Seagate Cheetah 18XL, Product Manual

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Cheetah 18XL Product Manual, Rev. A 27
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
With cooling designed to maintain the case temperatures of Table 3, Column 2, the drive meets all specifi-
cations 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. The enclosure for the drive should be designed such that the tempera-
tures at the locations specified in Table 3, column 1 are not exceeded. Air flow may be needed to achieve
these temperature values (see Section 8.3 and 8.3.1). Operation at case temperatures above these values
may adversely affect the drives ability to meet specifications.
The MTBF specification for the drive is based on operating in an environment that ensures that the case
temperatures specified in Table 3, column 2 are not exceeded. Occasional excursions to drive ambient tem-
peratures of 131°F (55°C) or 41°F (5°C) may occur without impact to specified MTBF. Air flow may be
needed to achieve these temperatures (see Section 8.3.1). Continual or sustained operation at case tem-
peratures above these values may degrade MTBF.
To confirm that the required cooling for the electronics and HDA is provided, place the drive in its final
mechanical configuration, perform random write/read operations. After the temperatures stabilize, measure
the case temperature of the components listed in Table 3 (see note [3]).
The maximum allowable HDA case temperature is 65°C. Operation of the drive at the maximum case tem-
perature is intended for short time periods only. Continuous operation at the elevated temperatures will
reduce product reliability.
Table 3: PCBA and HDA temperatures
Notes.
[1] Section 8.3.1 describes the air-flow patterns to be used to meet case temperatures in column 2. Air
flow was opposite that shown in Section 8.3.1. Air velocity should be adequate to ensure that the case
temperatures in column 2 are not exceeded during drive operation.
[2] The temperatures in columns 1 and 2 are calculated and may not reflect actual operating values. Suffi-
cient cooling is required to ensure that these values are not exceeded.
[3] Measure HDA temp at point labeled “HDA” on Figure 11.
[4] PCB mounted integrated circuit case.
Items in
Figure 11
Column 1
Maximum case
[4]
temperature (
°
C)
operating (55
°
ambient)
[3]
Column 2
Maximum allowable
case
[4]
temperatures (°C)
to meet MTBF spec.
[3]
HDA [3] 65 50
U2 123 103
U5 123 103
U11 105 85
U8 105 85