An electrical device like this requires a reverse leakage current of 1μA @ 42.6V.While the device is operating, the maximum voltage - Zener (Nom) is reduced to 56V.
1SMB5943 R5G Features
reverse leakage current of 1μA @ 42.6V 1μA @ 42.6V is the maximum voltage (Tol)
1SMB5943 R5G Applications
There are a lot of Taiwan Semiconductor Corporation 1SMB5943 R5G applications of zener single diodes.