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LM5113-Q1: Input digital stability

Nicholas Benavides
Prodigy 30 points
Part Number: LM5113-Q1
Other Parts Discussed in Thread: LMG1205, LMG1210, , LM5113, LMG5200

Does the LM5113-Q1 component have the input stability problem that was seen in the LM5113 which necessitated the input filter and requires >3ns input pulses?   My understanding is that it was corrected in LMG1205, but not yet in the experimental samples of the LMG1210.  I would also add that we have recreated this phenomenon in the LMG5200 integrated phase leg as well, though there seems to be no mention in it's datasheet

  • 0
    TI__Genius 12990 points
    Hi Nicholas,

    Thanks for asking about this and welcome to e2e! Im an apps eng with this device. LM5113 and LM5113-Q1 both have this bug of producing 10-100ns output with <3ns input. LMG1205 fixes this bug which includes the internal input lowpass filter to filter the minimum pulse width. LMG1205 is recommended for new designs.

    There was a pre-production issue with LMG1210 which was not related to the 5113 bug. 1210 experiences higher than normal (140mA) IDD operating current if a L-H-L pulse of less than 3ns in applied to the input. The 1210 pre-production issue has been fixed and should be reflected in the pre-production stock currently available.

    Thanks,
  • 0 in reply to Jeffrey Mueller
    Prodigy 30 points
    Any chance you could comment on the LMG5200 part with respect to this 3-ns issue? We have observed this there as well.

    Thanks,
    -Nick
  • 0 in reply to Nicholas Benavides
    TI__Prodigy 645 points

    Hi Nicholas,

    The LMG5200 does not have the issue with the very short input pulse. What issue did you see? Do you have scope captures of it? 

    Regards,

    Nathan

  • 0 in reply to Nathan Schemm
    Prodigy 30 points

    I dug back through my old test files, but it was nearly a year ago  and I couldn't find a nice smoking gun trace capture.  What we had found was that we were having failures at initialization of a PI loop (in TI 28027 Piccolo DSP) as the duty cycle lifted off zero, which was causing a shoot-through on phase-leg.  When we limited to pulse width to >10 ns, we no longer had any failures. Just after having discovered this, we ran into issues with the LM5113, which were eventually pointed out in the datasheet, so we have since assumed it is the same basic problem.    Unfortunately it is not easy for me to recreate now on a bench because the event tends to destroy the PCB when it occurs.

    Thanks,

    -Nick

  • 0 in reply to Nicholas Benavides
    TI__Prodigy 645 points

    Hi Nick,

      It does sound like it could be the issue we are describing. Most pre-production units of the LMG5200 did have this issue, however production units don't.  Nonetheless, the timelines don't match up for you to have tested pre-production units though. I guess since it is not a current problem and can't reproduce it now, we will have to leave at that. If you do ever re-test units and find a similar problem, please bring it to our attention.

    Regards,

    Nathan