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LM2623: 5V to 12V at 1.29A load current

Andrew Baek
Intellectual 915 points
Part Number: LM2623
Other Parts Discussed in Thread: BQ25895, LM5157, TPS55330

Can LM2623 support the following configurations?

  1. Config 1
    1. Input: 5V at 3.1A (PMID from BQ25895)
    2. Output: 12V with 15W output (5V x 3.1A), the estimated current would be 1.29A
  2. Config 2
    1. Input: Li-Ion battery (5000 mAh, 3.7V to 4.2V))
    2. Output: 12V, 15W output

If possible, could you provide an example schematic?

Regards,

Andrew

  • 0
    TI__Guru* 78060 points

    Hi Andrew,

    Thank you for considering our device.  I am afraid your power levels exceed LM2623's peak current limit (2.2A for LM2623A, and 1.2A for LM2623).   Please consider the LM5157.

    Best Regards,

    Youhao

  • 0 in reply to Youhao Xi
    Intellectual 915 points

    Hi Youhao,

    I thank you for prompt response.

    For my understanding, does the peak current limit apply to both the input and output?

    For instance, the max input current at 5V is also 2.2A so the theoretical output power maxes out at 11W (= 5V x 2.2A).

    Regards,

    Andrew

  • 0 in reply to Andrew Baek
    TI__Guru* 78060 points

    Hi Andrew,

    It is the peak switch current, also the peak inductor current.  Your 2.2A is just a dc current, and the switch also sees the inductor ripple (or ramp) current. 

    For theoretical output power, please also taken into account the efficiency :-).

    The LM5157 should be able to support your two configurations.  You need to watch your inductor selection to prevent the peak current hitting the LM5157's peak current limit. 

    Best Regards,

    Youhao

  • 0 in reply to Youhao Xi
    Intellectual 915 points

    Understood.

    The issue with LM5157 is no availability.

    Previously we have used TPS55330, which also is out of stock at TI and other distributors.

    I would appreciate if you can suggest other alternatives.

    Thank you,

    Andrew

  • 0 in reply to Andrew Baek
    TI__Guru* 78060 points

    Hi Andrew,

    Sorry to hear.  Our team is offering technical supports. This needs to be handled by TI sales team. Have you contacted TI sales team in your region? 

    Thanks,

    Youhao