An electrical device like this requires a reverse leakage current of 50nA @ 12.6V.While the device is operating, the maximum voltage - Zener (Nom) is reduced to 17.95V.For operation, diode reaches 900mV @ 10mA at the maximum voltage - Forward (Vf).
BZT52-C18J Features
reverse leakage current of 50nA @ 12.6V 50nA @ 12.6V is the maximum voltage (Tol)
BZT52-C18J Applications
There are a lot of Nexperia USA Inc. BZT52-C18J applications of zener single diodes.