US4881(2006) Просмотр технического описания (PDF) - Melexis Microelectronic Systems

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US4881
(Rev.:2006)

Bipolar Hall Switch Low Voltage & Very High Sensitivity

Melexis Microelectronic Systems  

US4881

Bipolar Hall Switch

Low Voltage & Very High Sensitivity

9 Detailed General Description

Based on mixed signal CMOS technology, Melexis US4881 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 techniques 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 operating voltage from 2.2V to 18V, low current consumption and large choice of operating temperature

range according to “L”, “K” and “E” specification make this device suitable for automotive, industrial and

consumer low voltage 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 US4881 exhibits bipolar magnetic switching characteristics. Therefore, it operates with both south and

north poles.

Typically, the device behaves as a latch with symmetric

operating and release switching points (BOP=|BRP|). This means

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.

Latch characteristic

Depending on the magnetic switching points, the device may also behave as a unipolar positive switch (BOP

and BRP strictly positive) or negative switch (BOP and BRP strictly negative). That is the output can be set high

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

In latch, positive or negative switch behaviour, a magnetic hysteresis BHYST keeps BOP and BRP separated by

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

3901004881

Rev 011

Page 5 of 11

Data Sheet

Feb/06

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