Contactless-Type Sensor Detects Speed And Rotary Direction

The integration of two Hall plates on a single chip for about half the cost of existing solutions has led to the development of the HAL 700 family of contactless-type chip sensors for detecting speed and rotary direction in automotive applications, such as sliding roofs, windshield wipers, seat adjusters and power windows. The one-chip solution also eliminates the need for external logic circuitry, it's claimed. The two integrated Hall plates enable a sensor to detect if a wheel or shaft moves forward or backward by detecting the magnetic fields of multi-polar, rotating ring magnets. The HAL 710 sensor with added logic circuitry can measure both speed and direction of the rotation without the need for external logic circuitry. The on-chip circuitry determines the direction and speed in which the permanent magnet rotates and transmits the information through the output pins. In 4-pin SOT89B packages, the HAL 700 and 710 are priced below $0.50 each/500,000.