Industrial electronics
Myth vs fact
Does Inductor Current Always Flow in Converters?
Your converter formula might be wrong at light load.
Quick check · tap an answer to continue
Lesson notes
Key points
- At light load the average inductor current drops below half the ripple, so current falls to zero before the cycle ends.
- Once current stops, the simple gain formula no longer holds, and output voltage rises with load resistance and switching frequency.
Definitions
- Critical inductance
- The minimum inductance that keeps inductor current just touching zero at the boundary of CCM and DCM.
Myth: Converter inductor current always flows continuously.
Fact: At light load, current can drop to zero each cycle: discontinuous mode.
Takeaway: Simple gain formulas assume continuous inductor current.
Quick check: Myth or fact: Vout = D × Vin for a buck converter at every load.
- Myth
- Fact
- Depends
It only holds in continuous mode; in DCM the output also depends on load.
Discontinuous modeGain changes
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