ls7260 LSI Computer Systems, Inc., ls7260 Datasheet - Page 6

• Manufacturer Part Number: ls7260
• Description: Brushless Dc Motor Commutator/controller
• Manufacturer: LSI Computer Systems, Inc.

7260-012703-6
FROM MOTOR
P O S I T I O N
SENSOR
C2
R7
R3
OVERCURRENT
LS7262
Vss
BRAKE INPUT
Vss
S E N S E
R4
COMMON
D1
R5
O1
O3
O4
O6
12
9
R2
5
2
4
6
8
C1
FIGURE 4. FOUR PHASE OUTPUT DRIVER CIRCUITRY
C3
R6
-
+
FIGURE 4A
C4
R8
Vss
Vss
Vss
R1
15
13
14
S1
V TRIP
OSCILLATOR
L S 7 2 6 0
L S 7 2 6 2
or
L1
L2
L3
L4
Vss
MOTOR SUPPLY
BRAKE
A closed loop system can be configured by differentiating
one of the motor position sense inputs and integrating only
the negative pulses to form a DC voltage that is applied to
the inverting input of an op-amp. The non-inverting input
voltage is adjusted with a potentiometer until the resultant
voltage at VTRIP causes the motor to run at desired speed.
The R2-C1 differentiator, the R3-D1 negative pulse trans-
mitter and the R4-C2 integrator form a frequency to voltage
converter. An increase in motor speed above the desired
speed causes VTRIP to increase which lowers the PWM
and the resultant motor speed. A decrease in speed lowers
VTRIP and raises the PWM and the resultant motor speed.
For proper operation, both R5 and R6 should be greater
than R4, and R4 in turn should be greater than both R2 and
R3. Also, the R4-C2 time constant should be greater than
the R2-C1 time constant. C3 may be added across R6 for
additional VTRIP smoothing.
CLOSED-LOOP SPEED CONTROLLER
The information included herein is believed to be
accurate and reliable. However, LSI Computer Systems,
Inc. assumes no responsibilities for inaccuracies, nor for
any infringements of patent rights of others which may
result from its use.
O V E R C U R R E N T
LS7262
S E N S E
COMMON
BRAKE
O1
O3
O4
O6
5
9
2
4
6
8
12
FIGURE 5
FIGURE 4B
Vss
L2
L4
L1
L3
Vss
MOTOR SUPPLY
BRAKE