How to Use INA228: Examples, Pinouts, and Specs

The INA228 is a high-precision, low-power current shunt monitor designed to measure small voltage drops across a shunt resistor. It features a wide common-mode voltage range (up to 85V) and provides a digital output proportional to the current flowing through the shunt. This makes it an excellent choice for applications requiring accurate current, voltage, and power monitoring.

• Battery management systems
• Power monitoring in servers and data centers
• Solar inverters and energy storage systems
• Industrial automation and motor control
• Electric vehicle (EV) power systems

The INA228 is typically available in a 10-pin WSON package. Below is the pinout and description:

1. Power Supply: Connect the V_CC pin to a 2.7V to 5.5V power source and the GND pin to ground.
2. Shunt Resistor: Place a precision shunt resistor between the V_IN+ and V_IN- pins. The resistor value should be chosen based on the expected current range.
3. I²C Communication: Connect the SCL and SDA pins to the corresponding I²C lines of your microcontroller. Use pull-up resistors (typically 4.7kΩ) on these lines.
4. Address Configuration: Set the I²C address using the ADDR pin. Refer to the datasheet for address selection details.
5. Alert Pin: Optionally, connect the ALERT pin to a microcontroller GPIO for over-limit condition monitoring.

• Use a low-inductance, high-precision shunt resistor to ensure accurate measurements.
• Ensure the common-mode voltage does not exceed the specified range (-0.3V to +85V).
• Keep the traces between the shunt resistor and the INA228 as short as possible to minimize noise.
• Use decoupling capacitors (e.g., 0.1µF) near the V_CC pin to stabilize the power supply.

Below is an example of how to interface the INA228 with an Arduino UNO using the I²C protocol:

#include <Wire.h>

// INA228 I2C address (default is 0x40, but check your configuration)
#define INA228_ADDRESS 0x40

void setup() {
  Wire.begin(); // Initialize I2C communication
  Serial.begin(9600); // Initialize serial communication for debugging

  // Configure INA228 (example: set calibration register)
  Wire.beginTransmission(INA228_ADDRESS);
  Wire.write(0x05); // Calibration register address
  Wire.write(0x00); // High byte of calibration value
  Wire.write(0x10); // Low byte of calibration value
  Wire.endTransmission();

  Serial.println("INA228 initialized.");
}

void loop() {
  // Request shunt voltage measurement
  Wire.beginTransmission(INA228_ADDRESS);
  Wire.write(0x01); // Shunt voltage register address
  Wire.endTransmission();

  Wire.requestFrom(INA228_ADDRESS, 2); // Request 2 bytes of data
  if (Wire.available() == 2) {
    int16_t shuntVoltage = (Wire.read() << 8) | Wire.read();
    float voltage = shuntVoltage * 0.00000125; // Convert to volts (example scaling)
    Serial.print("Shunt Voltage: ");
    Serial.print(voltage, 6);
    Serial.println(" V");
  }

  delay(1000); // Wait 1 second before the next reading
}

• Replace the calibration value and scaling factor with values specific to your application.
• Ensure the I²C address matches the configuration of your INA228.

1. No I²C Communication:

   • Ensure the SCL and SDA lines are connected properly.
   • Verify the pull-up resistors on the I²C lines.
   • Check the I²C address configuration.

2. Incorrect Measurements:

   • Verify the shunt resistor value and connections.
   • Ensure the common-mode voltage is within the specified range.
   • Check for noise or interference on the shunt resistor traces.

3. Alert Pin Not Functioning:

   • Confirm the alert threshold configuration in the INA228 registers.
   • Ensure the ALERT pin is connected to a valid GPIO.

• Use an oscilloscope or logic analyzer to monitor the I²C communication.
• Double-check all connections and component values.
• Refer to the INA228 datasheet for detailed register descriptions and configuration options.