UCC28780: UCC28780 can not start.

henry-liu

Intellectual 280 points

Part Number: UCC28780

Hi:

As the SCH, the voltage of the source pin (Q3) is about 2V, so the voltage of VDD is locked to 0V.

Could you pls check if any mistake in this SCH. Thanks!

over 7 years ago

0 Kuan Wei Chen (Kevin Chen) over 7 years ago

TI__Genius 9710 points

Dear Henry,

Thanks for choosing TI's product in your design. As I checked your SWS and HVG pins schematic is correct.
Can you also provide VDD part schematic for more information on it?

Best Regards
Kevin

0 henry-liu over 7 years ago in reply to Kuan Wei Chen (Kevin Chen)

Intellectual 280 points

Hi Kevin:

Enclosed the Full SCH.

UCC28780 48W SCH 20180126.pdf

0 Kuan Wei Chen (Kevin Chen) over 7 years ago in reply to henry-liu

TI__Genius 9710 points

Dear Henry,

Can you help me to check the soldering of ZD1 and ZD2?
I think it might be wrong polarity.

Also can you help me to check the Q4?
I think it should be PNP MOSFET, like TIDA-01622
www.ti.com/.../tidrvm3.pdf

If you still have any problem, please feel free to let me know

Best Regards
Kevin

Power management

Power management forum

UCC28780: UCC28780 can not start.