MA300GQ-P Datasheet, PDF (7/18 Pages) MPS Industries, Inc. – Angular Sensor for 3-Phase Brushless Motor Commutation and Position Control with Side-Shaft Positioning Capability

MA300
Angular Sensor for 3-Phase Brushless Motor
Commutation and Position Control with Side-Shaft
Positioning Capability
Figure 6: Connection for Supply Decoupling
7. Sensor Front-End
The magnetic field is detected with integrated Hall
devices located in the center of the package. The
particularity of this sensor is that the angle is
measured using the spinaxis method, which
digitizes directly the direction of the field without
any ATAN computation or a feedback loop based
circuit (interpolators, etc.).
The spinaxis method is based on phase detection.
It requires a sensitive circuitry generating a
sinusoidal signal with a phase that 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.
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 that
automatically compensates these shifts, resulting
in the stability displayed in Table 2. In short, the
front-end delivers in a straightforward and open-
loop manner a digital number proportional to the
angle of the magnetic field at the rate of 500kHz.
Side-Shaft
The default current biasing of the Hall devices is
adjusted by programming to accommodate a low
field or compensate non-linearities inherent to
side-shaft configurations (see Figure 8).
Figure 7: Phase Detection Method. Top: Sine Waveform.
Bottom: Clock of Time-to-Digital Converter.
Monolithic Power Systems, Inc. | Gland, Switzerland | Tel: [phone] | [e-mail] | www.sensimatech.com
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Reserved. MA700 Rev 1.0 September 2014
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