Hi, if I have 500mW zener, 2V, like MMSZ4679-TP, that would mean it could maximum take 250mW, wouldnt it? Does that mean the ibv must/can be set to 0.25?
Thanks,
Jan
No.
Please have a look at the data sheet. You will find a Vz (Zner voltage) and an Iz (current at the Zener voltage in reverse bias). These may become the BV and IBV parameters of a standard diode model, but …
The breaddown curve of a low voltage Zener is much less steep than the breakdown curve of a standard diode model in avalanche. Thus a standard diode will not describe the Zener adequately.
Have a look at https://www.diodes.com/part/view/BZT52C2V0, where you find a 2 V Zener including Spice model. Put both the standard diode and the Zener onto the Eeschema canvas, add a voltage source and run a dc simulation. Then plot both currents to compare. I have done this (using standard ngspice), and you see the astonishing difference.
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