LMC6482_15 Datasheet, PDF (18/39 Pages) Texas Instruments – CMOS Dual Rail-to-Rail Input and Output Operational Amplifier

LMC6482
SNOS674E – NOVEMBER 1997 – REVISED APRIL 2015
7 Detailed Description
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7.1 Overview
The LMC6482 is a dual CMOS operational amplifier that supports both rail-to-rail inputs and outputs. It may be
operated in both dual supply mode and single supply mode.
7.2 Functional Block Diagram
7.3 Feature Description
7.3.1 Amplifier Topology
The LMC6482 incorporates specially designed wide-compliance range current mirrors and the body effect to
extend input common-mode range to each supply rail. Complementary paralleled differential input stages, like the
type used in other CMOS and bipolar rail-to-rail input amplifiers, were not used because of their inherent
accuracy problems due to CMRR, crossover distortion, and open-loop gain variation.
The LMC6482s input stage design is complemented by an output stage capable of rail-to-rail output swing even
when driving a large load. Rail-to-rail output swing is obtained by taking the output directly from the internal
integrator instead of an output buffer stage.
7.3.2 Input Common-Mode Voltage Range
Unlike Bi-FET amplifier designs, the LMC6482 does not exhibit phase inversion when an input voltage exceeds
the negative supply voltage. Figure 53 shows an input voltage exceeding both supplies with no resulting phase
inversion on the output.
An input voltage signal exceeds the lMC6482 power supply voltages with no output phase inversion.
Figure 53. Input Voltage
The absolute maximum input voltage is 300 mV beyond either supply rail at room temperature. Voltages greatly
exceeding this absolute maximum rating, as in Figure 54, can cause excessive current to flow in or out of the
input pins possibly affecting reliability.
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