Calculator for Zener Diode Series Resistor

Zener Diodes require a minimum current to flow through them in order to allow them to actually regulate the voltage. But at the same time they can only sustain a maximum amount of current flowing through them before they essentially go up in flames.
The goal of this calculator is to find a suitable series resistor for a given Zener Diode and load current.
It will also output the worst case scenario values for the Zener's power dissipation when the load has suddenly been disconnected and the entire current flows through the diode.


Zener Diode Series Resistor

The values for Pz_max and Iz_min need to be obtained either by experiment or from the diode's datasheet. Where Iz_min is the minimum required current through the diode at which the diode will start conducting.

Inputs
Input voltage [V] (> 0)
Load current IRL [mA] (> 0)
Zener voltage [V] (> 0)
Zener min. current Iz_min [mA] (> 0)
Zener max. power dissip. Pz_max [mW] (> 0)
Zener Pz_max derating [%] (≥ 0 and ≤ 90)

Illustration:

Illustration Zener Diode Series Resistor

Default scenario: constant load (aka w/ RL):

Example Simulation Zener Diode with Series Resistor

Worst-case scenario: load disconnected (aka w/o RL):

Example Simulation Zener Diode without Series Resistor

Formula Zener Diode find Series Resistor