& Quality Management
calculation with Telcordia SR 332
similar to the Mil-HDBK-217
methodology, however it tends to be
contrast to Mil-HDBK-217,
Telcordia uses only up to 2 component specific parameters
per component type. Aditionally, these 2 parameters are easier to
determine (with the # of transistors or gates in ICs being the only
These similar methodologies make it quite easy to transform
Mil-HDBK-217 MTBF values into Telcordia MTBF
values (and vice versa), provided that a reliability prediction
software is used.
shares the same environment types with Mil-HDBK-217, however, the
latter offers even
more environment types. The same is true for component coverage:
Telcordia uses the same component categories like Mil-HDBK-217, but
Mil-HDBK-217 offers more component categories.
- Calculated MTBFs can be improved (or impaired) using laboratory
test data and field failure data
- Telcordia uses the gamma distribution with standard deviations
for all component failure rates.
Telcordia MTBFs can be featured with confidence bounds, resulting in
sligthly lower MTBFs but with higher statistical certainty.
- This makes the Telcordia standard quite complex (however, the
french standard IEC-TR-62380
is even more complex, in a different way).
- Some Telcordia software don't offer this feature at all, and
many analysts aren't even aware of this feature.
consideration every known aspect, Telcordia is probably the
best available standard of all electronic
reliability prediction standards.