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LMR51606-Q1: LMR51606 issue of usage

Herbert Wang
Intellectual 685 points
Part Number: LMR51606-Q1
Other Parts Discussed in Thread: LMR51606

Tool/software:

Dear Expert:

When we tested LMR51606, we found that the node in front of the inductor after the switch SW had voltage waveform as shown in the figure below. What is this phenomenon? Do you need to process the waveform? How to deal with it?

Yellow: node voltage

Green: output voltage

  • 0
    TI__Mastermind 31315 points

    Hi Herbert,

    This is normal at light load for a PFM device. It is called discontinuous-mode conduction (DCM). Basically, this happens when the inductor current hits 0A before the start of the new switching cycle. The low-side switch will turn off, and the parastiic capacitance will resonate with the inductance to generate the ringing until the high-side switch turns on again.

    Thanks,

    Richard