Technical Reference
51
2.7 Reliability
The Mean Time Between Failures (MTBF) prediction is calculated using component and
subassembly random failure rates. The calculation is based on the Telcordia SR-332-2 Issue 2,
Method I, Case 3, 55⁰C ambient. The MTBF prediction is used to estimate repair rates and spare
parts requirements. The MTBF for the board is 61,444 hours.
2.8 Environmental
Table 21 lists the environmental specifications for the board.
Table 21. Environmental Specifications
0 C to +35 C
The operating temperature of the board may be determined by measuring the air
temperature from the junction of the heatsink fins and fan, next to the attachment
screw, in a closed chassis, while the system is in operation.
50 g trapezoidal waveform
Velocity change of 170 inches/s²
Free fall package drop machine set to the height determined by the weight of the
package.
5 Hz to 20 Hz: 0.01 g² Hz sloping up to 0.02 g² Hz
20 Hz to 500 Hz: 0.02 g² Hz (flat)
5 Hz to 40 Hz: 0.015 g² Hz (flat)
40 Hz to 500 Hz: 0.015 g² Hz sloping down to 0.00015 g² Hz
Note: Before attempting to operate this board, the overall temperature of the board must be above the minimum
operating temperature specified. It is recommended that the board temperature be at least room temperature
before attempting to power on the board. The operating and non-operating environment must avoid condensing
humidity.
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