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AC/DC and Isolated DC/DC Power
AC/DC and Isolated DC/DC Power Forum
UCC28600EVM-65W modifications for 36VDC, 1A Output
Could you tell me the proper modifications for UCC28600EVM-65W so that it may supply 36VDC, 1A to LED strings?
From the User Guide(sluu263c.pdf) I have read it has dual outputs, but only one is available.
What I want is proper specifications for transformers and unpopulated parts so that I may use it as a LED power supply.
Thanks in advance,
There is a design calculator in the software section of the UCC28600 product folder that calcualtes the required components and transformer for specific requirements but it doesn't really take multiple outputs into consideration. Keep in mind that if the main output is lightly loaded and forces burst mode, all secondary outputs will lose regulation. And lightly loaded slave outputs will have higher output voltages when the main output is heavily loaded. Multiple outputs are possible with this controller but maybe not ideal over wide operating ranges.
Thanks for your reply.
If I need just a single output - 36VDC, 1A., could you provide me with a sample setup of the Calculator?
Could you also send me Gerber files of UCC28600EVM-65W?
What would be the power factor of the EVM?
The EVM was never designed to meet any kind of PFC requirement so my slightly educated guess would be somewhere between 0.3 and 0.5, especially considering the input capacitor is relatively large to keep the input ripple on the bulk voltage within 25%. This input capacitor is very important as the power stage design is based upon the minimum valley voltage on the bulk rail.
I have enclosed the spreadsheet calculated with the overall requirements but if you modify the MOSFET you need to update it, also if you use a different inductance or turns ratio you need to modify those parameters as well.
the gerbers for UCC28600 65W EVM
Thanks for your valuable info.
Could you recommend a few reference designs which is similar to UCC28600EVM-65W but with good power factor(> 0.9) ?
What I need is a small size, universal input, isolated, DC 36VDC, 1A output, good power factor PSU to drive 4 LED strings.
Thanks for the Gerber files.
But it faild to load on GerberLogix V2.1.
Please have a look.
Do you need each string to be 1A or are the combined strings 1A? Is TRIAC dimming required?
The files have can be opened in Gerbtool; Import gerbers, select all files and not the default extensions and they will appear in the selection screen to be imported.
Thanks again for your reply.
The total current is 1A, at 36VDC and a separate equalizer/dimming board(with CC2530 RF control) will supply drive current to 4 LED strings.
I don't have any suggestions off hand but I relayed your requirements to the Lighting Power Products group to see if they had any ideas. I'll let you know what they come back with. Meanwhile you could research the vast supply of lighting applications and reference designs on the TI website: http://www.ti.com/solution/led-lighting-general-diagram#Selection and Solution Guides
Thanks for your valuable support.
What makes UCC28600EVM-65W's power factor not so good, compared to somewhat similiar design(at least to my untrained eyes) like PMP5560?
short answer is the size of the bulk capacitor that supports the input rail.
Do you mean the capacitor just after bridge diodes or capacitor bank on the secondary of FB transformer?
The capacitor after the bridge diodes; note that the 65W EVM uses 120uF, the PMP design uses 0.22uF.
Now I see.
One more question - then what makes the design difference - the chip, the money, the transformer, the size?
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