4.2 Power Supply Requirements; Figure 4.7 Current Waveform (+12V Dc) - Fujitsu MAY2036RC Product/Maintenance Manual

4.2 Power Supply Requirements
(1) Allowable input voltage and current
The power supply input voltage measured at the power supply connector pin of the HDDs (receiving
end) must satisfy the requirement given in Subsection 2.1.3. (For other requirements, see Items (4)
below.)
(2) Current waveform (reference)
Figure 4.7 shows the waveform of +12V DC.
MAY2073RC
Time (2 sec/div)
(3) Power on/off sequence
The order of the power on/off sequence of +5V DC and +12V DC, supplied to the HDDs, does not
matter.
(4) Sequential starting of spindle motors
After power is turned on to the HDDs, a large amount of current flows in the +12V DC line when the
spindle motor rotation starts. Therefore, if more than one HDDs are the spindle motors should be
started sequentially using one of the following procedures to prevent overload of the power supply
unit.
a) Control the sending of the NOTIFY (ENABLE SPINUP) primitive so that the spindle motors of
individual disk drives are started in intervals of 12 seconds or more.
b) Turn on the +12V DC power in the power supply unit at intervals of 12 seconds or more to start
the spindle motors sequentially.
C141-E230
Figure 4.7 Current waveform (+12V DC)

4.2 Power Supply Requirements

MAY2036RC
Time (2 sec/div)
4-7