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PDF ( 数据手册 , 数据表 ) A3211

零件编号 A3211
描述 Micropower, Ultrasensitive Hall-Effect Switches
制造商 Allegro MicroSystems
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A3211 数据手册, 描述, 功能
FEATURES AND BENEFITS
• AEC-Q100 automotive qualified
• Micropower operation
• Operation with north or south pole
• 2.5 to 3.5 V battery operation
• Chopper stabilized
□Superior temperature stability
□Extremely low switchpoint drift
□Insensitive to physical stress
• High ESD protection
• Solid-state reliability
• Small size
• Easily manufacturable with magnet pole independence
Packages:
DFN (EL)
DFN (EH)
SOT23W (LH) Not to scale
SIP (UA)
A3211 and A3212
Micropower, Ultrasensitive
Hall-Effect Switches
DESCRIPTION
TheA3211 andA3212 integrated circuits are ultrasensitive, pole
independent Hall-effect switches with latched digital output.
These devices are especially suited for operation in battery-
operated, hand-held equipment such as cellular and cordless
telephones, pagers, and palmtop computers. A 2.5 to 3.5 V
operation and a unique clocking scheme reduce the average
operating power requirements to less than 15 μW with a
2.75 V supply.
Unlike other Hall-effect switches, either a north or south pole
of sufficient strength will turn the output on in the A3212,
and in the absence of a magnetic field, the output is off. The
A3211 provides an inverted output. The polarity independence
and minimal power requirements allow these devices to easily
replace reed switches for superior reliability and ease of
manufacturing, while eliminating the requirement for signal
conditioning.
Improved stability is made possible through chopper
stabilization (dynamic offset cancellation), which reduces the
residual offset voltage normally caused by device overmolding,
temperature dependencies, and thermal stress.
This device includes on a single silicon chip a Hall-voltage
generator, small-signal amplifier, chopper stabilization, a
latch, and a MOSFET output. Advanced CMOS processing
is used to take advantage of low-voltage and low-power
Continued on next page....
SUPPLY
SWITCH
X
TIMING
LOGIC
OUTPUT
GROUND
3211-DS, Rev. 22
Functional Block Diagram
Dwg. FH-020-5







A3211 pdf, 数据表
A3211 and
A3212
Micropower, Ultrasensitive
Hall-Effect Switches
Operation
The output of the A3212 switches low (turns on) when a magnetic
field perpendicular to the Hall element exceeds the operate point
BOPS (or is less than BOPN). After turn-on, the output is capable
of sinking up to 1 mA and the output voltage is VOUT(ON). When
the magnetic field is reduced below the release point BRPS (or
increased above BRPN), the device output switches high (turns
off). 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. The A3211 functions in
the same manner, except the output voltage is reversed from the
A3212, as shown in the figures to the right.
As used here, negative flux densities are defined as less than zero
(algebraic convention), i.e., -50 G is less than +10 G.
Applications
Allegro's pole-independent processing technique allows for opera-
tion with either a north pole or south pole magnet orientation,
enhancing the manufacturability of the device. The state-of-the-
art technology provides the same output polarity for either pole
face.
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 both external noise
and noise generated by the chopper-stabilization technique. This
is especially true due to the relatively high impedance of battery
supplies.
The simplest form of magnet that will operate these devices is
a bar magnet with either pole near the branded surface of the
device. Many other methods of operation are possible. Extensive
applications information for Hall-effect devices is available in:
Hall-Effect IC Applications Guide, Application Note 27701;
Hall-Effect Devices: Guidelines for Designing Subassemblies
Using Hall-Effect Devices, Application Note 27703.1;
Soldering Methods for Allegro’s Products — SMD and Through-
Hole, Application Note 26009.
All are provided at
www.allegromicro.com
A3211
OUTPUT OFF
5V
MAX
BRPN
BRPS
OUTPUT OFF
B OPN
OUTPUT ON
B OPS
0
-B 0
MAGNETIC FLUX
A3212
+B
5V
MAX
B OPN
OUTPUT OFF
B OPS
OUTPUT ON
0
-B
BRPN
BRPS
0
MAGNETIC FLUX
OUTPUT ON
+B
OUTPUT
0.1 F
S UP P LY
(3 V BATTE R Y)
Dwg. E H-013-2
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
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