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ADP2301 Switching Node Waveform

Category: Hardware
Product Number: ADP2301AUJZ

Does anyone know what causes this waveform at the switching node of a buck?

This was configured for 12V in 5V out .  It uses a 10uH inductor.  The load was 100 ohms.  

I see a typical hysteretic mode when I remove the load:

When I zoom in in the switching edges, I see something similar to that "oscillation"-like waveform.

It looks like the transistor turns on partially, which can't be good.  

If I increase the load to 50 ohms, the switching node looks normal.

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  • Hi cgervasi,

    What you are seeing is expected when operating at light load. To learn more, you can read page 14 of the data sheet (Power Saving Mode) and Figure 27 for waveform of Light load performance at steady state. The oscillation on SW node is due to parasitics at switches and inductor forming LC tank.

    We do this because we want to achieve higher efficiency at light load.

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  • Hi cgervasi,

    What you are seeing is expected when operating at light load. To learn more, you can read page 14 of the data sheet (Power Saving Mode) and Figure 27 for waveform of Light load performance at steady state. The oscillation on SW node is due to parasitics at switches and inductor forming LC tank.

    We do this because we want to achieve higher efficiency at light load.

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