output voltage is not stable (Linkswitch TN )
Hi I design circuit giving attachment.
I use LNK305DN as a IC, Dın2 are 1N4007,
Lın 1000uH, Rf 10R
C1 and C2 are 4,7uF 400V Electrolytic Cap,
Cbp 100nF 63V Ceramic cap,
Rbais 2K05 %1 , Rfb 4K75 %1
CFB 10uF 16V Electrolytic Cap(attention please not ceramic cap, I have sample design use electrolytic cap. for CFB),
DFB and DFW are STTH1R06A diodes,
L is 680uH,
Co is 100uF 10V electrolytic cap,
Rpl is none
I want to 5V output and 0,75W power adapter.
But when ı give power (220 VAC), output is not stable and when there is not load output always change, but ı load some load output become more lower with current more higher for example when load is 3K9 output is 6,84V when load is 120R output is 5,21V
Can you help me,
Best regards.....
Comments
I solve my problem of output is not stable. But now in big scale output is not constant that ı want. for example at 0,65W power output is 5,03V but at lower power like 0,02W 5,6V. Is this normal about 0,6 volt drop voltage for this design. And according to datasheet ı have to see 1,65V at FB pin but ı see 6,5V why?
Did you follow AN-37? You need to follow step by step to get a good design
When you selected the value of your components, did you follow application note AN-37? This is a step by step guide for you to design your buck converter using link TN. Is is very important that you follow this guide to get a good working design.