ATS645LSH Datasheet, PDF (1/14 Pages) Allegro MicroSystems – True Zero Speed Miniature Gear Tooth Sensor

ATS645LSH
Two-Wire True Zero Speed Miniature Differential
Peak-Detecting Gear Tooth Sensor
Features and Benefits
• Fully optimized differential digital gear tooth sensor
• Single chip IC for high reliability
• Internal current regulator for 2-wire operation
• Small mechanical size (8 mm diameter x 5.5 mm depth)
• Air gap independent switchpoints
• Digital output representing gear profile
• Precise duty cycle signal over operating temperature
range
• Large operating air gaps
• Automatic Gain Control (AGC)
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Packages: 4 pin SIP (suffix SH)
Description
The components in speed sensing applications continue to
diminish in size to meet spatial constraints and weight reduction
requirements. As the geometries of gears become smaller, this
can compromise the capabilities of a gear speed sensor. The
ATS645 Hall-element-to-Hall-element spacing of only 1.5 mm
makes this device uniquely capable of accommodating very
fine-pitch gears. In addition, the ATS645 signal peak-detecting
algorithm supports consistent switching at relatively large air
gaps, where the peak-to-peak amplitude is small. These features
make the ATS645 the ideal solution to detect the speed of fine-
pitch targets such as those found in ABS (antilock braking)
systems.
The ATS645 combines a Hall-effect sensing integrated circuit
and magnet to provide a manufacturer-friendly solution for true
zero-speed digital gear-tooth sensing in two-wire applications.
The device consists of a single-shot molded plastic package
that includes a samarium cobalt magnet, a pole piece, and a
Hall-effect integrated circuit that has been optimized to the
magnetic circuit. This small package can be easily assembled
and used in conjunction with a wide variety of gear shapes
and sizes.
Not to scale
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Functional Block Diagram
Hall
Amplifier
Gain
VCC
Automatic Offset
Control
AOA DAC
Tracking
DAC
Peak Hold
AGC DAC
Internal Regulator
Test Signals
GND
Test
ATS645-DS, Rev. 3