GIANT MAGNETORESISTANCE (GMR) BASED MAGNETIC SENSORS AND SPEED SENSOR MODULE
The use of multi-sensor system is becoming more important in widespread applications in different sectors such as automotive, aerospace, consumer electronics and industrial sectors. With advancement of semiconductor technology, the sensing elements with less power consumption, smaller size and low cost are now becoming popular. At SED, in the last five years, research efforts were focused towards the development of high sensitivity and low cost magnetic field sensing element based on Giant Magnetoresistive (GMR) technology. SED has developed a series of GMR based magnetic field sensing chips for rotary and linear position sensing applications. The sensor has been integrated with CMOS based programmable signal conditioning hardware. The product has been tested for speed measurements with commercially available different types of ABS toner wheels used in the automobile sector. A maximum air gap in the range of 3 - 4 mm was achieved which is significantly larger than the existing Hall sensor. The speed sensor has been certified by ARAI, Pune for two-wheeler applications.
(a) Plastic packaged (3 mm x 3 mm) magnetic field sensor chip, (b) Wheel sensor board made with NAL MRA 1427 and CMOS ASIC IC (ZSC31150), (c) Both analog (top) and digital (bottom) output characteristics of the board with an air gap of 3.6 mm between the toner wheel and the sensor and (d) Speed sensor module enclosing the PCB for testing and validation at industry sites.