Inductor devices – Coil or coil turn supports or spacers – Printed circuit-type coil
Reexamination Certificate
1999-09-22
2001-10-23
Mai, Anh (Department: 2832)
Inductor devices
Coil or coil turn supports or spacers
Printed circuit-type coil
C336S223000, C336S232000
Reexamination Certificate
active
06307458
ABSTRACT:
TECHNICAL FIELD
The invention relates generally to logic integrated circuits and more particularly, to a simplified split winding inductor configuration, easily adapted to a synchronous rectifier circuit. More particularly, the present invention provides an output inductor for a power module that integrates the output inductor winding into the printed circuit board assembly to decrease the cost and complexity of the design and improve noise performance.
BACKGROUND OF THE INVENTION
The growth of the distributed power market has lead to increased research in the area of power modules. As a result, the power density of power modules has increased four times in the past few years, and the efficiency of power modules has significantly increased due to the improvement of current semiconductor devices and the utilization of synchronous rectification for power module applications. As logic integrated circuits have migrated to lower working voltages in the surge for higher operating frequencies and as overall system sizes have continued to decrease, power supply designs with smaller and higher efficiency power modules have increased in demand.
In an effort to improve the efficiencies and increase power densities, synchronous rectification has become necessary for these types of applications. Synchronous rectification has gained great popularity in the last ten years as low voltage semiconductor devices have advanced to make this a viable technology. The power electronics design engineer, however, is still challenged to design power modules with high power density, high efficiency, low output voltage and high output current.
Power modules having synchronous rectification have generally comprised a single winding output inductor connected to the output load of the synchronous rectifier circuit. This has generally been the most popular approach because of its simplicity and reduced part count. A power module configuration known as a “quarter brick” can be used in applications where board space is limited. One version of a quarter brick power module measures 2.28″ long by 1.45″ wide by 0.5″ in height.
The quarter brick power module, as well as other similar power module configurations, typically places the input pins and output pins on opposite ends of the assembly. Essentially, the packaging and layout constraints require the output inductor to be terminated at opposite ends with respect to both the input and output sides of the inductor. This configuration results in a winding configuration with an extra half turn which, in turn, effects the resultant magnetic flux patterns of the inductor core. In particular, the inductance of the fractional turn created by the termination of the output inductor increases with current so that the inductor is easily saturated.
SUMMARY OF THE INVENTION
The present invention achieves technical advantages as a split inductor that can be easily adapted to a synchronous rectifier circuit as an output inductor. The present invention, which comprises a new split inductor design, can be integrated within a quarter brick power module to combine the inductor windings and magnetics onto a scale platform. An optimum layout and package configuration is attained without compromising the design of the output inductor.
As such, according to one embodiment, disclosed is a split inductor winding configuration comprising an inductor core having first, second, and third legs extending from a base member. The first and second legs are predisposed and spaced about a surface of the base member to form a first channel area. The second leg also forms, along with the third leg, a second channel area separated from the first channel area by the second leg. The inductor also comprises inductor windings arranged about the inductor core to provide relatively equal magnetic flux through the first, second, and third legs when current flows through the inductor winding.
In one embodiment of the present invention, the split inductor is integrated within a printed circuit board (PCB) assembly which comprises a plurality of PCB layers. Each of the PCB layers includes a conductive core sub-layer predisposed between two base material sub-layers with each conductive core sub-layer formed into desired circuit pathways. The PCB assembly also comprises a plurality of insulation layers predisposed between the PCB layers and first, second, and third openings extending through the PCB layers. The openings are arranged to accept an inductor core, according to the teachings of the present invention, with a corresponding leg of the inductor core capable of being inserted through a corresponding opening of the PCB assembly.
In yet another embodiment, the present invention is utilized in a synchronous rectifier circuit with the split inductor configuration forming the output inductor on the secondary side of a synchronous rectifier circuit.
A technical advantage of the present invention is the easy adaptation of the inductor configuration of the present invention into power module assembly, such as the quarter brick power module.
Yet another technical advantage of the present invention is that the new inductor configuration can be used to filter out the common mode noise and reduce the output noise of the filter circuit.
Still another technical advantage of the present invention is the use of the split inductor configuration of the present invention in other power supply circuit topologies, such as full-bridge and push-pull.
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Farrington Richard
Hart William
Zhang Jun
Ericsson Inc.
Mai Anh
Navarro Arthur I.
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