Temperature Dependency of Zener Voltage
The Zener voltage (VZ) of a Zener or avalanche diode depends on the diode’s junction temperature. Any current running through the p/n junction barrier generates the electrical power of: P = IZ * VZ This electrical power is equivalent to the thermal power applied to this junction. Depending on the duration and the intensity of the current, the applied thermal energy increases and heats the junction. The upper diagram shows the Zener voltage change of a BZX85C43 Z-Diode in a DO-41 wired glass package during a constant current pulse. The diode is mounted between large heat sinks (copper blocks) with a stable temperature of 25 °C.