Programmable Hall effect sensor addresses fast response current sensing applications

February 05, 2013 // By Christoph Hammerschmidt
The drive for green power and mobility demands next generation current sensor technology. Melexis’ introduction of its MLX91209 high-speed custom programmable Hall effect sensor addresses these needs.

Melexis advances the state of the art in contact-less current sensing for renewable energy, Hybrid Electric Vehicle (HEV) and Electric Vehicle (EV) applications. The MLX91209 is a fully customer programmable monolithic sensor IC packaged in a standard SIP package and providing a high speed analog output signal proportional to the external applied flux density. The MLX91209 enables the user to construct a precise and programmable current sensor solution with fast response time.

The MLX91209 is particularly appropriate for precise DC and/or AC current measurements up to 200kHz with galvanic isolation, fast response time and small package size. SIP packaging allows an easy implementation into a ferromagnetic core design.

The MLX91209 was designed to meet the demand in the widespread use of electronics in automotive applications, renewable power conversion (solar and wind power), power supplies, motor control, and overload protection. Typical applications are particularly found in battery current monitoring in solar power converters and automotive inverters driving the traction motor in HEVs and EVs.

The high-speed Hall effect sensor is automotive-qualified and senses current by converting the magnetic field generated by currents flowing through a conductor to a voltage, which is proportional to the field.

The transfer characteristic of the MLX91209 is fully customer programmable. Parameters such as sensitivity and offset are stored in an internal EEPROM memory. Calibration is done using Melexis' well-established PTC (Programming Through Connector) protocol. This method modulates the supply voltage and does not require any additional pin for programming, enabling the most efficient production flows. A linear analog output permits use of the sensor in applications where a very fast response of 3µs is required.

Custom calibration is best performed in-situ after the sensor is fixed with respect to the current conductor and ferromagnetic core so that a calibrated current sensitivity is achieved. Typical accuracy of a current sensing system based on the MLX91209 is better than ±0.5% at room temperature or ±2% over the full