Power Supply Requirements; Figure 4.7 Current Waveform (+12V Dc) - Fujitsu MAU3147RC 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 HDD (receiving
end) must satisfy the requirement given in Subsection 2.1.3. (For other requirements, see Items (4)
and (5) below.)
(2) Current waveform (reference)
Figure 4.7 shows the spin-up current waveform of +12V DC.
MAU3147RC
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 HDD, does not
matter.
(4) Sequential starting of spindle motors
After power is turned on to the HDD, a large amount of current flows in the +12V DC line when
the spindle motor rotation starts. Therefore, if more than one HDD is used, 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-E222
MAU3073RC
Time (2 sec/div)
Figure 4.7 Current waveform (+12V DC)
4.2 Power Supply Requirements
MAU3036RC
Time (2 sec/div)
4-7