UCC28780: UCC28780

Hi Robin,

400W is likely too high to make a reasonable design with active clamp flyback unfortunately. Other soft switching topologies like LLC resonant converter would likely be better suited. Take a look at PMP20289. This is a 500W half bridge LLC with a peak efficiency of 96.8%.

Best Regards,

Ben Lough

Thanks a lot Ben.

We will jump at your suggestion!

Plus we have key products in design using UCD3138 as well...

We have looked into the interleaved LLC design in 2017...so kind of primed to get on with it now.

A few things : 

- Where will I find the LLC code files for PMP20289.1 version of course? In the Digital control ...some downloadable files?

- We will have to trim to 5.0V  with remote control through a twisted wire from remote load back to the controller. It is well known how the analog version works. Any suggestions for the digital version?

-There is some LLC sensitivity about losing control if it gets towards capacitive mode: so does the control developed for LLC contain an algorithmic approach to avoid getting into that mode?

In interleaved mode, it is possible to obtain a fairly flat load vs efficiency curve by "load shedding"...is any such algorithm embedded in the code with this application? (Infineon has it...but you cannot use their products in our applications!)

Appreciate your help.

robin

Hi Robin,

I will need to check with the designer for the software files. To reduce the output voltage, typically this means some adjustment to the transformer design (higher turns ratio). If an analog LLC controller is acceptable then UCC25630x might be of interest. This controller has integrated capacitive region avoidance (ZCS protection). UCC25630x does not have phase shedding ability but it does have a built in burst mode to improve light load efficiency.

Best Regards,

Ben Lough

Ben

Thnx for the info.

We will prefer sticking with UCD3138 & we can easily change turns ratio- our xmfr is very different so it is easy. Can it be assumed that the design support pkg including the setting up of output voltage, output load & output capacitor etc. are open and can be changed to suit any application. YEs?

r

After reading about UCD7138, I am convinced about using this chip in place of UCC24612 for sure.

However, there are some observations I make on its application suggested in the document.

Pl see attached pdf where I   raise some observations.

Will appreciate a quick resolution: we are right in the design phase for 380V dc input to 5V@ 80 amp with remote control ability. This latter still needs to be understood andPMP20289LLC_SYNC_RECT_OBSERVATIONS.pdf we are hoping to get some enlightening design approaches about remote adjustment of 5V from load point sensing.

r

Hi Robin,

I have asked someone from the digital controller team to comment on your questions regarding UCD. May I ask where did you obtain the scematic in the PMP20289LLC_SYNC_RECT_OBSERVATIONS.pdf? The PMP20289 schematic I have shows no diode in between Vout and the transformer. 

Best Regards,

Ben Lough

Ben:

Pl see the attached document: where you can see EPC2024 in circuit with a diode.tidrn83.pdf

Hi Robin,

The schematic in tidrn83.pdf does not have a diode between Vout and the transformer either.

Best Regards,

Ben Lough

Hi Ben

Are we looking at the same document with same id ?

pl see the attached screenshot of tidrn83  I downloaded from the website.

I do not think I modified the doc # because it is pdf.

EPC2024DIODE_BEN.pdf