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TPS54260: How it works if vin fall under vout?

Luciano Pautasso
Prodigy 60 points
Part Number: TPS54260
Other Parts Discussed in Thread: LMR16020, LM76002

I have to develope a low drop out, switching dc-dc regulator.

I tinked at TPS54260.

Nominal vout is 33v (approx < 2 amp out)

Nominal vin is 42v

Approximately, can you complete this table of expected values?

  • Vin-> Vout
  • 42 -> 33
  • 41 -> 33
  • 40 -> 33
  • 39 -> 33
  • 38 -> 33
  • 37 -> 33
  • 36 -> 33
  • 35 -> 33
  • 34 -> ??
  • 33 -> ??
  • 32 -> ??
  • 31 -> ??
  • 30 -> ??
  • 29 -> ??

More better suggestion about I.C.  Part Number to use?

  • 0
    TI__Mastermind 23845 points
    Hi,

    Are you looking for synchronous solution or non-synchronous solution?
    One part that comes to mind is LMR16020 for non-synchronous solution
    As for Synchronous, i would recommend LM76002 which is full featured part, internal FETs and better efficiency with internal compensation
    www.ti.com/.../LM76002

    Thanks
    -Arief
  • 0
    TI__Genius 11085 points
    Hi Luciano,

    We would not recommend the TPS54260 for Vin falls under Vout operation condition. The two devices Arief recommended are better choices. What will happen on these two parts when Vin falls low is that frequency will reduce to maintain Vout in regulation as long as possible. When regulation cannot be maintained anymore, Vout will drop when Vin drops. The difference between Vin and Vout under dropout condition depends on load current. The higher load current, the more difference between Vin and Vout. You can find dropout curves on LMR16020/30 and LM76002/3 datasheet for your reference.

    Yang