LED driver with inherent current limiting and soft startup capability

摘要

An inductor-less LED driver circuit is provided with soft startup and inherent current limiting capabilities. A diode rectifier is coupled across an AC mains input, with the outputs for the rectifier coupled directly across an LED array. A bi-directional switching circuit and current limiting capacitor are coupled in series between a first mains input and a first rectifier input. A controller turns the bi-directional switching circuit on and off to enable or disable conduction of power from the AC power source, wherein the bi-directional switching circuit is turned on in association with a detected zero voltage state for AC input power, and the bi-directional switching circuit is turned off in association with a detected zero current state for AC input power. The controller further adjusts switch states for the bi-directional switching circuit in response to a dimming control signal corresponding to a desired lighting output level.

主权项

1. A lighting device comprising:
an input having first and second terminals connectable to an AC power source; a controllable switch module coupled to the first AC power source input terminal, the controllable switch module configured to conduct power in association with a detected zero voltage state for power received from the AC power source, and to disable conduction in association with a detected zero current state; a capacitor coupled to the output for the controllable switch module and defining a maximum peak output current for the device; and a rectifier circuit having a first input coupled to the capacitor and a second input coupled to the second AC power source input terminal, and first and second outputs, the rectifier circuit configured to rectify AC input power received thereby into DC output power across the first and second rectifier outputs.