US2884 Datasheet, PDF (5/11 Pages) Melexis Microelectronic Systems – Bipolar Hall Switch - Very High Sensitivity

US2884
Bipolar Hall Switch – Very High Sensitivity
9 Detailed General Description
Based on mixed signal CMOS technology, Melexis US2884 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, wide operating temperature according to “L” specification 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 US2884 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 (B_OP=|B_RP|). 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 (B_OP
and B_RP strictly positive) or negative switch (B_OP and B_RP 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 B_HYST keeps B_OP and B_RP separated by
a minimal value. This hysteresis prevents output oscillation near the switching point.
3901002884
Rev 004
Page 5 of 11
Data Sheet
Jan/06