Patent ID: 11870333
Assignee: LUTRON TECHNOLOGY COMPANY LLC
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. An illumination device configured to receive power from an alternating-current (AC) mains supply through a dimmer, the illumination device comprising:
a light-emitting load configured to emit light;
a power supply configured to conduct a supply current from the AC mains supply and produce a drive current through the light-emitting load when the power supply is active; and
a control circuit coupled to receive a phase-cut signal from the dimmer, the control circuit configured to control the power supply to be active for a length of an operating time period during a conduction period of a half-cycle of the phase-cut signal, the control circuit configured to determine a maximum duration of the operating time period during the half-cycle based on a length of the conduction period of the phase-cut signal;
wherein the power supply comprises a first stage configured to produce a direct-current (DC) voltage from the phase-cut signal, and a second stage configured to receive the DC voltage and produce the drive current through the light-emitting load;
wherein the control circuit is configured to receive a feedback voltage indicating a magnitude of the DC voltage and to determine the average magnitude of the supply current to be drawn from the AC mains supply in response to the feedback voltage; and
wherein the control circuit is configured to set the length of the operating time period equal to the maximum duration when an average magnitude of the supply current to be drawn from the AC mains supply over multiple cycles is greater than a threshold, and set the length of the operating time period to be less than the maximum duration when the average magnitude of the supply current to be drawn from the AC mains supply is less than the threshold.