US5781EUA Melexis Inc, US5781EUA Datasheet - Page 28
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US5781EUA
Manufacturer Part Number
US5781EUA
Description
IC HALL EFFECT SWITCH TO-92UA
Manufacturer
Melexis Inc
Type
Unipolar Switchr
Specifications of US5781EUA
Sensing Range
15mT Trip, 3.5mT Release
Voltage - Supply
3.5 V ~ 24 V
Current - Supply
5mA
Current - Output (max)
50mA
Output Type
Digital, Open Drain
Operating Temperature
-40°C ~ 85°C
Package / Case
TO-92UA
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Features
-
Flux Concentrators
A flux concentrator, or pole piece, is a ferrous material used to significantly increase the performance of
a Hall Effect Sensor System. When a flux concentrator is placed opposite the pole face of a magnet, the
magnetic field channels through the concentrator, thereby increasing the flux density between the con-
centrator and the pole face.
Figure 13, Flux Concentrator
The reason this magnetic flux channels through the concentrator is because of the reluctance of the fer-
rous material. Reluctance is the resistance that magnetic flux lines experience as they flow from the North
pole into the South pole of a magnet. Ferromagnetic materials have lower reluctance than air, therefore a
pole piece provides an easier path for the flux to flow through, while increasing the flux density at the
same time. There are three benefits to adding a flux concentrator to a magnetic circuit. First, a less sensi-
tive Hall Effect Sensor can be implemented, a result of the increased flux density. The second benefit of
using a flux concentrator is that Hall Effect Sensor with a specific operate level can be actuated a greater
distance from the magnet, than if one were not in use. The addition of a pole piece also allows the use of
a magnet with a lower field intensity. A flux concentrator makes it possible to use a smaller magnet or a
magnet of different material to achieve the same operating characteristics as one with higher flux density
or a larger size. When choosing materials for a pole piece, pay attention to the following characteristics:
The permeability and reluctance of the material will affect its performance as a flux concentrator. Also,
pay close attention to the mechanical characteristics of machining and corrosion. These properties are
very important when selecting an alloy.
Concentrator
Ferrous
Magnet
3-9
N
S
Section 3 - Applications