Abstract: A circuit and method are provided for recuperating energy and decreasing driver power consumption in a switching converter. An inductor is directly connected between a gate driver and a gate electrode of a switch. A first burst pulse signal is generated, wherein energy from a power source is stored in the inductor and transferred to a parasitic capacitance of the switch. A driving pulse signal is subsequently generated to the gate electrode of the switch, wherein the gate voltage is equal to the supply voltage and no balancing current flows through the inductor. After the driving pulse signal is terminated a second burst pulse signal is generated, wherein energy is accumulated in the inductive element and returned to the power source. The energy provided from the power source during the first burst pulse signal is equal to the energy returned to the power source during the second burst pulse signal.

Abstract: A distributed planar inductor is provided with energy storage components featuring high energy storage density, multilayer winding and low copper losses. The inductor includes a magnetic core with a plurality of vertically oriented posts, a plurality of horizontally oriented plates coupled to define an interior, and a conductive winding extending through the interior. The vertical posts each include a plurality of energy storage elements coplanar in orientation with respect to the winding and having a substantially two dimensional structure. The conductive winding may comprise co-planar winding tracks extending through the interior, for example vertically coupled in parallel. A set of co-planar winding tracks may correspond to respective layers in a multilayer printed circuit board, and for example may comprise printed circuit board tracks vertically interconnected by vias extending there-through.

Abstract: A DC/DC converter is provided for operation within a narrow voltage range during normal conditions, while allowing for a wider input voltage range for short periods of time. A first switch is coupled across first and second input terminals, and a capacitor is coupled in parallel with the first switch and across the input terminals. A second switch is coupled in series with the first input terminal and between the first switch and the capacitor. Operation of the switches is regulated in accordance with a bypass mode of operation when received input power is within a defined range, and a boost mode of operation when received input power is less than a threshold value, wherein the received input power is boosted to a bulk output power within the defined range. Boost operations may in various embodiments be provided via, for example, a critical conduction scheme or continuous conduction scheme.

Abstract: A method is provided of operating a resonant converter, the converter having a controller and power stage and providing an output voltage, by determining a characteristic frequency of the power stage. The characteristic frequency is defined as a natural oscillation frequency of the power stage observed right after the power stage control signals from the controller are disabled. The converter is operated at the characteristic frequency during ramp-up or ramp-down of the converter output voltage and/or during overload or input overvoltage conditions.

Abstract: A commutation current steering method is provided for a power converter having an isolation transformer, a plurality of primary ZVS switches, a plurality of secondary switches for synchronous rectification, and a boosting resonant circuit. A commutation current is shared between all of the switches, and a resonance is induced in the boosting resonant circuit by controlling each of the synchronous rectifier switches to turn off at a time prior to a turn-off time for a corresponding one of the switches operating under ZVS conditions, wherein the primary current is boosted above a minimum commutation value during ZVS periods. The ZVS switches are further driven with a constant dead time, and the synchronous rectifier switches are driven to provide a fixed time relation with respect to all of the switches.

Abstract: A dense and efficient output stage for a DC/DC converter includes center tapped secondary windings of a transformer having an offset core with respect to a PCB, two pairs of synchronous rectifiers configured to define two pairs of paralleled symmetrical AC loops respective to the secondary windings, and at least two bus bars disposed within a forced cooling airstream to act as heat sinks for the synchronous rectifiers, while further providing a filtering impedance between the transformer windings and an output capacitance. A split capacitance is disposed in close proximity with the synchronous rectifiers to filter out ripple current, in one embodiment characterized by first and second capacitors each respectively coupled between opposing ends of the first and second bus bars, wherein the bus bars are arranged about at least three sides of the transformer core.

Abstract: A resonant DC/DC power converter is provided with isolated primary and secondary circuits. The primary circuit includes at least four switches as first and second pairs in a bridge configuration, an isolation transformer having at least one primary and at least one secondary winding, and a resonant tank including a resonant capacitor and a split resonant inductor having two separate windings. In one embodiment, the split resonant inductor windings are substantially identical. Synchronous switching of diagonally opposed switch pairs in the bridge configuration thereby produces a center point voltage of the primary transformer winding is substantially free of stepwise voltage changes.

Abstract: A hybrid diode-less power converter topology of the present invention converts power from an AC power source to a variable load with high efficiency. The power converter includes a non-symmetrical arrangement of rectifying switches for rectifying an input AC voltage and shaping switches for shaping an input AC current. The shaping switches are operated in Continuous Conduction Mode (CCM) based on an input AC current. Operation of each of the rectifying switches and shaping switches are further controlled wherein a commutation time for the shaping switches is associated with a first voltage rise and fall time (e.g., less than 10 ns), and a commutation time for the rectifying switches is associated with a second voltage rise and fall time (e.g., at least 100 ns), wherein the first voltage rise and fall time is less than the second voltage rise and fall time by a factor of nine or more.

Abstract: A commutation current steering method is provided for a power converter having an isolation transformer, a plurality of primary ZVS switches, a plurality of secondary switches for synchronous rectification, and a boosting resonant circuit. A commutation current is shared between all of the switches, and a resonance is induced in the boosting resonant circuit by controlling each of the synchronous rectifier switches to turn off at a time prior to a turn-off time for a corresponding one of the switches operating under ZVS conditions, wherein the primary current is boosted above a minimum commutation value during ZVS periods. The ZVS switches are further driven with a constant dead time, and the synchronous rectifier switches are driven to provide a fixed time relation with respect to all of the switches.

Abstract: A multiphase power converter includes one or both of a phase control circuit and a valley switching locking circuit. The phase control circuit measures a phase difference between a first phase circuit and a second phase circuit and varies an on-time of a drive switch of the second phase circuit to produce and maintain a predetermined phase difference between the first phase circuit and the second phase circuit. When the multiphase power converter is operating in a discontinuous mode of operation, the valley switching locking circuit counts the number of zero crossings of an input current of the first phase circuit and blocks a second zero crossing detection signal from a waveform generator (i.e., PWM driver) associated with the second phase circuit until an input current of the second phase circuit has as many zero crossings as that of the first phase circuit input current.

Abstract: A hybrid diode-less power converter topology of the present invention converts power from an AC power source to a variable load with high efficiency. The power converter includes a non-symmetrical arrangement of rectifying switches for rectifying an input AC voltage and shaping switches for shaping an input AC current. The shaping switches are operated in Continuous Conduction Mode (CCM) based on an input AC current. Operation of each of the rectifying switches and shaping switches are further controlled wherein a commutation time for the shaping switches is associated with a first voltage rise and fall time (e.g., less than 10 ns), and a commutation time for the rectifying switches is associated with a second voltage rise and fall time (e.g., at least 100 ns), wherein the first voltage rise and fall time is less than the second voltage rise and fall time by a factor of nine or more.

Abstract: A power converter operable to draw an input current that is in phase with an input voltage of the power converter and proportional to a voltage of the input voltage of the power converter includes a drive switch, a waveform generator, and a current shaping circuit. The drive switch is connected between an input inductor and ground and draws current through the input inductor when turned on. The current shaping circuit provides an on-time of the drive switch for a next cycle of the drive switch as a function of an input current decay time, a switching period of the waveform generator, and an output voltage of the power converter. The waveform generator is responsive to the on-time provided by the current shaping circuit for selectively turning the drive switch on and off to cycle the drive switch as a function of the received on-time.

Abstract: A multiphase power converter includes one or both of a phase control circuit and a valley switching locking circuit. The phase control circuit measures a phase difference between a first phase circuit and a second phase circuit and varies an on-time of a drive switch of the second phase circuit to produce and maintain a predetermined phase difference between the first phase circuit and the second phase circuit. When the multiphase power converter is operating in a discontinuous mode of operation, the valley switching locking circuit counts the number of zero crossings of an input current of the first phase circuit and blocks a second zero crossing detection signal from a waveform generator (i.e., PWM driver) associated with the second phase circuit until an input current of the second phase circuit has as many zero crossings as that of the first phase circuit input current.

Abstract: A power converter operable to draw an input current that is in phase with an input voltage of the power converter and proportional to a voltage of the input voltage of the power converter includes a drive switch, a waveform generator, and a current shaping circuit. The drive switch is connected between an input inductor and ground and draws current through the input inductor when turned on. The current shaping circuit provides an on-time of the drive switch for a next cycle of the drive switch as a function of an input current decay time, a switching period of the waveform generator, and an output voltage of the power converter. The waveform generator is responsive to the on-time provided by the current shaping circuit for selectively turning the drive switch on and off to cycle the drive switch as a function of the received on-time.