ls7262 LSI Computer Systems, Inc., ls7262 Datasheet - Page 7

• Manufacturer Part Number: ls7262
• Description: Brushless Dc Motor Commutator/controller
• Manufacturer: LSI Computer Systems, Inc.

7262-051711-7
O V E R ‐C U R R E N T
P O S IT IO N
S E N S O R
M O T O R
F R O M
B R A K E IN P U T
S E N S E
L S 7 2 6 2
C O M M O N
C 2
R 4
R 3
R 7
V S S
V S S
D 1
O 1
O 3
O 4
O 6
R 5
1 2
R 2
5
9
2
4
6
8
FIGURE 4A
C 4
C 1
R 6
R 8
V S S
+
C 3
‐
V S S
V S S
R 1
1 5
1 4
1 3
FIGURE 4. FOUR PHASE OUTPUT DRIVER CIRCUITRY
V T R IP
S 1
O S C IL L A T O R
L 2
M O T O R S U P P L Y
L 1
L 3
L 4
V S S
L S 7 2 6 2
B R A K E
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
transmitter 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
C O M M O N
LS 7 2 6 2
C U R R E N T
O V E R ‐
S E N S E
B R A K E
O 3
O 6
O 4
O 1
FIGURE 5
5
9
8
2
4
6
1 2
V S S
FIGURE 4B
L 3
L 1
L 2
L 4
M O T O R S U P P L Y
V S S
B R A K E