The Hall-effect was discovered by Edwin Hall in 1879. He discovered that a current flowing through a conductive plate, when subjected to a magnetic field that is orthogonal to the surface of the plate, will induce a voltage across the plate that is proportional to magnetic flux density. Allegro’s magnetic sensor ICs utilize the Hall-effect as a method of converting a magnetic field into a measurable electrical voltage. Hall-effect transducers are easily integrated into Allegro’s custom BiCMOS wafer fabrication process, allowing for the marriage of high-performance signal processing circuits and a Hall-effect transducer on a single silicon IC. When current flows through a conductor, it generates a magnetic field around the conductor that is directly proportional to the magnitude of the applied current. A Hall-effect transducer (or Hall plate) can be used to convert this magnetic field into a voltage that is proportional to the current flowing in the conductor. Since Hall-effect transducers sense both AC and DC current, Hall-effect current sensor ICs can be easily configured to sense AC and DC currents, unlike current transformers which sense AC currents but cannot sense DC currents. Hall-effect sensor ICs have been used as current sensors for decades. However, Allegro revolutionized the Hall-effect based current sensor IC through the development of patented packaging and signal processing technology that increases the accuracy and resolution of the sensor while at the same time reducing the size of the sensor solution.