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Cheetah 36LP Product Manual, Rev. B
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, 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. The enclosure for the drive should be designed such that the temperatures at the
locations specified in Table 3 are not exceeded. Air flow may be needed to achieve these temperature val-
ues (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 are not exceeded. Occasional excursions to drive ambient temperatures
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 temperatures
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 [2]).
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
Maximum allowable
Items in
case temperature (
Figure 7
operating
HDA [2]
65
1
85
2
73
3
81
4
76
Notes.
[1]
Section 8.3.1 describes the air-flow patterns used when generating the 1,200,000 hours MTBF guide-
lines in column 2. Air flow was opposite that shown in Section 8.3.1. Local air velocity was 0.92 m/sec
(180 lfpm). Inlet air temperature to the drive was 70°F (21°C), plus 9°F (5°C) temperature rise in the
test enclosure (79°F/26°C ambient local to the drive).
[2]
Measure HDA temp at point labeled "HDA" on Figure 7.
[3]
PCB mounted integrated circuit case.
Maximum allowable
°
C)
case [3] temperatures (°C)
to meet MTBF spec.
50
65
53
61
56
25
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