BASF 6106 - Drive Motor Control

2.2.3. DRIVE MOTOR CONTROL
(Fig.
2
-
18)
The drive motor
used in the
BASF 6106
is
a
DC-
motor. Start
and
stop of the
motor
is
controlled
from
the host system
by the
inter-
face
signal MOTOR
ON.
After the drive
motor
is started,
a delay
of
0,5
sec
is needed
to
allow
proper
motor speed,
before reading
or
writing.
The speed
of the
drive motor
is con-
trolled
by the
integrated
circuit
ESM 227.
This
IC holds the EMF
of the drive DC- motor
to a constant
value. Because
the speed of the
drive motor
is proportional
to it's EMF, the
speed
will
be also
constant.
With
the
poten-
tiometer
R40 the
drive
motor
must
be adjus-
ted to
300
RPM.
The
output
voltage
of
the ESM
227
is controlled
by
the MOTOR
ON/-signal
at
Pin
12
of the chip.
If MOTOR
ON
is
inactive
(low)
T1 will
be
closed
and
holds
T2
open.
The
drive
motor
stops. An
active MOTOR
ON
-
signal
opens T1
and
T2 is
enabled.
The drive
motor
is
running
and
regulated,
so that the
mini
disk
is rotatiting
at
300 rpm.
12V
J/P6
RPM
ADJUST
FROM
INPUT
H0TOR0N
INTERFACE
DC-MOTOR
\^S*
^ ^
FIGURE
2
-
18 . DRIVE
MOTOR CONTROL
2-14