3121, 3122,
AND
3123
HALL-EFFECT SWITCHES
FOR HIGH-TEMPERATURE OPERATION
These Hall-effect switches are monolithic integrated circuits with
tighter magnetic specifications, designed to operate continuously over
extended temperatures to +150°C, and are more stable with both tem-
perature and supply voltage changes. The unipolar switching character-
istic makes these devices ideal for use with a simple bar or rod magnet.
The three basic devices (3121, 3122, and 3123) are identical except for
magnetic switch points.
Each device includes a voltage regulator for operation with supply
voltages of 4.5 voltas to 24 volts, reverse battery protection diode,
quadratic Hall-voltage generator, temperature compensation circuitry,
small-signal amplifier, Schmitt trigger, and an open-collector output to
sink up to 25 mA. With suitable output pull up, they can be used with
bipolar or CMOS logic circuits. The 3121 is an improved replacement
for the 3113 and 3119.
The first character of the part number suffix determines the device
operating temperature range. Suffix ‘E–’ is for the automotive and
industrial temperature range of -40°C to +85°C. Suffix ‘L–’ is for the
automotive and military temperature range of -40°C to +150°C. Three
package styles provide a magnetically optimized package for most
applications. Suffix ‘–LT’ is a miniature SOT-89/TO-243AA transistor
package for surface-mount applications; suffix ‘–U’ is a three-lead
plastic mini-SIP while suffix ‘–UA’ is a three-lead ultra-mini-SIP.
Data Sheet
27621.4B
V
X
CC
1
2
3
GROUND
Dwg. PH-003A
Pinning is shown viewed from branded side.
ABSOLUTE MAXIMUM RATINGS
OUTPUT
SUPPLY
at T
A
= +25
°
C
FEATURES and BENEFITS
I
Superior Temp. Stability for Automotive or Industrial Applications
I
4.5 V to 24 V Operation … Needs Only An Unregulated Supply
I
Open-Collector 25 mA Output … Compatible with Digital Logic
I
Reverse Battery Protection
I
Activate with Small, Commercially Available Permanent Magnets
I
Solid-State Reliability … No Moving Parts
I
Small Size
I
Resistant to Physical Stress
Supply Voltage, V
CC
...........................
30 V
Reverse Battery Voltage, V
RCC
........
-30 V
Magnetic Flux Density, B .......
Unlimited
Output OFF Voltage, V
OUT
................
28 V
Reverse Output Voltage, V
OUT
........
-0.5 V
Continuous Output Current, I
OUT
...
25 mA
Operating Temperature Range, T
A
Suffix ‘E–’ .................
-40
°
C to +85
°
C
Suffix ‘L–’ ...............
-40
°
C to +150
°
C
Storage Temperature Range,
T
S
..............................
-65
°
C to +170
°
C
Always order by complete part number, e.g.,
A3121EU
.
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
