UCC25630 application

Hi Jerry,

Yes, you can use UCC25630 for LCC applications.

Best Regards,

Ben Lough

Hi Benjamin,

The voltage of the resonant capacitor is used to realize the HHC control, which is well implemented in the LLC. The voltage of the resonant capacitor reflects the input current status very well, and the loop is controlled by the VCR pin. If we use the LCC topology, how can we implement the HHC loop control, and VCR take the voltage of the shunt capacitor (ripple is small), and the resonant capacitor voltage has been clamped by output ,  Our problem is how to take VCR signals without sacrificing HHC performance too much.  Our switching frequency should be above 500KHZ. What are the problems we need to consider ?  Are specifications in page 17, formula 2, page 22, and the descriptions between figure 34 and figure 33 incorrect ? Thank you.

Hi Jerry,

I will look into your questions and get back to you later today. Are you referring to the pages/formulas in the datasheet? www.ti.com/.../ucc256301.pdf. If not, please email me the document and I will take a look: ben.lough@ti.com

Best Regards,
Ben Lough

Hi Benjamin,

I got the datasheet.
thank you.

Hi Benjamin,

Do you have any suggestions?
Thank you.

Hi Jerry,

You can choose the capacitor divider such that the sign on VCR pin is big enough, but not exceed the 0-6V range. You need also make sure the capacitor used in the divider is much smaller than the resonant capacitor. 

Regards,

Bosheng

Hi Benjamin,

Where can I get the VCR (through capacitive voltage divider) signal? by the DC capacitor? or where? Our topology is LCC, not LLC, and does the ISNS signal also from the DC capacitor? The resonant capacitance of the LCC is in parallel with the transformer.
thank you

Hi Jerry,

The VCR signal is from the capacitor divider, the capacitor divider is in parallel with CA, as shown in your drawing. The ISNS signal is also from CA. I saw your CA is only 0.22pF, is it possible to make it bigger? The capacitance used in the capacitor divider should be much smaller than CA.

Regards,
Bosheng

Hi Benjamin,

The CA is the 0.22UF, the DC capacitor, not the resonant capacitor, and the resonant capacitor is Cr.
thank you.