Difference between mosfet with and without logic level.

Aug 22, 2007 2 Replies

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saturnlee 18 years ago

I am looking for a replacement for AOD444, a n-channel mosfet in an inverter

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AOD 444 , vds :60v, vgs:20v, id: 12A

I checked digikey.com, but only 2 similar one are available. They are IPD640N06L G

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and

MTD3055VL

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They both look similar to AOD 444, but they are logic level.

QUUESTION Will it work if i substitute a mosfet (without logic level ) with another mosfet that has logic level?

Also, i found another similar one ,std12nf06l

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The Continuous drain current ID at 25 degree C is the same as aod444. BUT it is smaller than AOD444 at 100 C.

QUUESTION When replacing mosfet, do we have to consider the ID at TC=100 degree?

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Ray King 18 years ago

Is there a way to see the schematic? There is probably another reason the fet failed. More than likely any of the below should work otherwise. Ray

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Steve Wolfe 18 years ago

Maybe, maybe not. A lot of it depends on just how much Rds you can stand. I've seen a number of FETs (particularly on motherboards) which are

*not* marketed specifically as "logic level", but are designed to operate relatively well at 5V, and make an explicit point of it in the datasheet.

One such part that I have handy is an fr3704. Nowhere does the term "logic level" appear in the description or datasheet, but the Rds is 8.4 milliohms at 10V, and just 11.4 milliohms at 4.5 volts. Unfortunately, it doesn't meet the voltage requirement that you need, so it's not a viable substitute - but you should be aware that there may very well be parts out there that will work for your application yet not specifically labeled "logic level".

steve

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