1
\$\begingroup\$

In the datasheet of a DC-DC Converter IC, a specific inductor is mentioned, but that one is out-of-stock on the website I am buying electronics. So, I wanted to replace it with another inductor. But there are some differences between the two of them.

Original Inductor:
Current Rating - 3.9A
Saturation Current - 3.8A

Replacement Inductor:
Current Rating - 6.7A
Saturation Current - 10.7A

And except these, all the other specifications are the same. So can I replace the original inductor with the other one?

\$\endgroup\$

1 Answer 1

Reset to default
1
\$\begingroup\$

Higher than necessary saturation current should be no problems for 99.99 % of DC-DCs out there. Edge cases could be some arcane or obsolete one which relies on inductor saturation for regulation or protection.

Be aware of low self-resonant frequency with a big(ger) inductor. If still way above your switching frequency, the only downside would be cost, space occupied and weight.

As noted by John D in the comments, the core loss would suffer a bit. A larger core of the same material will have higher Al value. For an inductor with same inductance with a larger core, this means fewer turns and more core volume, resulting in more losses. If you have very high AC current, this won’t be negligible. For a “normal” CCM choke, less of a concern. Test it and see if you can measure any increase in consumption or drop in efficiency. If not or low enough to tolerate, you are fine.

\$\endgroup\$
6
  • \$\begingroup\$ The self resonant frequency of both the inductors are the same and cost, space and weight are not a problem. So you would say it is fine for saturation current and current rating to be higher compared to the original inductor, Am I right? \$\endgroup\$
    – B.S.S.SRIKAR
    Commented Oct 25, 2023 at 11:36
  • \$\begingroup\$ @B.S.S.SRIKAR Yes, then you are fine. The equivalent example on a capacitor is to choose one with too high voltage rating. \$\endgroup\$
    – winny
    Commented Oct 25, 2023 at 11:58
  • 1
    \$\begingroup\$ The only other unusual edge case could be core loss. If the converter frequency is high and the core material on the bigger inductor isn't suitable for the frequency and flux density then the losses could be a lot higher. Unfortunately, manufacturers don't usually specify core loss characteristics for off-the-shelf inductors, though some provide online tools to estimate the losses. \$\endgroup\$
    – John D
    Commented Oct 25, 2023 at 17:20
  • \$\begingroup\$ @JohnD Excellent point. I’ll add that in. \$\endgroup\$
    – winny
    Commented Oct 26, 2023 at 9:52
  • 1
    \$\begingroup\$ Extremely low. Biggest risk would be to pull out the though holes in the PCB when desoldering. \$\endgroup\$
    – winny
    Commented Oct 29, 2023 at 7:25

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.