MLX90254 Datasheet, PDF (5/9 Pages) Melexis Microelectronic Systems – Differential Dynamic Hall Effect Sensor

MLX90254
Differential Dynamic Hall Effect Sensor
6. MLX90254 Sensor Specific Specifications
DC Operating Parameters T_A = -40^oC to 150^oC, V_DD = 4V to 24V (unless otherwise specified)
Parameter
Preinduction
Differential Induction(4)
Operating Point
Release Point
Positive margin
Negative margin
Magnetic Hysteresis
Symbol Test Conditions
BDC
∆BAC
Bop
Brp
M+
M-
Bhyst
Min Typ Max
-500
500
6
100
-0.5
0
0.5
-0.5
0
0.5
0.5
2
3
-3
-2 -0.5
0
Units
mT
mT
mT
mT
mT
mT
mT
(4) The differential field must exceed 6 mT to assure the switching of the output
7. General Description
Let us model the magnetic flux densities by sinusoids. If the wheel confirms a certain geometrical
property, the two Hall cells see two magnetic flux densities in phase opposition. They are illustrated by the
dashed sinusoid on figure 1.
The difference between the two Hall signals is computed and amplified. The remaining DC offset is
removed by the high-pass filter. The noise that is out of the signal bandwidth is attenuated by the low-
pass filter in order to minimize the output jitter.
The AC differential signal is compared to the Bop and Brp threshold and the result of that comparison
commands the open drain output transistor.
Output Voltage Vs the Angle
40
12
B1
B2
35
BAC
OUT 10
30
25
8
20
15
6
10
5
4
0
1
2
3
4
5
6
7
8
9
10 ₂
-5
-10
0
-15
-20
-2
Angle (Degree)
Figure 1: Output toggling according to the differential magnetic signal.
3901090254
Rev. 005
Page 5 of 9
Datasheet
Jun/04