Hi,
Attached is the configuration for the subject. Here are the datasheet values:
IF = 2A
PT = 21W
VF = 9.07V @I=20A

Please advise on what zener diode I can use for this.

Thanks,
Law

 

Well, that would be over 180 Watts instantaneous power dissipation in the Zener, which is quite a bit. Any idea what the average power might be?

Rod Elliot over at ESP has a page about using a transistor & low-power Zener to emulate a high-power Zener:
http://sound.westhost.com/appnotes/an007.htm
You'll probably find a configuration like he suggests will be a great deal easier than trying to find a Zener rated for that kind of power.

 

Search for Megasquirt's "Megamanual" and look at the amplified zeners it uses to eat fuel injector back emf spikes.

 

I think it would be better if I show you the device I am referring to. I attached the datasheet of the module I am looking at right now. I cannot understand how they were able to come up with the datasheet values for boost inverse diode. Do you have any idea how?

Cheers,
Law