Abstract: A controller for use in a power converter includes a first terminal to provide a turn on signal to initiate turning on of a power switch and a second terminal to provide a turn off signal to initiate turning off the power switch. A detection circuit is coupled to detect a turn off time delay. The turn off time delay is the duration of time between an initiating of a turn off of the power switch by the turn off signal and an actual turn off of the power switch. A control circuit is coupled to control the turn on signal to regulate the turn off delay time to a target time value. The control circuit controls the turn on signal by controlling an amount of charge delivered to turn on the power switch.

Abstract: The invention generally relates to switch mode power converters (SMPCs).

Abstract: A controller for use in a power converter includes a first terminal to provide a turn on signal to initiate turning on of a power switch and a second terminal to provide a turn off signal to initiate turning off the power switch. A detection circuit is coupled to detect a turn off time delay. The turn off time delay is the duration of time between an initiating of a turn off of the power switch by the turn off signal and an actual turn off of the power switch. A control circuit is coupled to control the turn on signal to regulate the turn off delay time to a target time value. The control circuit controls the turn on signal by controlling an amount of charge delivered to turn on the power switch.

Abstract: A switch mode power converter (SMPC) includes a switching control system to control the turn off time delay of a switching device. The SMPC also has an inductive component including an input winding to receive power from an input and a switching device to conduct input winding current. The switching control system applies turn on and turn off signals to the switching device. The turn off signal initiates turning off of the switching device and a sensing signal from a further winding inductively coupled to the input winding is detected to indicate an end of a turn off time delay or duration. The turn on signal for a subsequent switching cycle of the SMPC device is controlled to regulate the turn off delay time.

Abstract: A charging circuit supplies charge to a charge store to provide power to a controller of a power converter. The power converter includes an inductive component having a winding coupled to receive power from an input to the power converter. A switching circuit includes a field effect transistor (FET) and a switching element. The FET is coupled in series between the winding and the switching element. A controller is coupled to control the switching of the switching element, and a charge store is coupled to provide power to the controller. The charging circuit includes a current diversion circuit coupled to conduct a winding current from the FET to the charge store. The switching element is arranged to allow the winding current to flow through the current diversion circuit to the charge store.

Abstract: 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.

Abstract: The invention generally relates to switch mode power converters (SMPCs).

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: We describe a switch mode power supply (SMPS) current regulation system comprising: a current sense signal input sensing a primary current of the SMPS; a voltage sense input to receive a voltage sense signal from a primary or auxiliary winding; a switch drive signal input to receive a drive signal; a timing signal generator coupled to said voltage sense input and to said drive signal input to generate a timing signal T0 indicating a duration of a period for which current is flowing through said primary winding and a timing signal T1 indicating a duration of a period for which current is flowing through said secondary winding; and a regulator to provide an output current regulation signal responsive to an average of the current sense signal multiplied by a ratio of T1 to T0, and wherein T0 and/or T1 are generated responsive to the voltage or current sense signal.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: We describe a switch mode power supply (SMPS) current regulation system comprising: a current sense signal input sensing a primary current of the SMPS; a voltage sense input to receive a voltage sense signal from a primary or auxiliary winding; a switch drive signal input to receive a drive signal; a timing signal generator coupled to said voltage sense input and to said drive signal input to generate a timing signal T0 indicating a duration of a period for which current is flowing through said primary winding and a timing signal T1 indicating a duration of a period for which current is flowing through said secondary winding; and a regulator to provide an output current regulation signal responsive to an average of the current sense signal multiplied by a ratio of T1 to T0, and wherein T0 and/or T1 are generated responsive to the voltage or current sense signal.

Abstract: 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.

Abstract: This invention relates to methods and apparatus for sensing the output current in a switch mode power supply (SMPS) using primary side sensing. We describe a module which senses a current in a primary winding of a transformer and a voltage on a primary or auxiliary winding of the transformer, and which includes a multiplier coupled to an output of a signal averager averaging a primary winding current and to an output of a timing signal generator using the sensed voltage to signal when a secondary winding is powering an output of the SMPS, to multiply an averaged current sense signal by a fraction of a total cycle period of said SMPS during which the secondary winding is providing power to provide a signal estimating an output current of the SMPS.

Abstract: 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.

Abstract: Methods and apparatus for sensing the output current in a switch mode power supply (SMPS) using primary side sensing are described. A system includes a primary current sense input, a charge input to sense a charging time of an SMPS transformer; a discharge input to sense a discharging time of the transformer; at least one averager; and a calculator. The primary current is averaged by the averager over at least a switching cycle of the SMPS and the calculator estimates the output current of the SMPS using the averaged primary current, the charge signal and the discharge signal.