The INA3221 is a high-side current and bus voltage monitor capable of tracking three independent channels simultaneously. It communicates via an I2C or SMBus-compatible interface, making it a powerful upgrade from the single-channel INA219. This module is designed for precise power monitoring, allowing you to measure both the voltage drop across a shunt resistor and the overall bus supply voltage for three separate power rails.

Specifications

• Sensed Bus Voltage: 0V to 26V
• Supply Voltage (VCC): 2.7V to 5.5V
• Supply Current: 350uA (Typical)
• Channels: 3 Independent High-Side Channels
• Accuracy:
  • Offset Voltage: +/-80uV (Max)
  • Gain Error: 0.25% (Max)
• Interface: I2C / SMBus with 4 Programmable Addresses
• Operating Temperature: -40°C to +125°C

Operating Modes and Logic

• High-Side Sensing: Measures current by monitoring the voltage drop across a shunt resistor placed between the power source and the load.
• Programmable Conversion Times: Allows the user to adjust how long the ADC spends sampling voltages, balancing speed versus noise reduction.
• Averaging Modes: Built-in hardware averaging can aggregate multiple samples to provide a smoother, more stable reading without taxing the host microcontroller.
• Critical & Warning Alerts: Features programmable thresholds for each channel. If a voltage or current goes out of range, the module can trigger an interrupt via the alert pins.

Features

• Triple-Channel Monitoring: Consolidates three separate power sensors into a single module, saving space and reducing I2C bus traffic.
• Wide Voltage Range: Capable of monitoring power rails from 0V up to 26V, covering most standard 3.3V, 5V, 12V, and 24V systems.
• Dual Alert Outputs: Provides both "Critical" and "Warning" pins, allowing for multi-stage safety responses (e.g., cooling at warning level, shutdown at critical level).
• Flexible Addressing: Includes an address pin that can be tied to GND, VCC, SDA, or SCL to allow up to four INA3221 modules on the same I2C bus.
• High Precision: Low offset and gain error ensure reliable data for energy auditing and battery management systems.

Common Applications

• Power Management: Monitoring CPU, GPU, and peripheral power rails in embedded systems.
• Battery Charging: Tracking charge and discharge rates for multi-cell battery packs.
• Solar Systems: Simultaneously measuring output from solar panels, battery storage, and load consumption.
• Telecom Equipment: Precision monitoring of 24V industrial power distribution.

Usage Tips

• Shunt Resistors: The module typically comes with pre-installed 0.1$\Omega$ shunt resistors. If you need to measure higher currents, these can be replaced with resistors of a lower value.
• VPU Pin: If using the alert pins, remember that they are open-drain. The VPU (Voltage Pull-Up) pin is used to provide the reference voltage for these internal pull-ups.
• Common Ground: Ensure the ground of the module (GND) is common with the ground of the buses being measured to maintain accurate voltage references.