Electric power conversion systems – Current conversion – Having plural converters for single conversion
Reexamination Certificate
2000-02-15
2001-02-27
Nguyen, Matthew (Department: 2838)
Electric power conversion systems
Current conversion
Having plural converters for single conversion
Reexamination Certificate
active
06195275
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to switching power supplies, and more particularly to multi-output DC-DC switching power supplies.
There are about fourteen basic topologies (basic block diagrams) commonly used to implement a switching power supply. Each topology has characteristics which make it a suitable candidate for use in a particular application.
One of the most fundamental switching power supply topologies is the “buck” converter or “step-down” switching regulator. The buck converter includes a switch, usually in the form of a transistor, whose “on” time is controlled so that a series of rectangular voltage pulses of adjustable width can be appropriately filtered to provide a well-regulated average DC output.
Other switching power supply topologies are better suited for use as DC-DC converters. A DC-DC converter is a device which converts a DC voltage at one level to a DC voltage at another level. The converter typically includes a transformer, having primary and secondary windings wound around a common magnetic core. By opening and closing the primary circuit for appropriate intervals, control over the energy transfer between the primary and secondary windings is accomplished. The transformer provides an alternating voltage whose amplitude can be adjusted by changing the number of turns of the primary and secondary windings. Moreover, the transformer provides DC isolation between the input and the output of the converter.
One of the most common DC-DC converter topologies is the forward converter. When the primary winding of the forward converter is energized by closing the primary circuit, energy is immediately transferred to the secondary winding.
Recently, in the field of switching power supplies, greater attention has been directed toward compactness, energy efficiency, and higher performance. As integrated circuits pack more features in smaller volumes, it becomes increasingly important that the size of the system's power supply also decreases. Moreover, the complexity of many systems have increased with different parts of the system's circuitry requiring different power supply voltages. Thus, power supply designers are faced with the problem of providing smaller power supplies with multiple outputs and better performance.
SUMMARY OF THE INVENTION
The invention features a multi-output power supply including independently controlled forward and buck converters disposed within a housing having half-brick dimensions.
In one general aspect, the multi-output power supply includes a forward converter which receives a DC input voltage and generates a first DC output voltage; a first control circuit which controls the level of the first DC output voltage; a buck converter which receives the first DC output voltage and generates the second DC output voltage; a second control circuit which controls the level of the second DC output voltage; and a housing having half-brick dimensions, with the forward converter, the buck converter, the first control circuit and the second control circuit disposed within the housing.
The present invention combines a pair of independently controlled switching DC circuit topologies which can be disposed within a relatively compact housing having “half-brick” dimensions. Independent control of the forward and buck converters ensures that the outputs of each converter are well-regulated. The topologies are interconnected in a way to allow available output power to be flexibly distributed to each of the pair of voltage outputs.
Preferred embodiments include the following features. The multi-output power supply includes a synchronization circuit which ensures that a second control signal from the second control circuit is applied to the buck converter at substantially the same time a first control signal from the first control circuit is applied to the forward converter. The multi-output power supply also includes a voltage regulator circuit disposed within the housing and connected to the forward converter and buck converter to maintain the difference between the first DC output voltage and the second DC output voltage below a predetermined threshold value
In another aspect of the invention, a multi-output power supply which generates first and second DC output voltages to respective loads includes a housing having half-brick dimensions and first and second pairs of voltage output terminals corresponding to the first and second DC output voltages, respectively. In a preferred embodiment, each of the voltage terminals of the first and second pair of voltage output terminals are adjacent to each other.
Because the terminal pins of each of the first and second pairs of output terminal pins are adjacent to each other, lead lengths associated with the physical layout of the circuit associated with each pair are reduced.
Other features and advantages of the invention will become apparent from the following description of the preferred embodiments and from the claims.
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Fish & Richardson P.C.
International Power Devices, Inc.
Nguyen Matthew
LandOfFree
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