A3260ELH データシートの表示（PDF） - Allegro MicroSystems
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A3260ELH Datasheet PDF : 12 Pages
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3260
2-WIRE, CHOPPER-STABILIZED,
PRECISION HALL-EFFECT
BIPOLAR SWITCH
FUNCTIONAL DESCRIPTION
Chopper-Stabilized Technique. These devices use a
proprietary dynamic offset cancellation technique, with an
internal high-frequency clock to reduce the residual offset
voltage of the Hall element that is normally caused by device
overmolding, temperature dependencies, and thermal stress.
This technique produces devices that have an extremely stable
quiescent Hall output voltage, are immune to thermal stress, and
have precise recoverability after temperature cycling. This
technique will also slightly degrade the device output repeat-
ability.
The Hall element can be considered as a resistor array
similar to a Wheatstone bridge. A large portion of the offset is
a result of the mismatching of these resistors. The chopper-
stabilizing technique cancels the mismatching of the resistors by
changing the direction of the current flowing through the Hall
plate and Hall voltage measurement taps, while maintaining the
Hall-voltage signal that is induced by the external magnetic
flux. The signal is, then, captured by a sample-and-hold circuit.
Operation. The output of these devices turns ON when a
magnetic field (north pole) perpendicular to the Hall sensor
exceeds the release point threshold (BRP). After turn-ON, the
output will source current equal to the device operating current
plus a current source (IGND(H)). When the magnetic field is
increased (south pole) above the operate point (BOP), the output
will source current equal to the Hall-effect sensor operating
current with the current source turned OFF (IGND(L)). The
difference in the magnetic operate and release points is the
hysteresis (Bhys) of the device. The hysteresis allows clean
switching of the output even in the presence of external me-
chanical vibration or electrical noise.
Applications. It is strongly recommended that an external
bypass capacitor be connected (in close proximity to the Hall
sensor) between the supply and ground of the device to reduce
both external noise and noise generated by the chopper-
stabilization technique.
Extensive applications information on magnets and Hall-
effect sensors is also available in the Allegro Electronic Data
Book AMS-702 or Application Note 27701.
'UA' PACKAGE
X
0.1 µF
REG
X
B
+V
+I
—
HALL
VOLTAGE
+
Dwg. AH-011-2
IOUT + ICC
ICC
0
-B
BRP
BOP
0
FLUX DENSITY
0.95 V
–
+
100 Ω
SUPPLY
Dwg. EH-011-2A
Dwg. EH-012
+B
Dwg. GH-034-6
www.allegromicro.com
7
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