UCC28740: doesn't start to switch

lucas delmonte

Prodigy 20 points

Part Number: UCC28740

Hello

I am working with the ucc28740 controller but i never have pulse in DRV.

Vdd capacitor go from 21 to 7 V continually but don't have anything in DRV.

any idea?

Thanks for help.

over 8 years ago

0 John Stevens over 8 years ago

TI__Expert 7395 points

Lucas,

thanks for your interest in TI. Can you provide a schematic of your design, input/output voltage and load conditions and what condition you are looking at. I'm assuming you are trying to startup?
If this is the TI evm or your own design hardware please specify. If it is your own design please be sure to take a look at our excel design calculator here: www.ti.com/.../toolssoftware

Regards,
John

0 lucas delmonte over 8 years ago in reply to John Stevens

Prodigy 20 points

Placa.pdf

Jhon,

Input 220V RMS, output 5V 1.5A and +-12V 0.5A . Without load.Yes i am trying to startup.

The schematic is in the PDF file

thanks

0 Billy Long over 8 years ago in reply to lucas delmonte

TI__Expert 4015 points

Hi Lucas, have a look at this TI training video, it goes through the startup sequence for the UCC287xx which includes the UCC28740 as well as common issues. Hopefully it will help.

thanks

Billy

0 user5108121 over 8 years ago

Prodigy 20 points

I have the same problem. I see a very narrow pulse in DRV pin. VDD is switch between 21 and 7V.

0 user5108121 over 8 years ago in reply to Billy Long

Prodigy 20 points

Could you please give me the video file, once more. As I have the same problem as this topic. Thanks

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UCC28740: doesn't start to switch