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TPS54140 & TPS54160 on SwitcherPro

Hidekazu Someno
Expert 5130 points
Other Parts Discussed in Thread: TPS54140, TPS40140, TPS54160

When we designed the application circuit  with the same conditions(VIN=10V-16V, VO=5V, IOmax=1A, Fsw=2.2MHz) on both TPS40140 and TPS40160, We had  a different result.   In case of TPS54160, the following commnt was displayed. but,no comment  for TPS54140.  Both devices should have the same characteristics regarding minimum controllable On time.  Why does TPS54160 only has the following comment?

Duty cycle is too low for the device in this situation. Calculated on time is below the 'Minimum Controllable On Time'of the device! Use the analysis tab to view the calculated on time. This device has a 'Minimum Controllable On Time' of 130ns.

  • 0
    TI__Intellectual 1280 points

    Looks like both devices calculate the same on time of 125ns.  Both devices have a minimum on time of 130ns According to the datasheets.  The TPS54160 design is giving the correct warning message about the design whereas the TPS54140 let's 125ns fly as acceptable.  On further investigation the internal minimum controllable on time of TPS54140 was erroneously set to 100ns.  So it will be updated to 130ns and this design will also be flagged as violating the minimum on time constraint.  Thanks for letting us know about this bug.  

  • 0 in reply to Heath Gallimore
    Prodigy 10 points

    The minimum controllable on time is chnaged to 130 for both  TPS54140 & 54160.

    To test: TPS54160:  Inputs -50, 53, 4.2, 0.5 - We can see that min on time is 128 in analysis page and there is an error at the bottom of the schematic . " Min. on time of 130"

    if you change vout  to 4.3, then min.on time becomes 130.7 and the error will be gone.