US5781LUA Melexis Inc, US5781LUA Datasheet - Page 23

• Manufacturer Part Number: US5781LUA
• Description: IC HALL EFFECT SWITCH TO-92UA
• Manufacturer: Melexis Inc
• Type: Unipolar Switchr

Specifications of US5781LUA

• 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 ~ 150°C
• Package / Case: TO-92UA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -

Graph 4, Slide-by With Magnet B, Steep Slope
The effects of mechanical tolerance on a Hall Effect System have just been illustrated. Temperature range
can also affect this system. Temperature will expand or contract the mechanical assembly, but will also
affect the field strength of the magnet and the distance from BOP t BRP of the Hall IC. The Neodymium
sample magnets used in this kit have a temperature coefficient of -).1098%/0C. This means that as tem-
perature increases by one degree Celsius, the Flux Density will decrease by 0.1098%.
Graph 5, Effects of Temperature on Flux Density
Due to the temperature coefficient, the magnet will have a difference in flux density of 30% and a change
in activation distance of 1mm over this range of temperature. This may not appear tobe a significant dif-
ference in field strength or distance, but in conjunction with other mechanical factors, temperature could
become a factor.
Design Example 2: Now that Design Example 1 illustrated the effects of mechanical, magnetic and Hall
IC tolerances within a Hall Effect System. Design Example 2 illustrates how they produce tolerance
buildup.
Tolerances:
Air Gap Tolerance = 2mm +0.5mm
US5881EUA BOP/BRP Range = 90G min. BRP to 300G max. BOP
(IC Temperature Selection (EUA) = -40oC to 85oC)
Temperature Range =-40oC to 85oC
Magnet Temp. Coefficient = -0.1098%/oC
700
600
500
400
300
200
100
600
500
400
300
200
100
0
0
0
0
Distance (mm)
2
5
4
Distance mm
Always "ON"
6
10
8
Always "ON"
Air Gap = 2 mm
Air Gap = 3 mm
Air Gap = 4 mm
Flux Denisity @ 25C
Flux Denisity @ -40C
Flux Denisity @ 85C
Always "OFF"
10
15
Always "OFF"
12
20
3-31
Section 3 - Applications