APEX MICROTECHNOLOGY CORPORATION • 5980 NORTH SHANNON ROAD • TUCSON, ARIZONA 85741 • USA • APPLICATIONS HOTLINE: 1 (800) 546-2739

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FEATURES

• LOW BIAS CURRENT, LOW NOISE — FET Input

• FULLY PROTECTED INPUT — Up to ±150V

• WIDE SUPPLY RANGE — ±15V to ±150V

APPLICATIONS

• HIGH VOLTAGE INSTRUMENTATION

• ELECTROSTATIC TRANSDUCERS & DEFLECTION

• PROGRAMMABLE POWER SUPPLIES UP TO 290V

• ANALOG SIMULATORS

DESCRIPTION

The PA83 is a high voltage operational amplifier designed

for output voltage swings up to ±145V with a dual (±) supply or

290V with a single supply. Its input stage is protected against

transient and steady state overvoltages up to and including

the supply rails. High accuracy is achieved with a cascode

input circuit configuration. All internal biasing is referenced

to a zener diode fed by a FET constant current source. As

a result, the PA83 features an unprecedented supply range

and excellent supply rejection. The output stage is biased in

the class A/B mode for linear operation. Internal phase com-

pensation assures stability at all gain settings without need

for external components. Fixed current limits protect these

amplifiers against shorts to common at supply voltages up to

120V. For operation into inductive loads, two external flyback

pulseprotectiondiodesarerecommended.However,aheatsink

may be necessary to maintain the proper case temperature

under normal operating conditions.

This hybrid circuit utilizes beryllia (BeO) substrates, thick

(cermet) film resistors, ceramic capacitors and silicon semicon-

ductor chips to maximize reliability, minimize size and give top

performance. Ultrasonically bonded aluminum wires provide

reliable interconnections at all operating temperatures. The

8-pin TO-3 package is hermetically sealed and electrically iso-

lated. The use of compressible thermal isolation washers and/or

improper mounting torque voids product warranty. Please see

Application Note 1 “General Operating Considerations”.

EXTERNAL CONNECTIONS

TYPICAL APPLICATION

While piezo electric transducers present a complex imped-

ance, they are often primarily capacitive at useful frequen-

cies. Due to this capacitance, the speed limitation for a given

transducer/amplifier combination may well stem from limited

current drive rather than power bandwidth restrictions. With

its drive capability of 75mA, the PA83 can drive transducers

having up to 2nF of capacitance at 40kHz at maximum output

voltage. In the event the transducer may be subject to shock

or vibration, flyback diodes, voltage clamps or other protection

networks must be added to protect the amplifier from high

voltages which may be generated.

EQUIVALENT SCHEMATIC

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8-PIN TO-3

PACKAGE STYLE CE