A3211_16 Datasheet, PDF (1/13 Pages) Allegro MicroSystems – Micropower, Ultrasensitive Hall-Effect Switches

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
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SUPPLY
SWITCH
X
TIMING
LOGIC
OUTPUT
GROUND
3211-DS, Rev. 22
Functional Block Diagram
Dwg. FH-020-5