MC33035 Motorola, MC33035 Datasheet - Page 14

• Manufacturer Part Number: MC33035
• Description: BRUSHLESS DC MOTOR CONTROLLER
• Manufacturer: Motorola

Inputs
The SN74LS145 is an open collector BCD to One of Ten decoder. When con-
nected 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.
BCD
14
Figure 31. Differential Input Speed Controller
V
V
14
V
12
13
15
Pin 13
A
B
P3
P2
P1
P0
R
R
Figure 33. Digital Speed Controller
16
R
3
8
1
+
Gnd Q
V
4
5.0 V
CC
V
R
A
2
12
13
Q2
11
Q
Q
Q
Q
Q
Q
Q
Q
8
7
9
7
6
5
4
3
1
0
8
R 3
R 1
11
10
9
6
5
4
1
7
3
2
)
)
R 4
R 2
92.3 k
77.6 k
63.6 k
51.3 k
40.4 k
166 k
126 k
108 k
145 k
REF
EA
R 2
R 3
25 A
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
100 k
*
V
V
R 3
PWM
Pi
B
R 4
R 3
n
+
§§
Figure 35. Closed Loop Temperature Control
12
13
3
11
8
7
+
V
R 5
R 6
B
R 5
V
V
ref
ref
)
ø
R 6
REF
1
R 3
R 1
EA
)
)
25 A
R 4
R 2
R
R
5
6
1
MC33035
PWM
and R
R 2
R 3
R
R
1
3
*
2
.
R
4
R 4
R 3
T
R
2
V
Resistor R
controls the deceleration. The values of R
times greater than the speed set potentiometer to minimize time constant
variations with different speed settings.
B
Input (Pin 4)
To Sensor
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.
Figure 32. Controlled Acceleration/Deceleration
12
13
11
8
7
10 k
0.01
Figure 34. Closed Loop Speed Control
Increase
Speed
1
0.1
with capacitor C sets the acceleration time constant while R
REF
EA
MOTOROLA ANALOG IC DEVICE DATA
1.0 M
10 k
25 A
100 k
R
R
Enable
PWM
2
1
0.22
C
1.0 M
12
13
11
8
7
11
12
13
8
7
1
and R
2
REF
REF
should be at least ten
EA
EA
25 A
25 A
PWM
PWM
2