EL8176

FN7436 Rev 9.00

Page 12 of 16

January 6, 2015

Applications Information

Introduction

The EL8176 is a rail-to-rail input and output micro-power

precision single supply operational amplifier with an enable

feature. The device achieves rail-to-rail input and output

operation and eliminates the concerns introduced by a

conventional rail-to-rail I/O operational amplifier as discussed

below.

Rail-to-Rail Input

The input common-mode voltage range of the EL8176 goes from

negative supply to positive supply without introducing offset errors

or degrading performance associated with a conventional

rail-to-rail input operational amplifier. Many rail-to-rail input stages

use two differential input pairs, a long-tail PNP (or PFET) and an

NPN (or NFET). Severe penalties have to be paid for this circuit

topology. As the input signal moves from one supply rail to

another, the operational amplifier switches from one input pair to

the other causing drastic changes in input offset voltage and an

undesired change in magnitude and polarity of input offset

current.

The EL8176 achieves input rail-to-rail without sacrificing

important precision specifications and without degrading

distortion performance. The EL8176's input offset voltage

exhibits a smooth behavior throughout the entire common-mode

input range. The input bias current versus the common-mode

voltage range for the EL8176 gives us an undistorted behavior

from typically 10mV above the negative rail all the way up to the

positive rail.

0.09

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TEMPERATURE (°C)

n = 12

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TEMPERATURE (°C)

n = 12

MEDIAN

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-40

-20

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20

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TEMPERATURE (°C)

n = 12

MEDIAN

MAX

MIN