solve issue for lyt4227E of 50 watt design

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hello ,

i have problem in lyt4227e 50 watt design that if i use 47uf capacitor on v pin than not got perfectly 1.2a but if i use 4.7uf capacitor i perfectly got 1.2a please solve my issue what is best for my design i attched hear...........


and what is best for my circut 1.2a 36 volt load can i drive for 64 watt

and how it convert 600mA 72 volt design 



첨부 파일Size
50WATT-LED-DRIVER.png108.05 KB


Is it Vpin or BP pin? BP pin sets the current limit. 4.7 uF capacitor will provide higher current limit. If you design using PIXLS, then if the current limit mode was set to FULL, then you should use 4.7 uF.

Please utilize PIXLS on you other designs. Let me know if you have any trouble using the software.

hello sir ,

for low heating what is consider 4.7uf or 47uf


if i use 4.7uf with R11-68k and R7=120k than i got 1.2A

but when use 47uf i am not get 1.2A proper 

please find my attchment hear...

schematic108.05 KB


Using either 4.7 uF or 47 uF does not affect the thermal performance of the device. Some designs, however, require higher current limit, and your design is one of them.

The schematic does not indicate exactly what is the bias voltage on your design. I would have wanted to check the PIXLS, but after doing a design with your  parameters, it looks like the design is based on full current limit. This is why you can get 1.2A on 4.7uF but not on 47 uF.

i use  at bp to fb pin 4.7uf  with 10uf/63 volt + 120k + 68K i got 1.2A but the driver ic is too much heat and after that circut is off after few minutes

i use  at bp to fb pin 47uf  with 10uf/63 volt + 100k + 39K i not got 1.2A  i got 1.10-1.16A but the driver ic is too much heat and after that circut is off aftersome minutes more than i use 4.7uf what is issue in this driver 

and watts also decres after few minutes 

i attached both schematic and transformer design please find hear



transformer1.08 MB
schematic108.05 KB

Did you use a heatsink? If not, please add a heatsink. At 50W, LYT-4 may need heatsink.

yes sir i use heat sink at ic and byQ200 both on i use heatsink

Please check the drain current and voltage and find out if there is any sign of abnormality such as transformer saturation or excessive leakage. I advise you to review your transformer design if that's the case.