Barracuda 18LP Family: ST39175LW/LC ST318275LW ... - Seagate

Barracuda 18LP Product Manual, Rev. E 19
6.0 Physical/electrical specifications
This section provides information relating to the physical and electrical characteristics of the Barracuda 18LP
drive.
6.1 AC power requirements
None.
6.2 DC power requirements
The voltage and current requirements for a single drive are shown in the following table. Values indicated apply
at the drive power connector. The single ended power requirements includes the internal disc drive SCSI I/O termination.
The table shows current values in Amperes. See also Figure 3c for current values vs. number of I/O
operations.
Table 2:
DC power requirements
Notes
ST39175
LC/LW
LVD
ST318275
LC/LW
LVD
Voltage +5 V +12 V +5 V +12 V
Regulation [5][2] ±5% ±5% ±5% ±5%
Average idle current DCX [1] .75 .35 .75 .5
Maximum starting current
(peak DC)
(peak AC)
[3]
[3]
1.0 1.3
2.4
1.05 1.6
2.4
Delayed motor start (max) DC [1][4] .65 .05 .65 .05
Peak operating current
Typical DCX
Maximum DC
Maximum (Peak)
[1][6]
[1]
1.0
1.3
1.7
.7
1.4
2.1
[1] Measured with average reading DC ammeter. Instantaneous +12 V current peaks will exceed these values.
Power supply is at nominal voltages.
[2] For +12 V, a –10% droop is permissible during initial start of spindle, and must return to ±5% before 7,200
rpm is reached. The ±5% must be maintained after the drive signifies that its power-up sequence has
been completed and that the drive is able to accept selection by the host initiator.
[3] See +12 V current profile in Figure 3a.
[4] This condition occurs when the Motor Start Option is enabled and the drive has not yet received a Start
Motor command.
[5] See Section 6.2.1 “Conducted Noise Immunity.” Specified voltage tolerance is inclusive of ripple, noise,
and transient response.
[6] Operating condition is defined as random 8 block reads at 148 I/Os per second. Current and power specified
at nominal voltages. Increasing +5 V supply by +5% increases 5 V current by 6.80%. Decreasing
+12 V supply by 5% increases +12 V current by 7.56%.
General Notes from Table 2:
1. Minimum current loading for each supply voltage is not less than 4% of the maximum operating current
shown.
2. The +5 and +12 volt supplies shall employ separate ground returns.
3. Where power is provided to multiple drives from a common supply, careful consideration for individual drive
power requirements should be noted. Where multiple units are powered on simultaneously, the peak starting
current must be available to each device.
1.05
1.4
1.7
.8
1.5
2.4