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ST336754FC
Typical power dissipation under idle conditions in 2Gb operation is 9.88 watts (33.7 BTUs per hour).
To obtain operating power for typical random read operations, refer to the following I/O rate curve (see Figure
8). Locate the typical I/O rate for a drive in your system on the horizontal axis and read the corresponding +5
volt current, +12 volt current, and total watts on the vertical axis. To calculate BTUs per hour, multiply watts by
3.4123.
ST336754FC Specification random 8 block read
1 .800
1 .600
1 .400
1 .200
1 .000
0.800
0.600
0.400
0.200
0.000
0.0
50.0
Figure 10.
ST336754FC DC current and power vs. input/output operations per second
6.4
Environmental limits
Temperature and humidity values experienced by the drive must be such that condensation does not occur on
any drive part. Altitude and atmospheric pressure specifications are referenced to a standard day at 58.7°F
(14.8°C). Maximum wet bulb temperature is 82°F (28°C).
6.4.1
Temperature
a. Operating
The maximum allowable continuous or sustained HDA case temperature for the rated MTBF is 122°F
(50°C) The maximum allowable HDA case temperature is 60°C. Occasional excursions of HDA case tem-
peratures above 122°F (50°C) or below 41°F (5°C) may occur without impact to specified MTBF. Continual
or sustained operation at HDA case temperatures outside these limits may degrade MTBF.
Provided the HDA case temperatures limits are met, the drive meets all specifications over a 41°F to 131°F
(5°C to 55°C) drive ambient temperature range with a maximum temperature gradient of 36°F (20°C) per
hour. Air flow may be needed in the drive enclosure to keep within this range (see Section 8.3). Operation at
HDA case temperatures outside this range may adversely affect the drives ability to meet specifications. To
confirm that the required cooling for the electronics and HDA case is provided, place the drive in its final
mechanical configuration, perform random write/read operations and measure the HDA case temperature
after it has stabilized.
32
1 00.0
1 50.0
200.0
I/Os per Second
250.0
300.0
350.0
Cheetah 15K.4 FC Product Manual, Rev. C
1 8.00
5Vo lt A
1 2 Vo lt A
1 6.00
Watts
1 4.00
1 2.00
1 0.00
8.00
6.00
4.00
2.00
0.00
400.0
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