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LM5121-Q1: Project of DC/DC converter

Gabriel Cassio Moreira Freitas
Prodigy 85 points
Part Number: LM5121-Q1
Other Parts Discussed in Thread: LM5122-Q1, LM5122, LM5170-Q1, LM5170, LM5119

Support Path: /Reference designs/Search for reference designs/

Hi everyone.

In the last days, I've been searching some components for a project of a DC/DC converter. The requirements are: input voltage 32 up to 44 V (lithium-ion batteries), output voltage of 48V, maximum outup current of 18A. One of the IC for this project is the LM5121-Q1, and I'd like to know if this component can handle this requirements. If not, could indicate some IC that support the project?

Thank you for the help.

  • 0
    TI__Guru* 78440 points
    Hi Gabriel,
    Thank you for considering the LM5121-Q1. We also have LM5122-Q1, similar part but not having the disconnect FET control. The reason for suggesting the latter is regarding your power level. 18A@48V is close to 900W and you may need multi phase to share the power. Please refer to the multiphase reference designs published in TI LM5122 or LM5122-Q1 webpage.

    Another approach is to use our high power LM5170-Q1, a dual phase controller which alone can support your power level. It is a bidirectional controller but it does not preven you from using just for boost mode. You can order an LM5170EVM to evaluate.

    Thanks,
    Youhao Xi, System and Applications Engineering, APP-BMC-BCS, TI
  • 0 in reply to Youhao Xi
    Prodigy 85 points
    Thank you so much about your tips about the ICs.

    Other question is, if you think is better to use a step-down converter to the same requirements (48V and 18A), but with a bigger battery (above of the 48V). If you think is better to use it, which IC is recommended?

    Thanks.
  • 0 in reply to Gabriel Cassio Moreira Freitas
    TI__Guru* 78440 points
    If the input voltage is higher than the output, you need a buck. For your power level, the LM5170-Q1 is still a proper choice: only run in buck mode. You may also consider multiphase with TI LM5119, but its max input voltage rating is limited to 65V. The LM5170 can handle 100V abs max input.