TPS40210: Load regulation issue with aux winding control

Hello Devaraj,

The converter is working in this configuration, but the output voltage of the isolated output is heavily dependent on the coupling of the transformer AUX winding to the output winding. In addition, transformers for flyback converters are not real transformers, but coupled inductors, so they need to have inductance to store energy which is different to a standard transformer that is directly delivering the energy to the output. Please check if the transformer you are using is capable of being used as flyback transformer.

Best regards,
Brigitte

Hi Brigitte

As per the TI application note suggested inductance value for primary and secondary, I have used.

The following values i got.

Primary: 2.5uH

Secondary: 10uH

Aux: 0.6uH

Are these values will not enough for this application? I need to increase this inductance value?

Hello Devaraj,

Which application note are you referring to?

I expect that there are more parameters that need to be set. Where did you get the transformer model from?

Best regards,
Brigitte

Hi 

I have used UCC28710 application note for flyback design.

The transformer model taken from the pspice default model.

Hi Devaraj,

Could you please attach the link to the app note? UCC28710  is a TI device.

BR,

Haroon

Hi Haroon

Please check the below link for UCC28710 datasheet/application note.

UCC2871x Constant-Voltage, Constant-Current Controller With Primary-Side Regulation datasheet (Rev. C)

Hi Devaraj,

That is a whole different device and I am not sure if it will work. Instead you can use the excel calculator for Flyback design here for your design. https://www.ti.com/tool/FLYBUCK-FLYBACK-DESIGN-CALC

Hope this helps.

BR,

Haroon