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No damage to data occurs if power is applied or removed in any order
.or manner, but data may be lost in the sector being written at the
time of power loss.
This includes shorting out or opening up either
voltage or return line, transient voltages +10% to -100% from nominal,
and while powering up or down.
Table 2-2: DC Power Requirements
Specified
Typical Typical Maximum
Max. Ripple
POR Voltage
Voltage
Idle
Seeking Current
and Noise
Limits*
4.75-5.25
0.8 A
0.8 A
1.8 A
50 mV p-p
4.6
-
4.2
10.8-13.2
1.2 A
1.5 A
3.0 A
150 mV p-p
10.4
-
9.7
*Typical POR hysteresis is 50 mV on 5 Vi 100 mV on 12 V.
Figure 2-8 shows the drive startup current profile.
The wait Spin
shorting plug option can be used to delay startup until the host
issues SCSI START/STOP UNIT commands, thereby limiting the surge
current when starting multiple drives.
Before the motor is started,
the +12 V current is 0.4 A.
An additional 0.8 A is required from the 5 V supply if the SCSI line
TERMPWR, pin 26, is connected.
This current supplies the terminators
at the two SCSI devices that are equipped with terminators, if the 5 V
fails at those units.
See Figure 2-6 for the schematic.
A drive is reset by the POR circuit on the PCB if the voltage falls
below the POR limits.
However, the drive may not operate correctly
at those limits, which are below normal.
The POR circuit does not
guarantee that supply levels are within specification.
2-15
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