4.2 Power Supply Requirements
Figure 4.7 shows the Max Seek current waveform of +5V DC and +12V DC.
Time (10msec/div)
Current (500mA/div)
Current (500mA/div)
+12VDC
+5VDC
MBC2073RC
MBC2073RC
MBC2036RC
MBC2036RC
Current (500mA/div)
Current (500mA/div)
Time (10msec/div)
Time (10msec/div)
Time (10msec/div)
Figure 4.7 Current waveform (Max seek)
(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 HDDs 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-E266 47
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