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FUJITSU MAV2036RC User Manual

Page 49

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4.2 Power Supply Requirements

C141-E219

4-7

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)
below.)

(2)

Current waveform (reference)

Figure 4.7 shows the waveform of +12V DC.


MAV2073RC

Curre

nt (500mA

/div)

Time (2 sec/div)

MAV2036RC

Curre

nt (500mA

/div)

Time (2 sec/div)

Figure 4.7

Current waveform (+12V DC)


(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.

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