LMC6482QML_16 Datasheet, PDF (14/29 Pages) Texas Instruments – LMC6482QML CMOS Dual Rail-To-Rail Input and Output Operational Amplifier

LMC6482QML
SNOSAR9A – DECEMBER 2010 – REVISED MARCH 2013
APPLICATION INFORMATION
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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 53 shows an input voltage exceeding both supplies with no resulting phase
inversion on the output.
Figure 53. An Input Voltage Signal Exceeds the
LMC6482 Power Supply Voltages with
No Output Phase Inversion
The absolute maximum input voltage is 300mV 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.
Figure 54. A ±7.5V Input Signal Greatly
Exceeds the 3V Supply in Figure 55 Causing
No Phase Inversion Due to R_I
Applications that exceed this rating must externally limit the maximum input current to ±5mA with an input
resistor (R_I) as shown in Figure 55.
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