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Saeid Jabbari
01-14-2014 06:05 AM

OVP and Noisy Output Voltage problem with Single Stage LED Driver

Hi for all and excuse me for my English.
I have a big problem with output regulation! I want to have 34 volt at no load but the voltage go to 70 volt!!! I read some of ST application notes about L656x and i know for obtain good PF , crossover frequency must be less than 25Hz, so i design compensation network with TSM101AC and after simulation transfer functions in MATLAB, i get ( Fc=11.6Hz , PM=52.6 ) for C.V and ( Fc=25.6Hz , PM=51.8 ) for C.C. My LED driver at full load work good and voltage decrease to 31 volt but output voltage ripple has very noisy!!!
Below link included schematic, bode plot and picture of my driver, please help me to solve to the problems.

http://www.4shared.com/rar/dpDklnTsce/Feedback_Info.html