Magnetics Business & Technology - November/December 2022 - 15

TECH TIPS
(NdFeB) magnet, whereas Case 2 assumes a Ceramic magnet.
NdFeB is the strongest magnet grade available, but also one of
the most expensive. Ceramic (also called " ferrite " ) has a lower
magnetic strength than NdFeB, but is also lower in cost. Case 3
assumes the same magnet material as Case 1 (NdFeB N42), but
with a smaller diameter. The relative costs of all three magnets are
also included in Table 1, and are based on commercially available
products.
ics and can provide valuable input on how to best implement a
magnetic sensing solution into a specific product. This input can
come in the form of lab testing and/or specialized magnetic simulation
software. With these tools, the supplier can quickly and efficiently
determine the specifications for the sensor / magnet combination
that will work best within the customer's application.
Conclusion
A " Magnet-Sensor Solution " approach to building your application's
BOM can reduce the overall cost of your device significantly.
By choosing a more sensitive sensor, the cost of the magnet can
be reduced - and your supply chain kept more stable. If your application
is more complex, work with a supplier with a firm understanding
of magnetic sensors to provide you with the best, most
cost-effective solution.
About the author:
Assuming a baseline case where the magnet in Case 1 is paired
with a 30 Gauss sensor, the sensor would activate when the magnet
is up to 23mm away. If the sensor was swapped with one that
activates with 9 Gauss, the magnet in Case 2 (Ceramic magnet),
can achieve a similar distance (22mm) with only 20% of the cost
of the baseline magnet. And the magnet in Case
3 (NdFeB with smaller diameter) can match the
baseline distance with only 35% of the baseline
magnet cost. For reference, 30-40G is a common
activation threshold for Hall Effect sensors. Alternatively,
RedRock® RR122 sensors, can activate
with as little as 9 Gauss.
In addition to the cost benefit, switching to a ceramic
magnet can also help with availability issues.
Over the past few decades there have been rising
concerns over both the availability and price fluctuations
of rare earth magnets, such as NdFeB.
While the great majority of rare earth magnets are
manufactured in China, ferrite magnets are more
easily accessible through worldwide manufacturing
and are cheaper to manufacture.
Complex applications can be game-changers
It should also be noted that there are still other issues
that could come into play within more complex
applications; one example might be the unanticipated
presence of stray magnetic fields that might
inadvertently activate the sensor when the activation
magnet is out of range of the sensor. Additionally,
some applications have other ferromagnetic
components nearby, such as coin-cell batteries,
screws, etc., which could affect the magnetic field
seen by the sensor. Temperature and demagnetization
performance is also different between various
magnet materials. For all these reasons, it's
always a good idea to work with a magnetic sensor
supplier who has a solid understanding of magnetwww.MagneticsMag.com
Eduardo
Montalvo works as
Applications Engineer for Coto
Technology, where he helps
customers to successfully integrate
the company's line of
low power, high sensitivity TMR
sensors into their products. He
obtained his B.S.E.E. from the
University of Puerto Rico, Mayaguez
and his M.S.E.E. from
Michigan State University. He
can be contacted at AppSupport@cotorelay.com.
www.ichaus.de/pvs
phone:
+49 6135 92 92-300
Linear/Off-Axis Battery-Buffered
Absolute Position Hall Sensor
* Configurable pole width or gear tooth module
* High-performance Hall position sensors
with analog output
* Battery-buffered absolute position data
* Serial I/O interfaces
(BiSS, SSI, SPI, and I²C)
sps 2022
Nuremberg, Nov. 08 - 10, hall 4a, booth 146
electronica 2022
Munich, Nov. 15 - 18, hall B4, booth 420
November/December 2022 * Magnetics Business & Technology 15
http://www.ichaus.de/pvs https://www.youtube.com/user/iCHausVideo https://www.linkedin.com/company/ic-haus-gmbh/ https://www.instagram.com/ic_haus_germany/ http://www.MagneticsMag.com
Magnetics Business & Technology - November/December 2022

Table of Contents for the Digital Edition of Magnetics Business & Technology - November/December 2022
