DRV5032_17 Datasheet, PDF (14/33 Pages) Texas Instruments – Ultra-Low-Power Digital-Switch Hall Effect Sensor

DRV5032
SLVSDC7A – APRIL 2017 – REVISED MAY 2017
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9.2.1.2 Detailed Design Procedure
When designing a digital-switch magnetic sensing system, three variables should always be considered: the
magnet, sensing distance, and threshold of the sensor.
Magnets are made from different ferromagnetic materials that have tradeoffs in cost, shift across temperature,
absolute max temperature ratings, magnetic remanence, and magnetic coercivity. The magnetic remanence and
the dimensions of a magnet determine the magnetic flux density it produces across a distance.
The DRV5032 device has a detection threshold specified by parameter B_OP. To reliably activate the sensor, the
magnet must apply greater than the max specified B_OP. In such a system, the sensor typically detects the
magnet before it has moved to the closest position. When the magnet moves away from the sensor, it must apply
less than the minimum specified B_RP to reliably release the sensor.
9.2.1.3
Application Curve
60
55
50
45
40
35
30
25
20
15
10
5
0
1 1.5 2 2.5 3 3.5 4 4.5 5
Distance (cm)
D017
Figure 16. Magnetic Profile of a 1-cm Cube NdFeB Magnet
9.2.2 Three-Position Switch
This application uses the DRV5032FD for a three-position switch.
123
PCB
Figure 17. Three-Position Slider Switch with Embedded Magnet
9.2.2.1 Design Requirements
For this design example, use the parameters listed in Table 2.
Table 2. Design Parameters
DESIGN PARAMETER
Hall effect device
V_CC
Switch travel distance
Magnet
Mechanical tolerance per position
EXAMPLE VALUE
DRV5032FD
5V
5 mm in each direction
10 mm cylinder
±0.5 mm
14
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