LMC6482_15 Datasheet, PDF (21/39 Pages) Texas Instruments – CMOS Dual Rail-to-Rail Input and Output Operational Amplifier

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LMC6482
SNOS674E – NOVEMBER 1997 – REVISED APRIL 2015
Application Information (continued)
8.1.3 Instrumentation Circuits
The LMC6482 has the high input impedance, large common-mode range and high CMRR needed for designing
instrumentation circuits. Instrumentation circuits designed with the LMC6482 can reject a larger range of
common-mode signals than most in-amps. This makes instrumentation circuits designed with the LMC6482 an
excellent choice of noisy or industrial environments. Other applications that benefit from these features include
analytic medical instruments, magnetic field detectors, gas detectors, and silicon-based transducers.
A small valued potentiometer is used in series with R_g to set the differential gain of the 3-op-amp instrumentation
circuit in Figure 57. This combination is used instead of one large valued potentiometer to increase gain trim
accuracy and reduce error due to vibration.
Figure 57. Low Power 3-Op-Amp Instrumentation Amplifier
A 2-op-amp instrumentation amplifier designed for a gain of 100 is shown in Figure 58. Low sensitivity trimming
is made for offset voltage, CMRR, and gain. Low cost and low power consumption are the main advantages of
this 2-op-amp circuit.
Higher frequency and larger common-mode range applications are best facilitated by a 3-op-amp instrumentation
amplifier.
Figure 58. Low-Power Two-Op-Amp Instrumentation Amplifier
8.1.4 Spice Macromodel
A spice macromodel is available for the LMC6482. This model includes accurate simulation of the following:
• Input common-mode voltage range
• Frequency and transient response
• GBW dependence on loading conditions
• Quiescent and dynamic supply current
• Output swing dependence on loading conditions
Many more characteristics are listed on the macromodel disk.
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