Abstract: A tappet having a contiguous body, an outer wall and transverse web. The outer wall defines a cylindrically-shaped outer surface and a recess. The recess is disposed within cylindrical surface of the body. An alignment member is press-fit between two staked ends of the recess, which engage opposite sides of the alignment member. The alignment member extends outwardly from the cylindrically-shaped surface. A roller is mounted to the contiguous body at the cam contacting end of the tappet.

Abstract: A tappet having a contiguous body, an outer wall and transverse web. The outer wall defines a cylindrically-shaped outer surface and a recess. The recess is disposed within cylindrical surface of the body. An alignment member is press-fit between two staked ends of the recess, which engage opposite sides of the alignment member. The alignment member extends outwardly from the cylindrically-shaped surface. A roller is mounted to the contiguous body at the cam contacting end of the tappet.

Abstract: A power converter includes an isolated or a nonisolated current-doubler rectification circuit including two magnetic circuit elements, each magnetic circuit element formed with a primary winding and a voltage-sensing winding. The primary windings are coupled in series. The voltage-sensing windings are also coupled in series but with a coupling sense opposite from that of the primary windings. A properly sized inductor and capacitor are coupled in series with the voltage-sensing windings to produce a ripple-cancellation current with slope opposite to a net slope error of currents produced in the two magnetic circuit elements. The current-doubler rectification circuit is preferably coupled to a rectangular ac input waveform. By sensing a scaled voltage difference between two magnetic circuit elements, a very low level of output ripple is produced by the circuit with very low power losses over a range of operating conditions.

Abstract: A power converter including a power switch, an output filter, and a controller. The output filter receives a switched input voltage and produces a filtered power converter output characteristic represented by a state vector. A controller coupled to the power switch and the output filter estimates the state vector of the output filter and controls the power switch by partitioning a state-vector plane into a first region and a second region employing a line passing through a desired output characteristic. The controller turns the power switch on when the estimated state vector lies in the first region and off when it lies in the second region. The steady-state switching frequency of the power converter is controlled by offsetting a state-vector component at a desired switching frequency. To estimate the state vector of the output filter, the controller may advantageously be coupled to the switched input voltage.

Abstract: A power converter includes an isolated or a nonisolated current-doubler rectification circuit including two magnetic circuit elements, each magnetic circuit element formed with a primary winding and a voltage-sensing winding. The primary windings are coupled in series. The voltage-sensing windings are also coupled in series but with a coupling sense opposite from that of the primary windings. A properly sized inductor and capacitor are coupled in series with the voltage-sensing windings to produce a ripple-cancellation current with slope opposite to a net slope error of currents produced in the two magnetic circuit elements. The current-doubler rectification circuit is preferably coupled to a rectangular ac input waveform. By sensing a scaled voltage difference between two magnetic circuit elements, a very low level of output ripple is produced by the circuit with very low power losses over a range of operating conditions.

Abstract: A power converter including a power switch, an output filter, and a controller. The output filter receives a switched input voltage and produces a filtered power converter output characteristic represented by a state vector. A controller coupled to the power switch and the output filter estimates the state vector of the output filter and controls the power switch by partitioning a state-vector plane into a first region and a second region employing a line passing through a desired output characteristic. The controller turns the power switch on when the estimated state vector lies in the first region and off when it lies in the second region. The steady-state switching frequency of the power converter is controlled by offsetting a state-vector component at a desired switching frequency. To estimate the state vector of the output filter, the controller may advantageously be coupled to the switched input voltage.

Abstract: A dc-dc converter is disclosed comprising an active clamp topology, including an active clamp resonant transition system to provide substantially zero or reduced voltage for turn-on of the primary switch. The resonant transition system includes an inductor in series with the primary winding of the power transformer and a clamp diode that operate cooperatively to turn on the primary switch with reduced voltage. A second diode is included in series with a balancing resistor to discharge a snubber capacitor with improved efficiency. The addition of these circuit components provides low switching losses and low component stresses in the overall design.

Abstract: A DC—DC converter is disclosed comprising an active clamp topology, including an active clamp resonant transition system to provide substantially zero or reduced voltage for turn-on of the primary switch. The resonant transition system includes an inductor in series with the primary winding of the power transformer and a clamp diode that operate cooperatively to turn on the primary switch with reduced voltage. The addition of these circuit components provides lower switching losses and lower component stresses in the overall design.

Abstract: The present invention is directed to an auxiliary active clamp circuit and a method of clamping a voltage of a rectifier switch associated with a power converter. The power converter includes a main active clamp circuit associated with a main power switch coupled to a primary winding of a transformer and a rectifier switch coupled to a secondary winding of the transformer. The main power switch conducts during a main conduction period of the power converter and the rectifier switch conducts during an auxiliary conduction period of the power converter. In one embodiment, the auxiliary active clamp circuit includes an auxiliary clamp capacitor, coupled across the rectifier switch, that stores a clamping voltage substantially equal to an off-state voltage of the rectifier switch.

Abstract: A gate driver and a method of driving a switch for use with a power converter having a main active clamp circuit associated with a main power switch coupled to a primary winding of a transformer and a rectifier switch coupled to a secondary winding of the transformer. The main power switch conducts during a main conduction period of the power converter and the rectifier switch conducts during an auxiliary conduction period of the power converter. In one embodiment, the gate driver includes a DC offset bias circuit, coupled to a secondary winding of the transformer, that provides a gate drive signal having a DC bias voltage to a gate terminal of the rectifier switch.

Abstract: A DC-DC converter is disclosed comprising an active clamp topology, including an active clamp resonant transition system to provide substantially zero or reduced voltage for turn-on of the primary switch. The resonant transition system includes an inductor in series with the primary winding of the power transformer and a clamp diode that operate cooperatively to turn on the primary switch with reduced voltage. The addition of these circuit components provides lower switching losses and lower component stresses in the overall design.

Abstract: A bias supply circuit and a method of operating a bias supply circuit for use with a switching power supply employing a main switch and an auxiliary switch and having an input voltage and a voltage across a clamp capacitor coupled to a transformer. In one embodiment, the bias supply circuit includes a bias supply winding associated with the transformer and configured to provide a first voltage dependent on at least one of the input voltage and the voltage across the clamp capacitor during a conduction period of the main switch or the auxiliary switch. Additionally, the bias supply circuit further includes a bias supply storage capacitor coupled to the bias supply winding and configured to provide a second voltage dependent on at least another of the input voltage and the voltage across the clamp capacitor during a conduction period of another of the main switch or the auxiliary switch. A sum of the first voltage and the second voltage provides a bias supply voltage.

Abstract: For use with an electronic circuit having first and second reference nodes, a voltage reference translation system and a method of converting signals between the first and second reference nodes are provided. In one embodiment, the voltage reference translation system includes first and second inductors coupled to a common magnetic core and interposed between the first and second reference nodes. Additionally, the voltage reference translation system includes a conversion path coupled through a portion of the common magnetic core configured to substantially convert a signal associated with the first reference node into a signal associated with the second reference node.

Abstract: A local loop control system and method of operating the same for use with a power converter. The power converter includes a first output coupled to a first synchronous rectifier circuit and a second output coupled to a second synchronous rectifier circuit. The power converter employs a main controller configured to regulate a voltage proportional to a weighted sum of the first and go second outputs. In one embodiment, the local loop control system includes: (1) a first output controller configured to regulate a voltage at the first output and (2) a second output controller configured to regulate a voltage at the second output, one of the first and second output controllers configured to reduce a drive signal to a corresponding one of the first and second synchronous rectifier circuits when a corresponding voltage at one of the first and second outputs exceeds a voltage proportional to the weighted sum.

Abstract: A system and method for reducing a DC magnetic flux bias in a transformer and a power converter employing the system or the method. The power converter has a full bridge switching circuit coupled across a primary winding of a transformer and a hybridge rectifier circuit coupled across a secondary winding of the transformer. The transformer is subject to the DC magnetic flux bias as a result of an imbalance in the hybridge rectifier circuit. In one embodiment, the system includes: (1) a sensor configured to develop a signal representing the DC magnetic flux bias in the transformer; and (2) a controller, coupled to the sensor, configured to operate the full bridge switching circuit as a function of the signal thereby to reduce the DC magnetic flux bias.

Abstract: A system and method for improving response of a control loop of a power supply. The power supply is configured to drive a load having at least one characteristic associated therewith. In one embodiment, the system includes: (1) a sensing circuit, associated with the power supply, configured to sense the characteristic; and (2) a compensation circuit, coupled to the sensing circuit, configured to adaptively adjust the control loop based on the characteristic to improve the response.

Abstract: A system and method for estimating magnetic flux in an isolation transformer and a power converter employing the system or the method. The power converter has a full bridge switching circuit coupled across a primary winding of an isolation transformer. In one embodiment, the system includes a conductive path, including an observer, established across at least a portion of the primary winding. A voltage developed by the observer depends upon a value of the magnetic flux in at least the portion of the primary winding.

Abstract: For use with a synchronous rectifier coupled to a secondary winding of a transformer and having a rectifier switch, a circuit for, and method of driving the rectifier switch and a power converter employing the circuit or the method. In one aspect of the present invention wherein the synchronous rectifier has at least first and second rectifier switches, the circuit includes: (1) a series-coupled drive winding and capacitor, coupled between a first control terminal of the first rectifier switch and a second control terminal of the second rectifier switch, that generates first and second drive signals and delivers the first and second drive signals to the first and second control terminals, respectively, and (2) first and second clamps, coupled to the first and second control terminals, respectively, that control first and second capacitive charges within the first and second rectifier switches to limit voltage excursions of the first and second drive signals.