MC33033 Motorola, MC33033 Datasheet - Page 19

• Manufacturer Part Number: MC33033
• Description: BRUSHLESS DC MOTOR CONTROLLER
• Manufacturer: Motorola

Sensor Phasing Comparison
phasing of the sensor signals in three phase motors. With six
step drive, an input signal change must occur every 60
electrical degrees, however, the relative signal phasing is
dependent upon the mechanical sensor placement. A
comparison of the conventions in electrical degrees is shown
in Figure 38. From the sensor phasing table (Figure 39), note
that the order of input codes for 60 phasing is the reverse of
300 . This means the MC33033, when the 60 /120 select
(Pin 18) and the FWD/REV (Pin 3) both in the high state
(open), is configured to operate a 60 sensor phasing motor
in the forward direction. Under the same conditions a 300
sensor phasing motor would operate equally well but in the
reverse direction. One would simply have to reverse the
FWD/REV switch (FWD/REV closed) in order to cause the
300 motor to also operate in the same direction. The same
difference exists between the 120 and 240 conventions.
S A
MOTOROLA ANALOG IC DEVICE DATA
1
1
1
0
0
0
There are four conventions used to establish the relative
120
240
300
60
60
S B
0
1
1
1
0
0
Figure 38. Sensor Phasing Comparison
S A
S B
S C
S A
S B
S C
S A
S B
S C
S A
S B
S C
S C
0
0
1
1
1
0
Figure 39. Sensor Phasing Table
Sensor Electrical Phasing (Degrees)
0
S A
60
1
1
1
0
0
0
Rotor Electrical Position (Degrees)
120
120
S B
0
0
1
1
1
0
180
S C
240
1
0
0
0
1
1
300
S A
1
1
1
0
0
0
360
240
S B
1
0
0
0
1
1
420
S C
480
0
0
1
1
1
0
540
S A
1
1
1
0
0
0
600
300
S B
1
1
0
0
0
1
660
720
S C
MC33033
1
0
0
0
1
1
in electrical degrees since the mechanical position is a
function of the number of rotating magnetic poles. The
relationship between the electrical and mechanical position is:
electrical revolutions for a given mechanical revolution.
General purpose three phase motors typically contain a four
pole rotor which yields two electrical revolutions for one
mechanical.
Two and Four Phase Motor Commutation
of providing a four step output that can be used to drive two or
four phase motors. The truth table in Figure 40 shows that by
connecting sensor inputs S B and S C together, it is possible to
truncate the number of drive output states from six to four.
The output power switches are connected to B T , C T , B B , and
C B . Figure 41 shows a four phase, four step, full wave motor
control application. Power switch transistors Q 1 through Q 8
are Darlington type, each with an internal parasitic catch
diode. With four step drive, only two rotor position sensors
spaced at 90 electrical degrees are required. The
commutation waveforms are shown in Figure 42.
controller. It has the same features as the circuit in Figure 36,
except for the deletion of speed adjust.
Electrical Degrees
*With MC33033 sensor input S B connected to S C
Sensor Electrical
In this data sheet, the rotor position has always been given
An increase in the number of magnetic poles causes more
The MC33033 configured for 60 sensor inputs is capable
Figure 43 shows a four phase, four step, half wave motor
Spacing* = 90
S A
1
1
0
0
1
1
0
0
Figure 40. Two and Four Phase, Four Step,
Inputs
MC33033 (60 /120 Select Pin Open)
S B
0
1
1
0
0
1
1
0
Commutation Truth Table
+
Mechanical Degrees #Rotor Poles
F/R
1
1
1
1
0
0
0
0
B T
Top Drives
1
0
1
1
1
1
1
0
C T
1
1
0
1
0
1
1
1
Outputs
Bottom Drives
B B
0
0
0
1
0
1
0
0
2
C B
1
0
0
0
0
0
1
0
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