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Número de pieza | A1120 | |
Descripción | Chopper Stabilized Precision Hall Effect Switches | |
Fabricantes | Allegro MicroSystems | |
Logotipo | ||
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Chopper Stabilized Precision Hall Effect Switches
Features and Benefits
▪ Unipolar switchpoints
▪ Resistant to physical stress
▪ Superior temperature stability
▪ Output short-circuit protection
▪ Operation from unregulated supply
▪ Reverse battery protection
▪ Solid-state reliability
▪ Small package sizes
Packages:
3-pin SOT23W (suffix LH)
Not to scale
3-pin SIP (suffix UA)
Description
The A1120 and A1125 Hall-effect, unipolar switches are
extremely temperature-stable and stress-resistant sensor ICs,
especially suited for operation over extended temperature
ranges to 150°C. Superior high-temperature performance is
made possible through dynamic offset cancellation, which
reduces the residual offset voltage normally caused by device
overmolding, temperature dependencies, and thermal stress.
Each device includes on a single silicon chip a voltage regulator,
Hall-voltage generator, small-signal amplifier, chopper
stabilization, Schmitt trigger, and a short-circuit protected
open-collector output to sink up to 25 mA.
An on-board regulator permits operation with supply voltages
of 3 to 24 V. The advantage of operating down to 3 V is that
the device can be used in 3 V applications or with additional
external resistance in series with the supply pin for greater
protection against high voltage transient events.
For the A1120, a south pole of sufficient strength turns the
output on. Removal of the magnetic field turns the output off.
The A1125 is complementary to the A1120 in that, for the
A1125, a south pole turns the output off, and removal of the
magnetic field turns the output on.
Two package styles provide a magnetically optimized package
for most applications. Package type LH is a modified SOT23W,
surface mount package, while UAis a three-lead ultra-mini SIP
for through-hole mounting. Each package type is lead (Pb) free
(suffix, –T), with a 100% matte tin plated leadframe.
Functional Block Diagram
VCC
Amp
Regulator
Low-Pass
Filter
To All Subcircuits
Control
Current Limit
VOUT
A1120-DS, Rev. 9
GND
1 page A1120 and
A1125
Chopper Stabilized Precision Hall Effect Switcheswww.DataSheet4U.com
Functional Description
Operation
The output of the A1120 devices switches low (turns on) when
a magnetic field perpendicular to the Hall element exceeds the
operate point threshold, BOP (see panel A of figure 1). When the
magnetic field is reduced below the release point, BRP, the device
output goes high (turns off). The output of the A1125 devices
switches high (turns off) when a magnetic field perpendicular to
the Hall element exceeds the operate point threshold, BOP (see
panel B of figure 1). When the magnetic field is reduced below
the release point, BRP, the device output goes low (turns on).
After turn-on, the output voltage is VOUT(SAT). The output tran-
sistor is capable of sinking current up to the short circuit current
limit, IOM, which is a minimum of 30 mA.
The difference in the magnetic operate and release points is the
hysteresis, BHYS, of the device. This built-in hysteresis allows
clean switching of the output even in the presence of external
mechanical vibration and electrical noise. Powering-on the device
in the hysteresis range (less than BOP and higher than BRP) will
give an indeterminate output state. The correct state is attained
after the first excursion beyond BOP or BRP.
Applications
It is strongly recommended that an external bypass capacitor be
connected (in close proximity to the Hall element) between the
supply and ground of the device to reduce external noise in the
application. As is shown in panel B of figure 1, a 0.1 μF capacitor
is typical.
Extensive applications information for Hall effect devicers is
available in:
• Hall-Effect IC Applications Guide, Application Note 27701
• Guidelines for Designing Subassemblies Using Hall-Effect
Devices, Application Note 27703.1
• Soldering Methods for Allegro’s Products – SMT and Through-
Hole, Application Note 26009
All are provided in Allegro Electronic Data Book, AMS-702, and
the Allegro Web site, www.allegromicro.com.
V+
0
0
VCC
V+
VOUT(SAT)
B+
0
0
VCC
VOUT(SAT)
B+
VS
VCC
CBYP
0.1 μF
A1120
A1125 VOUT
GND
RL
Output
BHYS
(A)
BHYS
(B)
(C)
Figure 1. Device switching behavior. In panels A and B, on the horizontal axis, the B+ direction indicates increasing south polarity magnetic field strength.
This behavior can be exhibited when using an electrical circuit such as that shown in panel C.
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
5
5 Page |
Páginas | Total 9 Páginas | |
PDF Descargar | [ Datasheet A1120.PDF ] |
Número de pieza | Descripción | Fabricantes |
A1120 | Chopper Stabilized Precision Hall Effect Switches | Allegro MicroSystems |
A1120 | (A1120 - A1125) Chopper Stabilized Precision Hall Effect Switches | Allegro |
A1121 | (A1120 - A1125) Chopper Stabilized Precision Hall Effect Switches | Allegro |
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