A voltage of 4.99% indicates the maximum voltage (Tol) that can be supplied.The design flexibility of this device is extremely high since its zener current is 20mA.If you want this device to work properly, you should set the peak reverse voltage to 5μA.
MMBZ5231BW-7 Features
the zener current of 20mA
MMBZ5231BW-7 Applications
There are a lot of Diodes Incorporated MMBZ5231BW-7 applications of zener single diodes.