6 Detailed Description

6.1 Overview

The INA2227 is a dual channel digital current-sense amplifier with an I2C- and SMBus-compatible interface. The

device reports current, voltage, power, and energy for each of the channels and features programmable out-of-

range limits to issue alerts when selected parameters are outside the normal range of operation. The integrated

analog-to-digital converter (ADC) can be set to different averaging modes and configured for continuous-versus-

triggered operation. Device Registers provides detailed register information for the INA2227.

6.2 Functional Block Diagram

Load 2

Supply1

(-0.3V to 48V)

GND

Load 3

Supply2

(-0.3V to 48V)

IN+1

IN-1

IN+2

IN-2

Power Register

Current Register

I

2C-, SMBus-,

Compatible

Interface

Voltage Register

ADC

A0

A1

SDA

SCL

CBYPASS

0.1µF

Alert Registers

VS

Supply Voltage

(1.7V to 5.5V)

Energy Register

ALERT

EN

MUX

VBUS2

VBUS1

6.3 Feature Description

6.3.1 Integrated Analog-to-Digital Converter (ADC)

The INA2227 integrates a low offset 16-bit delta-sigma (ΔΣ) ADC. This ADC is multiplexed for each channel to

process both the shunt voltage and bus voltage measurements. The shunt voltage measurement is a differential

measurement of the voltage developed when the load current flows through a shunt resistor between the IN+

and IN– pins for each channel. The shunt voltage measurement has a maximum offset voltage of only 75µV and

a maximum gain error of 0.5%. The low offset voltage of the shunt voltage measurement allows for increased

accuracy at light load conditions for a given shunt resistor value. Another advantage of low offset is the ability to

sense a lower voltage drop across the sense resistor accurately, thus allowing for a lower-value shunt resistor.

Lower-value shunt resistors reduce power loss in the current-sense circuit and help improve the power efficiency

of the end application. This device also features independent bus voltage pins that allow power and energy

measurements for both high-side and low-side sensing applications.

There are no special considerations for power-supply sequencing because the bus common-mode at the IN+

and IN- pins and power-supply voltage at the VS pin are independent of each other; therefore, the bus common-

mode voltage can be present with the supply voltage off, and so forth.

6.3.2 Internal Measurement and Calculation Engine

The internal round robin measurement scheme for the INA2227 is shown in Figure 6-1. For each channel the

current, power, and energy registers are calculated from the shunt and bus voltage measurements and are not

directly affected by ADC conversion times. Register values are updated for each channel before preceding to the

next channel. When averaging is enabled, the registers for each channel updates once the number of averages

INA2227

SBOSAL5 – JUNE 2025

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