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LM1084: schmatic review

ALEX jack
Prodigy 80 points
Part Number: LM1084

Tool/software:

hello 

      I want to implement a design from 3.5V to 2.2V with LM1084_ADJ， load current is 2A  。

      Please help  to check   whether  the  SCHMATIC is correct  ，thanks。

  • 0
    TI__Intellectual 790 points

    Hello there,

    Some notes I can give is that your resistor values a bit off. The formula to calculate: Vout = Vref(1+ R2/R1). In this case, R1 = 121Ω and R2 = 159Ω and we can ignore the Iadj current since R1 is greater than 100Ω. The current Iadj from the adjustment terminal introduces an output error. But because it is small (120 uA max), it becomes negligible when R1 is in the 100 Ω range. These resistor values results in Vout = 2.89V.

    My work:

    Vout = 1.25(1 + (159/121)) = 2.89V

    To get your desired 2.2V, you would have to switch your R2 (159 Ω) to 92 Ω.

    Work:

    Vout = 1.25(1 + (92/121)) = 2.20V

    Your capacitors at the input and output are sufficient and meet datasheet specifications.