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LM317L-N: Power management forum

Tamio Yokokura
Expert 3960 points
Part Number: LM317L-N


Hi, LDO support team

LM317L-N defines the Minimum Load Current in the datasheet, and it is depending on (Vin - Vout). What is happened if the actual load current is lower than the Minimum Load Current?

I would like to know why LM317L-N defines the Minimum Load Current.

Thanks

Tamio

  • 0
    TI__Guru 55940 points

    Hi Tamio,

    If the load current is bellow the minimum load current requirement performance may be outside of the performance depicted in the datasheet.  In addition the output voltage can increase.

    Very Respectfully,

    Ryan

  • 0 in reply to Ryan Eslinger
    TI__Expert 3960 points

    Hi, Ryan

    Than you for your reply.

    The datasheet is mentioned that  the "Adjustment pin current" is  as follows.

    What is the minimum value of  "Adjustment pin current"? This data needs to consider the variation of output voltage.

    Thanks

    Tamio

  • 0 in reply to Tamio Yokokura
    TI__Guru 55940 points
    Hi Tamio,

    You should use the Maximum Adjustment pin current when calculating as this is going to yield the maximum variation in the output voltage. As Iadj reduces, the last term in the equation for Vout (Iadj x R2) will become negligible.

    Very Respectfully,
    Ryan
  • 0 in reply to Ryan Eslinger
    TI__Expert 3960 points
    Hi, Ryan

    My customer need to understand the minimum adjustment current to configure the total resistance of R1 and R2 to higher value because their application is the mobile device which operates by battery. Please inform me about the minimum limiter value of the adjustment current configured at ATE. Is it 10uA or 20uA?
    Thanks
    Tamio
  • 0 in reply to Tamio Yokokura
    TI__Guru 55940 points

    Hi Tamio,

    We do not have a specified minimum adjust pin current and therefore cannot provide one.  Your battery life will be limited by the maximum adjust pin current; therefore, we recommend using the maximum Adjustment pin current which is provided.

    In addition Figure 3 provides how this current will drift with temperature:

    Very Respectfully,

    Ryan