NVE Corporation's ADT001 and ADT002 rotation sensors are ultra-low-power, digital-output, magnetic rotation sensors. The sensors have two digital, binary outputs. The two outputs are 90 degrees out of phase to provide directional information. An additional output indicates a fault if the magnetic field is too high for accurate measurements. The ADT001 is optimized for edge-sensitive applications and the ADT002 for absolute position. The ADT001 has high hysteresis for high noise immunity in applications such as speed sensing and counting rotations. The ADT002 is low hysteresis to provide accurate, absolute rotational quadrant information. The heart of the unique sensor is an array of four tunneling magnetoresistance (TMR) elements, one in each quadrant. TMR technology enables low power and miniaturization, making the sensors ideal for battery operation. The sensor operates with as little as a 30 Oersteds magnetic field, and is accurate up to 200 Oersteds. This wide magnetic field range allows inexpensive magnets and operation over a wide range of magnet spacing. Larger or stronger magnets require more distance to avoid oversaturating the sensor; smaller or weaker magnets may require closer spacing. Low-cost, radially magnetized ferrite disk magnets can be used with these sensors. Bar magnets can also be used in some configurations.