How to Use INA219: Examples, Pinouts, and Specs

The INA219 is a high-side current shunt monitor with an integrated I2C interface, designed for precise current, voltage, and power measurements. It is capable of measuring the voltage across a shunt resistor and the bus voltage, enabling accurate power monitoring. The INA219 is widely used in applications such as battery management systems, energy monitoring, and power optimization in embedded systems.

• Battery management systems (BMS)
• Solar power monitoring
• Energy consumption tracking
• DC motor current monitoring
• Power optimization in IoT devices

The INA219 offers high accuracy and flexibility for power monitoring applications. Below are its key technical specifications:

The INA219 is typically available in an 8-pin SOIC package. Below is the pinout description:

The INA219 is straightforward to use in a circuit, thanks to its I2C interface and built-in ADC. Below are the steps to integrate and use the INA219:

1. Power Supply: Connect the Vcc pin to a 3.3V or 5V power source, and GND to the ground.
2. Shunt Resistor: Place a shunt resistor between the load and the INA219. Connect the V+ pin to the high side of the shunt resistor and the V- pin to the low side.
3. I2C Interface: Connect the SDA and SCL pins to the corresponding I2C pins on your microcontroller (e.g., Arduino).
4. Address Configuration: Use the A0 and A1 pins to set the I2C address if multiple INA219 devices are used on the same bus.

Below is an example of how to use the INA219 with an Arduino UNO to measure current, voltage, and power:

#include <Wire.h>
#include <Adafruit_INA219.h>

// Create an instance of the INA219 class
Adafruit_INA219 ina219;

void setup() {
  Serial.begin(9600); // Initialize serial communication at 9600 baud
  while (!Serial) {
    delay(10); // Wait for the serial monitor to open
  }

  // Initialize the INA219 sensor
  if (!ina219.begin()) {
    Serial.println("Failed to find INA219 chip");
    while (1) {
      delay(10); // Halt execution if the sensor is not found
    }
  }
  Serial.println("INA219 initialized successfully");
}

void loop() {
  float shuntVoltage = ina219.getShuntVoltage_mV(); // Shunt voltage in mV
  float busVoltage = ina219.getBusVoltage_V();      // Bus voltage in V
  float current_mA = ina219.getCurrent_mA();        // Current in mA
  float power_mW = ina219.getPower_mW();            // Power in mW

  // Print the measurements to the serial monitor
  Serial.print("Shunt Voltage: ");
  Serial.print(shuntVoltage);
  Serial.println(" mV");

  Serial.print("Bus Voltage: ");
  Serial.print(busVoltage);
  Serial.println(" V");

  Serial.print("Current: ");
  Serial.print(current_mA);
  Serial.println(" mA");

  Serial.print("Power: ");
  Serial.print(power_mW);
  Serial.println(" mW");

  Serial.println("-----------------------------------");
  delay(1000); // Wait 1 second before the next reading
}

• Shunt Resistor Selection: Choose a shunt resistor with a low resistance value to minimize power loss, but ensure it provides a measurable voltage drop within the INA219's range.
• I2C Pull-Up Resistors: Ensure that the SDA and SCL lines have appropriate pull-up resistors (typically 4.7kΩ).
• Address Conflicts: If using multiple INA219 devices, configure unique I2C addresses using the A0 and A1 pins.

1. INA219 Not Detected on I2C Bus:

   • Ensure the SDA and SCL lines are correctly connected to the microcontroller.
   • Verify that pull-up resistors are present on the I2C lines.
   • Check the I2C address configuration (default is 0x40).

2. Incorrect Current or Voltage Readings:

   • Verify the shunt resistor value and ensure it matches the value used in calculations.
   • Check for loose or incorrect connections to the shunt resistor.

3. No Output on Serial Monitor:

   • Ensure the baud rate in the Serial Monitor matches the Serial.begin() value in the code.
   • Confirm that the INA219 is properly powered and initialized.

4. Overcurrent or Overvoltage Alerts:

   • If using the ALERT pin, ensure it is configured correctly in your circuit.
   • Check the load and shunt resistor to ensure they are within the INA219's operating range.

Q: Can the INA219 measure negative currents?
A: Yes, the INA219 can measure bidirectional currents if configured appropriately. Ensure the shunt voltage range is within ±320mV.

Q: What is the maximum current the INA219 can measure?
A: The maximum current depends on the shunt resistor value. For example, with a 0.1Ω shunt resistor, the maximum measurable current is ±3.2A.

Q: Can I use the INA219 with a 3.3V microcontroller?
A: Yes, the INA219 is compatible with both 3.3V and 5V systems.

Q: How do I change the I2C address of the INA219?
A: Use the A0 and A1 pins to configure the I2C address. Refer to the datasheet for the address mapping.

By following this documentation, you can effectively integrate the INA219 into your projects for precise power monitoring and energy management.