ACS712

The Allegro TM ACS712 provides economical and precise solutions for AC or DC current sensing in industrial, commercial, and communications systems. The device package allows for easy implementation by the customer. Typical applications include motor control, load detection and management, switch-mode power supplies, and overcurrent fault protection. The device is not intended for automotive applications.

The device consists of a precise, low-offset, linear Hall circuit with a copper conduction path located near the surface of the die. Applied current flowing through this copper conduction path generates a magnetic field which the Hall IC converts into a proportional voltage. Device accuracy is optimized through the close proximity of the magnetic signal to the Hall transducer.

Features and Benefits

• Low-noise analog signal path
• Device bandwidth is set via the new FILTER pin
• 5 μs output rise time in response to step input current
• 80 kHz bandwidth
• Total output error 1.5% at Ta = 25°C
• Small footprint, low-profile SOIC8 package
• 1.2 mΩ internal conductor resistance
• 2.1 kVRMS minimum isolation voltage from pins 1-4 to pins 5-8
• 5.0 V, single supply operation
• 66 to 185 mV/A output sensitivity
• Output voltage proportional to AC or DC currents
• Factory-trimmed for accuracy
• Extremely stable output offset voltage
• Nearly zero magnetic hysteresis
• Ratiometric output from supply voltage

The library

How it work

This library offert a simple way to operate the ACS712 sensor. You can found an example in the example folder.

• Setup

    ACS712 mySensor = ACS712(A0, ACS712_30);
    
    void setup(){
        mySensor.begin(); // calibrate the sensor
    }

Methods

    ACS712(uint8_t input, uint8_t sensitivty)

The constructor take two parameter:

• input: the analog input used for the sensor
• sensitivity: the sensitivit of the sensor. This value depends on the range of the sensor measurement. So, we get three predefined constant for that
  • ACS712_5 - 185 mV/A
  • ACS712_20 - 100 mV/A
  • ACS712_30 - 66 mV/A

    int16_t raw();      // read raw data from the sensor

    float readDC(uint8_t unit);   // read DC current (process raw data)
    
    float readRMS(uint8_t unit);   // read RMS value of alternatif current

uint specifie the unit of the returned value of the readDC methods. It could be two of the predefined constant:

• A for Ampere
• mA for milli Ampere

    float calibrate();  // Make first calibration of the sensor

    float getOffset();  // read the sensor offset after calibration done

If none calibration is done the offset of the sensor is512