US2881

Bipolar Hall Switch – Very High Sensitivity

3901002881

Page 5 of 12

Data Sheet

Rev 012

Aug/06

9 Detailed General Description

Based on mixed signal CMOS technology, Melexis US2881 is a Hall-effect device with very high magnetic

sensitivity. It allows using generic magnets, weak magnets or larger air gap.

The chopper-stabilized amplifier uses switched capacitor technique to suppress the offset generally observed

with Hall sensors and amplifiers. The CMOS technology makes this advanced technique possible and

contributes to smaller chip size and lower current consumption than bipolar technology. The small chip size is

also an important factor to minimize the effect of physical stress.

This combination results in more stable magnetic characteristics and enables faster and more precise design.

The wide operating voltage from 3.5V to 24V, “L” and “E” operating temperature range and low current

consumption make this device especially suitable for automotive and BLDC motor applications.

The output signal is open-drain type. Such output allows simple connectivity with TTL or CMOS logic by using

a pull-up resistor tied between a pull-up voltage and the device output.

10 Unique Features

The US2881 exhibits bipolar magnetic switching characteristics. Therefore, it operates with both south and

north poles.

Latch characteristic

Typically, the device behaves as a latch with symmetric

magnetic fields with equivalent strength and opposite direction

drive the output high and low.

Removing the magnetic field (B→0) keeps the output in its

previous state. This latching property defines the device as a

magnetic memory.

and low by only using one magnetic pole. In such case, removing the magnetic field changes the output level.

Unipolar positive switch characteristic

Unipolar negative switch characteristic

a minimal value. This hysteresis prevents output oscillation near the switching point.