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Recommend a suitable buck converter to step down 12V to 4.3V to power up a Lipo Charger IC

Kian
Expert 1595 points
Other Parts Discussed in Thread: TPSM843B22, TPS54KB20, TPS543B22, TPS541620, TPSM5D1806, TPS564252, TPS565247, TPS564255, TPS565242

Hi.

I am designing a power supply to charge multiple devices at the same time. I have a 12V 45W output laptop charger that provides the input to a power supply circuit that I am planning to design. The power supply circuit should provide 16 channels of output, each with an output voltage of 4.3V and 1A of current. This output is used to provide the input voltage and current to a charger IC (TPS4056 - configured to charge a single 4.2V Lipo battery with 1A charging current). The power supply should be able output on all 16 channels at the same time. I am thinking if I can design 4 buck converter circuits each providing 4.3V, 4A output. Then each buck converter circuit output will be split into 4 channels (in parallel), therefore providing a total of 16 channels.

I hope to get advise on a buck converter IC that would be suitable for my application as described above. Thank you in advance!

  • 0
    TI__Guru 52745 points

     

    First, 12V @ 45W is not going to provide the input power necessary to source 16x 4.3V @ 1A (68.8W) of output power, so your sourcing supply could be an issue.  I would recommend a minimum of a 75W supply for powering 16x 4.3V @ 1A 

    Second, TI offer BUCK converters that can source more than 16A at 4.3V if you are interested in a single BUCK rather than 4.  You can use this link to search through all of the regulators:

    https://www.ti.com/power-management/non-isolated-dc-dc-switching-regulators/step-down-buck/products.html

    If you want a module (MOSFETs and Inductor integrated) I could recommend the TPSM843B22 

    If you want a converter (MOSFETs integrated) I could recommend the TPS54KB20 or TPS543B22 

    If you want a 4x 4A solution instead

    I can recommend the TPS541620 dual output 6A converter or the TPSM5D1806 dual output 6A module.  Each could provide 2 outputs so you'd only need 2 converters for the 4x 4.3V at 4A rails. 

  • 0 in reply to Peter James Miller
    Expert 1595 points

    Thanks Peter for the recommendations.

    TI has more than a thousand buck regulator parts. I understand that I should choose a buck regulator with a Vin that supports 16V. And the output of the buck regulator should provide the output current I need ( either 1 regulator with 1 output of 16A or greater, or  1 regulator with 2 outputs of 8A each, or multiple regulators as long as the total output current meet my needs of 16A). Should I also consider any other specifications such as switching frequency, control mode etc? Are there also specific features that I need for my application?

    BOM cost is an important factor for me. I am able to find many parts that cost $0.110 | 1ku and meet my basic requirements (if I use 4 pcs) of the input voltage, output voltage and output current. For example the TPS564357, TPS564252 and TPS564255 share the same datasheet but operates in different modes. Or the TPS565242/TPS565247 seems suitable too, again differing in their modes of operation. Are the parts suitable and which mode should I be looking at?

  • 0 in reply to Kian
    TI__Genius 15417 points

    Hi Kian,

    For TPS56425x family, the three parts operate in different mode at light-load. Datasheet 7.4 describes the details. Also this article makes a comparison table you may refer to.

    TPS56524x is 5A part, while TPS56425x is 4A part, current ratings are different. Also TPS56524x Pin4 is AGND, while TPS56425x Pin4 is PGood.

  • 0 in reply to Miranda Gu
    Expert 1595 points

    Hi Miranda,

    Which Functional Mode should I use for my application? Thanks in advance!

  • 0 in reply to Kian
    TI__Genius 15417 points

    Hi Kian,

    Do you care about higher light-load efficiency or lower light-load Vout ripple?