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UCC284: UCC28470: What exactly is VIN(run) when finding RS1?

Craig Dekker
Intellectual 350 points
Part Number: UCC284
Other Parts Discussed in Thread: UCC28740

Note:  This question is for part UCC28470 - for some reason this part number is not on your drop down list (perhaps I am in the wrong forum).

Page 10 of the produce data sheet defines VIN(run) as:

VIN(run) is the AC RMS voltage to enable turnon of the controller (run).

If the input ranges from 85 to 264 VRMS then is VIN(run) = 85 VRMS?

Thank you,

Craig

  • +1
    TI__Genius 12511 points

    Hi Craig,

    Did you mean the UCC28740? the constant current, constant voltage, Flyback controller?

    I will send it over to the team responsible for this part.

    Regards,

    John

  • +1
    TI__Guru 50190 points

    HI Craig,

    I admit the datasheet is not very clear on this, but VIN(RUN) is where you want the controller to start running. So yes, you can use 85VRMS in the calculation. On page 10, equation 3 is showing how to use the turns ratio from Primary to Auxilary to set the turn-on threshold for the controller. 

    Does this answer your question?