Current Sensing Module

20 April 2015 User Review

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25 in stock

Allegro ACS712 senses DC and AC currents. The current sensor works on the basics of Hall-effect, which was implemented by Dr. Edwin Hall in 1879.

Hall Effect:

The Hall Effect is based on the nature of the current in a conductor. Current is defined as the movement of charge carriers mainly electrons, holes, ions. When a magnetic field is present, these charge carriers experience a force, called the Lorentz force. Lorentz force is the combination of electric and magnetic force acting on a point charge due to electromagnetic field. When magnetic field is absent, the carriers follow approximately in straight line paths between collisions. When a magnetic field perpendicular to the current flow is applied, path of the carrier’s in-between collisions will be random so that charge carriers get accumulated on one side of the hall element. This causes equal and opposite charges accumulate on the other side. The alignment of charge carriers develops an electric field, so a steady electrical potential is developed. This potential is known Hall voltage and its value is in the order of few microvolts.  Hall voltage is directly proportional to the magnitudes of current and magnetic field. So if any one of them (I and B) is known, then the obtained Hall voltage can be used to estimate the other quantity.

The ACS712 IC is available in SOIC8 package. It consists of a Hall sensor circuit with a copper conductive path. When current is passed through the copper conductive path, a magnetic field will be generated which is sensed by the Hall element. The strength of the generated magnetic field is proportional to the magnitude of the current passed through the conductive path. Now, a Hall voltage which is proportional to the current and magnetic field will be induced. Hall voltage could be measured through ADC channel of a microcontroller.


  • analog output fluctuates with  measured current
  • output voltage varies
  • pin 5V power supply


  • over-current protection circuits
  • digital watt meters
  • programmable current sources
  • switching mode power supplies
  • battery chargers


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