Driver circuit and method for powering an LED and illuminant

摘要

A power factor correction circuit (36) determines actual value between positive potential (64) of capacitor (52) and measured input of control circuit (40) connected in measuring branch (60). A measuring unit (108) determines voltage drop (109) across current regulator (82). A control unit (112) adjusts influence of voltage drop measure. A modifying circuit (72) connected between node of measuring branch (74) and driver circuit reference potential influences determined actual value of switch (78), to vary strength of current (80) between node of measuring branch and reference potential. The power factor correction circuit has controllable loading unit (44) for charging the capacitor in the rectifying circuit (26) with rectified sinusoidal alternating current line voltage (35). The control circuit is provided for determining an actual value of the capacitor voltage (57) and for regulating the actual value to a target value determined by controlling the loading unit. Independent claims are included for the following: (1) lighting unit; and (2) method for supplying sinusoidal alternating current line voltage to LEDs in lighting unit.