Di/dt, Inc.

California Institute of Technology

Other

Power-one Limited

Pai Capital LLC

Bel Power Solutions Inc.

Milivoje Brkovic

Slobodan Cuk

Apurba Roy

Andrzej Pietkiewicz

Jovan Zivkovic

Milan Stefanovic

A switch-mode power converter includes a power isolation transformer and a drive transformer having their various windings collectively wound on a magnetic core having a center leg and outer legs. A primary winding and one or more secondary windings of the power transformer are wound on the center leg, and first and second windings of the drive transformer are wound on an outer leg. A primary control circuit controls one or more primary switches to supply the input voltage to the primary winding. A secondary control circuit controls secondary switches connected between the secondary windings and a load. Another control circuit controls operation the primary and secondary control circuits based at least in part on a feedback signal. The drive transformer windings are further configured to provide isolation between the primary control circuit and the synchronous rectifier control circuit.

Integrated magnetics with isolated drive circuit

The invention relates to a switch-mode power converter including a bias circuit. A power converter power transformer includes a magnetic core. The switch-mode power converter power transformer also includes an initial bias primary winding and an initial bias secondary winding, both wound on the magnetic core, wherein the initial bias secondary winding shares at least one magnetic path in common with the initial bias primary winding. A driver is configured to drive the initial bias primary winding with high frequency pulses when enabled by an enable signal. A rectifier and capacitor are configured to provide a voltage to power a control circuit during a power converter start-up. A method provides an initial bias power for a power converter output side referenced controller, powering the output side referenced controller from the initial bias windings.

Method and apparatus for providing an initial bias and enable signal for a power converter

The invention is a test apparatus incorporating high current test pins, forced into contact with a circuit assembly under test by opposing compliant pressure pins. An advantageous test pin for low voltage, high current testing is a solid, one piece test pin. The solid test pin, when supplied with adequate contact force, provides both low resistance and low inductance. The required compliant force is applied to the test circuit, opposite and substantially in line with the solid test pin, by a compliant pressure pin. Since the test pin does not supply the compliant force, it can be designed primarily for the desired electrical parameters of the test contact. The only mechanical considerations for the conductive solid pin are the amount of desired surface contact area, the dominant mechanical parameter in setting the contact resistance, and the body dimensions, which determine the resistance and inductance of the pin itself. And since, the opposing compliant pressure pin is not part of the electrical test circuit, it can be designed for its mechanical properties alone. The advantage of the conductive pin&#x2014;compliant pressure pin pair over the prior art compliant pin is that the compliant element, usually a spring, is no longer part of the test circuit. Also, a much higher contact force is achievable, resulting in significantly lower contact resistance.

Apparatus and method for testing high current circuit assemblies

A switching regulator includes at least two power switches and two rectifier switches, power transformer having a primary and secondary windings, control circuit for generating control pulses for the power switches, an inductor for providing output current to the load and connected, and a current sensor coupled to the secondary windings and the inductor for sensing current passing through the inductor. The current sensor preferably includes a first and second resistor and a capacitor connected together, and provides a sensed voltage at its output proportional to the product of output current of the inductor and inherent DC resistance of the inductor and the secondary windings. The current sensor is coupled to the control circuit for regulation and protecting the switching regulator against overload or short circuit conditions.

Inductor current sensing in isolated switching regulators and related methods

A drive transformer and associated circuitry for providing power and appropriate delays to primary switches and synchronous rectifiers in switch-mode power converters in a full-bridge topology. The invention takes advantage of the leakage inductances of the drive transformer windings as well as the input capacitance of the primary switches (MOSFETs) to provide the delays. No separate circuitry is needed to provide such delays, thereby providing reliability. Exemplary embodiments further disclose means to disable or enable the primary winding from a condition sensed on the secondary side even with a control and feedback circuit located on the secondary side. The invention further discloses means to use one drive transformer winding to control two switches completely out of phase.

Isolated drive circuitry used in switch-mode power converters

The invention employs a coreless isolated transformer, with associated electronic circuitry, for providing an initial bias and enable signal for control and drive circuitry that is referenced to the output of a converter. The improvement is accomplished by embedding the transformer primary and secondary windings into a multi-layer PCB so that the transformer does not occupy space on the top and bottom surfaces of the PCB The initial bias voltage is used to initialize operation of the control circuit when referenced to the output side of the converter. Thus, complete regulation and drive signals are generated on the output side.

For use in a power converter having a power switch and a synchronous rectifier device coupled between input and output thereof, a control circuit, method of disabling a synchronous rectifier device and power converter employing the control circuit and method. In one embodiment, the control circuit includes a synchronous rectifier controller, coupled to the output of the converter and the synchronous rectifier device, that senses time derivative of the output voltage and disables the synchronous rectifier when derivative is negative and greater than a predetermined magnitude.

Method and apparatus for controlling synchronous rectifiers of a power converter

In accordance with the invention, a circuit module is provided with a plurality of dual capacity connector pads, each pad holding a miniature surface mount connector and/or a connection pin. The preferred I-channel surface mount connector is sufficiently small that the module can be connected by either surface mount or pin to the same region of the circuit board.

Circuit module with universal connectivity

A switching regulator provides load dependent output voltage regulation by sensing voltage drop across inherent DC resistance of the output inductor and secondary windings of power transformer with a first and second resistor and a capacitor and feeding back sensed voltage into an error amplifier for controlling the switching regulator. The regulator may be paralleled for more output current by connecting the outputs together and providing a common reference voltage to all the regulators.

Simple and efficient isolated switching regulator for fast transient loads

In accordance with the invention, a low profile magnetic device comprises a crelenated ferrite body having first and second conductive paths winding around the body. Current applied to one of the conductive windings can adjust the threshold current level in the other conductive winding at which the inductance characteristic changes to a relatively constant inductance.

Low profile surface mount magnetic devices with controlled nonlinearity

A soft-switching dc-to-dc converter for providing regulated voltage to a load combines the functions of loss-less soft switching at zero voltage and at a constant switching frequency on the primary side and soft switching at zero current on the secondary side of an isolation transformer for all load currents from full load to no-load and PWM output voltage regulation on the secondary side. This is made possible by using voltage bidirectional switching element in series with a low-pass filter on the secondary side and current bidirectional switching element on the primary side driven at close to 50% duty ratio with adjustable dead time between switching. The adjustable dead-time is realized by sensing voltages across paired primary side current bidirectional switching element in order to enable alternate turn ON of said pair only at zero voltage, thereby eliminating or greatly reducing switching losses under all load current conditions. The output voltage is regulated by PWM control of the voltage bidirectional switching element comprising one of the following: a bipolar transistor, or a MOSFET in series with a diode, or preferably a saturable reactor in series with a diode to form a magnetic amplifier on the secondary side.

Soft-switching converter DC-to-DC isolated with voltage bidirectional

A DC voltage to a load is provided from a rectified AC power line source with unity power factor using Cuk dc-to-dc switching converter, either unisolated or isolated extensions, operated as an automatic current shaper with unity power factor performance. This is obtained by operating the Cuk converter in a discontinuous inductor current mode (DICM) at a constant switching frequency and constant duty ratio without input current feedback control customarily used, but operating in an open-loop fashion. Even though the Cuk converter is operated in DICM, its input current is nonpulsating and flowing throughout the switching cycle, unlike other converters having pulsating input current in DICM, thus reducing input harmonic currents due to switching frequency and its harmonics. Further improvement is obtained and even the remaining ripple in the input current is entirely eliminated to result in ideal, clean, harmonic-free input current waveform with unity power factor performance, when the coupled-inductor and/or integrated magnetics extensions of the Cuk converter conditions are implemented. They could be operated at low to moderate switching frequency, thus providing high efficiency and without the need for additional input filtering customarily used in other converters.

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Carlsbad, CA, United States of America

Milivoje Brkovic