An electrical device like this requires a reverse leakage current of 1μA @ 160V.While the device is operating, the maximum voltage - Zener (Nom) is reduced to 220V.For operation, diode reaches 1.2V @ 200mA at the maximum voltage - Forward (Vf).
BZD17C220P R3G Features
reverse leakage current of 1μA @ 160V 1μA @ 160V is the maximum voltage (Tol)
BZD17C220P R3G Applications
There are a lot of Taiwan Semiconductor Corporation BZD17C220P R3G applications of zener single diodes.