4.2 Power Supply Requirements

Figure 4.7 shows the Max Seek current waveform of +5V DC and +12V DC.

+5VDC

MBB2147RC

MBB2073RC

 

Current(500mA/div)

 

Current(500mA/div)

 

Time(2 sec/div)

Time(2 sec/div)

+12VDC

MBB2147RC

MBB2073RC

 

Current(500mA/div)

 

Current(500mA/div)

 

Time(2 sec/div)

Time(2 sec/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-E257

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Fujitsu MBB2073RC, MBB2147RC manual Power Supply Requirements, Current waveform Max seek