Ballast control IC with power factor correction

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;
• and
• power factor control circuitry that regulates the voltage at which power is provided to the load circuit by the power supply circuit, further wherein
• the power supply circuit includes a half bridge circuit with low and high side power devices, the drive signals including low side drive signals to control the low side power device and high side drive signals to control the high side power device;
• the ballast control and driver circuitry including a low side drive output for providing the low side drive signals to the low side power device and a high side drive output for providing the high side drive signals to the high side power device.

A control circuit for controlling a power supply circuit which delivers power to a load circuit that includes a fluorescent lamp, comprising:

• driver circuitry that provides drive signals to the power supply circuit, the driver circuitry providing off drive signals that prevent the power supply circuit from providing power to the load circuit, then providing on drive signals that cause the power supply circuit to provide power to the load circuit for preheating the lamp;
• power factor correction circuitry that boosts the voltage at which power is provided to the load circuit;
• and
• enable circuitry that receives a coordination signal indicating whether the driver circuitry is providing off drive signals or on drive signals and, in response, disabling the power factor correction circuitry while off drive signals are provided and enabling the power factor correction circuitry no sooner than when on drive signals begin;
• when the power factor correction circuitry is enabled at the beginning of the on drive signals, power being initially provided at an unboosted voltage at which the lamp cannot ignite.

A control 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 voltage at which power is provided to the load circuit;
• and
• enable circuitry that receives a mode signal with information about the mode in which the ballast control and driver circuitry is operating and, in response, enables or disables the power factor correction circuitry.

A method of controlling a power supply circuit which provides power from a DC bus to a load circuit that includes a fluorescent lamp, comprising the steps of:

• providing drive signals that cause the power supply circuit to provide power to the load circuit, the drive signals including ignition ramp drive signals for ramping the fluorescent lamp to ignition and run drive signals for running the lamp;
• while providing the ignition ramp drive signals, regulating voltage on the DC bus at a first control loop speed;
• and
• while providing the run drive signals, regulating voltage on the DC bus at a second control loop speed that is less than the first control loop speed.

A control circuit for controlling a power supply circuit which provides power from a DC bus 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 modes in which it can operate;
• the ballast control and driver circuitry making transitions between the modes in response to the sense signals;
• regulation circuitry that regulates a voltage on the DC bus;
• and
• loop speed circuitry that receives a 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 mode signal.

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 current sense signals indicating current through the lamp, and that responds to the current sense signals by modifying the drive signals;
• the ballast control and driver circuitry including:
• drive circuitry that provides the drive signals;
• fault detection circuitry that receives the current sense signals and provides a detect signal when current through the lamp exceeds a threshold;
• and
• 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.

A control 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 voltage sense signals indicating a voltage across the lamp, and that responds to the voltage sense signals by modifying the drive signals;
• the ballast control and driver circuitry including:
• drive circuitry that provides the drive signals;
• 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.

A method of controlling a power supply circuit which supplies power to a load circuit that includes a fluorescent lamp, comprising the steps of:

• providing a first sequence of drive signals that cause the power supply circuit to provide power to the load circuit to start the fluorescent 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 sense signals indicating operating conditions of at least one of the power supply circuit and the load circuit, ceasing to provide drive signals at a time while the lamp is running;
• and
• providing 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.

A control 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 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 sense signals indicating operating conditions of at least one of the power supply circuit and the load circuit, 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.