Description

The A1120, A1121, and A1125 Hall-effect, unipolar switches

are extremely temperature-stable and stress-resistant sensor

ICs, especially suited for operation over extended temperature

ranges to 150°C. Superior high-temperature performance is

made possible through dynamic offset cancellation, which

reduces the residual offset voltage normally caused by device

overmolding, temperature dependencies, and thermal stress.

Each device includes on a single silicon chip a voltage regulator,

Hall-voltage generator, small-signal amplifier, chopper

stabilization, Schmitt trigger, and a short-circuit protected

open-drain output to sink up to 25 mA.

An on-board regulator permits operation with supply voltages

of 3 to 24 V. The advantage of operating down to 3 V is that

the device can be used in 3 V applications or with additional

external resistance in series with the supply pin for greater

protection against high voltage transient events.

For the A1120 and A1121, a south pole of sufficient strength

turns the output on. Removal of the magnetic field turns the

output off. The A1125 is complementary, in that for these

devices, a south pole turns the A1125 output off, and removal

of the magnetic field turns the output on.

Two package styles provide a magnetically optimized package

for most applications. Package type LH is a modified SOT23W,

surface mount package, while UAis a three-lead ultra-mini SIP

for through-hole mounting. Each package type is lead (Pb) free

(suffix, –T), with a 100% matte tin plated leadframe.

A1120-DS, Rev. 11

Features and Benefits

▪ Unipolar switchpoints

▪ Resistant to physical stress

▪ Superior temperature stability

▪ Output short-circuit protection

▪ Operation from unregulated supply

▪ Reverse battery protection

▪ Solid-state reliability

▪ Small package sizes

Chopper Stabilized Precision Hall Effect Switches

Packages:

Functional Block Diagram

Not to scale

A1120, A1121, and A1125

3-pin SOT23W (suffix LH)

3-pin SIP (suffix UA)

Regulator

GND

VCC

VOUT

Control

Current Limit

To All Subcircuits

Amp

Low-Pass

Filter