Linear Hall-effect sensors enable smaller magnet designs

11th February 2015
Posted By : Siobhan O'Gorman
Linear Hall-effect sensors enable smaller magnet designs

Designed for safety critical applications, the HAR 24xy family of Linear Hall-effect sensors has been introduced by Micronas. The devices integrate two fully automotive qualified dies in a thinner than 1mm TSSOP14 package, enabling highly accurate redundant measurements and smaller magnet designs. 

As well as automotive applications such as throttle position measurement, pedal position detection and exhaust gas recirculation, the sensors can be used for current measurement, position detection or as an alternative to contactless potentiometers. The thin TSSOP14 package allows the HAR 24xy sensors to fit into space-constrained applications with reduced air gap. The small distance between the hall plates of the dies significantly improves the correlation between the two output signals, resulting in improved sensitivity and a smaller magnet design. A smaller design means that the magnet is located closer to the sensor's active area, making the overall design less sensitive to stray parasitic fields.

The HAR 2425 and HAR 2455 are the first devices to be released from the HAR 24xy family. The sensors' high accuracy is based on a 16-bit signal path with an integrated digital signal core delivering a ratiometric 12-bit analogue (HAR 2425) or up to 2kHz PWM (HAR 2455) output signal. To correct magnet linearity errors or increase distance measurements, the devices feature an output linearisation compensation function with uses16 programmable set points. The HAR 24xy sensors are offered with enhanced detection functions and error diagnostic coverage, which enable numerous capabilities including wire break detection and thermal supervision in the case of over-current or short circuit events. When an over-temperature between two sensor outputs is detected, different modes can be defined as to how the device reports the failure, with output set to ground, supply or tristate configuration. During normal operation, a continuous self-test of various circuit blocks supervises the sensor signal path and the memory map.

"This integration of two dies brings true system redundancy at the supply and output levels while offering the best features of our proven HAL 24xy Linear Hall-sensor family, for example its high immunity against temperature variations or its design flexibility", said Dirk Behrens, Vice President Automotive, Micronas. "The HAR 24xy family members offer our automotive customers extremely robust sensor solutions with redundant capabilities allowing at the same time to significantly reduce their system costs."

Micronas will be showcasing the HAR 2425 and HAR 2455 Linear Hall-effect sensors at Embedded World 2015, which takes place from 24th to 26th February, in Nuremburg, Germany.

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