+

±

REF2

REF1

VS

GND

OUT

PWM

Rejection

IS+

IS±

IN+

IN±

SH+

SH±

2 m

0.1%

50 k

50 k

12

INA253

SLOS954A – JULY 2018 – REVISED DECEMBER 2018

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8 Detailed Description

8.1 Overview

The INA253 features a precision, 2-mΩ current-sensing resistor and supports common mode voltages up to 80

V. The internal amplifier features a precision zero-drift topology with excellent common-mode rejection ratio

(CMRR). The internal amplifier also features an enhanced pulse-width modulation (PWM) rejection current-

sensing amplifier integrated into a single package. High-precision measurements are enabled by matching the

shunt resistor value and the current-sensing amplifier gain, thus providing a highly-accurate, system-calibrated

method for measuring current. 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.

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 that provides accurate measurements over the

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

measurement stability over temperature, and simplifies printed circuit board (PCB) 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 through the SH+ and SH– pins, this resistor is not intended to be used as a stand-

alone component. The INA253 is system-calibrated to makes sure 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. Of this total package resistance, 2 mΩ 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 IS+ and IS– 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 to carry 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

make sure that the heat dissipated across the package is limited so that no damage occurs to the resistor or the

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