Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
1997-05-14
2001-01-16
Sough, Hyung-Sub (Department: 2841)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C174S260000, C174S07100B, C174S0720TR, C361S807000, C361S810000, C361S775000, C439S212000
Reexamination Certificate
active
06175509
ABSTRACT:
BACKGROUND OF THE INVENTION
Modern microprocessors require the output of high current at relatively low voltage levels, typically in the range of zero to five volts. Further, although microprocessor requires high current, the current demands for requirements fluctuate widely. For example, in the sleep or idle mode a microprocessor might require currents in the range of 0.5 A to 5 A while a microprocessor in a faster computing mode might require currents in the range of 10 A to 100 A. However even though current requirements fluctuate widely, microprocessor specifications require that the voltage limits remain relatively stable, no matter what the operational mode of the microprocessor.
Requirements for tight voltage regulation in response to highly variable current demands mean that the main power supply output can no longer be fed directly to the microprocessor. Instead, a voltage regulator is used to deliver a tightly controlled voltage to the microprocessor. A local voltage regulator supplies a high level of DC current and minimizes the uncertainty in voltage drops between the main power supply and the microprocessor.
Although a voltage regulator circuit provides tight voltage regulation, it must be placed in close proximity to the microprocessor. If the voltage regulator is too far from the microprocessor, impedance between the voltage regulator and microprocessor increases, causing poor voltage regulation at the microprocessor. Further, an increase in impedance decreases speed and increases voltage drops. As the clock speed requirements for microprocessors increase, increases in impedance become less and less acceptable.
A problem with positioning the voltage regulator circuit in close proximity to the microprocessor is that other peripheral devices that work with the microprocessor may be displaced. For example, memory chips, etc. also need to be in close proximity to microprocessor. Thus, the voltage regulator circuit uses up a significant amount of board space which could otherwise be used effectively for the placement of cache memory or other integrated circuits peripheral to the microprocessor, which also need to be close to the microprocessor for reasons of signal integrity. Further, because space constraints are so tight, it is difficult to customize a board for the customer by adding different optional components since board space near the microprocessor is so limited.
A method and apparatus for locating a voltage regulator circuit close to microprocessor while minimizing the required board space and minimizing impedance is needed.
SUMMARY OF THE INVENTION
The present invention is a mounting platform for placement of a first device on a first plane in close proximity to a second device on a second plane. In the preferred embodiment, the first device is a voltage regulator circuit, the second device is a microprocessor, the first plane is the surface of the platform printed circuit board (PCB), and the second plane is the surface of the base printed circuit board. Typically the microprocessor is electrically coupled to the base printed circuit board and the voltage regulator circuit is electrically coupled to the platform printed circuit board. The mounting platform is mounted as a mezzanine over the base printed circuit board on the platform printed circuit board. Mounting the voltage regulator allows the voltage regulator output to be placed adjacent to the microprocessor chip while at the same time minimizing the amount of valuable board space that is used.
The mounting platform forms a “table” over the second plane and is typically comprised of a platform top and a plurality of elongate legs that are soldered or otherwise connected to the platform top. Typically, the platform top of the mounting platform includes of a platform printed circuit board having a power plane and a ground plane. Similarly, the base printed circuit board also includes a power plane and a ground plane. The plurality of elongate legs electrically connect the power plane of the platform PCB to the power plane of the base PCB and electrically connect the ground plane of the platform PCB to the ground plane of the base PCB.
The plurality of elongate legs that are connected to the platform top typically includes an output power leg, an input power leg, and at least a first support leg. Both the input power leg and the output power leg are comprised of a first conductor, a second conductor and an insulator positioned between the first and second conductors. The first and second conductors of the input and output power legs form a low impedance transmission line. The high dielectric constant of the insulator positioned between the first and second conductors provides distributed capacitance between the first and second conductors, lowering the AC impedance and improving the transient response.
Preferably, the first input conductor and the first output conductor are electrically coupled to the power plane of the platform printed circuit board. Similarly, the second input conductor and the second output conductor are electrically coupled to the ground plane of the platform printed circuit board. The input power leg of the mounting platform carries power to the voltage regulator. The output power leg of the mounting platform carries the output power of the voltage regulator to the microprocessor.
In the preferred embodiment, the platform top is comprised of a platform printed circuit board and a platform conductive frame. In the preferred embodiment, the second input conductor and the second output conductors extend from a unitary platform conductive frame that is electrically connected to the ground plane of the platform printed circuit board. The second output conductor and the second input conductors extend from and form part of the unitary platform conductive frame structure. Typically, the platform conductive frame is positioned underneath the platform printed circuit board. Preferably, the platform conductive frame is used as a ground plane for the voltage regulator circuit and for conducting ground current to the microprocessor through one or more of the “legs” of the mounting platform. Because the platform conductive frame acts as ground, the ground plane of the platform printed circuit board is no longer required.
The mounting platform offers a practical and cost-efficient way to locate a very high current voltage regulator in close proximity to the microprocessor chip without significantly reducing the amount of board space available for logic circuits peripheral to the microprocessor. The mounting platform is mechanically stable and is resistant to high levels of shock and vibration. Further, the conductive portions of the legs and the platform conductive frame of the mounting platform act as heat sinks, providing increased cooling for the system. In addition, the platform conductive frame and the platform legs of the mounting platform provide shielding to isolate the voltage regulator circuit from the microprocessor circuit.
A further understanding of the nature and advantages of the invention described herein may be realized by reference to the remaining portions of the specification and the drawings.
REFERENCES:
patent: 4008365 (1977-02-01), Carlson
patent: 4758927 (1988-07-01), Berg
patent: 4867696 (1989-09-01), Demler, Jr. et al.
patent: 4981449 (1991-01-01), Butchter
patent: 5184284 (1993-02-01), Ashelin et al.
patent: 5290971 (1994-03-01), Hamaguchi et al.
patent: 5313367 (1994-05-01), Ishiyama
patent: 5317479 (1994-05-01), Pai et al.
patent: 5430614 (1995-07-01), Difrancesco
patent: 6024589 (2000-02-01), Hahn, IV et al.
Hewlett--Packard Company
Lee Denise A.
Sough Hyung-Sub
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