Hybrid dimming control techniques for lighting drivers

摘要

Techniques are disclosed for independent control of individual LED strings driven from a single AC current source. A lighting driver circuit includes a DC-AC inverter with series resonance that provides a current that may be split into multiple currents for driving multiple LED assemblies. Current splitting transformers may be used to divide the current from the AC source, and the amplitude of the current from the AC source may be determined by a microcontroller. In some cases the current splitting transformers provide galvanic isolation to the LED assemblies. The multiple LED assemblies may be controlled by a number of switches that may independently activate the individual LED assemblies based on the duty cycle of multiple PWM signals provided to the switches by the microcontroller. When all of the PWM signals output from the microcontroller are on an off-cycle, the current source may be turned off.

主权项

1. A lighting driver circuit comprising:
an AC current source configured to provide a first current; at least one current splitting transformer configured to split the first current and provide a current to each of a plurality of LED assemblies, wherein the current to each of the plurality of LED assemblies is dependent upon a transformation ratio of the at least one current splitting transformer and the current source is configured to directly feed an LED assembly; a plurality of switches configured to control the current through each of the plurality of LED assemblies; and a controller operatively coupled to the plurality of switches, wherein the controller is configured to provide a PWM signal to each of the plurality of switches, wherein the duty cycle of each PWM signal independently controls each of the plurality of switches.