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TPS61042: R1 and R2 desgin value in datasheet Figure 19

user4782171
Intellectual 1560 points
Part Number: TPS61042


Hi Team,

  In TPS61042 datasheet Figure 19 (Page 14), there has two resistors(R1 30ohm, R2 30ohm) series with the LED string. My customer want to use this kind of topoloy in thier project. Would like to know if have any special causes or design procedure to design and calculate the resistance?

Best regards,

Albert Lee.

 

  • 0
    TI__Mastermind 22745 points
    Hi Albert,
    R1 and R2 was used to optimize the different LED strings's forward voltage. I think it depends on the real application, for your application, if you can know the maximum different voltage between led strings, you can use this equation: [Max(Vled_string1-Vled_string2)/Iout] to calculate the value of R1/R2. Thanks. If you can make sure the difference voltage is very small, you can just ignor R1/R2.
    Best Regrads
    Sean