Patent ID: 6617805
Filing Date: 2003-09-09
Classification: H05B,Y02B,Y10S

Abstract:
An integrated circuit for controlling a power supply circuit which delivers power to a load circuit that includes a fluorescent lamp, comprising:ballast control and driver circuitry that provides drive signals to the power supply circuit, that receives sense signals indicating operating conditions of at least one of the power supply circuit and the load circuit, and that responds to the sense signals by modifying the drive signals; the ballast control and driver circuitry further having a set of two or more modes in any of which it can operate; the ballast control and driver circuitry making transitions between the modes in response to the sense signals; power factor correction circuitry that regulates the power provided to the load circuit by the power supply circuit; enable circuitry that receives a first mode signal with information about the mode in which the ballast control and driver circuitry is operating and, in response, enables or disables the regulation circuitry; and loop speed circuitry that receives a second mode signal with information about the mode in which the ballast control and driver circuitry is operating and, in response, causes the regulation circuitry to operate at a control loop speed that depends on the second mode signal; the sense signals including current sense signals indicating current through the lamp and voltage sense signals indicating voltage across the fluorescent lamp; the ballast control and driver circuitry including: drive circuitry that provides the drive signals; fault detection circuitry that receives current sense signals and provides a detect signal when current through the lamp exceeds a threshold; filter circuitry that receives the detect signals and, if the detect signals meet a filter criterion, causes the drive circuitry to cease providing the drive signals; and end-of-life detection circuitry that receives the voltage sense signals and, if the indicated voltage across the lamp indicates that the lamp is nearing the end of its life, causes the drive circuitry to cease providing the drive signals; the ballast control and driver circuitry operating to: provide a first sequence of drive signals that cause the power supply circuit to provide power to the load circuit to start the lamp; the first sequence including preheat drive signals for preheating the lamp and run drive signals for running the lamp; the preheat drive signals being provided for a first duration; in response to the sense signals, cease providing drive signals at a time while the lamp is running; and provide a second sequence of drive signals that cause the power supply circuit to provide power to the load circuit for restarting the lamp; the second sequence including preheat drive signals for preheating the lamp and run drive signals for running the lamp; the preheat drive signals being provided in the second sequence for a second duration that is shorter than the first duration.