# Calculating the minimum and maximum $R_{load}$ for a zener voltage regulator

So, I have a generic zener voltage regulator with $$\R_{s}=650Ω\$$, $$\V_{in}=15V\$$, I'm using the zener BZX55C8V2 (datasheet). From the datasheet the test current is $$\5 mA\$$ and the maximum zener current is $$\74 mA\$$. I want to find out the minimum and maximum for the load resistance so that the Zener is still regulating at $$\V_{out}=8.2V\$$ and without the zener breaking.

I'm wondering how exactly I should utilize the datasheet to figure out the values for the load.

• If the output is 8.2V you have 6.8 V across Rs making 10 mA flow. That 10 mA can either flow completely through the zener diode or (almost) completely through Rl. So what does that mean for Rl? You use the datasheet to check that the current and power dissipation in the zener diode do not exceed the maximum ratings. – Bimpelrekkie Jan 29 at 13:02