EEVblog 1461 - The MOSFET Search CHALLENGE

I found the AO4455 -30V, -17A and the UM4447A -30V, -18.5A in a quick search, but i may be breaking the rule that they are not made in taiwan xD By the way, i just search for 30V p-channel mosfet esd protect and look in the imagen search.

When searching for specific mosfets I noticed that the ESD protected ones have a Vgs rating that is +-8V or similar, which is the TVS diode rating. That might be an easier way to search for them.

Invaluable. This is the sort of detail that you only learn by weeks of study or sitting with someone who has been there, done that. Thanks.

Hello Dave, Regarding ESD please note that ALL MOS devices have some form of ESD protection. More over, ALL MOS gates are ESD protected. In 40+ years of practicing electronics I encountered only once MOS transistors without ESD protection for gate terminal. So stating for some transistor that are ESD protected is misleading. If you look at the data sheet, the so called ESD MOS transistors are stated to resists to 8kV HBM stress. HBM stands for Human Body Model and is only one of the ESD resiliency test used in semiconductor industry. Regular device are designed and checked to be compliant at least to 2kV HBM stress test. In recent years the ESD requirement was updated to 4kV HBM. Devices stated as ESD are the ones able to sustain an 8kV HBM stress. As a former MOS IC designer I had more issues with other ESD models as “Machine model (MM)” and mostly with “Charged device model (CDM)” that imply higher stress than HBM. The replacement you performed is OK provided you take care when replacing the batteries. Thanks for the very informative post!

Many people don't realize how important this part of the job really is. Good video about important topic for anyone wanting to become a professional :)

Great Video. I'm glad you uploaded this. The salvaged mosfet was my favorite part of the last video. Now we have a side-quest of finding the replacement from a catalog .

One search technique I've had some luck with before when trying to find particular features (such as the ESD diode) is to try to "invent" the part number that a manufacturer I've found making similar parts would label the part I want with. For example, if I've found a 12 volt mosfet both with and without the protection diode carrying similar part numbers, and a 30 volt one without the diode, I might try tacking on whatever extra letter they added to the 12 volt mosfet part number to make it the ESD version to my 30 volt mosfet part number, and searching that.

When high dissipation is required the heat is removed by soldering the multiple leads to a copper plane. The power dissipation is usually specified with heat sinking of various thermal resistances or areas of copper planes. It is important to check the footnotes for this. One of these datasheets specifies a 1 inch pad. The thermal resistances of the junction to leads and ambient are also specified in this way. There are usually graphs or drawings of the performance of the different heat sinking techniques and or sizes. This can be on a separate application note. Sometimes not all of this data is supplied but a careful study can verify the design. Other types of device in this package might require this amount of care in heat sinking. For this application all this thinking is probably not necessary. It was easier when we just attached a heat sink to a TO-220.

Dave: Don't click on the ad, it's not the one you want. Also Dave: Clicks on ad without looking whether it matches the part number.

@9:50 Btw., if you really only want PDF files in your search, use filetype:pdf in your search query

As always, I hope I learned something. Have a great day :) "MooseFETs"... They have to be made in Canada!

On Semi FDS6681Z is the closest I could find with the ESD diode. -30V -20A. 3 times the price of that SinoPower 4303 though.

Good info. Great fun. Thanks Dave.

Pls make jellybean MOSFET , JFET and BJT. Video, it would be very useful

Super information from you Dave.

I accidentally blew up my TS80 soldering iron because I normally power it from my benchtop psu, but I gave it far too many volts which caused the P channel mosfet to go dead short. I happen to have an automotive style LED module that uses a P channel mosfet as input polarity protection. The specs seemed close enough so I used some hot air to swap the chip on the TS80 board, put it back together and I is working perfectly if not better because of lower drain source resistance... That's my mosfet story.

Thanks for this follow up!

I think that the ESD protected MOSFET has been chosen by the manufacturer because it's used for switching the batteries and their contacts are exposed outside of the casing, thus can get a direct ES discharge from your fingers. :)

Most illuminating !

Very Informative. Thank you.