Part Number: LM5160
Tool/software: WEBENCH® Design Tools
Our isolated design based on LM5160 doesnt regulate correct on our pcb compared to webench. Webench suggest 649 ohm to FB (pin 8) for 5,6V out. In practise we need 4,9kohm. I have a Webench link that I can share?
Hi Henrik,
Thanks for sharing the design. The primary voltage of the design should be lower than ½ of Vinmin as per the datasheet. WEBENCH uses this to design the primary output voltage to be around 2.725V. This means that the coupled inductor needs to have a turns ratio ( NOT 1:1) to get the secondary Vout of 5V.
The turns ratio recommended by WEBENCH is 2.07. Because you are using a 1:1 coupled inductor, you have to adjust the primary voltage accordingly and that’s what is making you to change your feedback resistor value to a different value other than 649 ohm.
Please let us know if you have further questions.
Regards,
Gerold
