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.

HALL-EFFECT SWITCHES

FOR HIGH-TEMPERATURE OPERATION

Always order by complete part number, e.g., A3121EU .

ABSOLUTE MAXIMUM RATINGS

at T

Supply Voltage, V

Reverse Battery Voltage, V

Magnetic Flux Density, B ....... Unlimited

Output OFF Voltage, V

Reverse Output Voltage, V

Continuous Output Current, I

Operating Temperature Range, T

A

Suffix ‘E–’ ................. -40

Suffix ‘L–’ ............... -40

Storage Temperature Range,

T

-65

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

Pinning is shown viewed from branded side.

3123

Dwg. PH-003A

1

V

CC

3

2