8/21/97 4:00 PM
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FEATURES
Precision Performance in Standard SO-8 Pinout
Low Offset Voltage: 50 V max
Low Offset Voltage Drift: 0.6 V/ C max
Very Low Bias Current:
+25 C (100 pA max)
–55 C to +125 C (450 pA max)
Very High Open-Loop Gain (2000 V/mV min)
Low Supply Current (Per Amplifier): 625 A max
Operates From 62 V to 620 V Supplies
High Common-Mode Rejection: 120 dB min
Pin Compatible to LT1013, AD706, AD708, OP221,
LM158, and MC1458/1558 with Improved Performance
APPLICATIONS
Strain Gauge and Bridge Amplifiers
High Stability Thermocouple Amplifiers
Instrumentation Amplifiers
Photo-Current Monitors
High-Gain Linearity Amplifiers
Long-Term Integrators/Filters
Sample-and-Hold Amplifiers
Peak Detectors
Logarithmic Amplifiers
Battery-Powered Systems
GENERAL DESCRIPTION
Dual Low Bias Current
Precision Operational Amplifier
OP297
PIN CONNECTIONS
Plastic Epoxy-DIP (P Suffix)
8-Pin Cerdip (Z Suffix)
8-Pin Narrow Body SOIC (S Suffix)
OUT A
1
+IN A
3
V–
4
–
8
A
–
B
V+
OUT B
–IN B
+IN B
+
–IN A
2
7
6
5
Errors due to common-mode signals are eliminated by the
OP297’s common-mode rejection of over 120 dB. The
OP297’s power supply rejection of over 120 dB minimizes
offset voltage changes experienced in battery powered systems.
Supply current of the OP297 is under 625
µA
per amplifier and
it can operate with supply voltages as low as
±
2 V.
The OP297 utilizes a super-beta input stage with bias current
cancellation to maintain picoamp bias currents at all tempera-
tures. This is in contrast to FET input op amps whose bias
currents start in the picoamp range at 25°C, but double for
every 10°C rise in temperature, to reach the nanoamp range
above 85°C. Input bias current of the OP 297 is under 100 pA
at 25°C and is under 450 pA over the military temperature
range.
Combining precision, low power and low bias current, the
OP297 is ideal for a number of applications including instru-
mentation amplifiers, log amplifiers, photodiode preamplifiers
and long-term integrators. For a single device, see the OP97;
for a quad, see the OP497.
400
1200 UNITS
T
A
= +25°C
V
S
=
±15V
V
CM
= 0V
+
The OP297 is the first dual op amp to pack precision perfor-
mance into the space-saving, industry standard 8-pin SO pack-
age. Its combination of precision with low power and extremely
low input bias current makes the dual OP297 useful in a wide
variety of applications.
Precision performance of the OP297 includes very low offset,
under 50
µV,
and low drift, below 0.6
µV/°C.
Open-loop gain
exceeds 2000 V/mV insuring high linearity in every application.
60
I
B
–
40
V
S
=
±15V
V
CM
= 0V
INPUT CURRENT (pA)
20
0
20
I
OS
NUMBER OF UNITS
I
B
+
300
200
100
–40
–60
–75 –50 –25
0
25 50 75
TEMPERATURE (°C)
0
–100 –80 –60 –40 –20 0 20 40 60 80 100
INPUT OFFSET VOLTAGE (µV)
100 125
Figure 1. Low Bias Current Over Temperature
Figure 2. Very Low Offset
REV. D
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 617/329-4700
World Wide Web Site: http://www.analog.com
Fax: 617/326-8703
© Analog Devices, Inc., 1997
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