UCC28180: Need help with reference Design TIDA-00652

Hi Dinar,

Thanks for your interest in UCC28180. Are you using the same BOM and layout as TIDA-00652? what package size is R5 on your board?

Best Regards,
Ben Lough

Sorry for late reply, I am traveling. Yes, the Resistor is as per BOM, the MOSFET is a equivalent. The board design is different, have traced the board there are no shorts. I had to do a different design so I could study the design.

Thanks

Dinar.

I am attaching the schematic with with part numbers and packages used.

Hello Dinar,
It looks like you have one side of R5 (labelled node PE in the schematic) connected to protective earth.
This should be connected to AGND at a single point
You need to remove this earth connection.
Also a buck pfc provides a floating low voltage output so you must make sure that any measuring instrumentation is floating.
For instance you cannot connect the earth clip of a scope probe to the negative of the pfc output capacitors.
Regards
John

Hello John

Thank you for the reply. So you mean I need to connect the PE (GND) and AGND on my schematic through Net Tie? any specific point on the board( circuit/schematic )? The diagram is as per the the PDF , the PE is not connected to anything on the board.
I do use a isolation transformer(1:1) when I connect the oscilloscope , but in this case I had just connected a multimeter at the output as mentioned on page 11 of TIDUAS3A.

Thanks and Regards
Dinar

Hello Dinar,
You can connect the PE to AGND wherever is the shortest route on your pcb layout.
At the moment the MOSFET gate drive is floating and that's why R5 is smoking.

Regards
John

Hello John

Thank you for the information, Will do a test by connecting PE and AGND , and update. Any else I have to look for while do initial tests?

Thanks and Regards
Dinar

Hi Dinar,

Were you able to perform a test with PE and AGND connected?

Best Regards,
Ben Lough

Hi Dinar,

I'll go ahead and close this thread for now. If you run into any additional issues with this design just let me know.

Best Regards,
Ben Lough

Hi Ben

Sorry I have been traveling on work and could not access net, I still have to test test the modification as , new board had to be solderd, I will update within 2 days.

Again very sorry for late reply.

Rgeards

Dinar

Hi Ben
I tested the board by connecting the PE to AGND , the board does not turn ON at all, No voltage at eh output.

Regards
Dinar

Hello Dinar,

Measure the voltage on ICOMP. It should be greater than 0.2V

Then measure the voltage on VSENSE. This should be greater than 0.82.

The voltage on VCC should be greater than 12.1V

If all of these values are ok and you  still have no gate drive then the ic is damaged  because the gate was floating in your previous setup.

Regards

John

Hi John

I have soldered a new board with all new components, VCC =0v , VSENSE=0v and ICOPM=0v, WTR to AGND.
since VCC =0V , the board won't turn on.
Could please explain the BaisHV and U4 operation?

Thanks and Regards
Dinar

Dinar,
Your schematic does not have a U4 or a "BaisHV"
Regards
John

I have marked the BAISHV and U4 section in the schematic, how do I check this section for proper functioning?  does this section power UCC28180 when power is turned ON?

also , can I run the board with external 24vdc supply, not connecting the 230VAC and check for functioning of UCC28180 ?

Thanks and Regards

Dinar

Hi John

Thank you for your time, it was very helpful in sorting out the issue on the board.

Thanks and Regards
Dinar