50

NŸ

150

NŸ

150

NŸ

A

1

A

3

V

OUT

V

IN-

6

REF

5

RFI Filtered Inputs

2

V+

7

V-

4

1

8

150

NŸ

150

NŸ

50

NŸ

A

2

V

IN+

RFI Filtered Inputs

3

INA317

R

G

G = 1 +

100

NŸ

R

G

RFI Filtered Inputs

RFI Filtered Inputs

Copyright © 2017, Texas Instruments Incorporated

13

INA317

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SBOS896 – NOVEMBER 2017

Product Folder Links: INA317

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Copyright © 2017, Texas Instruments Incorporated

7 Detailed Description

7.1 Overview

The INA317 is a monolithic instrumentation amplifier (INA) based on the precision zero-drift OPA333 (operational

amplifier) core. The INA317 integrates laser-trimmed resistors to ensure excellent common-mode rejection and

low gain error. The combination of the zero-drift amplifier core and the precision resistors allows this device to

achieve outstanding DC precision and is designed for 3.3-V and 5-V industrial applications.

7.2 Functional Block Diagram

7.3 Feature Description

The INA317 is a low-power, zero-drift instrumentation amplifier that offers accuracy. The versatile three-

operational-amplifier design and small size makes the amplifier designed for a wide range of applications. Zero-

drift chopper circuitry provides DC specifications. A single external resistor sets any gain from 1 to 10,000. The

INA317 is laser trimmed for high common-mode rejection (100 dB at G

≥ 100). Typically, the INA317 operates

with power supplies as low as 1.8 V and quiescent current of 50 µA.

7.4 Device Functional Modes

7.4.1 Internal Offset Correction

INA317 internal operational amplifiers use an autocalibration technique with a time-continuous 350-kHz

operational amplifier in the signal path. The amplifier is zero-corrected every 8 µs using a proprietary technique.

Upon power up, the amplifier requires approximately 100 µs to achieve specified VOS accuracy. This design has

no aliasing or flicker noise.

7.4.2 Input Common-Mode Range

The linear input voltage range of the input circuitry of the INA317 is from approximately 0.1 V below the positive

supply voltage to 0.1 V above the negative supply. However, as a differential input voltage causes the output

voltage to increase, the output voltage swing of amplifiers A1 and A2 limits the linear input range. As a result, the

linear common-mode input range is related to the output voltage of the complete amplifier. This behavior

depends on supply voltage; see Figure 20.

Input overload conditions can produce an output voltage that appears normal. For example, if an input overload

condition drives the input amplifiers to the respective positive output swing limit, the difference voltage measured

by the output amplifier is approximately zero. The output of the INA317 is approximately 0 V even though the

inputs are overloaded.