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LM25148: stackable function

Fred Cheng
Expert 4620 points
Part Number: LM25148
Other Parts Discussed in Thread: LM25145

Hi team,

I'm curious why I can't use regular controller like LM25145 to do the stackable function?

is this due to the compensation or the interleaving clock?

  • 0
    TI__Mastermind 22299 points

    Hi Fred, 

    For multi-phase the comp node is shared such that each device will have the same duty cycle and the same load transient response.

    The Comp node is the output of the error amplifier, for multi-phase you need to be able to disable the error amplifier of the other phases, only the primary error amplifier should be driving the COMP.

    Its not possible to disable the error amplifier and keep switching on LM25145, so a traditional multiphase system will not work. 

    Hope this helps,

    -Orlando

  • 0 in reply to Orlando Murray
    TI__Expert 4620 points

    Hi Orlando,

    what if I use two LM25145 with same compensation network?

    they will still have same duty cycle and load transient theoredically.

    but their clocks may not be 180 out of phase, is this gonna work?

  • +1 in reply to Fred Cheng
    TI__Mastermind 22299 points

    Hi Fred,

    No we don't recommend two free-running controllers with their own loops.

    The current sharing per phase may not be equal if they are free running. 

    You may end up with one controller sinking current instead of sourcing current, if running in FPWM mode.

    -Orlando