Abstract: A switch-mode DC/DC converter (101) and linear low drop out (LIDO) DC/DC regulator (105) are connected in parallel to drive a single load Both regulators share a common voltage reference, feedback network (103), input supply and output such that the regulated voltage is identical during each mode of operation. During heavy loads the switch-mode regulator (107) is in operation and the linear regulator is disabled for the highest efficiency possible. Conversely at light loads the linear regulator is in operation with the switch-mode regulator (107) disabled, also maximizing the efficiency. Each regulator senses load current (131) to automatically transition between the appropriate voltage regulators at fixed load current levels. The presented invention also includes a make before break transition scheme of the voltage regulators (103) to minimize the voltage transients.

Abstract: The described DC to AC inverter efficiently controls the amount of electrical power used to drive a cold cathode fluorescent lamp (CCFL). Additionally, during striking of the CCFL, a higher energy initial energy pulse is used. During normal operation, a lower energy pulse is used.

Abstract: A method for responding to an open lamp condition in a discharge lamp system is disclosed. The method monitors a current feedback signal flowing through a lamp and a voltage feedback signal indicative of a voltage across said lamp. A switch is used to switch between the current feedback signal to the voltage feedback signal upon detection of an open lamp condition.

Abstract: A technique is described that facilitates sensing current through a load. A method according to the technique includes mounting a discharge lamp in a floating point configuration, sensing current through the discharge lamp, and controlling current through the discharge lamp to improve power conversion efficiency. A device constructed according to the technique may include two AC voltage sources that are out-of-phase with respect to one another. A current sense circuit may be coupled between the AC voltage sources. When a load is connected to nodes of the AC voltage sources, the current sense circuit may sense current between the nodes that is associated with, or perhaps approximates, current through the load.

Abstract: A method of driving a lamp that uses a DC to AC inverter that is connected to a primary winding of a transformer is disclosed. The inverter frequency is variable, and in one embodiment, may be controlled by a voltage controlled oscillator. Circuitry is included that monitors the phase relationship between a voltage across a secondary of the transformer and a current through the primary of the transformer. The circuitry monitors the phase relationship and adjusts the inverter frequency, such as by adjusting voltage controlled oscillator, so that the phase relationship is maintained at a predetermined relationship.

Abstract: Methods and apparatus are disclosed for converting DC power to AC and for driving multiple discharge lamps and, more particularly, Cold Cathode Fluorescent Lamps (CCFLs), External Electrode Fluorescent Lamps (EEFLs), and Flat Fluorescent Lamps (FFLs). Disclosed methods, among other advantages, allow accurate current sharing among the lamps, minimization of the total number of power switches, and, in general, simplification of the complexity of the control system.

Abstract: The method and circuit of the present invention provides short-circuit detection and protection in a discharge lamp system. The transformer's primary current is sensed and used to provide short-circuit protection of the secondary winding side or high voltage side. The system and method with the present invention provides short-circuit detection and protection even when the transformer's secondary winding is shorted.

Abstract: The present invention introduces methods to modify the burst frequency of an inverter in a given LCD panel without any component change on the inverter board. The present invention also introduces methods to adjust the setting of a sensing system for duty cycles and accept Display Power Saving Technology (DPST) input signals with different frequencies. The universal inverter module with the present invention can be applied for different DPST technologies.

Abstract: Two out-of-phase inverters are used for driving a backlight for large LCD panels. The lamp currents of each inverter are regulated to substantially the same level to ensure the same brightness in the lamps without any current balancing devices. The switching frequencies in both inverters are synchronized and maintained in an out-of-phase condition during operation.

Abstract: The present invention introduces methods and systems to amplify digital audio signals for driving speakers. First, digital audio signals are converted to PWM audio signals by a liner PWM modulator that is open-loop. Then, PWM audio signals are amplified by a Class D audio amplifier that has at least one feedback loop.

Abstract: The present disclosure introduces a simple method and apparatus for converting DC power to AC power for driving discharge lamps such as a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL), or a flat fluorescent lamp (FFL). Among other advantages, the invention allows the proper protection under short circuit conditions for applications where the normal lamp current is greater than safe current limit.

Abstract: Control methods and apparatus are disclosed for operating a full-bridge inverter at resonant frequency mode, hybrid frequency mode, and fixed frequency mode. The operating frequency of the inverter equals to the user programmed frequency if the user programmed frequency is above the resonant tank frequency; and the operating frequency is synchronized with the resonant tank frequency if the user programmed frequency is below the resonant tank frequency.

Abstract: Embodiments of isolated gate driver circuits are disclosed for driving high- and low-side switching devices for half- and full-bridge power converter topology. Disclosed circuits provide sufficient dead-time, operate over a wide range of duty cycles, and require a single power supply (Vcc). Typical applications for such circuits include cold cathode fluorescent lamp (CCFL) inverters that are powered by a high voltage DC rail.

Abstract: A detector circuit monitors the phase relationship between the lamp voltage and the excitation voltage, and if one or more conditions are met, triggers the open lamp protection process in a discharge lamp system. The detection circuit can be incorporated into a lamp voltage feedback circuit and implemented on the integrated circuit level with less cost and circuit complexity.

Abstract: Methods and apparatus are disclosed for suppressing circuit noise due to parasitic elements in switch mode power supplies. The presented embodiments use actively controlled damping devices such as controllable resistors, current sources, and tri-state power devices to achieve required damping and to minimize power loss.

Abstract: A circuit comprises a detector circuit and a protection triggering circuit in a discharge lamp system. The detector circuit detects both open lamp and shorted lamp conditions and is coupled with detecting devices, such as sensing capacitors. A DC bias is added to the sensing capacitors so that capacitor voltages are always greater than zero volts. The output voltage of the detector circuit is coupled to the protection triggering circuit, which triggers an open lamp protection when open lamp condition occurs and a shorted lamp protection when shorted lamp condition occurs.

Abstract: The present invention introduces methods and circuits to provide a soft start for a switching regulator. A feedback voltage from output terminal is monitored and used to regulate the bias current of the regulator's error amplifier. The present invention also enables a smooth transition from the soft start to normal operation.

Abstract: Methods and apparatus are disclosed for converting DC power to AC and for driving multiple discharge lamps and, more particularly, Cold Cathode Fluorescent Lamps (CCFLs), External Electrode Fluorescent Lamps (EEFLs), and Flat Fluorescent Lamps (FFLs). Disclosed methods, among other advantages, allow accurate current sharing among the lamps, minimization of the total number of power switches, and, in general, simplification of the complexity of the control system.

Abstract: Methods and apparatus are disclosed for efficient switching regulators that adapt automatically to, and operate with, input voltages that are above, below, or equal to the output voltage. The disclosed switching regulators demonstrate advantages of both buck and boost converters at high efficiency.

Abstract: The present invention discloses a DC/AC converter in the backlight power supply system using cold cathode fluorescent lamp (CCFL). The DC/AC converter comprises a front end DC/DC converter, a full-bridge or half bridge inverter, and a piezoelectric transformer. Even with a wide range of input voltages, the front end DC/DC converter produces a predetermined DC voltage or a DC voltage with a predetermined small range and the cascaded inverter operates with a switching frequency close to the resonant frequency of the piezoelectric transformer, which helps the backlight power supply system achieve high efficiency.