LED-Based Lighting Power Supplies With Power Factor Correction And Dimming Control

Abstract

A power supply for powering one or more loads includes a boost circuit with power factor correction (PFC) that provides an operating voltage from an electrical power source, and a dimmer detection circuit that determines a dimming level applied to the electrical power source, and generates a pulse width modulated (PWM) signal based upon the dimming level. The power supply also includes one or more current control circuits, each current control circuit being associated with each of the one or more loads, and coupled in series with the operating voltage, its associated load, and a ground of the power supply, so as to control a current through its associated load in response to the PWM signal.

What is claimed is: 
     
         1 . A power supply for powering one or more loads, comprising:
 a boost circuit with power factor correction (PFC) that provides an operating voltage from an electrical power source;   a dimmer detection circuit that (a) determines a dimming level applied to the electrical power source and (b) generates a pulse width modulated (PWM) signal based upon the dimming level; and   one or more current control circuits, each current control circuit being (c) associated with each of the one or more loads, and (d) coupled in series with the operating voltage, its associated load, and a ground of the power supply, so as to control a current through its associated load in response to the PWM signal.   
     
     
         2 . The power supply of  claim 1 , the dimmer detection circuit comprising a microcontroller that (e) evaluates a waveform of the electrical power source to determine the dimming level applied by a dimming device connected to the electrical power source, and (f) generates the PWM signal based upon the dimming level. 
     
     
         3 . The power supply of  claim 2 , the dimmer detection circuit further comprising an analog filter that filters the electrical signal source to provide an analog signal indicative of the dimming level, the microcontroller evaluating a digitized representation of the analog signal. 
     
     
         4 . The power supply of  claim 3 , further comprising a switchable load under control of the microcontroller for drawing additional current through the dimming device when the dimming level is greater than a defined threshold, to prevent erratic operation of the dimming device. 
     
     
         5 . The power supply of  claim 2 , the microcontroller delaying initiation of the PWM signal to allow the boost circuit to stabilize the operating voltage upon start-up of the power supply with the load connected. 
     
     
         6 . The power supply of  claim 1 , each of the current control circuits configured to control the current through the load between a maximum current and no current. 
     
     
         7 . The power supply of  claim 1 , the operating voltage being substantially 48V DC with respect to the ground. 
     
     
         8 . The power supply of  claim 1 , each of the one or more loads comprising one or more light emitting diodes. 
     
     
         9 . A method for driving at least one load using a boost circuit with power factor correction (PFC), a dimmer detection circuit, and a current control circuit, comprising:
 receiving electrical power at the boost circuit;   generating an operating voltage within the boost circuit from the electrical power;   determining a dimming level within the dimmer detection circuit based upon a waveform of the electrical power;   generating, within the dimmer detection circuit, a pulse width modulated (PWM) signal indicative of the dimming level; and   controlling the current through the load using a switch of the current control circuit that is connected in series with the load, the switch being controlled based upon the PWM signal.   
     
     
         10 . A method for manufacturing LED-based lighting products, comprising:
 manufacturing power supply subsystems for the lighting products;   receiving a customer order for the lighting products, the customer order including an LED specification;   stocking LEDs to match the LED specification;   manufacturing LED-based lighting fixtures that utilize the LEDs; and   integrating the power supply subsystems with the LED-based lighting fixtures to form the lighting products.   
     
     
         11 . The method of  claim 10 , further comprising manufacturing the LED-based lighting fixtures without LEDs before receiving the customer order, and wherein manufacturing the LED-based lighting fixtures that utilize the LEDs comprises adding at least the LEDs to the LED-based lighting fixtures. 
     
     
         12 . The method of  claim 10 , further comprising manufacturing the power supply subsystems before receiving the customer order. 
     
     
         13 . The method of  claim 10 , wherein manufacturing the power supply subsystems comprises manufacturing the power supply subsystems to include a bus output that includes at least power, ground and a dimming signal, and integrating comprises connecting the bus outputs from the power supply subsystems to the LED-based lighting fixtures. 
     
     
         14 . The method of  claim 13 , wherein manufacturing the LED-based lighting fixtures comprises manufacturing the LED-based lighting fixtures to provide a pass-through connection for the bus output. 
     
     
         15 . A method for manufacturing LED-based lighting products, comprising:
 manufacturing power supply subsystems for the lighting products;   manufacturing cabling operable to connect the power supply subsystems with LED-based lighting fixtures;   receiving a customer order for the lighting products, the customer order including an LED specification;   stocking LEDs to match the LED specification;   manufacturing the LED-based lighting fixtures with the LEDs; and   shipping sets of the power supply subsystems, the cabling and the LED-based lighting fixtures to fill the customer order.   
     
     
         16 . The method of  claim 15 , further comprising manufacturing the LED-based lighting fixtures without the LEDs before receiving the customer order, and wherein manufacturing the LED-based lighting fixtures with the LEDs comprises adding at least the LEDs to the lighting fixtures. 
     
     
         17 . The method of  claim 15 , further comprising manufacturing the power supply subsystems before receiving the customer order. 
     
     
         18 . The method of  claim 15 , wherein manufacturing the power supply subsystems comprises manufacturing the power supply subsystems to include a bus output that includes at least power, ground and a dimming signal, and manufacturing the cabling comprises manufacturing cabling operable to connect the bus output from one of the power supply subsystems to one or more of the LED-based lighting fixtures. 
     
     
         19 . The method of  claim 18 , wherein manufacturing the LED-based lighting fixtures comprises manufacturing each of the LED-based lighting fixtures to provide a pass-through connection for the bus output.