Seagate ST11950N/ND/W/WD manual 18 ST11950 and ST12550 Installation Guide, Rev. D, From previous

18 ST11950 and ST12550 Installation Guide, Rev. D

continued from previous page

2A −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.

3See the +12V current profile in the Product Manual .

4This condition occurs when the Motor Start option is en- abled and the drive has not yet received a start motor command.

5See “Conducted noise immunity” in the Product Manual. The specified voltage tolerance is inclusive of ripple, noise, and transient response.

6At 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.

7Minimum current loading for each supply voltage is not less than 7% of the maximum operating current shown.

8Use separate ground returns for +5 and +12V supplies.

9Where 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.

10Operating condition is a third-stroke seek at OD and read one track. The command is issued every 0.07 seconds.

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