help choosing mosfets for a car amp SMPS

[Redwire]

I need some help choosing mosfets for a car amp SMPS, about 360W push-pull 50-75kHz so about 30A at 12Vin.
What are the limiting factors? I'm not sure how many to use and if super-low RDS on is worth it, as these have higher capacitance.
Many 12Vin SMPS designs use 2-6 pairs of TO-220 devices... seem to run about 9A per mosfet but Rod Elliot's is running 15A

I am looking on the safe operating area curves at DC with VDS<=0.1V (as the rest of the graph is "single pulse")
I like the IRF2805 55V/4.7mohm/75A part but it looks like one pair would work?!

https://ec.irf.com/v6/en/US/adirect/ir?cmd=catProductDetailFrame&productID=IRF2805
IRF2805 datasheet pdf

 

[MicrosiM]

Smps

See attached file, it may help you.

Language is not English, but it may give you some light

 

[Redwire]

Thanks, I went through the design and agree that a single pair of mosfets can do 400W.
I'm using the far left datapoint of SOA curves to set ID max. along with a safety factor.
The TO-220 package limit is about 75A and newer (low <10mΩ RDS ON) parts have higher (silicon limited) current ratings but a bit slower switching. I'm liking the IRF2805 and will try a pair

From the article Table2:
Part: Power:
BUZ11 100W 30A, 50V, 0.040 Ω
BUZ12 200W 42A, 50V, 0.028 Ω
BUK455-60A 100W 41A, 60V, 0.038 Ω
BUK456-60A 200W 52A, 60V, 0.028 Ω
IRFZ44E 300W 50A, 60V, 0.024 Ω
STP50N06 200W 50A, 60V, 0.028 Ω
STP60N06 300W 60A, 60V, 0.014 Ω
STP80N06 400W 80A, 60V, 0.010 Ω
IRF1010E 400W 84 A, 60V, 0.012 Ω

 

[rafsky]

I have used many times the IRF3205 and I found it very good in terms of reliability and durability, the internal resistance is 8 mohm, mind you 75A is the continuum limit, the peak can exceed 75A for a few milliseconds, and a few more ampere will not hurt in limit situation...

p.s. excuse me for my bad english ;-)

 

[norazmi]

what about IRL2203N, i`ve this mosfet by accident order, actually i want order irf3205. But i think this mosfet is good too but the max voltage is only 30v .

 

[rafsky]

good mosfet, but at 14,4 voltage of car smps these mosfet are almost at the limit of safety...for me irf3205 is the best choice