The INA219 is a precision digital current and bus voltage monitor that communicates via an I2C or SMBus-compatible interface. Unlike simple analog sensors, it features a built-in 12-bit ADC that monitors both the voltage drop across a shunt resistor and the overall bus supply voltage. This allows for the direct calculation of power (Watts) and current (Amps) within the module itself, reducing the processing load on your microcontroller.

Specifications

• Sensed Bus Voltage: 0V to 26V DC
• Operating Voltage (VCC): 3.0V to 5.5V DC
• Maximum Current: 3.2A (Default with 0.1 ohm shunt)
• Resolution: 0.8mA (at 3.2A range)
• Interface: I2C (Up to 3.4MHz high-speed mode)
• Bus Voltage Accuracy: 1% (Maximum)
• Operating Temperature: -40°C to +125°C

Features

• High-Side Sensing: Measures current on the positive rail, meaning it doesn't disturb the ground plane of your circuit, which is essential for stable communication and circuit integrity.
• Integrated Math Engine: Features internal registers that can be programmed to automatically calculate current in Amperes and power in Watts.
• Filtering and Averaging: Built-in 12-bit ADC allows for configurable conversion times and hardware averaging to provide stable readings even in noisy environments.
• Adjustable Current Range: By replacing the onboard 0.1$\Omega$ (R100) shunt resistor, the module can be modified to measure currents up to 32A.
• Addressable I2C: Features two address pins (A0, A1) allowing up to 16 different INA219 modules to be connected to the same I2C bus.

Common Applications

• Battery Monitoring: Tracking charge and discharge cycles for Li-Po or Lead-Acid batteries.
• Solar Power Systems: Measuring real-time energy production from solar panels.
• Power Supply Design: Monitoring the output and efficiency of DIY benchtop power supplies.
• Smart Home / IoT: Tracking energy consumption of connected appliances or individual DC loads.

Usage Tips

• Calibration: For the highest accuracy, use the Adafruit INA219 library, which includes pre-set calibration values for the standard 0.1$\Omega$ shunt.
• Soldering Required: These modules typically ship with loose pin headers and screw terminals; secure soldering is required to ensure a low-resistance path for the current being measured.
• V+ and V- Pins: The high-current load must be connected in series between the V+ and V- pins. V+ is the side closer to the power source, and V- is the side closer to the load.