A3150JUA Allegro MicroSystems, Inc., A3150JUA Datasheet - Page 5

• Manufacturer Part Number: A3150JUA
• Description: Programmable, Chopper- Stabilized, Hall-effect Switch
• Manufacturer: Allegro MicroSystems, Inc.

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 repeatabil-
ity.
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 switches low (turns
ON) when a magnetic field (south pole) perpendicular to the
Hall sensor exceeds the operate point threshold (B
turn-ON, the output is capable of sinking 25 mA and the output
voltage is V
the release point (B
The difference in the magnetic operate and release points is the
hysteresis (B
clean switching of the output even in the presence of external
mechanical vibration and 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-stabiliza-
tion technique.
is a bar magnet with the south-seeking pole towards the branded
surface of the device. Many other methods of operation are
possible. Extensive applications information on magnets and
Hall-effect sensors is also available in the Allegro Electronic
Data Book AMS-702 or Application Note 27701, or
www.allegromicro.com
The Hall element can be considered as a resistor array
The simplest form of magnet that will operate these devices
OUT(SAT)
hys
) of the device. This built-in hysteresis allows
www.allegromicro.com
RP
. When the magnetic field is reduced below
), the device output goes high (turns OFF).
FUNCTIONAL DESCRIPTION
OP
). After
+V
PROGRAMMABLE, CHOPPER-
0
X
0
+V
B
V
STABILIZED, PRECISION,
CC
HALL-EFFECT SWITCH
Dwg. AH-011-2
B
HALL
VOLTAGE
RP
REG
FLUX DENSITY
—
+
X
B
OP
0.1 F
V
SUPPLY
OUT(SAT)
Dwg. GH-007-2
3150
+B
Dwg. EH-013
OUTPUT
SUPPLY
Dwg. EH-012