7560-030599-5
7
8
6
19
9
V
R
OSC
ERROR AMP(-)
ERROR AMP
OUT
ERROR AMP(+)
R
T
C
T
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
V
M
ENABLE
BRAKE
23
2
R
C
V
R
FIGURE 4. THREE PHASE HALF WAVE MOTOR CONTROLLER
19
(+)
(-)
OVERCURRENT
SENSE
V
R
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
V
R
V
SS
V
DD
FAULT
V
M
V
M
FIGURE 3. THREE PHASE CLOSED LOOP FULL WAVE MOTOR CONTROLLER
C
S
V
R
C
T
R
T
10K
R2
100K
C1
0.1μF
*
*
*
R1
1.0M
TYPICAL
VALUES
*
*
V
R
S1
S2
S3
(-)
OUT
(+)
S1
S2
S3
R
s
( + )
( - )
FIGURE 3.
The closed loop
motor
control
achieved
by
Tachometer Output at Pin 5 into
the negative terminal of the
Error Amplifier (Pin 7) through
an R1-C1-R2 integrating net-
work. The R1-C1 network is
configured as a feedback circuit
around the amplifier. Since the
Tachometer Output has a fixed
positive pulse width, the aver-
age value of the pulse train is
directly
proportional
motor
speed.
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 Driv-
er Polarity Select must be tied
to Ground.
operation
applying
is
the
to
desired
the
The
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.