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componentes Descripción

Fabricante

MC33033DWR2

Brushless DC Motor Controller

ON Semiconductor 

MC33033, NCV33033

7

Enable

19

R1

9

Increase

Speed

R2

10

C

11

REF

40 k

EA

PWM

Resistor R1 with capacitor C sets the acceleration time constant while R2

controls the deceleration. The values of R1 and R2 should be at least ten times

greater than the speed set potentiometer to minimize time constant variations

with different speed settings.

Figure 31. Controlled Acceleration/Deceleration

To Sensor

Input (Pin 4)

0.01

10 k

0.1

7

19

10 k

100 k

9

Increase

Speed 10

1.0 M

10 M 11

0.22

REF

40 k

EA

PWM

BCD

Inputs

5.0 V

16

VCC

12 P3

13 P2

14

P1

15 P0

Gnd

11

Q9 10

Q8

Q7 9

Q6 7

Q5 6

Q4 5

Q3 4

Q2 3

Q1 2

Q0 1

166 k

145 k

126 k

108 k

92.3 k

77.6 k

63.6 k

51.3 k

40.4 k

8

100 k 7

19

9

10

11

REF

40 k

EA

PWM

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.

Figure 32. Digital Speed Controller

ǒ Ǔ ǒ Ǔ VPin 11 + Vref 

R3 ) R4

R1 ) R2

  RR23  – 

R4

R3

 VB

7

ǒ Ǔ VB +

Vref 

R5

R6

 ) 

1

R3§§ R6  ø  R6

R1 T

19

R5

9

R3

R2

10

R6

R4

11

REF

40 k

EA

PWM

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 33. Closed Loop Speed Control

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 R1 and R2.

Figure 34. Closed Loop Temperature Control

Drive Outputs

The three Top Drive Outputs (Pins 1, 2, 20) are open

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 23 and 24.

The three totem pole Bottom Drive Outputs (Pins 15, 16,

17) are particularly suited for direct drive of N−Channel

MOSFETs or NPN bipolar transistors (Figures 25, 26, 27,

and 28). Each output is capable of sourcing and sinking up

to 100 mA.

Thermal Shutdown

Internal thermal shutdown circuity is provided to protect

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

The three phase application shown in Figure 35 is an open

loop motor controller with full wave, six step drive. The

upper 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

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