An electrical device like this requires a reverse leakage current of 50nA @ 30.1V.While the device is operating, the maximum voltage - Zener (Nom) is reduced to 43V.For operation, diode reaches 1.5V @ 100mA at the maximum voltage - Forward (Vf).
BZX79C43_T50A Features
reverse leakage current of 50nA @ 30.1V 50nA @ 30.1V is the maximum voltage (Tol)
BZX79C43_T50A Applications
There are a lot of ON Semiconductor BZX79C43_T50A applications of zener single diodes.