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TNY278NP blew up fuse.

Posted by: Raul Diez on Fri, 03/12/2021

Hi.

I have built a Flyback converter with a TNY278PN and the PI Expert Suite
with a little modifications.

When I turn on power (AC100V 50Hz) to the mains it immediately blows the 1A fuse.
I tried one more time but the result is the same.

- The primary inductance of the transformer (hand-made) is 835uH.
- Add a 150ohms resistor in the coupler (AN-14 recommendation).
- C5 replaced by two 2.2nF in series.
- R3,R4 deleted.
- R1 replaced by two 100Kohm in series.
- Coupler LTV817A -> PC821.
- Diode replaced by similar.

I attach the design sheets of the PI expert and one more with the modifications (8 pages in total)

Thanks.

PD. Excuse me for my ugly english
Raul Diez.

Files

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PI-1600x1200@2x_SCALE-iDriver-SID11x1K.png 443.14 KB

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Submitted by Raul Diez on Tue, 03/23/2021

Something about the design?

Submitted by PI-Kryten on 일, 03/28/2021

Hi,

Thank you for considering Power Integrations for your solution.

Could you please send us the design files of PI Expert rather than the PDF? Please also share the layout.

Best Regards,
PI-Kryten

Submitted by Raul Diez on 일, 03/28/2021

Hi, PI-Kryten
Thanks for your answer.
I attach the PI design and the layout (PDF only, 7 pages in total).
Because i dont have the same EE19 bobbin as the PI design says, I use a differentt EE19 and the pin number changes about the design ones. The transformer detail it is in the layout PDF.
Please, help me with the design.
Thanks.

PD. Excuse me for my ugly english
Raul Diez.

첨부 파일 파일 크기
climate.jpg 6.14 KB
climate.png 7.5 KB
Submitted by Raul Diez on Tue, 04/06/2021

Something about the design?

Submitted by PI-Kryten on Fri, 04/09/2021

Hi Raul,

The design looks ok. Can you measure the Inrush current for your circuit?
Typically, the fuse is chosen such that its i2t > 5i2Tinrush

Best Regards,
PI-Kryten