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TPS7B84-Q1: divider wiht 3.3V output

Betty Guo
Expert 7300 points
Part Number: TPS7B84-Q1

Hi team,

what's your recommend divider resistors in 3.3V output with 16V input? 

Vout=0.65V*(1+R1/R2)

In the datasheet and EVM, I didn't finde the schematic and resistor value. Also, in EVM user guide, with 3.3V output, the R2 is 42.2kohm, but I didn't find the correct R1 value.

is there mistakes? thanks

  • 0
    TI__Expert 7300 points

    One more question, what the RTM schedule of TPS7B84-Q1

  • 0 in reply to Betty Guo
    TI__Mastermind 23361 points

    The TPS7B84-Q1 is scheduled to be RTMed by the end of this month or earlier. 

  • 0
    TI__Guru 50025 points

    Hi Betty,

    It is recommended that the resistors are sized such that the current from the output to ground through the feedback path is at least 100 times the leakage current into the FB pin to avoid accuracy problems.. For TPS7B84-Q1, the FB leakage current is 10nA max. So, the max current  through the feedback path should be 10nA * 100 = 1uA and then we have R1 + R2 <= 3.3V / 1uA = 3.3Mohm. In this case the resistors can be large if a small quiescent current is needed or if it is not much of a concern the resistors can be smaller. 

    42.2kohm for R2 is fine, and that would make R1 = 42.2kohm * (3.3 / .65 -1) = 172kohm. 

    Best regards,

    Nick