Seagate ST39102LC Product Manual - Page 32

Cheetah 9LP Product Manual, Rev. C, Power dissipation, ST39102, ST34502, Environmental limits, - spec

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22 Cheetah 9LP Product Manual, Rev. C 6.3 Power dissipation ST39102 For drives using single-ended interface circuits, typical operating random read power dissipation is 13.4 watts (46 BTUs per hour) of DC power average at nominal voltages. Typical power dissipation under idle conditions is 11.1 watts (38 BTUs per hour). For drives using low voltage differential interface circuits, typical operating random read power dissipation is 13.8 watts (47 BTUs per hour) of DC power average at nominal voltages. Typical power dissipation under idle conditions is 11.2 watts (38 BTUs per hour). ST34502 For drives using single-ended interface circuits, typical operating random read power dissipation is 10.6 watts (36 BTUs per hour) of DC power average at nominal voltages. Typical power dissipation under idle conditions is 8.3 watts (28 BTUs per hour). For drives using low voltage differential interface circuits, typical operating random read power dissipation is 10.9 watts (37 BTUs per hour) of DC power average at nominal voltages. Typical power dissipation under idle conditions is 8.4 watts (28.7 BTUs per hour). 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 122°F (5°C to 50°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 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 are not exceeded. Occasional excursions to drive ambient temperatures of 122°F (50°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 Cheetah 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 60°C. Operation of the drive at the maximum case temperature is intended for short time periods only. Continuous operation at the elevated temperatures will reduce product reliability. Table 3: PCBA and HDA temperatures Items in Figure 4 HDA [2] 1 (U12) 2 (U1) 3 (U5) 4 (U14) Maximum allowable case temperature (°C) operating 60 80 68 76 71 Maximum allowable case [3] temperatures (°C) to meet MTBF spec. 45 60 48 56 51

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22
Cheetah 9LP Product Manual, Rev. C
6.3
Power dissipation
ST39102
For drives using single-ended interface circuits, typical operating random read power dissipation is 13.4 watts
(46 BTUs per hour) of DC power average at nominal voltages. Typical power dissipation under idle conditions
is 11.1 watts (38 BTUs per hour).
For drives using low voltage differential interface circuits, typical operating random read power dissipation is
13.8 watts (47 BTUs per hour) of DC power average at nominal voltages. Typical power dissipation under idle
conditions is 11.2 watts (38 BTUs per hour).
ST34502
For drives using single-ended interface circuits, typical operating random read power dissipation is 10.6 watts
(36 BTUs per hour) of DC power average at nominal voltages. Typical power dissipation under idle conditions
is 8.3 watts (28 BTUs per hour).
For drives using low voltage differential interface circuits, typical operating random read power dissipation is
10.9 watts (37 BTUs per hour) of DC power average at nominal voltages. Typical power dissipation under idle
conditions is 8.4 watts (28.7 BTUs per hour).
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 122°F (5°C to 50°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 122°F (50°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 Cheetah 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 60°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
Items in
Figure 4
Maximum allowable
case temperature
(
°
C)
operating
Maximum allowable
case [3] temperatures (°C)
to meet MTBF spec.
HDA [2]
60
45
1 (U12)
80
60
2 (U1)
68
48
3 (U5)
76
56
4 (U14)
71
51