Multiple output flyback

[Mercury]

multiple output flyback

Hello,
I'm having some problems with a multiple output flyback converter (the Power Integrations TNY series). I have a transformer wind-up for 15V and 5V outputs. The 15V line goes to feedback and is rock stable at 14.8V, regardless of the load. However, the 5V line is a disaster. Even at small loads it falls to 4V, which is not enough to power my logic.

Is there anyway you can stabilise both outputs? Or at least keep them close to nominal voltage?

Best regards
George

 

[alec82]

flyback multi sortie

dear friend
whats the ratio turn for your output self ?
make sure the ratio is about 14 to 5 . for increasing voltage increase the self turn
if your feedbacked output is noload another output fall a lot.

 

[modbro]

flyback multiple outputs

Shared regulation can be a implimented. 5V output should also be connected to feedback via resistor.

 

[dipnirvana]

flyback multiple

It seems that you don't have enough energy in your primary. So try to look into the transformer design.

As suggested here , also try with share feedback from 5V , too by putting feedback resistor to 5V .

 

[eem2am]

design multiple output flyback

sorry to tell yuo this,

but multi-output converters have rubbish cross-regulation when the load of the sensed winding changes a lot.

i am afraid that there really is very few solutions.....there is onesolution involving putting indutos on the winding outputs.....sized in relation to the output voltage ratio of that winding to the sensed winding..but its not easy.

continuous mose gives better cross reg. than discont. mode

multi output is really only fully viable when you have pretty fixed loads on each winding...then you can just keep adjusting windings till yuo get those outputs right