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LM5169-Q1: LM5169FQDDAR

Part Number: LM5169-Q1
Other Parts Discussed in Thread: LM5169


We are planning to use fly buck application circuit given in the LM5169 datasheet for one of our projects.


I would like to know if we can get Vout1=5V and vout2=12V, also any recommendation from your end on the transformer part that needs to be used to get this outputs.


Also will we get same current of 0.65A in both Vout1 and vout2 with Vin = 120V.


Also please do share any excel sheet similar to LM5169_cal_revD for fly buck circuit



  • Hi Harish,

    Thank you for your question.

    Calculating your values using the datasheet equation yielded invalid results. You can use these resources to evaluate possible configurations for this part. It seems that your turn ratio and your desired current will violate peak current limits.

    Fly Buck Design

    Turns Ratio

    Additionally, in terms of an excel calculator, I found that most of the equations for other device flybucks work for this device as well. You can use this excel calculator to help figure out transformer configuration. 

    Thank you,

    Joshua Austria