LED driver with transformerless hysteretic boost

摘要

A system and apparatus including a light emitting diode (LED) driver provides an operating DC voltage to a plurality of LEDs connected in series (LED array) for providing illumination. A rectifier circuit and a filter are coupled to an AC power supply and provide a rectified and filtered DC source voltage to a transformerless voltage boost circuit, which provides the operating DC voltage to the LED array. A hysteretic self-oscillating circuit drives the transformerless voltage boost circuit at an oscillation frequency. A tap is connected between two LEDs in the LED array, which provides an auxiliary DC voltage, which is used to power the oscillating circuit and which eliminates the need for the LED driver to have a conventional transformer or auxiliary DC-DC power converter. The transformerless voltage boost circuit includes an inductor, a capacitor, a diode, and a switch wherein the switch is controlled by the oscillating circuit.

主权项

1. A light emitting diode (LED) driver for providing an operating direct current (DC) voltage to an LED array, the LED array including a plurality of LEDs connected in series for providing illumination, comprising:
a transformerless voltage boost circuit configured to receive a filtered DC source voltage and to provide the operating DC voltage to the LED array; a hysteretic self-oscillating circuit for driving the transformerless voltage boost circuit at an oscillation frequency; and a tap connected between two of the plurality of LEDs in the LED array for providing an auxiliary DC voltage to the hysteretic self-oscillating circuit, wherein the auxiliary DC voltage is at least a part of the operating DC voltage provided to the LED array from the transformerless voltage boost circuit and the auxiliary DC voltage provided by the tap connected between the two of the plurality of LEDs in the LED array powers the hysteretic self-oscillating circuit for driving the transformerless voltage boost circuit at the oscillation frequency.