Honeywell AMR Ring Magnet Sensor IC Instructions
- June 7, 2024
- Honeywell
Table of Contents
AMR Ring Magnet Sensor IC
Jitter Test Performance Results
A Technical Note
Introduction
Jitter is defined as the deviation from the true switch point of a sensor. Low
jitter performance is critical for many ring magnet speed sensor applications,
including wheel speed, transmission, and encoder sensing.
Multiple sensing technologies, such as AMR (anisotropic magnetoresistive)
operating in non-saturation mode, GMR (giant magnetoresistive), and
differential Hall effect have been used in ring magnet speed sensor
applications. In general, the jitter performance of these sensors varies with
the size of the airgap. Honeywell has developed a new AMR sensor IC which
operates in saturation mode, enabling extremely low jitter across the entire
usable airgap range.
Ring Magnet Speed Sensor Jitter Evaluation
Random samples from the four products shown in Table 1 were chosen for this jitter evaluation test.
Table 1. Test Products
| Product | Technology |
|---|---|
| Honeywell VM721V1 | AMR operating in saturation mode |
| Competitor 1 | AMR operating in a non-saturation mode |
| Competitor 2 | GMR |
| Competitor 3 | Differential Hall effect |
Explanation of Saturation Mode
As with most magnetic sensors, the signal decreases as the airgap between the sensor and the target decreases. For AMR sensors, once the sensor is in saturation mode, the magnetic field strength changes very little versus the airgap size. Figure 1 shows that once the field strength reaches 30 Gauss, the output of the AMR sensor in saturation mode shows very little change as the field strength increases to higher Gauss levels. It is this stability in the output signal that allows the AMR sensor in saturation mode to operate with similar characteristics over a wide airgap range.
Test Configuration Setup
A circular target with 32 magnetic pole pairs was used to trigger the product
samples. The target was rotated at 2500 RPM. Testing was performed at 25ºC and
150ºC, with an airgap range of 0,5 mm to 4,5 mm which provided a minimum field
strength of 10 Gauss.
The test products were mounted on the outside of the ring magnet target. The
Honeywell VM721V1 was mounted with the end of the IC toward the ring magnet,
while the competitor product samples were mounted with the face of the IC
toward the ring magnet target, as per the mounting instructions for each
sample. (See Figure 2.)
Figure 2. Sensor Mounting Orientation
Measurements were taken
using a Lecroy HDO6064 oscilloscope, using the hold time measurement
statistic. The test system used produces a reference pulse once per
revolution. The switch point variation from the reference pulse to the first
edge following the reference pulse was measured at least 1000 times, and the
standard deviation of the variance was plotted vs the airgap for each device
tested to show the jitter performance. (See Figure 3.)
Figure 3. Example Oscilloscope Plot from Testing Performed
Results (See Figures 4a and 4b)
The Honeywell VM721V1 AMR sensor operating in saturation mode had jitter of
around 1 s over the usable airgap of 0,5 mm to 4,5 mm at both 25ºC and 150ºC.
Although the jitter of Competitor 1’s AMR sensor operating in nonsaturated
mode was relatively consistent versus the airgap, the jitter was higher than
the VM721V1 and it increased at greater airgaps at 25ºC.
Competitor 2’s GMR sensor had low jitter at the larger airgaps; however, the
jitter was significantly higher at the smaller airgaps.
Competitor 3’s differential Hall-effect sensor had higher jitter than the
VM721V1 at smaller airgaps, and the jitter increased steadily as the airgap
distance increased.
Figure 4a. Jitter Versus Airgap Distance at 25ºC
Figure 4b. Jitter Versus Airgap Distance at 150ºC
Summary
Honeywell AMR sensors’ reduced jitter allows for more accurate feedback for
improving system control. The VM721V1 provides a superior airgap performance
ranging from 0,5 mm to 4,5 mm, which enables significant implementation
advantages compared to other technologies, such as AMR operating in non-
saturation mode, GMR, and differential Hall effect.
Warranty/Remedy
Honeywell warrants goods of its manufacture as being free of defective
materials and faulty workmanship during the applicable warranty period.
Honeywell’s standard product warranty applies unless agreed to otherwise by
Honeywell in writing; please refer to your order acknowledgment or consult
your local sales office for specific warranty details. If warranted goods are
returned to Honeywell during the period of coverage, Honeywell will repair or
replace, at its option, without charge those items that Honeywell, in its sole
discretion, finds defective. The foregoing is buyer’s sole remedy and is in
lieu of all other warranties, expressed or implied, including those of
merchantability and fitness for a particular purpose. In no event shall
Honeywell be liable for consequential, special, or indirect damages.
While Honeywell may provide application assistance personally, through our
literature and the Honeywell website, it is the buyer’s sole responsibility to
determine the suitability of the product in the application.
Specifications may change without notice. The information we supply is
believed to be accurate and reliable as of this writing. However, Honeywell
assumes no responsibility for its use.
For more information
Honeywell Advanced Sensing Technologies services its customers through a
worldwide network of sales offices and distributors. For application
assistance, current specifications, pricing or the nearest Authorized
Distributor, visit sps.honeywell.com/ast or
call:
Asia Pacific +65 6355-2828
Europe +44 (0) 1698 481481
USA/Canada +1-800-537-6945
Honeywell Advanced Sensing Technologies
830 East Arapaho Road
Richardson, TX 75081
sps.honeywell.com/ast
005994-2-EN | 2 | 05/21 © 2021
Honeywell International Inc.
References
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