ATS660LSB View Datasheet(PDF) - Allegro MicroSystems
Part Name
Description
MFG CO.
'ATS660LSB' PDF : 16 Pages View PDF
ATS660LSB
TRUE ZERO-SPEED,
HALL-EFFECT ADAPTIVE
GEAR-TOOTH SENSOR
APPLICATIONS INFORMATION — Continued
Recommended evaluation technique. The self-
calibrating feature of the ATS660LSB requires that a
special evaluation technique be used to measure its high-
accuracy performance capabilities. Installation inaccura-
cies are calibrated out at power on; hence, it is extremely
important that the device be repowered at each air gap
when gathering duty cycle data.
The ATS660LSB is designed to minimize performance
variation (caused by the large air-gap variations resulting
from installation) by self-calibrating at power-on. These
functions should be tested using the procedures described
below.
Duty cycle capabilities after correct self-calibration can
be measured as follows:
1. Set the air gap to the desired value.
2. Power down and then power up the device.
3. Rotate the gear at the desired speed.
4. Wait for calibration to complete (64 output pulses to
occur).
5. Monitor output for correct switching and measure
accuracy.
6. Repeat the above for multiple air gaps within the
operating range of the device.
7. This can be repeated over the entire operating tem-
perature range.
There is an internal update algorithm that will maintain
the correct duty cycle as air gap changes with temperature.
Large changes in air gap will require the part to be reset
(by cycling power) to maintain the correct duty cycle.
Measurement of the effect of changing air gap after
power up:
1. Set the air gap to the desired value (nominal, for
example). Rotate the gear at the desired speed. Apply
power to the subassembly. Wait for 64 output pulses to
occur. Monitor output for correct switching and measure
accuracy.
2. Change the air gap by ±0.25 mm. Do not re-power the
subassembly. Wait for update algorithm to finish adjust-
ing thresholds, typically 1 to 2 rotations on a 60-tooth gear.
Operation with fine-pitch gears. For targets with a
circular pitch of less than 4 mm, a performance improve-
ment can be observed by rotating the front face of the
sensor subassembly. This sensor rotation decreases the
effective sensor-to-sensor spacing and increases the
capability of detecting fine tooth or valley configurations,
provided that the Hall elements are not rotated beyond the
width of the target.
2.2
Allegro
www.allegromicro.com
A
α
TARGET FACE WIDTH, F
>2.2 SIN α
Dwg. MH-018-5 mm
11
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