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.