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DIP8 FET for 49W Flyback

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Jun 22, 2008
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We are laying out a flyback SMPS as follows:-

Vin = 400V
Vout = 16V
P(out) = 42W
F(sw) = 67KHz.
Mode: DCM

The PWM controller is a Sanken STR2A155.
It is a new PWM controller IC and not currently available to the market.

We haven't even seen it yet, but are told we must use it for the layout.

The thing is STR2A155 is a DIP8 package, with the switching FET inside the package, along with the PWM control parts.
Rds(on) at 25C is 1R1.
We have no idea what the internal FET's Qg is, as the datasheet does not say.

Surely our power level is far too high for a DIP8 package?

With 88% efficiency (we guess that its 88%) the input power would be 49W.

Using a DIP8 FET for this power level is surely ridiculous?

Its for a LCD-Television.

There is no air-flow cooling in the back of the television.

The worst case ambient is 50 degrees Centigrade.

There is very little room in the enclosure at the back of the TV because its a LED-LCD-TV and they have to be less than 30mm thick.

So surely you agree that a DIP8 FET-and-controller package is ridiculous for such high power levels?
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You'll remember, that I linked the japanese STR2A155 datasheet in your previous thread. It actually tells a 43W Pout number for 230 VAC (not wide range) operation. However, did you also notice the respective temperature rise? I generally assume, that designers at your company are able to read datasheets.
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Thankyou FvM, i remember your previous thread witht that datasheet........i started that thread in end of march 2011 but i unfortunately cannot find it in the "my posts" section.

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