7560-120497-5

7

8

6

19

9

OSC

ERROR AMP(-)

ERROR AMP

OUT

ERROR AMP(+)

FIGURE 5. OPEN LOOP CONTROLLER

FIGURE 5. In this configuration, the PWM output

duty cycle to the motor drivers is directly pro-

portional to the DC voltage applied to Pin 6, since

Pins 7 and 8 are tied together.

OUT6

OUT5

OUT4

12

13

14

10

11

ENABLE

BRAKE

23

2

R

C

FIGURE 4. THREE PHASE HALF WAVE MOTOR CONTROLLER

19

(+)

(-)

OVERCURRENT

SENSE

24

25

26

27

21

20

22

15

16

17

14

13

12

10

11

5

7

8

6

9

4

3

28

18

19

2

1

23

ROTOR

OUT1

OUT2

OUT3

OUT4

OUT5

OUT6

S1

S2

S3

F/R

PWM CNTRL

TOP DRV

POL SEL

BRAKE SEL

BRAKE

OVERCURRENT

SENSE

SEQ SEL

TACH OUT

ENABLE

ERROR

AMP

OSC

RC

FAULT

FIGURE 3. THREE PHASE CLOSED LOOP FULL WAVE MOTOR CONTROLLER

10K

R2

100K

C1

0.1µF

*

*

TYPICAL

VALUES

*

1.0M

*

S1

S2

S3

(-)

OUT

(+)

S1

S2

S3

(+)

(-)

R3

* *

FIGURE 3. The closed loop mo-

tor control operation is achieved

by applying the

Tachometer

Output at Pin 5 into the negative

terminal of the Error Amplifier

(Pin 7) through an R1-C1-R2 in-

tegrating network. The R1-C1

network is configured as a feed-

back circuit around the amplifier.

Since the Tachometer Output

has a fixed positive pulse width,

the average value of the pulse

train is directly proportional to

the

motor speed. The desired

speed is selected by applying a

voltage at the positive input

(Pin 6) of the Error Amplifier.

The resultant output voltage of

the Error Amplifier is applied to

an internal Comparator along

with a ramp waveform gener-

ated by the RC Network at Pin

9. The PWM signal at the Com-

parator output is used to drive

outputs 1 thru 6 and complete

the closed loop.

For this con-

figuration, Pin 20, the Top Driver

Polarity Select must be tied to

Ground.

FIGURE 4. This three phase half wave motor controller has no top power tran-

sistor to disconnect the windings from the power supply when the BRAKE is ap-

plied. Instead, a switching transistor is used which will permit braking for a time

determined by the RC time constant. When the capacitor discharges past the

ENABLE input switching point, the outputs will be turned off.