Zener single diode is a maximum voltage (Tol) that can be supplied at 5%.As part of the operation, the maximum voltage - Zener (Nom) is reduced to 8.5V.Setting the working test voltage to 1mA will allow this device to operate.
1N4781 Features
the working test voltage to 1mA minimal dynamic impedance is 1mA
1N4781 Applications
There are a lot of Microsemi Corporation 1N4781 applications of zener single diodes.