Texas Instruments Corporation

National Semiconductor Corporation

Irwin Nederbragt

Steven Michael Barrow

James Harbison Masson

Daniel Ross Herrington

Craig Steven Cambier

Yan Yin

Chi Yuen Lai

Steven Barrow

Circuits and methods for detecting the presence of a leading-edge phase-cut dimmer. The dimmer detector comprises an edge detector, a pulse stretcher and a filter. The edge detector detects whether an input signal has a rapidly rising edge and generates an output signal pulse if a rapidly rising edge is detected. If the edge detector outputs a signal pulse, the pulse stretcher generates a stretched pulse having a duration that is longer than the signal pulse received from the edge detector. The filter produces a dimmer detect signal that indicates whether a leading-edge phase-cut dimmer is detected. If the pulse stretcher output signal comprises at least a predetermined number of stretched pulses within a predetermined amount of time, the dimmer signal signals the presence of a leading-edge phase-cut dimmer.

Leading-edge phase-cut dimmer detector

A lighting system includes a switch configured so that when the switch is in a first state, current from a supply flows to a light emitter, and when the switch is in a second state, current from the supply flows through the switch bypassing the light emitter. A capacitor in parallel with the light emitter provides current to the light emitter sufficient to cause the light emitter to emit light when the switch is in the second state.

Lighting system

A method includes receiving a sense signal having multiple pulses, where the sense signal is based on an output of a dimmer. The method also includes, for each of multiple sampling periods, (i) identifying a pulse duty cycle by sampling at least one pulse in the sense signal and calculating a duty cycle of the at least one pulse and (ii) generating an output value identifying a duty cycle for driving one or more LEDs. The output value is based on the pulse duty cycle. The method further includes generating a holding current for the dimmer (i) during the sampling of the at least one pulse in at least one of the sampling periods and (ii) when the pulse duty cycle is less than a specified threshold. The holding current can be applied continuously when the pulse duty cycle is less than the specified threshold (such as 15%).

Dimmer decoder with low duty cycle handling for use with LED drivers

A method includes receiving a sense signal having multiple pulses, where the sense signal is based on an output of a dimmer. The method also includes, for each of multiple sampling periods, sampling a subset of the pulses in the sense signal during that sampling period. The method further includes generating a holding current for the dimmer during the sampling of the subset of pulses in at least one of the sampling periods. In addition, the method includes, for each of the sampling periods, generating an output value identifying a duty cycle for driving one or more light emitting diodes (LEDs). The subset of pulses in each of the sampling periods includes multiple pulses during that sampling period but not one or more initial pulses at a beginning of that sampling period.

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Brighton, CO, United States of America

Irwin Nederbragt