OK. I'm venturing into realms I've not been into in an LONG time... MOSFET retrofitting.
Got a box of big, high-end car amps and such... most need repair. One of the first (Alphasonik PMA2100) uses MOSFETS in the power supply (switching step-up with transformer). Here's what I'm thinking of doing:
Replacing THIS (BUZ71A)
http://pdf1.alldatasheet.co.kr/datasheet-pdf/view/22132/STMICROELECTRONICS/BUZ71A.html
...with THIS (STP16NF06)
http://www.st.com/stonline/books/pdf/docs/7980.pdf
Anyone see any reason this shouldn't work?
AFAIK, the only real significant operational difference, is that the newer mosfet has lower capacitance... I'd think that SHOULD NOT really be a problem. HIGHER capacitance, sure, that can overload driving transistors... but LOWER capacitance? Looks like it might just slew a bit better (better efficiency?)?
The extra current and power dissipation capacity (20% greater current, 10% greater power dissipation) certainly can't hurt either!
So, any comments/warnings?
Thanks!
Regards,
Gordon.
Got a box of big, high-end car amps and such... most need repair. One of the first (Alphasonik PMA2100) uses MOSFETS in the power supply (switching step-up with transformer). Here's what I'm thinking of doing:
Replacing THIS (BUZ71A)
http://pdf1.alldatasheet.co.kr/datasheet-pdf/view/22132/STMICROELECTRONICS/BUZ71A.html
...with THIS (STP16NF06)
http://www.st.com/stonline/books/pdf/docs/7980.pdf
Anyone see any reason this shouldn't work?
AFAIK, the only real significant operational difference, is that the newer mosfet has lower capacitance... I'd think that SHOULD NOT really be a problem. HIGHER capacitance, sure, that can overload driving transistors... but LOWER capacitance? Looks like it might just slew a bit better (better efficiency?)?
The extra current and power dissipation capacity (20% greater current, 10% greater power dissipation) certainly can't hurt either!
So, any comments/warnings?
Thanks!
Regards,
Gordon.
I would go with some 70N06's for mosfets, they have 70A handling 60V rating and are .014 Ohm on resistence and are 150W dissipation
Gate cap, isn't a big deal in the slow speed switching (35KHz) and of course the drive transistors can take a bit more current than there use to.
Gate cap, isn't a big deal in the slow speed switching (35KHz) and of course the drive transistors can take a bit more current than there use to.
With the toroidal power transformer, and the age of the design, I'd be worried about lowering the damping (raising the Q) of the transformer/MOSFET system (ie, inductive reactance interacting with the FETs), using a FET with THAT low of an on resistance (.008 ohms vs. .120 ohms). I don't want to have to possibly deal with current spikes as a result...
That's why I had looked at the STP16NF06... same range of on-resistance...
Regards,
Gordon.
That's why I had looked at the STP16NF06... same range of on-resistance...
Regards,
Gordon.
N-Channel said:I concur with ifrythings. Or better yet, try the IRF3205. Vdss = 55V; Rds(on) = 8mW; Id =110A, & Pdiss = 200W. Though the 70N06s should be plenty good enough.......
I will admit, the IRF3205 is an awesome MOSFET but it's expensive and is limited to 75A (maximum current of the TO-220 package as where the D² Pak (SMD-220, TO-263) can do the full 110A), It cost me 35 bucks (cad) just for 10 of them! As where the RFP70N06 only cost me <10 bucks for 10.
GordonW
I've done many upgrades of MOSFET's in car amps psu and never found any difference with current spikes as a result. I think this would matter if that design doesn't have snubber's incorporated.
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