'world's Smallest' Magnetic Field Sensor Comes With Gyroscope Function


'World's Smallest' Magnetic Field Sensor Comes With Gyroscope FunctionAlps Electric Co Ltd developed what it claims is the world's smallest magnetic field sensor chip measuring 1.15 x 1.15 x 0.56mm.

The company plans to start to ship samples in the spring of 2014 and begin volume production in the summer at a rate of two to three million units per month.

Before the development of the new sensor chip, the world's smallest magnetic field sensor chip was Asahi Kasei Microdevices Corp's "AK09911C." Though its official size is 1.2 x 1.2 x 0.5mm, the height of the chip is 0.57mm including solder balls, Alps Electric said.

The new product is nearly 60% smaller than Alps Electric's previous product (See related article). The measurement range of the new magnetic field sensor is ±4.9mT for each of the x, y and z axes while that of the previous product is ±2.4mT.

Its output resolution is about 0.15?T, which is equivalent to that of the previous product. It is in a BGA package. Its power supply voltage is 1.7-3.6V for both analog and digital parts.

Gyroscope function realized with software
The new sensor chip comes with software that realizes a gyroscope function. Based on the output value of the sensor, it estimates angular velocities for the three axes with the software. Compared with a case where a gyroscope chip is used, the new sensor chip cuts power consumption by 80-90%, Alps Electric said.

The sensor chip is also advantageous in terms of cost. In general, gyroscopes are more expensive than magnetic field sensors and acceleration sensors. Therefore, many middle- and low-price smartphones, which are gaining popularity especially in China, are not equipped with any gyroscope. On the other hand, most smartphones come with magnetic field and acceleration sensors.

"Manufacturers that gave up the idea of using a gyroscope because of its cost can add the gyroscope function realized with the the magnetic field sensor without concern about cost," Alps Electric said.

Though the measurement accuracy of the gyroscope function is lower than that of a gyroscope chip, the new product enables to easily add a gyroscope function.