An electrical device such as this requires reverse leakage current of 100nA @ 21V.During operation, the maximum voltage - Zener (Nom) is reduced to 28V volts.
MMBZ5255C-E3-08 Features
reverse leakage current of 100nA @ 21V 100nA @ 21V is the maximum voltage (Tol)
MMBZ5255C-E3-08 Applications
There are a lot of Vishay Semiconductor Diodes Division MMBZ5255C-E3-08 applications of zener single diodes.