INA236BIDDFR datasheet(12/44 Pages) TI

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7 Detailed Description

7.1 Overview

The INA236 is a digital current-sense amplifier with an I2C- and SMBus-compatible interface. The device reports

the sensed current and features programmable out-of-range limits to issue alerts when the current is 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 INA236.

7.2 Functional Block Diagram

Current Register

2C-, SMBus-,

Compatible

Interface

Voltage Register

GND

ADC

ALERT

SDA

SCL

0.1 µF

BYPASS

High-

Side

Shunt

Low-

Side

Shunt

Load

Alert Register

Supply Voltage

(1.7 V to 5.5 V)

Bus Voltage

(-0.3 V to 48 V)

IN-

TI Device

IN+

Power Register

7.3 Feature Description

7.3.1 Integrated Analog-to-Digital Convertor (ADC)

The INA236 integrates a low offset 16-bit delta-sigma (ΔΣ) ADC. This ADC is multiplexed to process both

the shunt voltage and bus voltage measurements. Bus voltage measurements are made with respect to IN–

and GND. The shunt voltage measurement is a differential measurement of the voltage developed when the

load current flows through a shunt resistor as measured between the IN+ and IN– pins. The shunt voltage

measurement has an maximum offset voltage of only 5 µV and a maximum gain error of 0.1%. 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.

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 vice-versa.

7.3.2 Power Calculation

Figure 7-1 shows that the current and power are calculated after a shunt voltage and bus voltage measurement.

Power is calculated based on the previous current calculation and the latest bus voltage measurement. If the

value loaded into the calibration register is zero, the power value reported is also zero. The current and power

values are considered intermediate results (unless the averaging is set to 1) and are stored in an internal

accumulation register. Following every measured sample, the newly-calculated values for current and power are

appended to this accumulation register until all of the samples have been measured and averaged. After all

INA236

SBOSA81C – MAY 2021 – REVISED DECEMBER 2022

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