The customer is using UCC28063 + L6598 (ST) to realize PFC + LLC. The input voltage range is 100~230V, and PFC output voltage is about 390V. The output voltage of LLC is +/-60V.
This project is from OEM. OEM offered schematic and PCB layout to our customer.
When our customer imported the file from OEM, they found the package layout became larger. So they changed some layout to avoid warning from Altium Designer. (The original file type is unknow, the software our customer used is Altium Designer.)
Below is the OEM board:
Below is the board of customer:
Below is the schematic of UCC28063.
Due to the policy and confidential, it is available to get the schematic and layout file now.
In test, they add load current to LLC, and then start up the circuit. (100V input voltage)
For OEM board, up to 650W (about 5.4A) could be added and the circuit could be started up normally. If larger load current is added, LLC circuit would go into protection.
While for the board of our customer, only about 500W (about 4.1A) could be added and start up normally. If larger load current is added, PFC circuit would go into protection.
And customer reflects that, if the current load is added step by step, such as from 4.1A to 4.8A, and then to 5.4A, the board of customer could support up to 650W.
And if the input voltage is 230V. Both OEM board and their own board could support up to 650W during start up test.
I have compared the layout, I have found that on customer board, the capacitors for several sensing pin (such as CS, VSENSE) is relatively far away from pin than OEM board. It would be easier to couple noise.
Do you think it would be the key reason to lead this issue?
Any suggestion to figure out the problem and is it easy to verify that if don’t make a new PCB?
Thank you.