8 Detailed Description

8.1 Overview

INA351 is a selectable gain instrumentation amplifier with integrated reference buffer designed to provide

an integrated, small size, cost-effective solution for applications employing general purpose INAs or discrete

implementation of INAs using commodity amplifiers and resistors. The device incorporates a three op amp INA

architecture integrating three operational amplifiers and seven precision matched integrated resistors. INA351 is

suitable for use in 10-bit to 14-bit systems without any additional effort, but calibrating offset and gain error at a

system level can further improve system resolution and accuracy, enabling use in precision applications.

One of the key features of INA351 is that the device does not need any external resistors to set the gain. Often

these external resistors require tighter tolerance and careful routing, which adds to system complexity and cost.

INA351 is offered in four gain options across two variants. INA351ABS has two gain options of 10 and 20.

INA351CDS has two other gain options of 30 and 50. Gains can be selected by connecting the GS pin to logic

high or logic low. Note that the GS pin can be left floating as well, as the pin is designed with an internal pull up

to default to the same configuration as GS tied logic high.

The INA351 is designed for industrial applications leveraging pressure and temperature sensing via bridge-type

sensor networks and load cells. The device can also be used in space-constrained applications such as patient

monitoring, sleep diagnostics, electronic hospital beds, and blood glucose monitoring for voltage sensing and

differential to single-ended conversion. INA351 can enable these applications to reduce their overall size through

the use of tiny packages, including a 2-mm × 1.5-mm X2QFN package and a 2-mm × 2-mm WSON package.

8.2 Functional Block Diagram

+

–

+

–

+

–

60 k

60 k

60 k

60 k

REF

V+

OUT

V

IN

+IN

2

3

4

5

6

7

90 k

/ 145 k

90 k

/ 145 k

RG

GS

1

SHDN

8

_____

Note: 90 kΩ for INA351ABS and 145 kΩ for INA351CDS

Simplified Internal Schematic

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INA351

SBOSAD5 – DECEMBER 2022

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