US5781LSE Melexis Inc, US5781LSE Datasheet - Page 30

• Manufacturer Part Number: US5781LSE
• Description: IC HALL EFFECT SWITCH TSOT-23
• Manufacturer: Melexis Inc
• Type: Unipolar Switchr

Specifications of US5781LSE

• 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: SOT-23
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Other names: US5781LSETR

Section 3 - Applications
Measuring Flux Density
The Melexis Hall-Effect design kit is supplied with a linear Hal-Effect sensor which has been calibrated
to 1mV/G, making it very easy to build a circuit which will measure flux density. This is done with the
fully programmable MLX90215, programmed in this case to deliver exactly 2.5V at zero magnetic field
rising 1mV for every 1 Gauss applied.
If a field of 100 Gauss is applied, the output will increase 100mV. Similarly, if a field of -100 Gauss is
applied, the output will decrease 100mV. It is very important to maintain a regulated supply voltage of
5V because the output has no internal regulator and is ratiometric. The Hall IC's output is exactly V D D /2,
so if the supply voltage changes the output voltage also changes.
Figure 15, Flux Measurement
Figure 9 shows a circuit which allows the Voltmeter to be calibrated to read in units of Gauss. Shifting the
ground reference of the Voltmeter to exactly the quiescent voltage of the Hall IC makes the 2.5V VOQ
appear to be zero. The potentiometer allows this to be set to exactly zero. When a magnetic field is
applied, the DVM will display units of Gauss in a range of +/- 2000 Gauss. The resistor network is to
divide the output voltage by 10 so it can be measured by
200mV meter. If your meter is 2V range, this divider is not
used. This circuit can be built into a small case with a battery
and voltage regulator for a very inexpensive flux measuring
device.
With no divider used:
Full Scale: (2.00V)
With 1/10 divider used:
Full Scale: (200mV)
1mT = 10Gauss, exactly
1 Gauss =
1 mT =
1 Gauss =
1 mT =
5V
+/-2000 Gauss
+/-200 mT
1 m V
0.1mV
+/-2000 Gauss
+/-200 mT
0.1mV
0.01mV
.1 F
90215
2501000
MLX
.1 F
2.00V Scale
DVM
A-16
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
3-16
-200
Output Voltage vs. Magnetic Flux Density
-100
Flux Density (mT)
0
Potentiometer
Figure 16, Flux
200
100
2k
2k
5V
+
1%
200
zero adjust
90215
2501000
1 F
A-17
MLX
.1 F
9k*
1k*
(optional)
divider
1/10
Voltmeter
Attach to