MA700GQ-P Datasheet, PDF (6/15 Pages) MPS Industries, Inc. – Angular Sensor for Position Control with Side-Shaft Positioning Capability

MA700
Angular Sensor for Position Control with
Side-Shaft Positioning Capability
When the end-of-shaft position is not available the
sensor can be positioned away from the rotation axis of
a cylinder or ring magnet (see Figure 5). In this case
the magnetic field angle is not directly proportional to
the mechanical angle anymore. The MA 700 can be
adjusted to compensate this effect and recover the
linear relation between the mechanical angle and the
sensor output. With multiple pole pairs, the MA 700
6. Power Supply Decoupling
For most applications, a single 100 nF bypass capacitor
placed close to the supply pins sufficiently decouples
the MA 700 from noise of the power supply. If better
decoupling is required, a larger capacitor (10 µF) can
be added in parallel with the 100 nF, and/or a resistor
(10) can be added between the supply line and the
capacitor node.
In any case, make sure that the connection between the
MA 700 ground and the power supply ground has a
low impedance, in order to avoid noise transmitted
from the ground.
VFLASH needs to be supplied only when flashing the
memory. Otherwise the VFLASH pin can remain
unconnected or grounded (see Figure 6).
7. Sensor Front-End
The magnetic field is detected with integrated Hall
devices located in the package center. The particularity
of this sensor is that the angle is measured using the
spinaxis method which directly digitizes the direction
of the field without any ATAN computation or any
feedback loop based circuit (interpolators, etc.).
The spinaxis method is based on phase detection. It
requires a sensitive circuitry generating a sinusoidal
signal whose phase represents the angle of the
magnetic field. The angle is then retrieved by a time-to-
digital converter, which counts the time between the
zero crossing of the sinusoidal signal and the edge of a
constant waveform (see Figure 7). The digitized time is
the front-end output.
will indicate multiple rotations for each mechanical
turn.
Figure 6: Connection for Supply Decoupling
Figure 7: Phase Detection Method. Top: Sine Waveform.
Bottom: Clock of Time-to-Digital Converter.
Looking further down the treatment chain, it is crucial
that the signal treatment does not add unwanted phase
shifts. For this purpose the MagAlpha incorporates an
architecture where these shifts are automatically
compensated, resulting in the stability displayed in
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Reserved. MA700 Rev 1.0 September 2014
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