MTBF, which is the abbreviated name for "Mean Time Between Failures", is generally used as a barometer of failure rate of power supply. It is the mean time between failures of a system (excluding repair time).

Failure rate: λ is constant, i.e. the reliability in the constant failure rate period is represented by exponential distribution.

R(t) = e^-λt

At this time, MTBF is the reciprocal of the failure rate.

MTBF = 1 / λ

We calculate MTBF by the part count reliability prediction instituted by EIAJ(Electronic Industries Association of Japan). This standard complying with the part count reliability prediction of MIL-HDBK-217D provides failure rate data for many electronic components.

EIAJ standard No. RCR-9102