LNK304PN Output Voltage Goes UP

Posted by: PROMETHEUS on 05/26/2021

Hello,

My circuit output voltage is starting from 10VDC and slowly increasing to 35VDC I didn't find any problem on schematic , PCB ,soldering

VIN:275VDC

Files

Attachment	Size
SCH.png	30.43 KB
pcb_0.png	78.27 KB

Comments

https://klasresim.com/i/wIVUms

https://klasresim.com/i/wIVB9M

Hi,

For direct feedback designs with <3mA minimum load using LinkSwitch, a pre-load resistor is required to maintain regulation. It is calculated as Vo/3mA and the value can be increased depending on the desired regulation. See Application Note AN-37 LinkSwitch-TN Family for futher details.

Thank you so much ZBDelta,

Problem solved with 1.5K resistor I didn't know about Vo/3mA , My load resistor was 3.2K