18
ST11950 and ST12550 Installation Guide, Rev. D
continued from previous page
2
A
−
10% tolerance is permissible during initial start of the
spindle but must return to
±
5% before reaching 7,200 RPM.
The
±
5% must be maintained after the drive signifies that its
power-up sequence has been completed and that the drive
is able to accept selection by the host initiator.
3
See the
+
12V current profile in the
Product Manual .
4
This condition occurs when the Motor Start option is en-
abled and the drive has not yet received a start motor
command.
5
See “Conducted noise immunity” in the
Product Manual.
The specified voltage tolerance is inclusive of ripple, noise,
and transient response.
6
At power-up, the motor current regulator limits the
+
12V
current to an average value of less than 2.0A, although
instantaneous peaks may exceed this value. These peaks
should measure 5 msec duration or less.
7
Minimum current loading for each supply voltage is not less
than 7% of the maximum operating current shown.
8
Use separate ground returns for
+
5 and
+
12V supplies.
9
Where power is provided to multiple drives from a common
supply, carefully consider individual-drive power require-
ments. Where multiple units are powered on simultaneously,
be sure the peak starting current is available to each device.
10
Operating condition is a third-stroke seek at OD and read
one track. The command is issued every 0.07 seconds.
continued
