EVKT-KNOB

– ROTARY KNOB KIT FOR THE MAGALPHA

EVKT-KNOB Rev. 1.0

MonolithicPower.com

6

4/2/2019

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MAGNETIC FIELD

An NdFeB cylinder magnet is mounted at the end of the aluminum shaft.

Table 4: Magnet Characteristics

Material

NdFeB (N35 or N35H)

Remanence (Br)

1.2T

Diameter

5mm

Height

2.5mm

Magnetization

Diametrical

How to Change the Mechanical Zero

Unscrew the knob with a 1/16-inch hex key (Allen wrench). Hold the shaft with a pin inserted in the 2mm

diameter hole, and rotate the knob to the desired position. When tightening the screw, ensure that the

key is fully inserted. Note that the zero position can also be adjusted through programming, as described

in the MagAlpha datasheet.

Figure 7: Adjusting the Magnet Angular Position

How to Change the Magnetic Field Amplitude

The performance of the MagAlpha remains the same from 75mT to 150mT and higher (the MagAlpha

has no maximum operating field). The critical region is the lower end of the specified range. Some

parameters (e.g. noise, linearity) deteriorate gradually when the magnetic field becomes weak. The two

spacers enclosed in this evaluation kit allow the sensor (the noise level in particular) to be tested at low

magnetic fields.

Figure 8: Magnetic Field vs. Air Gap for the Supplied Magnet