Programmable Hall effect current sensor

December 09, 2013 // By Graham Prophet
Melexis has added to its customer-programmable Triaxis Hall effect sensor IC range, with a device intended for use in electric vehicles (EVs), hybrid electric vehicles (HEVs) and renewable energy systems; the high speed devices in the MLX91208 series each offer a response time of 3μsec.

Accuracy is stable over operational lifespan and temperature, with typical thermal sensitivity drift of ±150 ppm/°C. The transfer characteristics of the MLX91208 devices are fully adjustable, with parameters such as sensitivity, gain and offset stored on the built-in EEPROM memory. Calibration is done using the company’s Programming Through Connector (PTC) protocol - where the supply voltage is modulated. As this dispenses with the need of an additional pin for programming, highly efficient production flows can be easily achieved.

Operational temperature range is -40°C to +150°C: the MLX91208 devices are suited to precision DC and AC current measurements up to 200 kHz. The sensors feature Melexis’ Triaxis technology, with sensitivity that stems from the Integrated Magnetic Concentrator (IMC) layer deposited onto the semiconductor die. Current sensing systems based on the MLX91208 series exhibit accuracy levels exceeding ±0.5% at room temperature or ±2% at the extremes of the specified temperature range.

In a standard SO-8 package, these ICs are an optimised current sensing solution with strong galvanic isolation. There are two versions; the MLX91208CAL having a large IMC layer for the detection of very low magnetic fields (100 mV/mT to 700 mV/mT) and MLX91208CAH aimed at detection of medium fields (50 mV/mT to 300 mV/mT). Among the key applications for these devices are battery current and motor current monitoring in automotive (HEV, EV, mild HEV, etc.) and renewable energy applications (such as solar power converters).