dimmable LNK PH series- separated input inductors or common mode ?

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Hi,

 

For a 30W output driver, for reference we are using DER314. But we have some questions:

 

1 - In place of L1 and L2 we try to use a comonn mode inductor 20mH, but it doesnt work well. The leds have some flikering. I see in all of your dimmable desing you dont use common mode choque.  Separeted inductors at AC input are better?

 

2 - for this power, 30W, we used a 220nF bulk capacitor, adjust R8 to 68ohms Do you have any experience in 30W or more dimmable designs at the damper circuit?  

 

Thanks 

 

 

The choice of using either a separate differential drum-type inductor or a CMC depends on EMI performance and space restriction.However, using 20mH CMC might be too high. We have some designs with CMC (DER-350, DER-396) but the CMC is only 5mH. You can try to reduce the CMC inductance and see if there's an improvement.