3421

3421 AND 3422 PRELIMINARY INFORMATION (subject to change without notice) September 6, 2000 HALL-EFFECT, DIRECTION-DETECTION SENSORS The A3421xKA and A3422xKA Hall-effect, direction-detection sensors are a new generation of special-function integrated sensors that are capable of sensing the direction of rotation of a ring magnet. These transducers provide separate digital outputs that provide information on magnet rotation speed, direction, and magnet pole count. These devices eliminate the major manufacturing hurdles encountered in fine-pitch direction-detection applications, namely maintaining accurate mechanical location between the two active Hall elements. Here, the two Hall elements are photolithographically aligned to better than 1 µm, as contrasted with 100 µm or worse mechanical location tolerance when manufactured discretely. These highly sensitive, temperature-stable, magnetic transducers are ideal for use in digital-encoder systems in the harsh environments of automotive or industrial applications. The A3421xKA is a high-hysteresis device designed for low-resolution pulse counting while the A3422xKA is a high-sensitivity device optimized for use with high-density magnets. The A3421xKA and A3422xKA monolithic integrated circuits contain two independent Hall-effect latches whose digital outputs are internally coupled to CMOS logic circuitry that decodes signal speed and direction. Extremely low-drift BiCMOS circuitry is used for the amplifiers to ensure symmetry be...