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lm5170-q1: How will Buck and Boost mode operation with unidirectional function of LM5170

Muthukrishnan P
Prodigy 110 points
Part Number: LM5170-Q1
Other Parts Discussed in Thread: LM5170

I am Planing use the above given part number of IC for Power supply in automotive application. I want to use Buck and Boost mode  with unidirectional. Input 30V  to 80V, Output 48V fixed. Out put Current  Max 420A at Peak power condition. Peak Power 20KW expected. How  will control Output voltage  of LM5170-Q1 IC. does it have inbuild feedback control or external voltage control loop  circuit has to add.  Could we use single IC  or mutiple IC  to meet required Peak Power Please advice for the same request

  • 0
    TI__Guru* 78440 points
    Please note that the LM5170 is not a conventional buck-boost controller. It does buck mode in one direction and boost in the other direction, and the bidirectional operation is supported with two different voltage rails of which one is always at higher voltage than the other.

    If you want both buck and boost control in one direction, you will need two LM5170 in back-to-back connection, say Buck down to 28V and then boost up to 80V.

    The LM5170 basically implement a current source. for your 420A load, you need multi phase namely multiple LM5170 to share the load. Output voltage regulation required external op-amp, and please refer to the LM5170 EVM's schematic to see how it does with the voltage regulation.

    Thanks,
    Youhao Xi, System and Applications Engineering, APP-BMC-BCS, TI
  • 0 in reply to Youhao Xi
    Prodigy 110 points
    Hi Youhao,
    Thank you for your reply and information that is realy very useful for us.
    What is maximum Power can support one LM5170-1Q? We have a question Is it possible one LM5170 to meet the rated power and current with using rated components like MOSFETs, Instructor etc. else we have to use multiple LM5170 IC to meet the rated power and current (420A and 20KW).



    Regards
    Muthukrishnan P
  • 0 in reply to Muthukrishnan P
    TI__Guru* 78440 points
    The LM5170 has very strong integrated gate drivers: 4A sourcing and 5A sinking. This will determine how big the MOSFETs can be efficiently driven. In the nominal 48V-12V system, each phase can easily handle up to 500~600W. For your 20kW, you may consider many phases. The advantage with the LM5170 is the ease of stackable: simply parallel more phases and the power will be shared evenly (+/-1%).
  • 0 in reply to Youhao Xi
    Prodigy 110 points
    Hi Youhao,
    Thank you for your confirmation.
    Could your please suggest Buck controller and boost controller IC for high power application like 1KW - 5KW( 48V-56V Output).
    This is intention automotive power train application

    Regards
    Muthukrishnan P