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BQ25758: BQ25758 L1 value issue

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Prodigy 20 points
Part Number: BQ25758

Tool/software:

HI Sir,

  BQ25758 pass inductor L1 "Table 7-1. Recommended Part Numbers for up-to 48-V EPR (5-A output): (continued)" show CMLB135T-100MS  value: 10 μH, 22 mΩ, 10.5~13A

  if i use 19.5V/15A input, is still can use the same inductor? or need another inductor that has higher current (maybe 30A)?  

  • 0
    TI__Expert 6985 points

    Hi,

    The table that you refer to is for 5A on the output. Since your input current is 15A, the average inductor current will be at least 15A. With this application, an inductor with a better saturation current rating is required.

    Taking a look at Section "8.2.1.2.3 Inductor Selection" (it may be Section "7.2.1.2.3 Inductor Selection" for the datasheet you are looking at), we mention that the saturation current should be higher than the inductor current plus one-half of the current ripple.

    30A should be good enough for your application since our device is limited to 20A, but you should make sure that your switching frequency and inductance selections keep your current ripple below 10A.

    Let me know if you have any further questions about selecting your inductor.

    Best,
    Michael