DC/DC converter for more output and low power?

[Astrid]

How do nowadays solves your power to drive the smallest, cheapest and most effective?

Input voltage Vin 11V - 27V
Outut voltage: Vout +5V,-5V,+15V, +3,3V
Output Power max 5W, most of the time <0.5W

 

[kam1787]

how do you define 'most effective'?

 

[Astrid]

Good question. Say anything with efficiency greater than 80%

 

[Mithun_K_Das]

I've Designed one recently. I got 96%. The points are, make your transformer good, make a stable HF oscillation. And use more FETs than required. That will reduce switching loss.

 

[Astrid]

Well, I'm just looking for some solution with integrated FET.
use for such a small powerful external FET seems like a waste of space
So far we have **broken link removed**.
Unfortunately, I'm not sure how far this IC can operate at 12V

 

[Mithun_K_Das]

You can use MC34063 if you wish.

 

[schmitt trigger]

Remember, engineering is the science of tradeoffs.

You have to define which parameters are most important for your application.
Cheap and efficient? Cheap and small? Efficient and small?

The remaining parameter will have to be compromised.

However to answer your questions specifically:

A discontinuous mode flyback, will yield multi-voltage outputs with the least amount of components.
And at the efficiency level you are looking at, it can be realized with inexpensive components.