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TPS63020 inductor selection for high output current

Daniel Kuo
Prodigy 120 points
Other Parts Discussed in Thread: TPS63020

Hello,

I would like to know how to choose an inductor for the TPS63020 converter.  My application will require 4.5V @ 1.5A output, boosting from a li-ion battery (2.7V to 4.2V input).

The datasheet for the TPS63020 provides the following equation for determining inducator value (boost mode operation):

L = 0.5 x Vout

For my application, this means I would need at least 2.25uH to boost from 4.5V.  However, the equation doesn't seem to take into account output current or input voltage.  Given that I need 1.5A on the output, would I need to increase the inductance value to to achieve the required output current?

Thanks in advance,

Daniel

  • 0
    TI__Mastermind 32360 points

    Hi Daniel,

     

    In your case you will use this equation to calculate the inductor Value:

    L=Vout/2

     

    The peak current for the inductor in steady state operation can be calculated using equations 4 and 5 from datasheet (TPS63020) on page 16. In these equations the input voltage and the output current are taken in consideration.

     

    I based my calculations on a minimum frequency of 2.2MHz and I found

     

    I1=1.8425A

    I2=3.2341A

     

    The critical current value for selecting the right inductor is the higher value of I1 and I2 which is the 3.25A.

     

    Thanks!

    Tahar Allag

  • 0 in reply to Tahar Allag
    Prodigy 120 points

    That's exactly the answer I needed.

    Thank you for the help!