UCC2805: Coudl we remove the auxiliary winding and use Vout as the Vcc

Dylan You

Intellectual 2630 points

Part Number: UCC2805

Dear Teams,

My customer is using UCC2805. Could you help them solve following doubts?

Vin: 8-32V

1. How to remove the auxiliary winding due to limited space of transformer.

2. Could customer us the Vout (10V) as the supply voltage for Vcc?

Schematic diagram:

Thanks!

Dylan

over 4 years ago

0 Dylan You over 4 years ago

TI__Intellectual 2630 points

Dear Teams,

Additional Infor: Customer plans to connect the Vout (10V) to a diode, then connect it to the pin 7 Vcc. Would that be possible? Are there any risks?

Thanks!

Dylan

0 Pye Naing over 4 years ago in reply to Dylan You

TI__Prodigy 590 points

Hello,

I have assigned this thread to an expert on the part. He should be getting back to you shortly.

0 Hong Huang over 4 years ago in reply to Pye Naing

TI__Guru 60265 points

Hi,

Where is that 10V from? If the 10V is from one of the secondary side, UB, VB, or UT, then the isolation between primary and secondary is lost.

But if you use VB 10V U and VGND, it is ok. Then you can remove winding 3-4, then connect D219 cathode to D222 cathode. I think you still need to keep R144, 114 and 126, and C226 and C228. But you need make sure winding 1-2 can provide enough bias power.

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UCC2805: Coudl we remove the auxiliary winding and use Vout as the Vcc