Servo Processor
The
servo processor provides index and start-of-sector timing signals,
and
controls
actuator
movement,
motor
spin-up and speed control, and synchronized spindle operation.
Actuator
movement control consists of track-to-track seeks, track following,
and
correction for
both
DC
and
repeatable AC errors. Motor spin-up
and
speed control consists of regulated
drive
motor
current modified by information derived from
the
dedicated servo surface.
Synchronized spindle control is derived from an external sync
input
that
is compared
to
position information from
the
disk surface.
Data Head Interface
The
data
head interface processes
the
data
signals transferred between
the
read/write
heads
and
the
data
encoder / decoder. This includes head selection, providing analog write
current
to
the
heads,
and
amplification and conversion of impulses from
the
heads
to
RLL
data.
Actuator Driver
The
actuator
driver provides
the
current necessary
to
operate
the
actuator
assembly.
The
driver amplifies
the
control information provided by
the
servo processor, and
outputs
the
resultant current
to
the
actuator.
Servo Timing
The
function
of
the
servo timing circuit is
to
amplify and convert impulses from
the
servo
head
into
position
and
rotation
speed information for
the
servo processor.
Spindle Motor Driver
The
spindle
motor
driver provides 3-phase current
to
start,
drive,
and
control
the
speed
of
the
in-hub spindle
motor.
Power Distribution
The
+5
and +
12
voltages provided by an external dc power supply are
distributed
to
the
spindle
motor
driver,
actuator
driver, analog amplifiers, and digital circuitry. A reset
output
alerts
the
other
circuits when power-on occurs
and
when power is lost. Each circuit responds
in a predefined
manner
to
the
reset condition.
DRAFT
Product Features 3·9
1/18/93
09:58
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