+

±

REF2

REF1

VS

GND

OUT

PWM

Rejection

50k

50k

IS+

IS-

IN+

IN-

SH+

SH-

2mO

0.1%

7

INA253

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SLOS954 – MAY 2018

Product Folder Links: INA253

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8 Detailed Description

8.1 Overview

The INA253 features a 2-mΩ, precision, current-sensing resistor and a 80-V common-mode, zero-drift topology,

precision, excellent common-mode rejection ratio (CMRR). It features enhanced pulse width modulation (PWM)

rejection current-sensing amplifier integrated into a single package. High precision measurements are enabled

through the matching of the shunt resistor value and the current-sensing amplifier gain providing a highly-

accurate, system-calibrated solution. Enhanced PWM rejection reduces the effect of common-mode transients on

the output signal that are associated with PWM signals. Multiple gain versions are available to allow for the

optimization of the desired full-scale output voltage based on the target current range expected in the application.

Multiple gain versions are available to allow for the optimization of the desired full-scale output voltage based on

the target current range expected in the application.

8.2 Functional Block Diagram

8.3 Feature Description

8.3.1 Integrated Shunt Resistor

The INA253 features a precise, low-drift, current-sensing resistor to allow for precision measurements over the

entire specified temperature range of –40°C to 125°C. The integrated current-sensing resistor ensures

measurement stability over temperature as well as improving layout and board constraint difficulties common in

high precision measurements.

The onboard current-sensing resistor is designed as a 4-wire (or Kelvin) connected resistor that enables accurate

measurements through a force-sense connection. Connecting the amplifier inputs pins (VIN– and VIN+) to the

sense pins of the shunt resistor (SH– and SH+) eliminates many of the parasitic impedances commonly found in

typical very-low sensing-resistor level measurements. Although the sense connection of the current-sensing

resistor can be accessed via the SH+ and SH– pins, this resistor is not intended to be used as a stand-alone

component. The INA253 is system-calibrated to ensure that the current-sensing resistor and current-sensing

amplifier are both precisely matched to one another. Use of the shunt resistor without the onboard amplifier

results in a current-sensing resistor tolerance of approximately 5%. To achieve the optimized system gain

specification, the onboard sensing resistor must be used with the internal current-sensing amplifier.

The INA253 has approximately 4.5 mΩ of package resistance. 2 mΩ of this total package resistance is a

precisely-controlled resistance from the Kelvin-connected current-sensing resistor used by the amplifier. The

power dissipation requirements of the system and package are based on the total 4.5-mΩ package resistance

between the IN+ and IN– pins. The heat dissipated across the package when current flows through the device

ultimately determines the maximum current that can be safely handled by the package. The current consumption

of the silicon is relatively low, leaving the total package resistance carrying the high load current as the primary

contributor to the total power dissipation of the package. The maximum safe-operating current level is set to

ensure that the heat dissipated across the package is limited so that no damage to the resistor or the package

itself occurs or that the internal junction temperature of the silicon does not exceed a 150°C limit.