# US 2019/0174589 A1 · Dynamic power supply for light emitting diode > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0174589 A1 - Document ID: US20190174589A1 - Status: Published application - Kind: A1 - Application number: 16/168,387 - Filed: 2018-10-23 - Published: 2019-06-06 - Earliest claimed: 2015-07-13 - Assignees: Soraa, Inc. - Applicants: Soraa, Inc. - Inventors: Laszlo Takacs - Web page: https://patentgrep.com/patent/US20190174589A1 ## CPC - H05B 45/38: using boost topology - 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 voltage control system for an LED operates to dynamically determine and set a minimum permissible voltage on an energy storage device such as a capacitor such that the energy storage device operates at a minimum possible voltage to compensate for component variations and dimming signal variations while maintaining flicker-free operation of the LED. ## Claims ### Claim 1 (canceled) ### Claim 2 A power supply for powering a light emitting diode (“LED”), wherein said LED has a forward voltage when operating, said power supply comprising: a boost circuit configured for increasing power from a first voltage to a second voltage; a capacitor coupled to said boost circuit to receive said power at said second voltage, said capacitor having a capacitor voltage when charged; a buck circuit coupled to said capacitor and said LED and configured to draw current from said capacitor and deliver a fixed and regulated current to said LED; and a voltage regulation circuit for controlling said power received by said capacitor to maintain said capacitor voltage just above said forward voltage. ### Claim 3 (depends on 2) The power supply of claim 2, wherein said voltage regulator is configured to control the output of said boost circuit to control said power received by said capacitor. ### Claim 4 (depends on 3) The power supply of claim 3, wherein said voltage regulator is configured to control the output of said boost circuit by turning said boost circuit on and off. ### Claim 5 (depends on 2) The power supply of claim 2, wherein said voltage regulator is configured to control the output of said buck circuit to control said fixed and regulated current to said LED. ### Claim 6 (depends on 5) The power supply of claim 5, wherein said voltage regulator is configured to control the output of said buck circuit such that said buck circuit operates only when said capacitor voltage exceeds said forward voltage. ### Claim 7 (depends on 5) The power supply of claim 5, wherein said voltage regulator is configured to control the output of said buck circuit by turning said buck circuit on and off. ### Claim 8 (depends on 2) The power supply of claim 2, wherein said voltage regulation circuit is configured to operate said boost circuit and said buck circuit in a bypass mode in which said capacitor is bypassed. ### Claim 9 (depends on 8) The power supply of claim 8, wherein said voltage control system is configured to disable said second voltage converter based on a determination that said capacitor satisfies an end-of-life condition. ### Claim 10 (depends on 8) The power supply of claim 8, wherein, in said bypass mode, said LED receives power directly from said boost circuit. ### Claim 11 (depends on 10) The power supply of claim 10, wherein, in said bypass mode, said voltage control system is configured to disable said buck circuit. ### Claim 12 (depends on 2) The power supply of claim 2, wherein said voltage regulation circuit is configured to monitor said forward voltage directly from said LED. ### Claim 13 (depends on 12) The power supply of claim 12, further comprising a comparator for receiving as input a voltage established on a terminal of said LED and a reference voltage source, and generating a control signal; and wherein said voltage control system is configured to monitor said forward voltage and control said capacitor voltage such that said capacitor voltage just exceeds said forward voltage based on said control signal. ### Claim 14 (depends on 13) The power supply of claim 13, wherein said voltage control system is configured to control said capacitor voltage by decreasing said capacitor voltage when said control signal is below a first threshold, and increasing said capacitor voltage when said control signal is above a second threshold, wherein said first and second threshold are established such that said capacitor voltage is maintained just above said forward voltage. ### Claim 15 (depends on 2) The power supply of claim 2, wherein said voltage regulation circuit is configured to monitor said forward voltage based on a secondary characteristic. ### Claim 16 (depends on 15) The power supply of claim 15, wherein said secondary characteristic is the frequency at which said buck circuit is turned on and off. ### Claim 17 (depends on 2) The power supply of claim 2, further comprising: a converter configured for receiving AC power and converting it to DC power having said first voltage. ### Claim 18 (depends on 17) The power supply of claim 17, wherein said capacitor is configured to store sufficient energy for said second voltage converter to deliver said regulated current without interruption during the periodic zero-power deliver times of said AC power. ### Claim 19 A method for powering a light emitting diode (“LED”) having a forward voltage, said method comprising: (a) charging a capacitor with a boost circuit to establish a capacitor voltage on said capacitor; (b) drawing current from said capacitor and delivering a regulated current to said LED when said capacitor voltage exceeds said forward voltage; (c) monitoring said forward voltage; and (d) maintaining said capacitor voltage just above said forward voltage by (i) reducing said charging of said capacitor in step (a) if said capacitor voltage is more than just above said forward voltage, or (ii) increasing said charging of said capacitor in step (a) if said capacitor voltage is below said forward voltage. ### Claim 20 (depends on 19) The method of claim 19, further comprising (e) bypassing said capacitor and supplying said LED with power from said boost circuit if an end-of-life condition of said capacity is detected. ### Claim 21 (depends on 20) The method of claim 20, wherein step (e) comprises at least: (i) measuring a voltage established on a cathode of said LED; (ii) comparing said voltage established on said cathode of said LED with a reference voltage to generate a control signal; and (iii) disabling said energy storage device and providing a fixed average current to said LED when said control signal remains an undervoltage control signal during a period during which said energy storage device is driven by a voltage converter.