Low voltage power circuits

[lamazoid]

Does anyone have a circuit which will convert low input voltage 2.0-3.0v max. to a high voltage around 400v or more? And also i need respectable power from it - 6 watt minimum. I've done a lot of search on this but there's nothing exept specialized ic's. No way i can get them. So this (considerably) must be self-oscillating ciruit with high efficency...

[Gary Lecomte]

At such Low Voltages this is Not very easy.
Especially for High Efficiency.
That usually requires a High Frequency converter.

There is Always a way to get Specialized IC's.

What IC did you want and what country do you live in?

[lamazoid]

Something like this:
www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1042,C1098,P12713
There are also few chips from MAXIM. I can order them (i live in Russia) but only from 100-500pcs.. I do need such a lot, but for a completely designed circuit, when i'll be 100% sure it satisfy my needs. As for now, i'm experimenting with different circuits and designs...

Actually i have one good russian IC rated to work down to 3v supply. It has two outputs to drive push-pull circuit, and fixed deadtime. So it's possible to drive two flyback-type converters. Main problems for now are:

1) design and calculation of the transformer - i have no clue how this should be done in such small dimensions (i can use 14mm POT core MAXIMUM)
2) Driving mosfets at such low voltage results into big losses.
3) Choosing optimal frequency of operation.

[lamazoid]

I have also experimented with self-oscillators like this:
www.uoguelph.ca/~antoon/circ/hv/dazer/dazer.htm
BAD result. I guess there's a way to make it work nice, but it lies through hard calculations and simulation possibly. I don't know how to do this So i left the tries..

[Gary Lecomte]

lamazoid said:

Something like this:
www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1042,C1098,P12713
There are also few chips from MAXIM. I can order them (i live in Russia) but only from 100-500pcs.. I do need such a lot, but for a completely designed circuit, when i'll be 100% sure it satisfy my needs. As for now, i'm experimenting with different circuits and designs...

Actually i have one good russian IC rated to work down to 3v supply. It has two outputs to drive push-pull circuit, and fixed deadtime. So it's possible to drive two flyback-type converters. Main problems for now are:

1) design and calculation of the transformer - i have no clue how this should be done in such small dimensions (i can use 14mm POT core MAXIMUM)
2) Driving mosfets at such low voltage results into big losses.
3) Choosing optimal frequency of operation.

I Tried that Link, But didn't get anywhere.

And This Design is a Total waste of time and money for what you want..
www.uoguelph.ca/~antoon/circ/hv/dazer/dazer.htm

As to Designing that Transformer for:

1) design and calculation of the transformer - i have no clue how this should be done in such small dimensions (i can use 14mm POT core MAXIMUM)
*** This Does require some Calculations.
** Most Important, you need to know the Specifications on the Particular POT CORE you have.
* Also your Operating Frequency, Voltages and a way to Calculate or Measure the Inductances that are required on your pot core.

2) Driving mosfets at such low voltage results into big losses.
*** NOT A PROBLEM, Just use a Mosfet with a LOW "ON RESISTANCE"

3) Choosing optimal frequency of operation.
***Typically the Higher the Frequency, the Better the Efficiency and the Smaller the Transformer.

***** ALSO be aware, Not all pot cores are Made for Power applications.
**** You need a Suitable type for the Frequency and Power that you intend to use.