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FEATURES
Versatile Op Amp Front End: Inverting, Non-Inverting,
Differential Applications
Low Nonlinearity: 0.025% max, Model 277K
Low Input Offset Voltage Drift: 1
µV/°C max, Model 277K
Floating Power Output: ±15V @ ±15mA
High CMR: 160dB min @ dc
High CMV: 3500V rms
1400 Providence Highway, Building #2
Norwood, MA 02062
Phone (781) 551-5500
FAX (781) 551-5555
www.intronicspower.com
APPLICATIONS
Programmable Gain Isolated Amplifier
Isolated Power Source and Amplifier for Bridge
Measurements Instrumentation Amplifier
Instrumentation Grade Process Signal Isolator
Current Shunt Measurements
GENERAL DESCRIPTION
Model 277 is a versatile isolation amplifier which combines a high-
performance, uncommitted operational amplifier front end with a
precision, isolated output stage and a floating power supply section.
This configuration, shown in Figure 1, makes the 277 ideally suited to
instrumentation applications where the need for various forms of signal
conditioning, high CMV protection and isolated transducer power
requirements are encountered.
The input stage is a low drift (±1
µV/°C max, model 277K) differential
op amp that may be connected for use in inverting, non-inverting and
differential configurations. The circuitry employed around the
operational amplifier input stage can be designed by the user to suit
each application's particular signal processing needs. A full ±10V
signal range is available at the output of the front-end amplifier.
output stage's low nonlinearity (0.05%, models 277J/A and 0.025%
model 277K), these high CMR and CMV ratings facilitate accurate
measurements in the presence of noisy electrical equipment such as
motors and relays. In addition, model 277A offers a -25
°C to +85°C
rated operating temperature range. All versions of model 277 have a
±10 volt output range.
The floating power supply section provides isolated ±15 volt outputs
capable of delivering currents up to ±15mA. This feature permits
model 277 to power transducers and auxiliary isolated circuitry,
thereby eliminating the need for a separate isolated DC/DC converter.
All of the features of the model 277 isolation amplifier are packaged
in a compact (3" x 2.2" x 0.59") module. As an assurance of high
performance reliability, every model 277 is factory tested for CMV
rating by application of 3500V rms (±4900V peak) between input and
output common terminals for one minute (meets NEMA and CSA
requirements for 660Vrms service.) In addition, the 277 has a
calculated MTBF of 133,000 hours.
The isolated output stage includes a special modulator/demodulator
technique which provides the 277 with l60dB minimum DC common
mode rejection between input and output common and an input-to-
output CMV rating of 3500V rms. When combined with the
Precision Isolation Amplifier
High CMV/CMR,
±15V Floating
Model 277
Figure 1. Model 277 Functional Block Diagram
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