6 Detailed Description

6.1 Overview

The INA226 is a digital current sense amplifier with an I2C- and SMBus-compatible interface. The device

provides digital current, voltage, and power readings necessary for accurate decision-making in precisely-

controlled systems. Programmable registers allow flexible configuration for measurement resolution as well as

continuous-versus-triggered operation. Detailed register information appears at the end of this data sheet. See

the Functional Block Diagram section for a block diagram of the INA226 device.

6.2 Functional Block Diagram

ADC

´

´

Shunt Voltage

Channel

Bus Voltage

Channel

Shunt Voltage

(1)

Data Registers

Calibration

(2)

Current

(1)

Bus Voltage

(1)

Power

(1)

(1) Read-only

(2) Read/write

6.3 Feature Description

6.3.1 Basic ADC Functions

The INA226 device performs two measurements on the power-supply bus of interest. The voltage developed

from the load current that flows through a shunt resistor creates a shunt voltage that is measured at the IN+ and

IN– pins. The device can also measure the power supply bus voltage by connecting this voltage to the VBUS

pin. The differential shunt voltage is measured with respect to the IN– pin while the bus voltage is measured with

respect to ground.

The device is typically powered by a separate supply that can range from 2.7 V to 5.5 V. The bus that is being

monitored can range in voltage from 0 V to 36 V. Based on the fixed 1.25-mV LSB for the Bus Voltage Register

that a full-scale register results in a 40.96 V value.

Note

Do not apply more than 36 V of actual voltage to the input pins.

There are no special considerations for power-supply sequencing because the common-mode input range and

power-supply voltage are independent of each other; therefore, the bus voltage can be present with the supply

voltage off, and reciprocally.

The device takes two measurements, shunt voltage and bus voltage. The device then converts these

measurements to current, based on the Calibration Register value, and then calculates power. Refer to

the Programming the Calibration Register section for additional information on programming the Calibration

Register.

INA226

SBOS547B – JUNE 2011 – REVISED SEPTEMBER 2024

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