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New Magnetic Structure for a Low Profile Planar Transformer

IP.com Disclosure Number: IPCOM000060145D
Original Publication Date: 1986-Mar-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Christensen, JJ: AUTHOR [+2]

Abstract

A low profile power supply for high technology office system equipment is described. The printed circuit (PC) board that is used for the power supply assembly is also used to fill the window of a low profile transformer. A single turn, printed on the PC board, encompasses each leg of the transformer. The use of a single turn on each leg makes it possible to simplify the winding pattern and print higher current lands on the PC board. Furthermore, the close proximity of a single turn to the transformer core minimizes leakage inductance. Since the transformer turns are placed directly on the PC board, the complexity of interconnection to other circuits is greatly reduced. It is known if a single turn is placed around each outside leg of a double E transformer core and then paralleled, an effective half turn can be produced.

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New Magnetic Structure for a Low Profile Planar Transformer

A low profile power supply for high technology office system equipment is described. The printed circuit (PC) board that is used for the power supply assembly is also used to fill the window of a low profile transformer. A single turn, printed on the PC board, encompasses each leg of the transformer. The use of a single turn on each leg makes it possible to simplify the winding pattern and print higher current lands on the PC board. Furthermore, the close proximity of a single turn to the transformer core minimizes leakage inductance. Since the transformer turns are placed directly on the PC board, the complexity of interconnection to other circuits is greatly reduced. It is known if a single turn is placed around each outside leg of a double E transformer core and then paralleled, an effective half turn can be produced. Now if the symmetry of the magnetic structure is maintained and the number of legs in the magnetic core increased, even smaller fractional turns can be obtained with the use of single turns. In such a manner, any primary-to-secondary ratio can be produced. For example, consider the transformer shown in Fig. 1, where Np=1 and Ns=1/4. the use of single turns has produced a transformer with a 4:1 ratio. This concept can be extended to any reasonable primary-to-secondary ratio.

Hence, to produce a 5-volt output from rectified line voltage, 15 transformer secondary legs would be needed. An ex...