INA231AIYFDR datasheet(28/44 Pages) TI1

28 / 44 page

Power Register

Current Register

I C

Interface

Voltage Register

INA231

GND

BUS

ADC

ALERT

SDA

SCL

0.1 F

BYPASS

High-

Side

Shunt

Low-

Side

Shunt

Load

Alert Register

(Supply Voltage)

Power Supply

(0 V to 28 V)

INA231

SBOS644B – FEBRUARY 2013 – REVISED AUGUST 2017

www.ti.com

Product Folder Links: INA231

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9 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

9.1 Application Information

The INA231 is a digital current shunt monitor with an I2C- and SMBus-compatible interface. This 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 towards the end of this data sheet, beginning

with Table 3. See Figure 20 for a block diagram of the INA231.

Figure 27 shows a typical application circuit for the INA231. For power-supply bypassing, place a 0.1-μF ceramic

capacitor as close as possible to the supply and ground pins.

Figure 27. High- or Low-Side Sensing

9.1.1 Filtering and Input Considerations

Measuring current is often a noisy task, and such noise can be difficult to define. The INA231 offers several

options for filtering by allowing the conversion times and number of averages to be independently selected in the

Configuration register. The conversion times can be independently set for the shunt voltage and bus voltage

measurements to allow added flexibility in configuring the monitoring of the power-supply bus.

The internal ADC is based on a delta-sigma (ΔΣ) front-end with a 500-kHz (±30%) typical sampling rate. This

architecture has good inherent noise rejection; however, transients that occur at or very close to the sampling

rate harmonics can cause problems. These signals are at 1 MHz and higher; therefore, manage them by

incorporating filtering at the input of the INA231. The high frequency enables the use of low-value series resistors

on the filter with negligible effects on measurement accuracy. In general, filtering the INA231 input is only

necessary if there are transients at exact harmonics of the 500-kHz (±30%) sampling rate (greater than 1 MHz).

Filter using the lowest possible series resistance (typically 10 Ω or less) and a ceramic capacitor. Recommended

values for this capacitor are 0.1 μF to 1.0 μF. Figure 28 shows the INA231 with an additional filter added at the

input.

INA231AIYFDR Datasheet(PDF) 28 Page - Texas Instruments

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