LMC6482

SNOS674D – NOVEMBER 1997 – REVISED MARCH 2013

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APPLICATION INFORMATION

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, cross-over distortion, and open-loop gain variation.

The LMC6482's 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.

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 56 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 56. Input Voltage

The absolute maximum input voltage is 300mV beyond either supply rail at room temperature. Voltages greatly

exceeding this absolute maximum rating, as in Figure 57, can cause excessive current to flow in or out of the

input pins possibly affecting reliability.

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