Patent application number | Description | Published |
20080284357 | BALLAST CONTROL IC WITH MINIMAL INTERNAL AND EXTERNAL COMPONENTS - A ballast controller integrated circuit which executes a specific set of instructions via an integrated state diagram architecture to control a fluorescent lamp or high intensity discharge lamp and protect the ballast. The state diagram architecture controls powering up and down of the IC and the half-bridge circuit driven by the IC, preheating and striking of the lamp, running of the lamp, sensing for numerous possible fault conditions, and recovering from these fault conditions based on the normal maintenance of a lamp, while requiring fewer internal and external components than previous electronic ballasts. | 11-20-2008 |
20090174341 | COLD-CATHODE FLUORESCENT LAMP (CCFL) CURRENT CONTROL CIRCUIT - A circuit to control an AC lamp current provided by an input AC voltage supply to a cold-cathode fluorescent lamp (CCFL). The circuit includes a capacitor connected in series between the AC voltage supply and one terminal of the CCFL, the capacitor biasing the CCFL with the AC lamp current; a switch having first, second, and control terminals, the first terminal being connected to the CCFL and the second terminal being connected to the other side of the supply; a diode connected in parallel to the switch; and a resistor connected in parallel to the diode, wherein the AC lamp current is controlled by controlling the switch to add and remove resistance in series with the CCFL. | 07-09-2009 |
20120025713 | System using shunt circuits to selectively bypass open loads - According to an exemplary embodiment, a shunt circuit includes a floating shunt switch configured to bypass at least one load, for example at least one LED, among a plurality of series-connected loads, such as a plurality of series-connected LEDs in a lighting system, responsive to a high-side control signal. The at least one load has terminals connected across the shunt circuit. The shunt circuit further includes a high-voltage level-shift up circuit configured to shift a low-side control signal up to the high-side control signal using a voltage of at least one of the terminals of the at least one load. The floating shunt switch can be configured to bypass the at least one load responsive to a failure of the at least one load. | 02-02-2012 |
20120200275 | Integrated High-Voltage Power Supply Start-Up Circuit - According to an exemplary embodiment, an integrated start-up circuit for a power supply includes a converter, which in one embodiment can be a buck converter. In one embodiment, the buck converter includes a gate driver configured to drive a power switch, where the power switch is coupled across a DC bus node and a switching node of the buck converter. The power switch is configured to provide a start-up voltage to the buck converter from the DC bus node during start-up of the buck converter. In one embodiment, the buck converter includes a bootstrap switch coupled across the gate driver and a Vcc node and a Schottky diode coupled across the bootstrap switch and the switching node, where the start-up voltage is provided at the Vcc node through the bootstrap switch. | 08-09-2012 |
20130229126 | Electronic Ballast with Power Factor Correction - According to an exemplary implementation, an electronic ballast includes an input filter coupled to a resonant tank. The resonant tank is configured to generate a resonant current. The input filter is configured to receive an AC input voltage and to generate an AC input current from the resonant current by smoothing the resonant current. The electronic ballast also includes a half-bridge configured to feed the resonant tank so as to generate the resonant current and to receive a supply voltage that is in phase with the AC input voltage. The electronic ballast can also include a controller configured to control a power factor of the electronic ballast by switching the half-bridge. The controller can be configured to adjust a shape of the AC input current by adjusting switching of the half-bridge to thereby adjust a power factor of the electronic ballast. | 09-05-2013 |
20130277362 | Power Converter with Over-Voltage Protection - In one implementation, a power converter with over-voltage protection includes a power switch coupled to a power supply through a tank circuit, and a control circuit coupled to a gate of the power switch. The control circuit is configured to turn the power switch OFF based on a current from the tank circuit, thereby providing the over-voltage protection to the power converter. In one implementation, the power converter is a class-E power converter. In one implementation, the control circuit is configured to sense the current from the tank circuit based on a voltage drop across a sense resistor coupled to the power switch. | 10-24-2013 |
20140022000 | Switching Circuit with a Base Discharge Switch - According to an exemplary implementation, a switching circuit includes a bipolar junction transistor, a base current supply configured to turn-on the bipolar junction transistor, and a base discharge switch configured to selectively draw current away from a base of the bipolar junction transistor so as to turn-off the bipolar junction transistor. The base discharge switch can further be configured to selectively prevent the base current supply from providing current to the base of the bipolar junction transistor. The base discharge switch may be coupled across the base of the bipolar junction transistor and an emitter of the bipolar junction transistor. The base discharge switch can further be configured to selectively cause the base of the bipolar junction transistor to have a base voltage substantially lower than an emitter voltage of the bipolar junction transistor. | 01-23-2014 |
20140210519 | Combined Sense Signal Generation and Detection - In an exemplary implementation, a detection circuit for regulating a power converter is configured to receive a combined sense signal comprising a first sense signal from the power converter superimposed with a second sense signal from the power converter. The detection circuit is further configured to generate a first detect signal from the combined sense signal and generate a second detect signal from the combined sense signal. The first detect signal can correspond to the first sense signal and the second detect signal can correspond to the second sense signal. The detection circuit can generate a filtered signal corresponding to the first sense signal from the combined sense signal to generate the first detect signal from the combined sense signal. Also, the detection circuit can generate an offset signal based on the combined sense signal to generate the second detect signal from the combined sense signal. | 07-31-2014 |