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Sensor FAQs

What is “GMR”?
Giant magnetoresistors, where resistance changes due to conduction electrons scattering at interfaces. GMR is an effect of spintronics, which utilizes electron spin rather than electron charge. The technology is smaller, more sensitive, and lower power than conventional semiconductors. In awarding the 2007 Nobel Prize in Physics for GMR, the Nobel Committee said, “GMR can be considered one of the first real applications of the promising field of nanotechnology.” This video has illustrative animations.

What is “TMR”?
Tunneling Magnetoresistance, which has even larger signals and lower power than GMR.

Why GMR/TMR sensors?
The advantages of GMR and TMR sensors are summarized with the four Bs: Boxes (smaller devices); Bits (more sensitive); Batteries (power as low as nanowatts); and Bullet-proof (extremely reliable).

What types of GMR/TMR sensors does NVE offer?
Analog sensors, digital sensors, smart sensors, current sensors, angle sensors, and GT™ (gear tooth) rotary sensors.

What types of smart sensors does NVE offer?
Smart magnetometers, smart magnetometers, smart angle sensors, and smart noncontact current sensors. Smart sensors are available with either SPI or I²C interfaces, and all are in ultraminiature TDFN packages.

What’s the difference between tesla, gauss, and oersteds?
Tesla and gauss are units of magnetic flux density. One tesla is 10,000 gauss. Oersteds are units of field strength. Oersteds and gauss have a one-to-one correspondence in air.

What’s the difference between a magnetometer and gradiometer?
A magnetometer sensor measures magnetic field strength. A gradiometer measures the magnetic field strength gradient, or change, over a distance.

What’s your most sensitive sensor?
The AAH002. AAH-Series high-sensitivity magnetic sensors have an amazing minimum sensitivity of 11 mV/V-Oe (more than one thousand times better than a typical Hall-effect sensor).

What’s the sensor minimum supply voltage?
Analog sensors can run on any voltage because they have no active components. For digital switch sensors, AHL-Series Low-Voltage Digital Sensors and certain AFL-Series Digital Sensors operate as low as 0.9 V supply voltage.

What packages are available?
The most popular packages are MSOPs, SOICs, 2.5 mm TDFNs, and 1.1 mm ULLGAs.

What’s the smallest package?
We offer sensors in a 1.1 mm square, leadless “ULLGA” package. If that’s still too big, we offer bare die for chip-on-board construction.

How far away can your sensors detect a magnet?
More than 20 inches (500 mm) with a strong magnet and sensitive sensor, although it depends on many factors. Here’s a demonstration.

I want to determine the current through a PCB trace. How can I figure out the magnetic field generated?
You can use Ampere’s law to estimate the magnetic field generated by current flowing through a circuit-board trace. Here’s a video, and we have a calculation spreadsheet.

What are NVE’s quality certifications?
NVE is certified under ISO9001:2015 and certified conforming with IATF 16949, First Edition 2016-10-01.

Where can I get magnets for experiments and prototypes?
Popular magnets are in-stock on NVE’s online store, and several sensor evaluation kits include magnets.

How can I try NVE sensors?
Distributors such as Digi-Key stock a wide variety of NVE sensors. The NVE Online Store has no minimum order and $9.95 flat-rate shipping within the U.S., and $17.95 outside the U.S. Sensor Evaluation Kits are available to try out a variety of parts.