low quiescent current MOSFET
operational amplifier designed for output currents up to 100mA.
Output voltages can swing up to
鹵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 PA88 features an unprecedented supply range
and excellent supply rejection. The MOSFET output stage is
biased on for linear operation. External compensation pro-
vides user flexibility.
This hybrid circuit utilizes beryllia (BeO) substrates, thick
film resistors, ceramic capacitors and semiconductor chips to
maximize reliability, minimize size and give top performance.
Ultrasonically bonded aluminum wires provide reliable inter-
connections at all operating temperatures. The 8-pin TO-3
package is hermetically sealed and electrically isolated. The
use of compressible thermal isolation washers and/or im-
proper mounting torque will void the product warranty. Please
see 鈥淕eneral Operating Considerations鈥?
+V
S
C
C
R
IN
PIEZO DRIVE
PA88
COMPUTER
FOCUS
COMMAND
VOLTAGE
鈥揤
S
V
OUT
LOWPOWER,PIEZOELECTRICPOSITIONING
Piezo positioning may be applied to the focusing of seg-
mented mirror systems. The composite mirror may be com-
posed of hundreds of elements, each requiring focusing under
computer control. In such complex systems the PA88鈥檚 advan-
tage of low quiescent power consumption reduces the costs of
power supplies and cooling, while providing the interface
between the computer and the high voltage drive to the piezo
positioners.
EQUIVALENT SCHEMATIC
D1
Q1
Q2
Q4
D19
COMP
7
8
鈥?IN
5
Q6
Q7
+ IN
4
Q9
CL
2
3
+V
S
EXTERNAL CONNECTIONS
+Vs
CL
R
CL
PHASE COMPENSATION
GAIN
C
C
68pf
33pf
15pf
3.3pf
R
C
100
鈩?/div>
100
鈩?/div>
100
鈩?/div>
鈥?/div>
3
2
1
OUT
Q8
+IN
4
TOP VIEW
鈥揑N
1
10
20
100
Q12
Q11
5
6
鈥揤s
8
7
COMP
R
C
COMP
C
C
R
CL
= .7
I
LIM
Q10A
Q10B
Q17
1
OUT
Q13
Q16
D2
Q18
C
C
RATED FOR FULL
SUPPLY VOLTAGE
鈥揤
S
6
APEX MICROTECHNOLOGY CORPORATION
鈥?TELEPHONE (520) 690-8600 鈥?FAX (520) 888-3329 鈥?ORDERS (520) 690-8601 鈥?EMAIL prodlit@apexmicrotech.com
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