Torque & Speed Closed Loop Control.

The motor’s rotational speed is determined by the frequency of the Hall effect signals. The speed control

loop has been achieved by comparing this frequency with a frequency of a reference oscillator (see fig.

14) that corresponds to a desired speed limit.

3

OUT3

L6234

C1

100uF

60V

EN3

IN3

IN2

IN1

EN1

EN2

OUT2

OUT1

Vboot

Vcp

Vs

7

912

17

18

6

5

15

4

14

8

13

D1

D2

C4

C3

10nF

C2

220nF

100nF

1N4148

1N4148

POWER SO20

1

2

GND

+5V

Vref

10 11 20

16

19

C5

1uF

R10 10K each

IN2

IN1

IN3

EN3

EN2

EN1

SENSE

R1

R2

R3

R4

REFERENCE

SPEED

CONSTANT toff

CHOPPING

CURRENT

CONTROL

Vsense

Vcontrol

TORQUE &

SPEED

CONTROL

PWM

BRUSHLESS MOTOR

HALL

EFFECT

SENSORS

CONTROL

LOGIC

HALL

EFFECT

SIGNALS

BRAKE

DIR

PWM

Hall effect signal

C6

220nF

1

2

IN

3

OUT

L7805

GND

10uF

C7

Z1

18V

R5

10k

T1

+5V

J7

Reference

Speed

Vs=8V to 42

1

Ω

1

Ω

1

Ω

1

Ω

Figure 12. Application board Schematic Circuit.

M74HC123

monostable

+5V

+5V

C11

330pF

R9

100nF

C10

23

16

4

15 14

8

1

100k

R11

10k

Vcontrol

PWM

+5V

100nF

LM393

R7 11 k

R8

1K

C8

470pF

R6 1K

2

Vsense

1

+5V

8

3

4

+

-

C9

_

Q

A

B

+5V

J1

Figure 13. Constant toff current control.

toff

R9

C11

20

µs

100k

270pF

30

µs

100k

330pF

45

µs

100k

560pF

70

µs

100k

1nF

Table 1. toff selection

PHASE/

FREQUENCY

DETECTOR

HALL

SENSORS

COMPENSATION

NETWORK

PWM

Vcontrol

Amp.

MOTOR

REFERENCE

FEEDBACK

D01IN1209

Figure 14. PLL Motor Control.

AN1088 APPLICATION NOTE

7/14