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LMR64010: Boost output Inductor and capacitor values for light load

Sergej Dziuba
Prodigy 40 points
Part Number: LMR64010

Hi!

I design power supply for 5.0V -> 36V or 12V-36V. Both variants should work. This is for MBUS interface power.

Load current: 0.0015A to 0.04A. 

Question: what value of inductor and output capacitor is better for such loads and voltages?

I tried many Inductors from 20u to 50u, all seems enough good from voltage stability point of view. But what is the from efficiency point of view and Ipeak/Iload current relation, I mean continuous/discontinuous mode?

Is continuous mode possible for such small load currents?

Thank you!

  • 0
    TI__Expert 5180 points

    Hi,

    There is no need to use such big inductor, typically 10uH inductor is okay for this application. If low cost and size are required, smaller inductor can be used. The calculation can be found in  MINIMUM INDUCTANCE part of datasheet, which is about 3-4uH for this application. The output capacitor is related to output voltage ripple and control loop requirement, which have smaller impact on efficiency. 

    I think for 1.5mA load, discontinuous mode is needed, otherwise efficiency will be very low. BTW when 5.0V -> 36V, duty cycle will be about 0.9, close to the chip's max duty cycle, which needs attention in real bench test.

    Best Regards,

    Eric Yue