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I was thinking of using the DER-305 design to power a 12W LED light. The output of DER-305 is 50V 200mA. Is it as simple as changing the current sense resistor to achieve 260mA output. Would I have to change the transformer design. Any suggestions would be great. Thanks

You may use PI Expert Software which is available on this website if you want to create new design, or modify existing DERs. In this way, you will have more freedom to do design iteration/optimization, especially in choosing the transformer/inductor values.

The circuit will work just by changing the current sense resistor, but you may need to adjust the inductance in order to maintain discontinuous mode operation.

I have attached an exported PIXLs design as a reference. Please try to do the same on PIXLS designer by choosing Linkswitch-PL Buck design so you can modify the spreadsheet.

I wanted to try DER-305 as it can be enclosed in a A19 LED Fixture. But, the starting voltage is 185V AC and i wanted it to start from 90V AC. So, what are the modifications to be made in the circuit or since it's a Buck configuration, will it start from 55V to 60V?

It is possible to start DER-305 at 90VAC, but the CC regulation will be  worse (10% or higher) if you operate from 90VAC to 265VAC. I recommend to limit the input voltage for low line only or high-line only to get the best regulation. If regulation requirement is not too tight, then you need to trim the value of the current sense resistors to the desired output current at the desired input voltage.


For a 50V output , it might not be able to operate properly at 60VAC and I recommend to start a 80VAC minimum.