What Is the ACS712? Hall-Effect Current Sensor: Specs and Uses
The ACS712 is a Hall-effect isolated current sensor. It produces an analog voltage proportional to the current (AC/DC, bidirectional); versions are ±5/±20/±30 A (185/100/66 mV/A). Its output is ~Vcc/2 at zero current, an offset subtracted in the MCU. Its difference from the INA219: isolated and analog; suited to high current/isolation.
The ACS712 is a Hall-effect isolated current sensor. It produces an analog voltage proportional to the measured current and electrically isolates the measurement circuit from the power line. For the concept, see what is a sensor.
What is the ACS712 used for?
Motor/relay current measurement, over-current protection, power monitoring and energy meters. It measures AC and DC current (bidirectional); its output is at Vcc/2 at zero current and swings up/down as current rises. Its difference from the INA219: it is isolated and analog.
Versions and sensitivity
| Model | Range | Sensitivity |
|---|---|---|
| ACS712-05B | ±5 A | 185 mV/A |
| ACS712-20A | ±20 A | 100 mV/A |
| ACS712-30A | ±30 A | 66 mV/A |
Watch out
Since the output is ~Vcc/2 (2.5 V) at zero current, this offset must be subtracted in the MCU. Being analog it is noise-prone (averaging is recommended). Resolution is limited at low currents; for precise low current the INA219 (shunt/digital) is better.
Equivalents
- INA219: shunt-based, digital (I2C), precise at low current.
- ACS758: a higher-current Hall sensor.
- INA226: high-precision current/power.
Find it in our catalog
Use the ACS712 search.