IRL640A Symbol Upload


I slightly modified a MOSFET symbol with correct diode type and pinout, for a IRL640A logic level MOSFET. They aren’t the highest tech MOSFET as far as Rds, but they are logic-level and moderately priced.

It seems to be correct, but please double-check use at own risk.


irl640a.kicad_sym (4.4 KB)

Hi @BrendaEM

Did you know this symbol is available in the Kicad “Device” library with all 8 pin-out versions… Q_NMOS_XXX(X) ?

I omit the circle from my bipolar and MOSFET transistor symbols. It decreases schematic clutter.

I prefer the shorter pins, finer circle width and matching filled diodes without wings.

I think that the “wings” indicate avalanche protection for the MOSFET. I do not know if the physics comparison to a zener diode is rigorous, but the earliest MOSFETs could be easily destroyed by modest drain-source overvoltage breakdown current. The manufacturers introduced avalanche protection which at least sort of seems like a zener diode. So I think it is intended to be meaningful.

Do you like deeper meaning in your electronic component symbols? Tell a story while in a submarine that is 200 meters down… :expressionless: No wait…I think it would be better to just read a dictionary while down in the submarine.

You could go with a thicker circle as on this bipolar transistor. This is an armored transistor.


I thought about that, and my research showed some manufacturers have wings and some not, and I decided whether winged or not, it is in the transistor case, I cannot change the diode, so any old diode symbol will do and if I need to know more, consult the data sheet.

No, I prefer surface mount :rofl:

Note: The symbol was based on Kicad’s MOSFET symbol.
It does not look like an 8-pin device to me.
Well, I tried to share something. Sigh.

Hi, there are eight different versions of this symbol… all the pin / terminal combinations. These are all compliant with the Kicad Library Convention found here under libraries; something else you probably haven’t stumbled across yet.
Thanks for the share.

I read your other thread.

A lot of the problems causing you frustration, I think, is a lack of good, current, in depth, documentation.
There is a great beginners guide here, but this only really gets you upto the start line. There is also some stuff in the FAQ, and there should be a lot more soon.

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@JMK, thank you for the link.

[Respectfully…coming from someone who once professionally wrote documentation and had a youtube user-interface suggestion video that 31,000 views and 663 likes, the Library, Footprint, and Symbol UI needs some work.]

Nahhh, hate that term.

And the thankyou for the links… My guess is you didn’t know about them because they are not documented? :upside_down_face:

Hello again @BrendaEM

Just to clarify:

These are the eight symbols I mentioned above.
The symbol you required has the cyan arrow. The GDS means pin1 = G, pin2 = D, pin3 = S
The one immediately above is: 1 = D, 2 = S, 3 = G
The fifth one down is: 1 = G, 2 = S, 3 = D

This convention is consistent throughout the official Kicad libraries.

Hi Brenda

There are a lot of MOSFETs which are packaged in SOIC-8 as well as some partially layout compatible packages. But IRL640 is in TO220 so is not one of them.

Here is one list:

This is one example:

Does this help to answer your question? I am really not sure. No kidding this time…

I guess like everything else, the symbols are not so well standardized. I see that the IRL640 claims to be avalanche protected but the symbol appears to be a non-zener symbol. So whomever wrote the datasheet had not “gotten the memo.”

This is a really sad state of affairs when you can’t trust the datasheets. :frowning:

I’ve stopped reading posts from bob. Signal to noise ratio is too low and I need to preserve my own sanity, and writing responses only further derails threads.

Tell me it does not happen! :flushed:

In this case (by my inference) it seems that the symbol does not reinforce the virtue claimed elsewhere on the front page of the datasheet.

In technical fields such as EE you expect the details to be right.

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Well yes. Of course we have all seen bad datasheets. In this case, the datasheet clearly states that the MOSFET is avalanche protected. I am not sure that the non zener type diode constitutes an error. At least at face value, I do not see a lot of harm from this.

Just irks me. Data sheet is 9 years old and look at the grouping. Maybe they need a bug bounty program. :wink:

Brenda SFAIK that is your first mention of an “8-pin device.” (I did not install or look at your KiCad symbol. I use my own symbols; I would have to delete it after viewing it in KiCad) So your mention of 8 pins in your sentence which I quoted seems like a “right turn” in your line of questions. Are you:
Looking for an 8 pin MOSFET?
Looking for an 8 pin MOSFET symbol?
It seems that you are not getting your concerns addressed but it is not clear what you are asking for?
FWIW it depends upon preferences and manufacturing considerations (as well as the footprint you use) but I usually use a 3 pin symbol (and 3 pin footprint) even for 8 pin MOSFETs if I will be building the board.