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LM3410: Attempting to calculate the inductor number

Connor Redding1
Prodigy 10 points
Part Number: LM3410

I have an input of 3-4.2 V from a battery, and 4 LEDs with forward voltages of 2.7 (10.8 total) and a rated current of 5 mA. When trying to do the calculations I've been having a tough time with the Delta iL P-P value, and what that value should be. I've been getting around 700 uH, which seems high to me, however it may also be because of the low current. Am I totally off on my calculations? (WEBENCH won't let me use a amperage below 10mA)

  • 0
    TI__Mastermind 28655 points

    Hello Connor,

    At low current the inductance will be higher from calculation.  Also, if webench only goes to 10 mA you can calculate there and double the inductor value and current sense resistor.

    If you are using the 2 MHz part and 700 uH rough calculations will give.

    duty cycle = 68% at 3.5V input

    ton = 340 ns

    di = 1.7 mA

    Best Regards,