A3211 and A3212
Micropower, Ultra-sensitive
Hall-effect Switches
Features and Benefits
▪
▪
▪
▪
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
Description
The A 3211 and A3212 integrated circuits are ultra-sensitive,
pole independent Hall-effect switches with latched digital
output. These sensors are especially suited for operation in
battery-operated, hand-held equipment such as cellular and
cordless telephones, pagers, and palmtop computers. A 2.5
volt to 3.5 volt operation and a unique clocking scheme reduce
the average operating power requirements to less than 15
μW
with a 2.75 volt 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.
▪
▪
▪
▪
Packages:
DFN/MLPD (EH)
DFN/MLPD (EL)
SIP (UA)
SOT23W (LH)
Not to scale
Continued on the next page…
Functional Block Diagram
SUPPLY
SWITCH
TIMING
LOGIC
DYNAMIC
OFFSET CANCELLATION
OUTPUT
SAMPLE
& HOLD
LATCH
X
GROUND
Dwg. FH-020-5
3211-DS, Rev. 3
Conceptual Data Sheet
Subject to Change Without Notice
March 24, 2006
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
