Highly Efficient LED Driver Tackles COVID But Also Benefits Lighting Applications

by Gregory Mirsky, Vitesco Technologies, A Spinoff Of Continental Automotive Systems, Deer Park, Ill., How2Power Today, Aug 14 2020

Focus:
This article describes the design of a very efficient current source for supplying a pre- determined current to LEDs, which can be connected in various configurations. It has no expensive current sensors like conventional LED drivers. Output voltage is defined by the overall voltage drop across the series-connected LEDs and can be higher than the supply voltage. Operation of this current source is based on series resonance, which makes the MOSFETs switch at zero current, reducing power loss. The author designed this current source to power UV-C LEDs used to kill bacteria and viruses but this circuit can also be used to power LEDs in conventional lighting applications. The article explains the principles of operation of a resonant current source; derives an expression for output current at resonance; presents a practical circuit implementation based on the LM5046 phase-shift PWM controller, explains its operation and calculates component values for a selected LED array. Since an adequate model is not available for the LM5046, it is replaced with the LT1160, and circuit performance is simulated.

What you’ll learn:

• How to drive LEDs using a resonant current source
• How to design a resonant current source LED driver

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