Components for velocity sensing applications continue to shrink in size to meet space constraints and weight reduction requirements. As the gear size becomes smaller, this can compromise the ability of the gear speed sensor IC. The ATS645 Hall element has a Hall element pitch of only 1.5 mm, making it the only unit capable of accommodating very fine pitch gears. In addition, the peak detection algorithm ATS645 supports a relatively large airgap consistent switching with a small peak amplitude. These features make the ATS645 ideal solution for detecting fine-pitch targets such as ABS speed (anti-lock braking) systems.
The ATS645 combines Hall-effect sensor ICs and magnets to provide a true zero-speed digital gear two-tooth manufacturing friendly solution for a variety of applications. The device is encapsulated in a single-rod molded plastic that includes samarium-cobalt magnets, electrodes, and Hall-effect integrated circuits that have been optimized. This small package can be easily assembled and used in combination with a pair of gears in various shapes and sizes.
The integrated circuit consists of a two-element Hall-effect sensor integrated circuit as well as signal processing, switching output states in response to changes in the magnetic gradient generated by the iron teeth. The circuit contains a sophisticated digital circuit that eliminates magnet and system offsets and enables true zero-speed operation (US patent 5917320). Analog-to-digital and digital-to-analog converters are used to adjust the gain of the power adjustment device and the width of the air gap that allows switching of independent air gaps.
The adjustable current output is configured for two-wire applications that require the operation of a less wire-ratio switch with a more traditional open-collector output. The package is available in a lead-free (Pb) free version with 100% matte tin plating.
Fully optimizedDifferential numbersGear tooth sensorIC
Single-chip sensingchipHigh reliability
2 linesThe inside of the operationCurrent regulator
smallmechanical dimensions（Diameter 8 mm× 5.5 mmDepth)
Air gap independent switching points
The digital output occupies the tooth profile
PreciseDuty cycle signalin the operating temperature range
Large air gaps
Automatic gain control（AGC）
automaticOffset adjustment（AOA）
True zero-speed operation
Undervoltage locking
Wide operating voltage range
Defined power-on status