With any HB-LED driver, the output should be a regulated current source that can provide the necessary output voltage to the string(s) of LEDs. Though linear regulators are cheap and small, design limitations and poor efficiency usually make them non-ideal for driving HB-LEDs. In general, a switching regulator will be the best choice.
Deciding on a topology
A power MosFET, diode and inductor form a three-terminal network which is the basis for all switching regulators. There are three basic topologies derived from this network using different input/output configurations: buck (step-down), boost (step-up) and buck-boost (step-up/down). The switching regulator topology is chosen based on the specific application.
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This article was published in the July/August 2009 issue of LEDs Magazine.
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