UCC28600 - 110V, 1A SMPS

I noticed that you are not using the latest revision of the UCC28600 Design Calculator.  The revised version limits the switching frequency at the low input so that it ideally does not switch at less than 80kHz.  This is to prevent the on-time at full load, low input from exceeding the internal signal that signals the end of the demagnetizing time.  Over-riding this signal results in extra pulses so the new revision of the calculator forces a smaller inductor and a shorter on-time under these conditions.  I would recommend using this new calculator BUT considering you are operating from a PFC output and the operating mode will be more like the high;line profile this may not be an issue except at start up.  The UCC28600 STATUS pin will ALWYS keep the PFC controller off at start up no matter what the line and load conditions, until FB determines the appropriate operating state, so a few cycles at least.

The inductor that you describe uses tape layers for isolation.  Tape layers result in high leakage inductance and are not recommended for the flyback inductor used with the UCC28600.  Triple insulated wire on the secondary is recommended. The gap is recommended on the inner layer only to reduce radiating excessive EMI.  Please refer to http://www.ti.com/general/docs/lit/getliterature.tsp?literatureNumber=slua418a&fileType=pdf Flyback Transformer Design for the UCC28600 for more details.

Hi,

Thanks for yr detailed mail. By the way, kindly share the latest design tool of UCC28610, also. I am not able to open the design tool of UCC28610 from T I website

Regards

Atul Bhakay

What?!? The UCC28610 Design Tool still has problems opening? I am so very sorry...time to take more drastic measures to get to the bottom of this.

In the mean time, here's what you should be able to see from the website. 

Best regards!