Quick MOSFET question

[surfsup]

I don't see any ESD listings on this NTE 2389. Can I assume there is built in gate protection with this mosfet? I'm trying to figure out if i need a zener soldered between the gate and source with this component but I can't figure out how to discern this from the datasheet since it doesn't have an internal schematic on it.

http://www.datasheetcatalog.org/datashe ... TE2389.pdf

[Cliff Schecht]

There isn't any ESD protection on discrete MOSFETs and if there is, they will explicitly state so. The ESD circuit will add input capacitance and change the drive requirements of the FET, something that must be accounted for in the design.

This is why they warn you to wear an ESD dissipative device when working with any MOS based circuit, the gate oxide will easily break down under even a tiny zap from something.

[surfsup]

Ok so if it doesnt say so i will assume there isnt anything built in. Damnit i didnt get the zener, either so another trip to the store...noob mistake, for soke reason i thought most had it built in.

[DonMoose]

If you don't mind my asking, what's your application that you need an ESD protector?

Unless your gate goes straight to an outside connector, they're usually not necessary.

[surfsup]

basically a cathode follower before a TS. I realize there is no capcitor or anything that will store a charge on the gate or the source, and I'm not using the MOSFET in front of a cathode biased power tube, but I'm no expert. I've seen people use these as CF without a zener but assumed since some people recommended it, it is a good "backup" plan. But I would certainly appreciate some clarification in this matter if you have some time to explain your thoughts.

[img:890:560]http://chicagocadcam.com/ChrisHahn/sche ... lower2.jpg[/img]

[DonMoose]

I don't see needing any ESD protection here, but I don't think a 60V part is gonna survive the first power-on.

You need a MOSFET good for at least your B+ rail voltage. An IRF820 or its NTE equivalent is R G Keen's device of choice for this application:
http://www.geofex.com/Article_Folders/m ... tfolly.htm

Hope this helps!

[surfsup]

That NTE is the IRF820 equivalent per NTE's site. My dyslexia typed in 2389 when I typed in the link for the PDF, not the correct 2398:

http://nte01.nteinc.com/nte/NTExRefSemi ... h?OpenForm

http://www.nteinc.com/specs/2300to2399/pdf/nte2398.pdf

The 2398 is 500V. Now I need to get home and see which one I actually bought off that rack with thousands of products all disorganized...obviously "cared" for by workers who believe the numbering system is completely random...geezus I am losing my mind. It is entirely likely I bought the wrong one after scouring the shelves for 15 minutes to find one mosfet. Why do I do this again???

[DonMoose]

Didn't know there was a Fry's in Chicagoland

[surfsup]

Yea its off highland near butterfield and 355. How did you know I was describing Frys? The endless product, or endless mess?

[Cliff Schecht]

Endless collection of unorganized NTE parts that you can sort through yourself kinda gives it away.

[surfsup]

I have the 2398! Phew....

[DonMoose]

How did you know I was describing Frys? The endless product, or endless mess?

Yes.

[DonMoose]

I have the 2398! Phew....

Hooray! Just don't ground the tab, and you should be good to go.

[passfan]

Pick your highest likely input voltage and drop a zener diode on the input to ground. Cheap and easy protection for the gate of any mosfet.

Well perhaps I should learn to read the whole thread before I toss my 2 cents in, nevermind.