1 Introduction

Current shunt monitors are a simple and easy way to measure current. The INA226/INA228 is a current shunt and power monitor with an I2C- or SMBUS-compatible interface. It measures the voltage across a sense resistor placed in the conduction path between a power source and a load. The device can monitor both shunt voltage drops and bus supply voltage. Programmable calibration value, conversion times, and averaging, combined with an internal multiplier, enable direct readouts of current in amperes and power in watts.

The INA226 reports current, bus voltage and power on common-mode bus voltages that can vary from 0 V to 36 V, independent of the supply voltage. The device operates from a single 2.7-V to 5.5-V supply, drawing a typical of 330 μA of supply current. It can measure a full-scale differential input of ±81.92 mV across a resistive shunt sense element.

The INA228 reports current, bus voltage, temperature, power, energy and charge accumulation on common-mode bus voltages that can vary from 0 V to 85 V, independent of the supply voltage. The device operates from a single 2.7-V to 5.5-V supply, drawing a typical of 640 μA of supply current. It can measure a full-scale differential input of ±163.84 mV or ±40.96 mV across a resistive shunt sense element with common-mode voltage support from –0.3 V to +85 V. The integrated temperature sensor is ±1°C accurate for die temperature measurement and is useful in monitoring the system ambient temperature.

The devices are specified over the operating temperature range between –40°C and 125°C and features up to 16 programmable addresses on the I2C-compatible interface. See the respective device datasheets for more information.