Adafruit INA3221 Triple 26V ±3.2A DC Power Monitor - STEMMA QT/Qwiic

Overview

Monitoring multiple power rails usually means juggling several multimeters, moving probes around, and still missing transient current spikes. This Adafruit INA3221 breakout board simplifies that entire workflow by allowing you to monitor three independent power supplies simultaneously, measuring both bus voltage and DC current over a single I2C connection.

Unlike traditional low-side current meters that require inserting a shunt resistor in the ground path, this board supports true high-side current sensing. That means you can place the measurement point between the power source and the load without disturbing the system ground reference—critical for sensitive digital and mixed-signal electronics. Despite being powered from just 3V or 5V, the INA3221 can accurately measure bus voltages up to 26V DC, making it ideal for battery-powered systems, solar panels, and multi-rail embedded designs.

Each channel includes a precision 0.05Ω, 1% sense resistor paired with an internal amplifier capable of handling a differential input of ±163.8 mV. This allows current measurement up to ±3.2A per channel with a fine 0.4 mA resolution thanks to the onboard 13-bit ADC. For advanced users, the onboard sense resistors can be removed and replaced with lower-value shunts—such as 0.01Ω—to extend the measurable current range up to 16A, at the cost of reduced resolution.

Getting started is straightforward: power the board with 2.7–5.5V, connect SDA and SCL to your microcontroller, and wire each monitored supply through the VIN+/VIN– terminals. Official libraries are available for Arduino, CircuitPython, and Python, making it compatible with everything from basic ATmega-based boards to Raspberry Pi and other Linux SBCs.

Specification

Technical details for Adafruit INA3221 Triple 26V ±3.2A DC Power Monitor.

Pinout