How to Use ACS712 Current Sensor 5A 20A 30A: Examples, Pinouts, and Specs

The ACS712 Current Sensor is an economical and precise solution for AC or DC current sensing in industrial, commercial, and communications systems. The device operates on the principle of Hall-effect, which is the production of a voltage difference across an electrical conductor, transverse to an electric current in the conductor and a magnetic field perpendicular to the current. The ACS712 outputs an analog signal that is linearly proportional to the current passing through the IP+ and IP- pins of the sensor.

• Power supply units
• Battery monitors
• Overcurrent protection systems
• Motor control
• Load detection and management
• Inverters

• Supply Voltage (Vcc): 4.5V to 5.5V
• Output Voltage (Vout): Analog 0-5V
• Sensitivity: 185 mV/A (5A), 100 mV/A (20A), 66 mV/A (30A)
• Operating Current: 13 mA
• Frequency Bandwidth: 80 kHz (typical)
• Operating Temperature: -40°C to +85°C

1. Connect the Vcc pin to a 5V power supply.
2. Connect the GND pin to the ground of the power supply.
3. Connect the IP+ and IP- pins in series with the load whose current you wish to measure.
4. The OUT pin will output an analog voltage proportional to the current through the sensor.

• Ensure that the current does not exceed the rated maximum for the specific model of the ACS712 you are using (5A, 20A, or 30A).
• The sensor is sensitive to magnetic fields; keep it away from magnets or wires carrying large currents.
• Use bypass capacitors close to the power pins to minimize noise.
• The output voltage is centered at Vcc/2 when no current is flowing through the sensor. This is typically 2.5V with a 5V supply.

// ACS712 Current Sensor Example Code for Arduino UNO
const int analogIn = A0; // Connect the sensor output to analog pin A0
float sensitivity = 0.185; // Sensitivity for the 5A model (change as needed)
float offsetVoltage = 2.5; // Offset voltage for zero current (Vcc/2)

void setup() {
  Serial.begin(9600);
}

void loop() {
  float voltage = analogRead(analogIn) * (5.0 / 1023.0); // Convert analog reading to voltage
  float current = (voltage - offsetVoltage) / sensitivity; // Convert voltage to current
  Serial.print("Current: ");
  Serial.print(current, 3); // Print current with 3 decimal places
  Serial.println(" A");
  delay(1000); // Wait for 1 second before next reading
}

• Inaccurate Readings: Ensure that the sensor is properly calibrated, and the offset voltage is correctly set to Vcc/2.
• No Output Voltage: Check the power supply connections and ensure that the sensor is not damaged.
• Noise in the Signal: Use capacitors for filtering and keep the sensor away from high-current wires and magnetic fields.

• Calibrate the sensor by measuring the output voltage with no current flowing and adjust the offset voltage in the code accordingly.
• Use twisted pair wires for the current leads to reduce electromagnetic interference.
• Implement software filtering techniques like moving average to smooth out the signal.

Q: Can the ACS712 sensor measure both AC and DC current? A: Yes, the ACS712 can measure both AC and DC currents.

Q: What is the accuracy of the ACS712 sensor? A: The accuracy can vary, but it is generally within a few percent of the actual current.

Q: How do I increase the resolution of my current measurements? A: Use a microcontroller with a higher resolution ADC or an external ADC with higher resolution.

Q: Is the ACS712 sensor isolated from the high current path? A: Yes, the sensor IC incorporates isolation to protect the electronics from high current paths.