ATS616LSG Allegro MicroSystems, ATS616LSG Datasheet - Page 10

• Manufacturer Part Number: ATS616LSG
• Description: Dynamic Self-Calibrating Peak-Detecting Differential Hall Effect Gear Tooth Sensor
• Manufacturer: Allegro MicroSystems

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AGC circuit sets the gain of the device after power-on. Up to a
0.25 mm air gap change can occur after calibration is complete
without significant performance impact.
Superior Performance.
gear-tooth sensor module has several advantages over conven-
tional Hall-effect gear-tooth sensors. The signal-processing
techniques used in the ATS616 solve the catastrophic issues that
affect the functionality of conventional digital gear-tooth sen-
sors, such as the following:
• Temperature drift. Changes in temperature do not greatly
• Timing accuracy variation due to air gap. The accuracy varia-
• Dual edge detection. Because this device switches based on
• Tilted or off-center installation. Traditional differential sensors
• Large operating air gaps. Large operating air gaps are achiev-
• Immunity to magnetic overshoot. The patented adjustable
• Response to surface defects in the target. The gain-adjust
• Immunity to vibration and backlash. The gain-adjust circuitry
• Immunity to gear run out. The differential sensor configura-
Differential vs. Single-Element Sensing.
Hall-effect configuration is superior in most applications to the
ATS616LSG-DS, Rev. 1
affect this device due to the stable amplifier design and the
offset rejection circuitry.
tion caused by air gap changes is minimized by the self-cali-
bration circuitry. A 2×-to-3× improvement can be seen.
the positive and negative peaks of the signal, dual edge detec-
tion is guaranteed.
can switch incorrectly due to baseline changes versus air gap
caused by tilted or off-center installation. The peak detec-
tor circuitry references the switchpoint from the peak and is
immune to this failure mode. There may be a timing accuracy
shift caused by this condition.
able with this device due to the sensitive switchpoints after
power-on (dependent on target dimensions, material, and
speed).
hysteresis circuit makes the ATS616 immune to switching on
magnetic overshoot within the specified air gap range.
circuitry reduces the effect of minor gear anomalies that would
normally cause false switching.
keeps the hysteresis of the device roughly proportional to the
peak-to-peak signal. This allows the device to have good im-
munity to vibration even when operating at close air gaps.
tion eliminates the baseline variations caused by gear run out.
Dynamic Self-Calibrating Peak-Detecting Differential Hall Effect Gear Tooth Sensor
The ATS616 peak-detecting differential
The differential
ATS616LSG
classical single-element gear-tooth sensor. The single-element
configuration commonly used (Hall-effect sensor mounted on
the face of a simple permanent magnet) requires the detection
of a small signal (often <100 G) that is superimposed on a large
back-biased field, often 1500 G to 3500 G. For most gear/target
configurations, the back-biased field values change due to
concentration effects, resulting in a varying baseline with air
gap, valley widths, eccentricities, and vibration (figure 4). The
differential configuration (figure 5) cancels the effects of the
back-biased field and avoids many of the issues presented by the
single Hall element design.
Figure 4. Affect of varying valley widths on single-element sensors.
Figure 4. Affect of varying air gaps on differential sensors.
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 [phone]
www.allegromicro.com
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