LM63625-Q1: FIT rate difference between FuSa document and MTBF and FIT rate estimator

Hi Shoji,

The functional safety FIT rate is different than the technology FIT rate. Our online mean time between failure (MTBF)/FIT estimator for technology FIT rate is derived using the JESD85 methodology from internal high-temperature operating life (HTOL) and early life failure rate (ELFR) reliability testing. The MTBF and FIT are estimated with a 60% confidence level for reliability.  This method provides an accurate FIT rate for the process technology but does not take into account transistor or gate count, die size or other important factors.

We provide functional safety FIT rate based on one of two standards, IEC TR 62380 or SN 29500, which offer a 99% confidence level. Functional safety standards, such as IEC 61508 and ISO 26262, often suggest 99% confidence levels be used for safety-related random failure FIT rate estimation.

For more on functional safety FIT rate, read this Understanding Functional Safety FIT Base Failure Rate Estimates per IEC 62380 and SN 29500. 

Hope this helps.

Let me know if you need more information.

Thanks,

Best Regards,

Taru