MA120GQ-Z Datasheet, PDF (8/14 Pages) MPS Industries, Inc. – Angular Sensor for 3-Phase Brushless Motor Commutation

MA120
Angular Sensor for 3-Phase Brushless Motor
Commutation
Once the command is sent, it will immediately be
effective and will affect the next data sent from the
MagAlpha.
Read back the register content
It might be helpful to check the content of a register,
for instance to verify that the programming was
successful. The user must send the REGISTER READ
command: 0001, then the 4-bit address 0100. The last
8-bit of the stream will be ignored. The user can send
for instance 0000 0000:
command reg. address MSB
value
LSB
0001 0010 00000000
The MagAlpha response is within the same
transmission:
Angle out
MSB
A(7:4)
A(3:0)
value
LSB
Z(7:0)
In the first byte (simultaneous to the 4-bit READ
command and the 4-bit address), the MagAlpha sends
the 8 bits of the measured angle A(7:0). The second
byte is the content of the register. The MagAlpha
delivers the register value only once.
9. Output Signals
The raw data coming out of the conditioning blocks is
an absolute angle, between 0 and 360 deg. This angle is
coded on 16 bits, depending on the value of AF. The
absolute output is sent out digitally as serial data. The
other outputs, ABZ or UVW, are constructed from the
absolute angles.
Absolute - Serial
The bit order of the transmitted data is MSB first, LSB
last. The timing requirements are indicated in section 3.
Every 2µs a new data is transferred into the output
buffer. The master device connected to the MagAlpha
triggers the reading by pulling the CS down. When a
falling edge of the CS signal occurs, the data remains
in the output buffer until the CS signal returns to
logic 1. As the CS is low, the master can read the data
by sending clock pulses with a maximum frequency of
25 MHz. There is not any minimum frequency or
timeout. See Figure 7 for a simple reading of 8 bit data.
A full reading requires 16 clock pulses. The MA120
delivers:
MSB
LSB
A(8:0)
In case the user needs less resolution, since the MSB is
sent first, he can read the angle by sending less than 8
pulses.
If the master triggers the reading faster than the refresh
rate the MagAlpha may send several times the same
data point.
Block commutation - UVW
The UVW output emulates the three Hall switches
usually used for the block commutation of 3-phases
electric motor. The three logic signals have a duty
cycle of ½ and are shifted by 60 deg relative to each
other (see Figure 8).
Figure 7: Timing Diagram for Simple SPI Readout
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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