INA228 datasheet(12/48 Pages) TI

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7 Detailed Description

7.1 Overview

The INA228 device is a digital current sense amplifier with an I2C digital interface. It measures shunt voltage,

bus voltage and internal temperature while calculating current, power, energy and charge necessary for accurate

decision making in precisely controlled systems. Programmable registers allow flexible configuration for

measurement precision as well as continuous or triggered operation. Detailed register information is found in

Section 7.6.

7.2 Functional Block Diagram

Oscillator

Voltage

Current

Power

Energy

Charge

Temp

Out-of-range

Threshold

SCL

SDA

Power

GND

ALERT

IN+

IN-

VBUS

20 Bit

ADC

Reference

MUX

7.3 Feature Description

7.3.1 Versatile High Voltage Measurement Capability

The INA228 operates off a 2.7 V to 5.5 V supply but can measure voltage and current on rails as high as 85 V.

The current is measured by sensing the voltage drop across a external shunt resistor at the IN+ and IN– pins.

The input stage of the INA228 is designed such that the input common-mode voltage can be higher than the

device supply voltage, VS. The supported common-mode voltage range at the input pins is –0.3 V to +85 V,

which makes the device well suited for both high-side and low-side current measurements. There are no special

considerations for power-supply sequencing because the common-mode input range and device supply voltage

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

versa without damaging the device.

The device also measures the bus supply voltage through the VBUS pin and temperature through the integrated

temperature sensor. The differential shunt voltage is measured between the IN+ and IN– pins, while the bus

voltage is measured with respect to device ground. Monitored bus voltages can range from 0 V to 85 V, while

monitored temperatures can range from -40 ºC to +125 ºC.

Shunt voltage, bus voltage, and temperature measurements are multiplexed internally to a single ADC as shown

in Figure 7-1.

PTAT Temp.

Sensor

IN+

IN-

VBUS

ADCp ADCn

MUX digital

Control

Bus Voltage

Shunt Voltage

Internal Temp.

ADC_IN+

ADC_IN-

To ADC Input

Figure 7-1. High-Voltage Input Multiplexer

INA228

SLYS021 – JANUARY 2021

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