clamp design for LYT switches

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Hi, We are working on a 25W Led driver  High line design  using LYT4226. Kindly guide us to select the correct value of Snubber capacitor and Resistor for the primary clamp ckt( with high efficiency) . Excel design sheet shows only clamp power dissipation. Kindly share the correct procedure to find the correct clamp component values.

Thanks

SDM

Hi,

Please refer  to figure 18 of the attached application note-59 for sample clamp circuits used in actual design.

p.13 also has some info about the clamp component selection. The amount of clamp you need depends on how much leakage inductance on the transformer so if you minimize the leakage, the less clamping you need.

Please measure the drain voltage to determine the maximum peak voltage that won't exceed the device rating.

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an59.pdf1.71 MB

Hi,

Thanks for your reply. We really interested to know How you got the component values of the RCD primary clamp.For  the design values - reflected output Vor  110V, Leakage inductance is 50uH, What is the equation to find the Cclamp and Rclamp in the case of LYT4226. Also provide the equation to find clamp dissipation too.

Thanks

SDM

 

Hi,

I am sorry but if the info you are looking for is not in the application note, then please try to find generic articles about RCD clamp.