MC33033 Motorola, MC33033 Datasheet - Page 14

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

Drive Outputs
collector NPN transistors capable of sinking 50 mA with a
minimum breakdown of 30 V. Interfacing into higher voltage
applications is easily accomplished with the circuits shown in
Figures 22 and 23.
17) are particularly suited for direct drive of N–Channel
MOSFETs or NPN bipolar transistors (Figures 24, 25, 26,
and 27). Each output is capable of sourcing and sinking up
to 100 mA.
Thermal Shutdown
the IC in the event the maximum junction temperature is
exceeded. When activated, typically at 170 C, the IC acts
as though the regulator was disabled, in turn shutting down
the IC.
SYSTEM APPLICATIONS
Three Phase Motor Commutation
loop motor controller with full wave, six step drive. The upper
Resistor R 1 with capacitor C sets the acceleration time constant while R 2
controls the deceleration. The values of R 1 and R 2 should be at least ten times
greater than the speed set potentiometer to minimize time constant variations
with different speed settings.
The rotor position sensors can be used as a tachometer. By differentiating the
positive–going edges and then integrating them over time, a voltage
proportional to speed can be generated. The error amp compares this voltage
to that of the speed set to control the PWM.
Input (Pin 4)
14
Figure 30. Controlled Acceleration/Deceleration
The three Top Drive Outputs (Pins 1, 2, 20) are open
The three totem pole Bottom Drive Outputs (Pins 15, 16,
Internal thermal shutdown circuity is provided to protect
The three phase application shown in Figure 34 is an open
To Sensor
10 k
Increase
Speed
0.01
Figure 32. Closed Loop Speed Control
0.1
1.0 M
100 k
10 k
R 2
R 1
Enable
0.22
C
Increase
Speed
10 M
19
10
11
7
9
19
10
11
7
9
REF
REF
EA
EA
40 k
40 k
PWM
PWM
MC33033
power switch transistors are Darlington PNPs while the lower
switches are N–Channel power MOSFETs. Each of these
devices contains an internal parasitic catch diode that is used
to return the stator inductive energy back to the power supply.
The outputs are capable of driving a delta or wye connected
stator, and a grounded neutral wye if split supplies are used.
At any given rotor position, only one top and one bottom
power switch (of different totem poles) is enabled. This
configuration switches both ends of the stator winding from
supply to ground which causes the current flow to be
bidirectional or full wave. A leading edge spike is usually
present on the current waveform and can cause a
current–limit error. The spike can be eliminated by adding an
RC filter in series with the Current Sense Input. Using a low
inductance type resistor for R S will also aid in spike reduction.
Figure 35 shows the commutation waveforms over two
electrical cycles. The first cycle (0 to 360 ) depicts motor
operation at full speed while the second cycle (360 to 720 )
shows a reduced speed with about 50% pulse width
modulation. The current waveforms reflect a constant torque
load and are shown synchronous to the commutation
frequency for clarity.
Inputs
This circuit can control the speed of a cooling fan proportional to the difference
between the sensor and set temperatures. The control loop is closed as the
forced air cools the NTC thermistor. For controlled heating applications,
exchange the positions of R 1 and R 2 .
The SN74LS145 is an open collector BCD to One of Ten decoder. When
connected as shown, input codes 0000 through 1001 steps the PWM in
increments of approximately 10% from 0 to 90% on–time. Input codes 1010
through 1111 will produce 100% on–time or full motor speed.
V
V
BCD
R 3
Pi
B
n 11
+
§§
Figure 33. Closed Loop Temperature Control
+
12
13
14
15
R 5
R 6
R 6
V
V
P3
P2
P1
P0
ref
ref
)
ø
16
8
R 6
Figure 31. Digital Speed Controller
V CC
Gnd
1
5.0 V
R 1
R 3
)
)
MOTOROLA ANALOG IC DEVICE DATA
Q 9
Q 7
Q 6
Q 5
Q 4
Q2
Q 3
Q 1
Q 8
Q 0
R 4
R 2
R 5
R 6
11
10
9
6
5
4
3
1
7
2
R 2
R 3
92.3 k
77.6 k
63.6 k
51.3 k
40.4 k
166 k
145 k
126 k
108 k
R 1
R 3
–
R 4
R 4
R 3
T
R 2
100 k
V
B
19
10
19
10
11
11
7
9
7
9
REF
REF
EA
EA
40 k
40 k
PWM
PWM