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10
TMR TECHNICAL & APPLICATIONS INFORMATION
GLOSSARY OF TERMS
Hysteresis:
Hysteresis refers to the dierence between two points
of interest for a particular device. For digital sensors and switches,
it represents the dierence between the operate sensitivity and the
release sensitivity, expressed either as an absolute value (B
OP
– B
RP
) or
the % dierence (B
OP
– B
RP
)/B
OP
. For an analog sensor, the hyster-
esis is the dierence between the “magnet approach curve” and the
“magnet recede curve.”
Magnet Approach Curve:
e magnet approach curve is the
characteristic change in resistance of an analog TMR sensor as an
applied magnetic eld approaches the sensor, typically plotted as a
function of the magnetic eld strength.
Magnet Recede Curve:
e magnet recede curve is the charac-
teristic change in resistance of an analog TMR sensor as an applied
magnetic eld recedes from the sensor, typically plotted as a function
of the magnetic eld strength.
Magnetoresistance:
Magnetoresistance is a phenomenon
wherein the electrical resistance of certain materials changes when
exposed to an externally-applied magnetic eld.
Magnetic Transfer Curve:
e magnetic transfer curve denes
the characteristic behavior of an analog TMR sensor by combin-
ing both the magnet approach curve and the magnet receive curve
together.
Magnetic Tunnel Junction:
A magnetic tunnel junction is a
thin lm structure consisting of two magnetic layers separated by a
thin insulator. Because the insulating layer is thin enough (typically
a few nanometers), electrons can tunnel from one magnetic layer into
the other.
Operate Sensitivity:
e operate sensitivity denes the upper
limit of the strength of an applied magnetic eld that a digital TMR
sensor or switch must operate.
Operate Time:
e operate time is the dierence, in time,
between the application of a magnetic eld and the output response
of the device. In an analog sensor, the response is a change in output
resistance. In a digital sensor, the response is a change in state of the
electrical output.
Release Sensitivity:
e release sensitivity denes the lower
limit of the strength of an applied magnetic eld that a digital TMR
sensor or switch must release.
Release Time:
e release time is the dierence, in time, between
the removal of an applied magnetic eld and the output response of
the device. In an analog sensor, the response is a change in output
resistance. In a digital sensor, the response is a change in state of the
electrical output.
Tunnel Magnetoresistance (TMR):
Tunnel Magnetoresis-
tance is the magnetoresistive eect that occurs in a magnetic tunnel
junction.
rev. 110 62017