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-   -   Substitute MOSFETS ( 8th November 2009 05:02 PM

Substitute MOSFETS
I have a damaged car amplifier that has 12 IRFZ44V in power supply section that need replacement.I have searched and couldn't find this version in Greece or in Europe.I could only find IRFZ44 (without V).It has the same VDSS=60V but different RDS(ON)=28mOhm vs 16.5mOhm and ID=50A vs 55A.

Can i substitute one type for the other?I don't care about max performance.I just need the amp to be functional.If i change something in circuit can i make IRFZ44 work with lower load to be on the safe side?

Do you know any European based MOSFET supplier but not asking to buy large quantities?

DIGIKEY told me they send from USA only and i will have to pay customs.

event horizon 8th November 2009 06:20 PM

In my opinion you could simply swap the lot with no problems ;) The switching times for the same current look very similar the the same "R Gen" & at the same current. As there is no way that the Mosfets will actually see 50Amps accross them each then the actual RDS on will be lower at a lower current.

All that'd happen is you'd have a SMPS with a slight bit more RDS on switching losses, however as the IRFZ44 has a lower input capacitance you may well find that as they will switch on & off slightly faster (with an inductive load - the transformer) that this will actually have less losses in the switching phase & tend to even things out ;)

I doubt you'd need to alter any snubber networks or anything else for that matter. If you feel like playing safe just make sure you don't drive the amplifiers into the lowest loudspeaker impedances that it can handle at full volume..


You might like to ask how many there are available.

Hope this helps :)

darkfenriz 8th November 2009 11:21 PM

The 'V' version has a lot less Qrr, which means better efficiency and less EMI.
You may try polish distributor I like:
Elementy i podzespoły części elektroniczne - TME - Electronic Components
if they don't count too much for a delivery or try to find something with similar parameters. Charges (Qgtot, Qgd, Qrr) are a lot more important then for example Rds-on.

Something like IRFB3806 could be some real upgrade

fumigamt 10th November 2009 10:46 PM

substitute of IRFZ44 , you can take FQP 50N06 , or TQP 50N06, only diferent have diferent manufatored , one is Fairchild , and other is ST eletronics.

55N06, works very great too.. i dont use more IRFZ44 , i use only 55N06.

so... if will be 2 or 3 mosfets in parallel , you can change for only one of IRF1404 ,
Igs = 196A , about 55 of the other fets relateds above.

i hope i have helped.

odnaizutra 21st November 2009 08:24 PM

irf3805.irf3806,ifrz46,irfz48, stp55nf06 are ok.

nigelwright7557 21st November 2009 08:55 PM


Originally Posted by odnaizutra (
irf3805.irf3806,ifrz46,irfz48, stp55nf06 are ok.

You dont say why they have blown.

12 is a lot to replace.
I would just replace one pair and try that before committing the full 12.
Just dont turn it up with one pair !

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