Modified DCR Current Sensing Expands Inductor Choices For Peak-Current-Mode Buck Regulators
by David Baba, Texas Instruments, Chandler, Ariz., How2Power Today, Dec 15 2025
Focus:
In buck regulators, use of power supply ICs with peak current mode control and internal
slope compensation may seem to restrict your design choices, requiring use of resistor-
based current sensing and use of a specific inductor value with a specific dc resistance.
However, in such applications, a method of inductor DCR current sensing introduced here,
gives designers more flexibility in inductor selection. This allows designers to optimize
the inductor for efficiency, size, cost or other criteria. The method involves tuning a
DCR current-sensing network to accurately replicate the inductor current in peak-current-
mode buck converters. By matching the RC network’s time constant to the ratio of
inductance and its DCR, you can align the sensed waveform with the actual inductor current
for both dc scaling and ac ripple attenuation. This enables current-limit control and
stable loop operation under different inductor values.
What you’ll learn:
- How to implement inductor DCR current sensing in buck converters with peak current mode control and internal slope compensation
- How to optimize inductor selection in buck converters with peak current mode control and internal slope compensation
- How to understand how inductor DCR current sensing works
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