flyback converter peak power vs cw power

Hi,

If I need peak power of 300Watt but I just use with an average power of 5 Watt, can I just design a 5 Watt converter with components rating meeting the 300Watt?

Thanks, JL

Reply to
John Lee
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Depends on how long you need the 300W, how often, and so on. Some more specs are needed.

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Regards, Joerg

http://www.analogconsultants.com/
Reply to
Joerg

I found this, looks like ok because my duty cycle is low (~2%), things for concern is output cap rating, temperature increasing inside the xfmr etc.

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Reply to
John Lee

I am not a fan of those integrated switches. Too boutiquish for me, and I've seen failures (but was another brand).

Again, things like cap size and device heating will also depend on the duration you need 300W for. 2% on-time every hour is very different than

2% every millisecond :-)
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Regards, Joerg

http://www.analogconsultants.com/
Reply to
Joerg

Since you don't say how the 5W average is arrived at, we can't say. If you're delivering 300W for one day, then off for 59, then on again, you need to design a 300W converter. Even if you're on for one minute, then off for 59, etc., then you _still_ need to design almost everything except for the bulk heat sinking for 300W -- and at that you may as well go all the way.

I think you probably just need to design a 300W converter and be happy.

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Tim Wescott
Wescott Design Services
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Reply to
Tim Wescott

The stuff from Powerint is pretty good and devices I designed in >10 years ago are still available for purchase from (for example) Digikey.

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Failure does not prove something is impossible, failure simply
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Reply to
Nico Coesel

BTW, Joerg, those FDC6020Cs half H-bridge FETs you recommended have since been discontinued.

Cheers

Phil Hobbs

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Dr Philip C D Hobbs
Principal Consultant
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Reply to
Phil Hobbs

Yeah, stuff can be short-lived these days and it was just an example. Mouser still has over 30,000 of them though, under 50 cents.

But they make lots and lots of others. A little larger but cheaper:

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If too large you can get TSSOP as well:

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Not sure if I remember the requirements right but take a look at the datasheet. There's oodles more like that. Companies such as Alpha&Omega, Diodes, IRF, Rohm, Thomson, Toshiba, Vishay and so on. If you can stomach SO8 size for each pair that would offer the most sources. Otherwise maybe TSSOP.

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Regards, Joerg

http://www.analogconsultants.com/
Reply to
Joerg

Yeah, I have a TSSOP one, the SI6562CDQ. Just wanted to let you know in case the other one was a favourite.

Cheers

Phil Hobbs

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Dr Philip C D Hobbs
Principal Consultant
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Reply to
Phil Hobbs

No such thing as peak power. Power is defined as instantaneous or average power. Often peak power is quoted by hi-fi buffs to make their amps seem more powerful than they are!

Hardy

Reply to
HardySpicer

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