SD100401 On Semiconductor, SD100401 Datasheet - Page 15

• Manufacturer Part Number: SD100401
• Description: GEARTOOTH SPEED AND DIRECTION SENSOR
• Manufacturer: On Semiconductor

G E N E R A L
MP Series Reed Sensors
Operating a Speed Sensor
N O T E S
R E E D A N D G E A R T O O T H S E N S O R S
A Reed Sensor is an omnipolar, magnetically activated switch. It can be
approached by a magnet from any angle, with either pole. Several possible
operating methods are shown below.
Perpendicular Magnet Travel
Nose-To-Nose Activation
Although commonly called a
geartooth sensor, a solid-state
speed sensor can detect the
motion of various ferrous
objects with some type of
discontinuous surface.
Solid-State Speed Sensor
Cherry’s solid-state magnetic proximity
sensors also make excellent speed
sensors when coupled with a rotating
ring magnet. Advantages of this
approach include: lower sensor
cost, larger airgaps and absolute
zero-speed sensing.
This Method
Maximizes
Air Gap
Both Ends of the Magnet
Work Equally Well
Spacing
Tooth
Sensing
Gap
Tooth
Thickness
N
Tooth
Width
Tooth
Height
S
release
N
operate
S
Parallel Magnet Travel
Rotational Magnet Travel
Examples of appropriate targets include:
For best results, we recommend targets made
from low carbon cold rolled steel. Other factors
that influence sensor performance include
geartooth height and width, space between
teeth, shape of the teeth and thickness of the
target. As a general guideline, consider a target
with the following minimum parameters:
Proximity Sensor with Ring Magnet
Up to Three
Operations
Possible
with One
Magnet
Multi-Pole Ring Magnets
Can Be Used to
Achieve a Larger
Number of
Operations per
Rotation
Sprockets
Bolt Heads
Roller Chains
Cavities in a Smooth Surface
Height
Tooth
.200”
N
S
S
N
N
Width
.100”
Tooth
S
S
N
N
op.
rel.
S
Between Teeth
Distance
.400”
op.
rel.
Thickness
Target
.250”
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