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TPS54228: 5V-to-3.3V Conversion

Kazuki Itoh
Genius 10125 points
Part Number: TPS54228
Other Parts Discussed in Thread: PMP4472, TPS562203, TINA-TI

Tool/software:

Hi team,

Is it okay to use TPS54228 for 5V-to-3.3V conversion?

My customer is using TPS54228 in the project in production.

At that time, the max. duty cycle limitation 65% was not described in the datasheet (Rev. C).

It is added in Rev. E. 

So my customer is asking questions below:

  1. Could you send me the collateral regarding duty cycle limitation? (Allowed duty cycle range details and graphs)
  2. Is the max output current allowed is 2A at the 65% duty cycle?
  3. If TPS54228 is used in light load, what is the maximum duty cycle? Is it okay to use at duty cycle >65%?

Best regards,

Kazuki Itoh

  • 0
    TI__Genius 12020 points

    Hi Kazuki,

    You can see this reference design, that's exactly your application.

    PMP4472 reference design | TI.com

    Thanks.

    Regards,

    Shipeng

  • 0 in reply to Shipeng Cheng
    TI__Genius 10125 points

    Hi Shipeng-san,

    The PMP4472 doesn't answer my customer's questions.

    It is still unclear that why TPS54228 is allowed to use for 5V-to-3.3V application.

    Could you please answer the questions again? 

    1. Could you send me the collateral regarding duty cycle limitation? (Allowed duty cycle range details and graphs)
    2. Is the max output current allowed is 2A at the 65% duty cycle?
    3. If TPS54228 is used in light load, what is the maximum duty cycle? Is it okay to use at duty cycle >65%?

    Regards,

    Kazuki Itoh

  • 0 in reply to Kazuki Itoh
    TI__Genius 12020 points

    Hi Kazuki,

    For 5V to 3.3V application the duty cycle should be 3.3/5=66%>65% so it's OK. If you think there's no margin, you can recommend our new device TPS562203.

  • 0 in reply to Shipeng Cheng
    TI__Genius 10125 points

    Hi Shipeng-san,

    As I mentioned, my customer is using TPS54228 in the project in production.

    So my customer need to assess the risk to keep using TPS54228 for 5V-to-3.3V application.

    As the duty cycle limitation is not specified in EE table and was not explicitly mentioned in the datasheet previous revisions, I believe it's TI's responsibility to answer my customer's questions.

    Again, could you please answer the questions?

    1. Could you send me the collateral regarding duty cycle limitation? (Allowed duty cycle range details and graphs)
    2. Is the max output current allowed is 2A at the 65% duty cycle?
    3. If TPS54228 is used in light load, what is the maximum duty cycle? Is it okay to use at duty cycle >65%?

    Best regards,

    Kazuki Itoh

  • 0 in reply to Kazuki Itoh
    TI__Genius 12020 points

    Hi Kazuki,

    I'm neither IC designer nor datasheet writer, all I know is thing in datasheet. As your need is slightly beyond datasheet (66% vs. 65%) and there's a reference design shows it is successful, and I run a TINA-TI simulation shows it's OK to run 4.5Vin 3.3Vout @ 2A. So personally I think it's OK. Thank you for your understand.

  • 0 in reply to Shipeng Cheng
    TI__Genius 10125 points

    Hi Shipeng-san,

    Could you please check with systems and design team?

    I think we need to make sure with systems/design team to make sure the risk that keeping the design is acceptable.

    Best regards,

    Kazuki Itoh

  • +1 in reply to Kazuki Itoh
    TI__Genius 12020 points

    Hi Kazuki,

    This device is designed by Japanese team in 2011, and the team is dissolved now so no one I can find. If you need check this spec, we need a designer to spend large effort(at least weeks) check the whole design and even I'm not sure the design files are still exist.

    I recommend your customer continue to use as they have used it in production and don't find any issue till now. If you think you must get a solid , please send out an email.