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I have to build a converter to get 300v from a 3.6v battery. Besides the hight conversion ratio it needs to be as small as posible.

I am planning to use a swticher IC like LMR64010 or similar configured as Flyback because, as far as I know, it is the best mode for low power & high ratio conversión. As flyback transformer I am planning to use the small ATB322515-0110 but I am worried because, unlike other flyback transformers, it has no special indication to be used in pulse flyback mode. I am not sure if a transformer should meet any special requirement to be used that way.

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  • \$\begingroup\$ The transformer you referred has a turns ratio of 1:10, so you cannot get 300V from 3.6V with it. \$\endgroup\$ – Rohat Kılıç Apr 6 '17 at 5:27
  • \$\begingroup\$ You can if you step up 30V flyback spikes. Not very efficient though. \$\endgroup\$ – Brian Drummond Apr 6 '17 at 6:23
  • \$\begingroup\$ @RohatKılıç 10:1 is fine for a flyback design of this type. \$\endgroup\$ – Andy aka Apr 6 '17 at 7:43
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Here is a design using the LT3757 flyback switcher and it uses a 10:1 transformer to obtain 300 volts from 5 volts. I'm not suggesting you use the chip because it might not work down to 3.6 volts with that transformer but it gives you a starting point with something that is pretty close: -

enter image description here

To open up your options, it might be sensible to get the 300 volts in two stages. Use a regular boost switcher to give (say) 12 volts, then use a flyback (like the 3757). A lot more options will fall into your open hands.

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I would reccomend buying one used in CRT televisions, or buy an CRT and get the flyback from it. A lot of the time you have to figure out which pin is the ground since there is no data sheet of the obtained flyback. https://www.instructables.com/id/How-to-find-the-primary-and-the-secondary-coils-of/%3Famp_page%3Dtrue

Now I bring up using this type of flyback because the primary (and the secondary, if needed) can be wound around the ferrite bar on the side, so configuring the voltage you need is easier. ![description here]!(https://i.stack.imgur.com/gkHWB.jpg).

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