INA233 datasheet(11/48 Pages) TI1

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Power

Bus Voltage

Current

Calibration

Shunt Voltage

ADC

Shunt Voltage

Channel

Bus Voltage

Channel

Power Accumulator

INA233

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SBOS790 – APRIL 2017

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7 Detailed Description

7.1 Overview

The INA233 is a digital current-sense amplifier with an I2C-, SMBus-, and PMBus-compatible interface. The

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

controlled systems. The INA233 also has a built-in power accumulator that can be used for energy or average

power measurements. Programmable out-of-range limits can be set to issue alerts when the voltage, current, or

power 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. The Register Maps section

provides detailed register information for the INA233.

7.2 Functional Block Diagram

7.3 Feature Description

7.3.1 High-Accuracy Analog-to-Digital Convertor (ADC)

The INA233 integrates a highly accurate, 16-bit, delta-sigma (ΔΣ) ADC. This ADC is multiplexed 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 as measured at the IN+ and IN–

pins. The shunt voltage measurement has an maximum offset voltage of only 10 µV and a maximum gain error

of only 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 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. The device can also measure the power-supply bus voltage by connecting this voltage to the VBUS

pin. Internally, the voltage at VBUS is divided down to a voltage that can be measured by the ADC. The

impedance of the VBUS pin to ground is approximately 830 kΩ. The differential shunt voltage is measured

between the IN+ and IN– pins and the bus voltage is measured between the VBUS pin and GND.

The device takes two measurements: shunt voltage and bus voltage. The INA233 then converts these

measurements to current, based on the calibration register value, and then calculates power; see the Calibration

INA233 Datasheet(PDF) 11 Page - Texas Instruments

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