by Haifeng Fan, Texas Instruments, Phoenix, Ariz, How2Power Today, Mar 15 2014
Focus:
In dc-dc converter applications, using a current-sense resistor to detect overloads
generates additional conduction loss, requires a large footprint for heat dissipation, and
adds cost. Inductor direct-current resistance (DCR) current sensing can eliminate the
current-sense resistor, reducing solution size while improving efficiency. This article
explains how to design an inductor DCR current-sensing circuit and discusses practical
design considerations to improve current-sensing accuracy in boost converter designs.
Article begins by explaining the principles of inductor DCR sensing, then discusses
factors affecting current-sense accuracy such as time constant mismatching and bias-
current-induced offset voltage. Techniques for minimizing the offset voltage error are
described. Loss mechanisms in resistor and DCR current sensing are explained and compared.
Experimental results compare the converter efficiency obtained with inductor DCR current
sensing versus resistor current sensing.
What you’ll learn:
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