3901090217 Page 4 Jun/04
Rev. 009
MLX90217
Hall-Effect Cam Sensor
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Application Notes
Maximum dynamic range is 500 mT. The
hysteresis is fixed at 5.0 mT. Best angular
accuracy will be obtained when the magnetic
circuit provides peak magnetic flux at the chip
near the high end of the linear range of 500 mT.
EMC protection using external components are
recommended. Two possibilities are shown on
the following page. Normally the South pole faces
the unbranded side of the device. A North pole
will enable a test sequence used in factory
testing.
Unique Features
The output is reset to the high state at power on
(output driver is off) whatever the field is. The
output only changes after the first min is detected.
The reset state holds no information about the
field. If the supply of the chip is raised slowly, the
reset state is not stable. This has been observed
at 0 field but it should be the same with small and
large fields.
Gear tooth sensors often need to be adjusted
after the module is assembled to align the
magnet with differential Hall plates or orient with
teeth. However the MLX90217 is “self adjusting”
over a wide range of back bias flux eliminating
the need for any trimming in the application. The
magnet may be glued to the back surface (non
branded side) of the IC using a cyanoacrylate
adhesive or suitable epoxy.
