Cambridge Semiconductor Limited Patent applications |
Patent application number | Title | Published |
20150035450 | SOLID STATE LIGHTING CONTROL - This invention generally relates to solid state lighting control, and more particularly to a dimmer interface circuit and a method for reducing ringing on a drive signal to a solid state lighting device. An embodiment is a dimmer interface circuit for controlling brightness of a solid state light emission device, the interface circuit having an input to receive a brightness control voltage from a dimmer circuit and comprising: a voltage converter to provide a converter output voltage and having an inductive component and a charge store, the charge store controllably coupled to receive charge from the inductive component to thereby convert the brightness control voltage to the converter output voltage; and control circuitry comprising: an input to receive a voltage level indication of the brightness control voltage; an input to receive a voltage level indication of the converter output voltage; a comparison circuit to compare a said received brightness control voltage level indication and a said received converter output voltage level indication; and a transition detector to detect a transition of the brightness control voltage, said transition for turning a said solid state light emission device on, wherein the control circuitry is configured to control the voltage converter dependent on a said comparison of said level indications received at a time of a said transition in a first cycle of the brightness control voltage, such that a difference between the brightness control voltage and the converter output voltage at a time of a said transition in a second, later said cycle is closer to a target voltage difference or target voltage difference range than a said difference at the time of the transition in the first cycle. | 02-05-2015 |
20140355314 | STORAGE TIME CONTROL - We describe a method of controlling turn off time delay of a switching device of a switch mode power converter (SMPC). The SMPC has an inductive component comprising an input winding coupled to receive power from an input; and a switching device to, when on, conduct input winding current. In embodiments the method comprises applying turn on and turn-off signals to the switching device; applying at least one turn off signal, to initiate turning off of the switching device, and detecting a sensing signal from a further winding of the inductive component, inductively coupled to the input winding, to thereby indicate an end of a turn off time delay or duration. The method controls the turn on signal for a subsequent switching cycle of the SMPC device to regulate the turn off delay time. | 12-04-2014 |
20140232187 | AUXILIARY RECHARGE - The present invention generally relates to powering a switching controller of a switch mode power converter (SMPC), and more particularly to a method of providing power to a switching controller of a SMPC, to a charging circuit for supplying charge to a charge store for providing power to a switching controller of a SMPC, and to an SMPC comprising such a circuit. A method of providing power to a switching controller of a switch mode power converter (SMPC), the SMPC having: an inductive component having a winding coupled to receive power from an input to said SMPC; a switching circuit comprising first and second switching transistors, said first transistor coupled in series between said winding and said second transistor; a switching controller to control switching of said second transistor; and a charge store to provide power to said switching controller, the method comprising: flow of current from said winding through said first transistor; and diverting said current through a conduction path to said charge store. | 08-21-2014 |
20100246216 | SWITCH MODE POWER SUPPLY CONTROLLERS - This invention relates to SMPS controllers employing primary side sensing. We describe a system for identifying a knee point in a sensing waveform, at which the output voltage of the SMPS may be sampled accurately on the primary side. The system identifies the knee point, broadly speaking, by tracking a portion of a power transformer voltage waveform, and samples the voltage waveform at the knee point to determine the SMPS output voltage. In preferred embodiments this technique is implemented using a circuit akin to a decaying peak detector, providing a timing signal indicating detection of the knee point. Sample/hold and error amplifier circuits may be employed to achieve output voltage regulation. | 09-30-2010 |
20100188008 | Lighting Controllers - This invention generally relates to lighting controller, more particularly to electronic ballast circuits, sometimes referred to as electronic control gears (ECG) or gas discharge lamps. | 07-29-2010 |
20100181840 | CABLE COMPENSATION - This invention generally relates to cable compensation, and is particularly applicable to cable compensation for an AC-DC voltage converter. In one embodiment, a cable compensation apparatus for compensating voltage drop of a cable connected between an electrical power supply and an electrical device comprises: a first capacitor; a timer circuit to time a predetermined time period; a current source to supply to said first capacitor during substantially said predetermined time period a first current substantially proportional to an output current outputted by the power supply to the cable; and a control circuit to adjust an output voltage outputted by said power supply to said cable dependent on a voltage on said first capacitor. The compensation in some embodiments is programmable by means of a discrete capacitor component. | 07-22-2010 |
20100165671 | Switched-mode Power Supplies - This disclosure relates to switched-mode power supplies, to transformers for such power supplies, and to methods of operating switched-mode power supplies. A switch mode power supply (SMPS), the switched-mode power supply having a power input, a switch, a transformer, and a power output; said transformer having a primary winding on a primary side of said power supply coupled to said power input via said switch, and a secondary winding on a secondary side of said switched-mode power supply coupled to said power output; wherein said transformer further includes first and second auxiliary windings, wherein said first auxiliary winding is more closely coupled to said primary winding than to said secondary winding and wherein said second auxiliary winding is more closely coupled to said secondary winding than to said primary winding. | 07-01-2010 |
20100085138 | CROSSED GAP FERRITE CORES - The invention relates to swinging inductors of a stepped-gap construction. We describe an inductor core structure having first and second core segments, constructed and arranged such that distal ends of legs of the first core segment are paired with distal ends of legs of the second core segment in an opposing relation. The at least one distal ends of the first core segment has a ridge projecting therefrom and is paired with the at least one distal ends of the second core segment which has a ridge projecting therefrom in an opposing relation, such that opposingly paired projecting ridges form a cross arrangement. | 04-08-2010 |
20100046258 | POWER SUPPLY CONTROL SYSTEM - A digital control system for a switch mode power supply (SMPS), the control system having a demand input for a signal indicating whether an output voltage of said SMPS is above or below a desired value, and a drive output for a switch controlling energy transfer between an input and an output of said SMPS during a power switching cycle, the control system further including: a signal processor coupled to said demand input and to said drive output to control said drive output responsive to said demand signal to regulate said output voltage at said desired value, and wherein said signal processor includes at least one storage element to store at least one value of said demand signal, and wherein said switching control signal for a said power switching cycle is responsive to a value of said demand signal in at least two previous power switching cycles. | 02-25-2010 |
20100039833 | POWER SUPPLY CONTROL SYSTEM - This invention relates to improved control systems and methods for switch mode power supplies. A control system for a switch mode power supply (SMPS), the SMPS having a input side for receiving a power supply input and an output side for providing a dc output voltage, said input and output side of said SMPS being coupled by a transformer, the control system having two operating modes, a first mode for regulating an output voltage of the power supply responsive to a feedback signal derived from a dc voltage on said power supply output side dependent upon said output voltage, and a second mode for regulating an output voltage of the power supply responsive to a feedback signal derived from an auxiliary winding of said transformer, said control system having a feedback input to receive a said feedback signal, a control output for regulating said output voltage, and a mode selector coupled to said feedback input to select one of said first and second control system operating modes responsive to said feedback signal. | 02-18-2010 |
20100032712 | POWER SEMICONDUCTOR DEVICE AND A METHOD OF FORMING A POWER SEMICONDUCTOR DEVICE - A power semiconductor device has a top surface and an opposed bottom surface below a part of which is a thick portion of semiconductor substrate. At least a portion of a drift region of the device has either no or only a thin portion of semiconductor substrate positioned thereunder. The top surface has a high voltage terminal and a low voltage terminal connected thereto to allow a voltage to be applied laterally across the drift region. At least two MOS (metal-oxide-semiconductor) gates are provided on the top surface. The device has at least one relatively highly doped region at its top surface extending between and in contact with said first and second MOS gates. The device has improved protection against triggering of parasitic transistors or latch-up without the on-state voltage drop or switching speed being compromised. | 02-11-2010 |
20090237960 | SWITCH MODE POWER SUPPLY CONTROLLERS - This invention relates to SMPS controllers employing primary side sensing. We describe a system for identifying a knee point in a sensing waveform, at which the output voltage of the SMPS may be sampled accurately on the primary side. The system identifies the knee point by fitting a tangent to a portion of a power transformer voltage waveform, and samples the voltage waveform at the knee point to determine the SMPS output voltage. In preferred embodiments this technique is implemented using a decaying peak detector, providing a timing signal indicating detection of the knee point. Sample/hold and error amplifier circuits may be employed to achieve output voltage regulation. | 09-24-2009 |
20090212754 | NOISE REDUCTION SYSTEMS AND METHODS - We describe a switch mode power supply having a power input, a switch, a transformer, and a power output. The transformer has a primary winding coupled to said power input via said switch, and a secondary winding coupled to said power output. The transformer further comprises an auxiliary winding and a coupling structure capacitatively coupled to said secondary winding of said transformer; wherein said coupling structure does not comprise a shield or screen between said primary and secondary windings. The switch mode power supply further comprises a coupling capacitor connected between said coupling structure and said auxiliary winding to provide a noise suppression voltage from said auxiliary winding to said secondary winding to at least partially cancel a common mode noise voltage on said secondary winding from unshielded coupling from said primary winding. | 08-27-2009 |
20090160015 | SEMICONDUCTOR DEVICE AND METHOD OF FORMING A SEMICONDUCTOR DEVICE - In a power semiconductor device and a method of forming a power semiconductor device, a thin layer of semiconductor substrate is left below the drift region of a semiconductor device. A power semiconductor device has an active region that includes the drift region and has top and bottom surfaces formed in a layer provided on a semiconductor substrate. A portion of the semiconductor substrate below the active region is removed to leave a thin layer of semiconductor substrate below the drift region. Electrical terminals are provided directly or indirectly to the top surface of the active region to allow a voltage to be applied laterally across the drift region. | 06-25-2009 |
20090058498 | HALF BRIDGE CIRCUIT AND METHOD OF OPERATING A HALF BRIDGE CIRCUIT - A half bridge circuit has a first switch having at least one control gate and a second switch having at least two control gates. A first driver has an output connected to a control gate of the first switch. A second driver has an output connected to a first control gate of the second switch. The output of the first driver is connected to a second control gate of the second switch by a circuit arrangement such that when the first driver is operated to apply a high, positive voltage to the control gate of the first switch, a positive voltage is applied to the second control gate of the second switch, and such that when the first driver is operated to apply a low, zero or small voltage to the control gate of the first switch, a negative voltage is applied to said second control gate of the second switch. | 03-05-2009 |
20090057831 | SEMICONDUCTOR DEVICE AND METHOD OF FORMING A SEMICONDUCTOR DEVICE - A high voltage/power semiconductor device has a semiconductor layer having a high voltage terminal end and a low voltage terminal end. A drift region extends between the high and low voltage terminal ends. A dielectric layer is provided above the drift region. An electrical conductor extends across at least a part of the dielectric layer above the drift region, the electrical conductor being connected or connectable to the high voltage terminal end. The drift region has plural trenches positioned below the electrical conductor. The trenches extend laterally across at least a part of the drift region in the direction transverse the direction between the high and low voltage terminal ends of the semiconductor layer, each trench containing a dielectric material. The trenches improve the distribution of electric field in the device in the presence of the electrical conductor. | 03-05-2009 |
20090040796 | BIPOLAR TRANSISTOR DRIVERS - We describe a switching power converter comprising a bipolar switching device (BJT or IGBT) switching an inductive load, and including a closed-loop control system. The control system comprises a voltage sensing system to sense a voltage on a collector terminal of the switching device and provide a voltage sense signal; a controller; and a drive modulation system coupled to an output of the controller for modulating a drive to the control terminal of said bipolar switching device responsive to a controller control signal; wherein said controller is configured to monitor changes in the sensed voltage during a period when said switching device is switched on and to control said drive modulation system to control the degree of saturation of said bipolar switching device when the device is switched on and hence improve turn-off times. | 02-12-2009 |