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HALL
---
SPINDLE MOTOR
SENSOR
CONTROL
LSI (IC6A)
MOTOR SPEED
~
MOTOR
~
SPINDLE
INTEGRATOR
DRIVERS
MOTOR
CURRENT LIMITER
DYNAMIC BRAKE
MOTOR
~
VOLTAGE
8.0
MOTORSPEED
CONTROL
FIGURE 27:
Motor Speed Control:
PC Board 20292-XXX
MOTOR SPEED CONTROL: PC BOARD 20292-XXX
HALL EFFECT TRANSDUCER
8.1
8.1.1
Located inside the spindle motor hub, this magnetic transducer senses spindle
position and provides dynamic feedback proportional ta the speed of the mo-
tore Two complete square waves are generated each motor revolution. The posi-
tional information is supplied ta the spindle motor L81
le
6A (pin 3). Ta prevent
bath phases of the motor from being selected simultaneously, the motor con-
trol L81 inverts Hall input ta coil A.
SPINDLE MOTOR CONTROL LSI
8.1.2
FIGURE 28:
Motor Speed Control
PC Board 20249-XXX
When power is applied ta the drive the motor control L81 pauses until 10 Volts
is reached before applying current ta the motor drive transistors.
Lf
10 Volts is
not achieved within approximately 1 second the motor control L81 will time-
out and will not apply power ta the motor drive transistors.
When current is applied, the spindle motor control L81 sets the motor speed
to 3,600 RPM nominal. The motor speed is crystal controlled (YI) with a fre-
quency lock circuit. There is no adjustment required for motor speed. The L81
integrates and transforms the error messages from the Hall effect transducer.
Using this information, it outputs the correct current flow each revolution and
corrects the motor phase driver at output pins 6 and 7.
When power is interrupted, the motor control L81 shorts bath phases of the
motor ta ground allowing the motor-generated back-EMF ta brake the spindle
motor.
MeTeR SPEED CONTROL PC BOARD: 20249-XXX
8.2
HALL
..---.
SPEED
~
PULSE
~
INTEGRATOR
~~
DYNAMIC
SENSOR
REFERENCE
SHAPER
BRAKE
+
CURRENT
~
MOTOR
1
L1MIT
DRIVERS
~
·MPU
~
SPINDLE
MOTOR
ST212 PRODUCT MANUAL/Rev. B
31
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