NCP3063 Flyback Converter Application

[sac1991]

Can this
https://www.onsemi.com/pub/Collateral/NCP3063-D.PDF

NCP3063 be use to make flyback converter. In datasheet it's only mentioned for boost/buck mode. But isn't flyback just a boost converter with multiple winding inductor. I have made a flyback converter with this with feedback from TL431, but unable to get results. Please suggest if anyone has worked on this before.

 

[treez]

flyback is derived from a buckboost.
Yes you could do a flyback with that, but there are many better chips you could use.
Why not try the nice UC3842 or ucc38c43 chip.....or one of the manyy other. That ncp3063 has quite high loss in internal bjt

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here is two flyback sims in ltspicem using lt1243 which is similat to uc3843

 

[schmitt trigger]

Not only that, but the UC3842 or UC3843 are current mode controllers, which simplify loop stability in boost derived converters.

 

[treez]

The Internal BJTs are connected in Darlington configuration. This is to reduce the drive current from the chip itself and get the Vce on down. However, it means that the swiching frequency is severely limited due to carrier injection swamping the BC region.
Another manufacturer does a version of this chip which allows you to drive the internal BJT in a non darlington way, because the collector of the behind BJT is not internally connected to the collector of the forward BJT. –But even that is not that great

 

[sac1991]

I have designed a flyback converter and tested it with NCP3063, with Isolated feedback, it's working fine. Switching frequency is below 300kHz, as mentioned in the datasheet.

 

[treez]

i hope your pin one does not go above 40v during the off stroke, when the primary shoots up to vin plus the clamp voltage......or maybe it was so low power that you only needed rc across primary as a snubber......? Either way, you would still have to be careful of the reflected voltage to the primary

 

[sac1991]

Yes I was only 8-16V - 12V (Output) 1A flyback converter. A have used a external MOSFET.

 

[rohithkrishnan]

https://www.onsemi.com/pub/Collateral/NCP1010-D.PDF

Use this.

 

[sac1991]

I have sucessfully implemented flyback converter with NCP3063 and feedback using TL431.