• State TI Thinks Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 1 answer
  • Subscribers 62 subscribers
  • Views 422 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS61022: use with 3.3uH inductor

Andrew Charnley
Intellectual 640 points
Part Number: TPS61022


Hi,

I'm using this part and have a ton of Coilcraft XEL5030 3.3uH inductors to use up. The datasheet says the TPS61022 is designed for 0.3uH-2.9uH. I've tested the 3.3uH and it appears to be working great, but as a sanity check is there any reason not to roll with it?

The 3.3uH still has a high saturation of 8.4A (and ripple will be lower) and a DCR of ~22mOhm. Losses at the lower voltage end of the boost will be a bit higher but I can live with that.

The application uses a maximum of 2.5A at 5V but isn't current protected other than the fold-current inside the TPS61022. My worry is the inductor could saturate under this condition leading to FET damage and hence my double check with an expert.

Regards,

Andrew

  • 0
    TI__Genius 12845 points

    Hi Andrew,

    0.3u~2.9uH is just the recommended value that we have tested, if you use 3.3uH and have tested it without any problem, I think it also will be fine, because 3.3uH is not very far from the recommended value.

    Regards,

    Nathan

  • 0 in reply to Nathan Ding
    Intellectual 640 points

    It's more for the valley current, ILIM_SW, which I read as 10A max. XEL5030-3.3u has a 8.4A saturation point, so I foresee a potential for the lower FET inside the TPS61022 to be destroyed.

    I have no current limitation other than the TPS61022, and it's fed by super-capacitors which will sink the 10A no problem. The condition shouldn't ever occur, it would need a USB device to short, but...

  • 0 in reply to Andrew Charnley
    TI__Genius 12845 points

    Hi Andrew,

    From my understanding, are you worried about the potential 10A from super cap may damage the inductor?

    The 10A current will always be or it just lasts for a short time? If there is only a short time, I think it not a big problem for inductor.

    Regards,

    Nathan

  • 0 in reply to Nathan Ding
    Intellectual 640 points

    No, the inductor won't be damaged.

    The super-caps can supply anything short-term, 100A will be possible, so the only line of defence is the TPS61022. The datasheet says the max valley current that it trips at is 10A. At 8.4A the XEL5030-3.3u is has a 30% indutance drop.

    I've dived into the XEL5030 datasheet and Coilcraft as usual have come through, at 10A it has 2uH inductance, well within the TPS61022 operating parameters. I now think it'll work ok during a short.

    It would be good to have this verified by a DC-DC expert as it could be an expensive mistake.

  • 0 in reply to Andrew Charnley
    TI__Genius 12845 points

    Hi Andrew,

    Yeah I think so,  it is not a big problem.

    Regards,

    Nathan