DIGITALLY-CONTROLLED SWITCH-MODE START-UP CIRCUIT WITH DIMMER COMPATIBILITY FOR LED-BASED LIGHTS

摘要

Power consumption in a start-up circuit for a LED-based light bulb may be reduced by digitally switching a transistor of the start-up circuit coupled to the input voltage. When the transistor is digitally switched between on and off, a reduced amount of power is dissipated by the transistor, because it may not enter a saturation region of operation where the resistance of the transistor between drain and source terminals increases. The transistor may be coupled to a voltage regulator for generating one or more output voltages, including a supply voltage for a host controller IC. The transistor may be switched on and off by a digital signal generated by logic circuitry, which may decide to switch the transistor on and off based on a voltage level at an output of the voltage regulator.

主权项

1. An apparatus, comprising:
a voltage regulator configured to provide an output voltage for operating a lighting controller; a field-effect transistor (FET) coupled to the voltage regulator and configured to provide a supply current to the voltage regulator from a line input; and a logic circuit coupled to the field-effect transistor (FET) and configured to control the field-effect transistor (FET) during a start-up phase of the lighting controller and to control the field-effect transistor (FET) to provide dimmer compatibility.