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LPV801, LPV802

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SNOSCZ3 – AUGUST 2016

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7 Detailed Description

7.1 Overview

The LPV80x is unity-gain stable and can operate on a single supply, making it highly versatile and easy to use.

Parameters that vary significantly with operating voltages or temperature are shown in the Typical Characteristics

curves.

7.2 Functional Block Diagram

7.3 Feature Description

The amplifier's differential inputs consist of a non-inverting input (+IN) and an inverting input (–IN). The amplifer

amplifies only the difference in voltage between the two inputs, which is called the differential input voltage. The

where

•

(1)

7.4 Device Functional Modes

7.4.1 Negative-Rail Sensing Input

The input common-mode voltage range of the LPV80x extends from (V-) to (V+) – 0.9 V. In this range, low offset

can be expected with a minimum of 80dB CMRR. Operation of the LPV80x beyond (V+) - 0.9V is possible,

however, the offset voltage is not specified. Because of this, the LPV80x is protected from output "inversions" or

"reversals" as long as the input common mode voltage range stays within the input pin Absolute Maximum

Ratings range.

7.4.2 Rail to Rail Output Stage

The LPV80x output voltage swings 3 mV from rails at 3.3 V supply, which provides the maximum possible

dynamic range at the output. This is particularly important when operating on low supply voltages.

The LPV80x Maximum Output Voltage Swing graph defines the maximum swing possible under a particular

output load.

7.4.3 Design Optimization for Nanopower Operation

When designing for ultralow power, choose system feedback components carefully. To minimize quiecent current

consumption, select large-value feedback resistors. Any large resistors will react with stray capacitance in the

circuit and the input capacitance of the operational amplifier. These parasitic RC combinations can affect the

stability of the overall system. A feedback capacitor may be required to assure stability and limit overshoot or

gain peaking.

When possible, use AC coupling and AC feedback to reduce static current draw through the feedback elements.

Use film or ceramic capacitors since large electolytics may have large static leakage currents in the nanoamps.