APEX MICROTECHNOLOGY CORPORATION
TELEPHONE (520) 690-8600 FAX (520) 888-3329 ORDERS (520) 690-8601 EMAIL prodlit@apexmicrotech.com
FEATURES
HIGH VOLTAGE — 450V (
±
225V)
LOW QUIESCENT CURRENT — 2mA
HIGH OUTPUT CURRENT — 100mA
PROGRAMMABLE CURRENT LIMIT
LOW BIAS CURRENT — FET Input
APPLICATIONS
PIEZOELECTRIC POSITIONING
HIGH VOLTAGE INSTRUMENTATION
ELECTROSTATIC TRANSDUCERS
PROGRAMMABLE POWER SUPPLIES UP TO 440V
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
±
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 “General Operating Considerations”.
EQUIVALENT SCHEMATIC
TYPICAL APPLICATION
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’s 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.
EXTERNAL CONNECTIONS
LOW POWER, PIEZOELECTRIC POSITIONING
F
R
PA88
IN
R
PIEZO DRIVE
S
–V
S
+V
OUT
V
C
C
COMPUTER
FOCUS
COMMAND
VOLTAGE
1
2
3
4
5
6
7
8
TOP VIEW
CL
+Vs
+IN
–Vs
COMP
OUT
R
CL
–IN
C
C
PHASE COMPENSATION
GAIN
C
C
1
10
20
100
68pf
33pf
15pf
3.3pf
COMP
R
C
100
100
100
—
R
C
R
CL
=I
LIM
C
RATED FOR FULL
SUPPLY VOLTAGE
PATENTED
2
1
3
6
4
5
8
7
+ IN
COMP
CL
OUT
+V
S
–V
S
Q1
Q2
Q4
Q8
Q9
Q6
Q7
Q12
Q10A
Q10B
Q11
Q17
Q13
Q16
Q18
D2
D19
D1
– IN
HTTP://WWW.APEXMICROTECH.COM (800) 546-APEX (800) 546-2739
M I C R O T E C H N O L O G Y
HIGH VOLTAGE POWER OPERATIONAL AMPLIFIERS
PA88 PA88A