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PA12 • PA12A
PA12 • PA12A
Power Operational Amplifier
FEATURES
• LOW THERMAL RESISTANCE — 1.4°C/W
• CURRENT FOLDOVER PROTECTION — NEW
• HIGH TEMPERATURE VERSION — PA12H
• EXCELLENT LINEARITY — Class A/B Output
• WIDE SUPPLY RANGE — ±10V to ±50V
• HIGH OUTPUT CURRENT — Up to ±15A Peak
APPLICATIONS
• MOTOR, VALVE AND ACTUATOR CONTROL
• MAGNETIC DEFLECTION CIRCUITS UP TO 10A
• POWER TRANSDUCERS UP TO 100kHz
• TEMPERATURE CONTROL UP TO 360W
• PROGRAMMABLE POWER SUPPLIES UP TO 90V
• AUDIO AMPLIFIERS UP TO 120W RMS
POWER RATING
8-PIN TO-3
PACKAGE STYLE CE
DESCRIPTION
The PA12 is a state of the art high voltage, very high output
current operational amplifier designed to drive resistive, induc-
tive and capacitive loads. For optimum linearity, especially at low
levels, the output stage is biased for class A/B operation using
a thermistor compensated base-emitter voltage multiplier circuit.
The safe operating area (SOA) can be observed for all operating
conditions by selection of user programmable current limiting
resistors. For continuous operation under load, a heatsink of
proper rating is recommended. The PA12 is not recommended
for gains below –3 (inverting) or +4 (non-inverting).
This hybrid integrated circuit utilizes thick film (cermet)
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 isolation washers voids the warranty.
Not all vendors use the same method to rate the power
handling capability of a Power Op Amp. Apex Precision Power
rates the internal dissipation, which is consistent with rating
methods used by transistor manufacturers and gives conser-
vative results. Rating delivered power is highly application
dependent and therefore can be misleading. For example, the
125W internal dissipation rating of the PA12 could be expressed
as an output rating of 250W for audio (sine wave) or as 440W
if using a single ended DC load. Please note that all vendors
rate maximum power using an infinite heatsink.
THERMAL STABILITY
Apex Precision Power has eliminated the tendency of class
A/B output stages toward thermal runaway and thus has vastly
increased amplifier reliability. This feature, not found in most
other Power Op Amps, was pioneered by Apex Precision
Power in 1981 using thermistors which assure a negative
temperature coefficient in the quiescent current. The reliability
benefits of this added circuitry far outweigh the slight increase
in component count.
EXTERNAL CONNECTIONS
+V
S
3
R
CL+
CL+
2
1
OUT
OUTPUT
EQUIVALENT SCHEMATIC
3
D1
Q1
Q3
1
7
8
4
A1
5
C1
6
Q6A
Q6B
Q2A
Q2B
2
+IN
4
TOP VIEW
–IN
5
6
7
8
CL–
R
CL-
–V
S
F.O.
Q4
Q5
PA12U
http://www.cirrus.com
Copyright © Cirrus Logic, Inc. 2009
(All Rights Reserved)
MAY 2009
1
APEX − PA12UREVS
CIRRUS [ CIRRUS LOGIC ]
