Apparatus and method for PCB winding planar magnetic devices
First Claim
1. An apparatus for planar magnetic windings on a PCB having a plurality of conductive layers, comprising:
- a plurality of electrical conductor lines formed into planar coils, wherein a plurality of the planar coils spiral inward and a plurality of the planar coils spiral outward, each planar coil being disposed upon a different one of the plurality of conductive layers of the PCB in a vertical stack such that the spirals of the planar coils of the plurality of conductive layers are alternating inward and outward interleaved from one conductive layer to another, said alternating and interleaved spirals of the planar coils enabling (a) electrical connections between the planar coils to be inside a magnetic field area of the coils, and (b) relatively better usage of conductive material inside the magnetic field area by the planar coils remaining within the magnetic field area to make connections and thereby (i) reducing an overall length of the planar coils which reduces electrical resistance of the coils, and (ii) minimizing leakage inductance.
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Abstract
A method and apparatus to layout planar magnetic coils on a PCB consists of maximizing the layer to layer overlap, and consequently maximizing total inductance for the given layout area, by spiraling alternating layers inward and outward. A further benefit of the matching opposite spirals is the ability to make the layer to layer electrical contacts within the magnetic field area, thus reducing leakage inductance, and minimizing the wasted extra conductor line length needed to make the connections outside the magnetic field. The reduced conductor line length results in reduced conductor line resistance. The method is applicable to voltage transformers and isolation transformers as well as simple inductors and other magnetic devices. In the transformer case the odd numbered layers are typically connected together in series to provide a larger turn ratio, and the even numbered layers are typically single turns (i.e., no spiral) connected together in parallel to provide more current capability.
78 Citations
7 Claims
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1. An apparatus for planar magnetic windings on a PCB having a plurality of conductive layers, comprising:
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a plurality of electrical conductor lines formed into planar coils, wherein a plurality of the planar coils spiral inward and a plurality of the planar coils spiral outward, each planar coil being disposed upon a different one of the plurality of conductive layers of the PCB in a vertical stack such that the spirals of the planar coils of the plurality of conductive layers are alternating inward and outward interleaved from one conductive layer to another, said alternating and interleaved spirals of the planar coils enabling (a) electrical connections between the planar coils to be inside a magnetic field area of the coils, and (b) relatively better usage of conductive material inside the magnetic field area by the planar coils remaining within the magnetic field area to make connections and thereby (i) reducing an overall length of the planar coils which reduces electrical resistance of the coils, and (ii) minimizing leakage inductance. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification