# US 9,049,761 B2 · Power factor control for an LED bulb driver circuit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,049,761 B2 - Document ID: US9049761B2 - Status: Granted - Kind: B2 - Application number: 13/912,143 - Filed: 2013-06-06 - Published: 2013-10-17 - Granted: 2015-06-02 - Earliest claimed: 2011-06-07 - Assignees: Switch Bulb Company, Inc. - Applicants: Switch Bulb Company, Inc. - Inventors: Stanley Canter; John D. Grainger - Web page: https://patentgrep.com/patent/US9049761B2 ## CPC - H05B 45/375: using buck topology - H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL ## Abstract A light-emitting diode (LED) bulb has a shell and a base attached to the shell. An LED is within the shell. A driver circuit provides current to the LED. The driver circuit has a power factor control circuit that includes a tracking circuit configured to produce a tracking signal indicative of the voltage of the supply line. The power factor control circuit also includes a switch-mode power supply (SMPS) controller having an input pin and an output pin. The tracking circuit is connected to the input pin. Based on the signal at the input pin, the SMPS controller is configured to change a frequency of an output signal on the output pin. ## Claims ### Claim 1 A light-emitting diode (LED) bulb comprising: a shell; an LED contained within the shell; a driver circuit for providing current to the LED, the driver circuit having a power factor control circuit that comprises: a tracking circuit connected to a supply line to the LED, wherein the tracking circuit is configured to produce a tracking signal indicative of the voltage of the supply line; a switch-mode power supply (SMPS) controller having an input pin and an output pin, wherein the tracking circuit supplies the tracking signal to the input pin, wherein, in response to the tracking signal being below a threshold voltage, the SMPS controller is configured to change a frequency of an output signal on the output pin based on the tracking signal, and wherein, in response to the tracking signal being above a threshold voltage, the SMPS controller is configured to provide the output signal on the output pin independent of the tracking signal; and a base attached to the bulb for connecting the LED bulb to an electrical socket. ### Claim 2 (depends on 1) The LED bulb of claim 1, wherein the driver circuit substantially fits within the base. ### Claim 3 (depends on 1) The LED bulb of claim 1, wherein, as the voltage supply of the supply line increases, the frequency also increases. ### Claim 4 (depends on 1) The LED bulb of claim 1, wherein the tracking circuit includes a first resistor connected between the supply line and the input pin and a second resistor connected between the input pin and ground. ### Claim 5 (depends on 1) The LED bulb of claim 1, wherein the SMPS controller is configured to limit a current supplied to the LED through the input supply line. ### Claim 6 (depends on 5) The LED bulb of claim 5, wherein the SMPS controller is configured to limit the current based on a sense signal from a current sense resistor. ### Claim 7 (depends on 6) The LED bulb of claim 6, wherein the current sense resistor is connected between the LED and ground. ### Claim 8 (depends on 1) The LED bulb of claim 1, wherein the SMPS controller is configured to modulate the output signal based on the sense signal. ### Claim 9 (depends on 1) The LED bulb of claim 1, wherein the driver circuit further comprises an input filter circuit. ### Claim 10 (depends on 1) The LED bulb of claim 1, wherein the driver circuit is configured to accept an alternating current (AC) supply voltage. ### Claim 11 A light-emitting diode (LED) bulb driver circuit having a power factor control circuit comprising: a tracking circuit connected to a supply line for an LED, wherein the tracking circuit is configured to produce a tracking signal indicative of the voltage of the supply line; and a switch-mode power supply (SMPS) controller having an input pin and an output pin, wherein the tracking circuit supplies the tracking signal to the input pin, wherein, in response to the tracking signal being below a threshold voltage, the SMPS controller is configured to change a frequency of an output signal on the output pin based on the tracking signal, and wherein, in response to the tracking signal being above a threshold voltage, the SMPS controller is configured to provide the output signal on the output pin independent of the tracking signal. ### Claim 12 (depends on 11) The driver circuit of claim 11, wherein, as the voltage supply of the supply line increases, the frequency also increases. ### Claim 13 (depends on 11) The driver circuit of claim 11, wherein the tracking circuit includes a first resistor connected between the supply line and the input pin and a second resistor connected between the input pin and ground. ### Claim 14 (depends on 11) The driver circuit of claim 11, wherein the SMPS controller is configured to limit a current supplied to the LED through the input supply line. ### Claim 15 (depends on 14) The driver circuit of claim 14, wherein the SMPS controller is configured to limit the current based on a sense signal from a current sense resistor. ### Claim 16 (depends on 15) The driver circuit of claim 15, wherein the current sense resistor is connected between an LED and ground. ### Claim 17 (depends on 11) The driver circuit of claim 11, wherein the SMPS controller is configured to modulate the output signal based on the sense signal. ### Claim 18 (depends on 11) The driver circuit of claim 11, wherein the driver circuit further comprises an input filter circuit. ### Claim 19 (depends on 11) The driver circuit of claim 11, wherein the driver circuit is configured to accept an alternating current (AC) supply voltage. ### Claim 20 (depends on 11) The driver circuit of claim 11, wherein the driver circuit further comprises a switching transistor connected to the output pin of the SMPS controller.