Sensing and controlling Voltage & Current flow is a fundamental requirement in a wide variety of applications including, over-current protection circuits, battery chargers, switching mode power supplies, digital watt meters, programmable current sources, etc.
The Allergo ACS712 current sensor is based on the principle of Hall-effect. According to hall-effect , when a current carrying conductor is placed into a magnetic field, a voltage is generated across its edges perpendicular to
the directions of both the current and the magnetic field. The ACS712 device is provided in a small, surface mount SOIC8 package. It consists of a precise,low-offset, linear Hall sensor circuit with a copper
conduction path located near the surface of the die.
The strength of the magnetic field is proportional to the magnitude of the current through the conduction path, providing a linear relationship between
the output Hall voltage and input conduction current. One of the simplest techniques of sensing current is to place a small value resistance (also known as Shunt resistor) in between the load and the ground and measure the voltage drop across it, which in fact, is proportional to the
current flowing through it. The electrical isolation between the conduction current and the sensor circuit also minimizes the safety concerns while dealing with high voltage systems.