LNK3209 Auto Restart

Posted by: sunil.bhattad on 09/15/2023

Hello Team,

I am using LNK3209 to convert from 24Vac to 3.3Vdc. I am driving load upto 500mA. Can you please help me to understand why there is auto restart?

I have attached waveforms for your reference.

Thanks

Sunil

Files

Attachment	Size
24V 400mA - 1.png	288.51 KB
24V 400mA - 2.png	289.35 KB
24V 400mA - 3.png	341.22 KB

Comments

Hi sunil.bhattad,

thank you for using PI-forums.

Can you share with me your schematic diagram so that I could assist you properly? thank you.

have a nice day.

regards,

Sigris

C2 is 68uF 100V, R2 is 2.21K. Remaining all components are same as mentioned. I am using this application for low voltage AC input from 18V to 30V.24V is nominal input voltage.

68uF is likely much too small a value for the bulk capacitor at 24 VAC input, and the cap is running down between AC 1/2 cycles. This would have shown up as a problem running the design in PIXLS. You will need a much larger bulk capacitor at such low input voltage - remember that the energy storage scales as V squared.

Try running the design in PIXLS and increasing the bulk capacitor value until the warnings messages go away.