An electrical device like this requires a reverse leakage current of 3μA @ 1V.While the device is operating, the maximum voltage - Zener (Nom) is reduced to 3.9V.For operation, diode reaches 900mV @ 10mA at the maximum voltage - Forward (Vf).
BZX84W-B3V9F Features
reverse leakage current of 3μA @ 1V 3μA @ 1V is the maximum voltage (Tol)
BZX84W-B3V9F Applications
There are a lot of Nexperia USA Inc. BZX84W-B3V9F applications of zener single diodes.