Flyback converter design with single input and multiple output

Hi Alexandru,

Thank you for reaching out.  Let me align with our converter experts. We will give you some recommendations tomorrow.

Thanks,

Youhao Xi, Applications Engineering

Alexandru

when you said two outputs are independents, do you mean we can't use two winding in the same transformer to generate the outputs or there is other requirement?

Hi Jasper,

my project requirement is to transform an input voltage rail (in range of 3...5V) to 2 outputs rails. The outputs should be isolated galvanic (1.5kV) among each other and simultaneosly isolated (4kV) to the primary side. The outputs rails should be in the range of 5...6V with a max. current of 100mA of each. I'm not sure if a flyback topology could be the solution. Maybe a push/pull would fullfill better the requirements. I hope you can help me with the right sollution.

Regards

Mixich Alexandru

Hi Alexandru

if use a push/pull, we may need a boost to get stable voltage 5.5V firstly, then push/pull from 5.5V to 5.5V with transformer.

for example a TPS61252 to get 5.5V and SN6505B for the isolated output.

Hi Jasper,

thank you for the proposal. I think the most work will be now to design a adequate transformator. However in the datasheet of SN6505B nothing is said about the use of a snubber circuit to damp the energy generated by the existing leakage inductance. Should this considered anyway?

Best regards,

Alexandru Mixich

Hi Alexandru,

I'm not sure as I normally don't support pull-push. please refer the EVM design. 

and I will re-assign the post to the response engineers.

Hi Alexandru,

A snubber circuit is not necessary for the SN6505B to operate. A dual-output isolation transformer can definitely be used here, and many transformer vendors are willing to design custom parts. 3V - 7V systems (largest expected range) will require a turns ratio >2.34 and V-t product >7.6V-us.


Thank you,
Manuel Chavez