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DCDC Recommendation

Hong Tay
Expert 2465 points
Other Parts Discussed in Thread: LM2623, LM3481, TPS61221

Dear Sir, Madam,

Is there any DCDC with input voltage range 0.5V-5.5V, Vout 3.3V, Iout 0.5A?

Please help to advise. Thanks.

  • 0
    TI__Mastermind 39980 points
    Hello Hong,

    Unfortunately we do not have a device that can start up at 0.5V in to my knowledge? The Lowest Vin Device I can think of is the LM2623 which has a vin min of 0.8V.

    However, if you only need to run down to 0.5V at the input, you can "boot strap" a device by feeding the regulated 3.3V back to the Vin of a Boost controller?

    The LM3481 (configured as a SEPIC)can start up with a Vin minimum of 2.97V. and will work down to a low Vin if you feedback its output voltage to the Vin pin (diode OR'd). If you need to start up at a lower Vin suggest using the LM2623 as a bias supply to the LM3481. But you will certainly need 0.8V minimum to get the LM2623 started.

    Hope this helps?

    David.
  • 0 in reply to David Baba
    Expert 2465 points
    Hi David,

    Thanks for your advice.
    Do I need a buck/boost for this case?
    How about TPS61221?

    Thanks.
  • 0 in reply to Hong Tay
    TI__Mastermind 46905 points
    why input voltage range from 0.5~5.5V? is it possible to narrow the input voltage
  • 0 in reply to Hong Tay
    TI__Mastermind 39980 points
    Hello Hong,

    The TPS61221 can be used to generate the Bias supply for your boost controller, you will not be able to use for the main power stage due to the current limit on the device will not support your output power requirements. The boost controller mentioned, should be used to control a SEPIC power stage, which indeed is a Buck Boost Topology.

    Hope this answers your question?

    David.
  • 0 in reply to Jasper Li
    Expert 2465 points
    Hi Jasper,

    Thanks for your reply.

    The power supply is from wireless power receiver. The input voltage may have huge changes due to the condition of power transmission caused by external factor.

    What is the input voltage of the product you are going to recommend? Thanks.
  • 0 in reply to David Baba
    Expert 2465 points
    Hi David,

    Thanks for your advice. Do you have any recommendation for wireless power receiver as the power input? This is for new technology exploration, not the tradition wireless charging.

    Hope to hear from you soon. Thanks.
  • 0 in reply to Hong Tay
    TI__Mastermind 39980 points

    Hello Hong,

    What is the input voltage range for the wireless power receiver?  If its 0.5 to 5.5V and it can actually deliver the power required to the input of the DC to DC with a certain  load on its output, I suggest you follow the recommendations above?  If the input voltage range is different, can you please detail what it is?

    Thanks.

    David.