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

DO NOT CLICK ON THE ABOVE LINK!!!! Our filters detected malware.

Hello Saeid ,

i have a solution for the no load voltage problem .

i guess you must use a opto coupler for feed back. use a zener from (+) of driver output to feedback path of opto .
if u need no load voltage 45 v than use 47v zener . this connection not requair opamp for voltage regulation .

Thanks to reply Ashish
Do you download attachment files on upper link?!!!
I use isolated topology. For control output variations, i use TSM101A ant LTV817B.
I guess this problem is for dynamic OVP of L6562N! I think can't design suitable circuit for dynamic OVP!

i also design a circuit on L6564 , i faced same problem that you did.

try zener may be this can solve ovp problem .

Check that you are not experiencing peak detection of noise on the output.
With no real load, you may be charging the output caps to the peak value of any
noise or ringing present on your output. The control circuit can not bring this voltage any lower . Does the output regulate well when loaded ?
Does your output drop slowly when you attach your voltmeter to measure it ? If so, try a small "preload" in the form of a non-inductive resistor. You must keep the noise to a minimum if you expect the no load regulation to be within limits.