MTBF Report (SFPs,GBICs, XFPs, SFP+s)

# C1-10.1 ©2010 Champion ONE

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METHODOLGY MTBF is predicted using the Parts Count Method (Method I), of Bellcore TR 332, Issue 6, December 1997 Reliability Prediction Procedure for Electronic Equipment. The failure rate of the unit (system) is calculated as the sum of the failure rates of the constituent components. Bellcore TR-332/SR-332 is partly based on MIL-HDBK- 217, but with additional information about failure rates gained from field data experienced by the telecommunications industry. Bellcore TR-332/SR-332 is widely thought to be a more accurate predictor of reliability than MIL-HDBK-217 when applied to commercial/industrial equipment. Case 3, General Case, is assumed. Devices are assumed to be operating at 40oC, and 50% rated electrical stress. A Ground Controlled, Ground Benign (GC, GB) environment, typical of an air-conditioned office, is assumed. 100% duty cycle is also assumed, and no effort is made to calculate the effects of stress cycling. Bellcore TR-332/SR-332 gives formulae for Device and Unit Steady State Failure Rates. Factors of these formulae are conveniently normalized so that for Case 3, most factors assume a value of 1.0, and effectively drop out of the calculation at the temperature specified. This greatly simplifies the computational effort. ASSUMPTIONS All components on the Bill of Materials for this assembly are assumed to be necessary for operation of the assembly. For the purpose of MTBF calculation, “failure” of any part is defined to occur when a part no longer meets its original specifications, and failure of a single part is assumed to result in failure of the assembly. (In reality, failure of a part may not be catastrophic, and might not result in failure of the assembly). Components are assumed to be specified at Quality Level II, as defined in Table C of the Bellcore document. This means the components are of good commercial quality, and are procured with adequate documentation and incoming inspection control. Bellcore TR-332/SR-332, Method 1, allows failure rate estimates to be adjusted to reflect laboratory or field data. This was done in the case of two components: The manufacturers supplied the failure rate estimates for the laser diode and photodiode subassemblies. Per paragraph 6.7.2 of the Bellcore document, Printed Wiring Boards are assumed to be failure free. There is no easy way to assign a failure rate to bare boards. Fastener and structural components that do not substantially affect assembly MTBF have been excluded from the worksheets.

MTBF for GBICs, SFPs, and XFPs was predicted per Bellcore TR-332, Issue 6, December, 1997, And Bellcore SR-332, Issue 2, September 2006 for SFP+’s.

COMPUTATIONAL NOTES • Failure rates are given in FITs (failures per 109 operating hours). • MTBF (Mean Time (hours) Between Failures) is calculated as 109 /FITs. • MTBF is defined for repairable items as MTTF (Mean Time To Failures) is defined for non-repairable items. • Champion ONE modules are non-repairable items. • As is customary, no distinction is made in this report between MTBF and MTTF.