llllllllllllllllllllllllllllllllgg?lulljgllylllllllllllllllllllllllllll
`
`US
`[11] Patent Number:
`[45] Date of Patent:
`
`5,479,331
`Dec. 26, 1995
`
`I
`
`United States Patent [19]
`Lenni
`
`[54] SMALL FORM FACTOR POWER SUPPLY
`
`[75] Inventor; Thomas W, Lenni, Laguna Niguel,
`Calm
`
`[73] Assignee: I(it/rim:rgzilllfvireless Technologies, Inc.,
`me’
`1 ‘
`
`[21] Appl. No.: 233,121
`[22] Filed:
`Apr. 26, 1994
`
`6
`[51] Int. Cl. .................................................. .. H02M 3/335
`[52]
`_
`363/21; 363/97
`[58] Field of Search ................................ .. 363/17, 20, 24,
`363/21, 25, 73, 79, 80, 97, 98, 132; 232/212
`I
`References C‘ted
`U_S_ PATENT DOCUMENTS
`
`[56]
`
`
`
`Ravis ...................................... .. 4,307,441 12/1981 Bello . . . . . . . . . . . . . . . . .. 363/25
`
`
`
`4,890,214 12/1989 Yamamoto .............................. .. 363/49
`5,019,954
`5/1991 Bourgeault et a1.
`....... .. 363/21
`5,146,394
`9/ 1992 Ishii et a1. ...................... .. 363/ 16
`5,177,675
`1/1993 Archer ........................... .. 363/25
`5,309,348
`5/1994 Lau ......................................... .. 363/71
`Primary Examiner_peter S. Wong
`Assistant Examiner—Adolf Berhane
`Attorney, Agent, or Firm-Spensley Horn Jubas & Lubitz
`
`ABSTRACT
`[57]
`A new, small form factor power supply is disclosed that
`provides a regulated DC power Supply in a package that
`radiates relatively little heat and that occupies 2.75" by 4.5"
`by ()_75"_ The secondary coil of the transformer is positioned
`at the summing node of the ?ux of the primary coils and the
`phase of the drive signals provided to the secondary coils is
`regulated to control the current and voltage provided by the
`secondary circuit._ Preferably, all circuit components are
`surface mount devices and the transformer cores are E block
`
`cores mounted on [he
`
`circuit
`
`4,734,839
`
`3/1988 Barthold . . . . . . . . . .
`
`. . . . . . .. 363/16
`
`4,885,674 12/1989 Varga et a1. ............................ .. 363/21
`
`12 Claims, 4 Drawing Sheets
`
`110
`/
`
`PR'MARY
`RECTIFIER
`
`FIRST
`PRIMARY
`
`l 120
`
`22
`“
`
`SECONDARY
`
`121 0
`
`SECOND
`PRIMARY
`1130
`
`A216
`
`220
`
`154
`
`152 N
`
`CONTROLLER “'"
`
`(150
`
`I100
`
`PRIMARY
`FEEDBACK
`(140
`
`SECONDARY
`FEEDBACK
`{230
`
`223
`
`Sorias Exhibit 2003, Page 1
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`

`
`US. Patent
`
`Dec. 26, 1995
`
`Sheet 1 0f 4
`
`5,479,331
`
`1/10
`
`—
`
`FIRST
`PRIMARY
`‘
`1 120 N
`
`22
`
`SECONDARY
`
`1210
`
`5500110
`PRIMARY
`a 130
`
`“2/5
`
`Z20
`
`'54
`
`152
`
`CONTROLLER ‘
`
`( 150
`
`PRIMARY
`FEEDBACK
`
`l 140
`
`SECONDARY
`FEEDBACK
`
`l 230
`
`2
`23
`
`10°
`
`FIG1
`
`2o /
`
`2'2
`no.2
`
`Sorias Exhibit 2003, Page 2
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`

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`Sorias Exhibit 2003, Page 3
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`

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`Sorias Exhibit 2003, Page 4
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`

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`US. Patent
`
`Dec. 26, 1995
`
`Sheet 4 of 4
`
`5,47 9,331
`
`cum
`
`Sorias Exhibit 2003, Page 5
`Prong, Inc. v. Sorias, Trial No. IPR2015-01317
`
`

`
`5,479,331
`
`1
`SMALL FORM FACTOR POWER SUPPLY
`
`NOTICE OF COPYRIGHTS
`
`A portion of the disclosure of this patent document
`contains material which is subject to copyright protection.
`The copyright owner has no objection to the facsimile
`reproduction by anyone of the patent disclosure, as it
`appears in the United States Patent and Trademark O?ice
`patent ?les or records, but otherwise reserves all copyright
`rights whatsoever.
`
`10
`
`BACKGROUND OF THE INVENTION
`
`2
`The secondary portion includes a secondary output circuit
`magnetically coupled by a coil to the core that provides the
`regulated DC output and a secondary feedback back circuit
`magnetically coupled to the second core to provide a signal
`to the primary feedback circuit.
`The controller provides a separate square wave signal to
`each of the two primary circuits and the phase of the square
`wave signals may be altered relative to each other as
`determined by the controller. The secondary circuit is posi
`tioned 0n the core relative to the two primary circuits so that
`the secondary circuit coil is positioned at a summing point
`on the core of the ?rst and second primary circuit coils. The
`DC voltage and current levels produced at the output of the
`secondary circuit are monitored by the secondary feedback
`circuit to provide through a secondary feedback coil and a
`primary feedback coil a signal to the controller. The con
`troller alters the phase between the signals driving the two
`coils to produce the desired output DC voltage and current
`at the secondary coils. This results in providing a regulated
`DC power supply with high e?iciency.
`By mounting all of the components on a printed circuit
`board using planar or low pro?le cores and surface mounted
`integrated circuits, a small form factor power supply can be
`attained. Given the high e?iciency of the conversion and
`regulation, the system minimizes dissipation of heat permit
`ting the entire power supply to be mounted within a high
`impact plastic container dimensioned approximately 2.75"
`by 4.5" by 0.75".
`
`BRIEF DESCRIPTION OF THE FIGURES
`
`FIG. 1 is a block diagram of a ?rst embodiment of the
`disclosed invention.
`FIG. 2 is a sectional view of the E core for use in the
`embodiments of FIG. 1.
`FIG. 3 is a detailed circuit schematic of the embodiment
`of FIG. 1.
`FIG. 4 is a top planar view of a printed circuit board
`containing the circuit of FIG. 3.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`FIG. 1 shows a block diagram of the power supply
`according to the invention. All components on the left side
`of a magnetic core 20 are part of the primary portion 100 and
`all portions on the right hand side are part of the secondary
`portion 200 of the power supply.
`The primary portion 100 includes a primary recti?er and
`input circuit 110, a ?rst primary and drive circuit 120, a
`second primary and drive circuit 130, a primary feedback
`circuit 140 and a controller 150. The secondary portion 200
`includes a secondary output circuit 210 and a secondary
`feedback circuit 240.
`The function of the primary recti?er and input circuit 110
`is to couple the embodiment 10 to the line voltage (for
`example 110 volt, 60 Hz), to rectify that voltage and provide
`DC power for the remainder of the primary portion 100 and
`a ground path for the primary circuits 120 and 130. The
`controller 150, which may be a Unitrode 3875 provides two
`square wave driver signals 152 and 154 having alterable
`phases to the ?rst and the second primary circuits 120 and
`130. The ?rst and second primary circuits are resonant
`circuits that are resonant at about the frequency of the driver
`signals and include coils that are coupled to the core 20,
`which may be a planar or low pro?le “E” type core, which
`
`25
`
`1. Field of the Invention
`This invention relates to power supplies and in particular
`relates to small form factor power supplies.
`2. Background of the Invention
`Prior art power supplies include a variety of techniques,
`particularly those used for powering microelectronics such
`as the class of computers commonly known as “notebook”
`computers such as the Powerbook Series available from
`Apple Computer of Cupertino California and the Thinkpad
`Series available from International Business Machines of
`Arrnonk, N.Y. More recently, even smaller personal com
`puters referred to as “sub-notebooks” have also been devel
`oped by various companies such as Hewlett-Packard’s
`Omnibook. The goal of these notebooks and sub-notebooks
`designs is to reduce the size and weight of the product.
`Currently, notebooks typically weigh about six pounds and
`sub~notebooks weigh slightly less than four: pounds.
`Many of these notebook and sub-notebook computers
`have a battery that must be recharged. Also, typically the
`computers are designed to be operated from external power
`sources such as line current and the electrical power system
`of automobiles.
`To power these computers, the manufacturer typically
`provides an external power source. The external power
`source may be a switching power supply that weighs close
`to a pound and is about eight inches long, four inches high
`and about four inches high.
`Such external power supplies therefore contribute sub
`stantial additional weight the user of the computer must
`carry with him or her to permit battery charging and opera
`tion from an electrical socket. Further, the external power
`supply is bulky and may not be readily carried in typical
`cases for such notebook and sub-notebook computers.
`While it has long been known to be desirable to reduce the
`size and weight of the power supply, that has not been
`readily accomplished. Many of the components such as the
`transformer core are bulky and have signi?cant weight.
`Further, such power supplies may need to be able to provide
`DC power of up to seventy-?ve watts, thereby generating
`substantial heat. Due to the inherent inefficiencies of power
`supplies, this results in substantial heat being generated
`within the power supply. Reduction of the volume, weight
`and heat are all critical considerations for a power supply of
`this type of application.
`
`SUMMARY OF THE INVENTION
`
`These and other objects are accomplished through novel
`embodiments of a power supply having a transformer. The
`primary portion includes a primary recti?er circuit, a con~
`troller, ?rst and secondary primary drive circuits each
`coupled magnetically by a coil to the core and a primary
`feedback circuit magnetically coupled by a separate core.
`
`30
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`35
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`40
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`45
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`5,479,331 '
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`3
`may be any low loss material, as is shown in a sectional view
`in FIG. 2. Hence, the driver signals are magnetically coupled
`to the core 20 by ?rst and second primary coils contained
`within the circuits 120, 130.
`The coil 212 in the secondary circuit 210 is preferably
`positioned relative to the coils of the two primary cores so
`that the coil in the secondary circuit is at a summing point
`of the magnetic ?ux from the primary circuit coils. If a
`planar “E” block type core as shown in FIG. 2 is used, the
`coil 212 for the secondary circuit 210 is positioned about the
`central leg 22. The coil for the feedback circuits 140 is
`positioned on one of the outer legs 24, 26. As a result, the
`magnetic ?ux from the two primary coils of the primary
`circuits 120, 130 are summed at the position where the
`secondary coil 212 for the secondary circuit 210 is posi
`tioned. (This positioning of the coils is shown in FIG. 1 by
`using the double line to indicate the central leg 22 and a
`single line to represent the outer legs 24, 26).
`The amplitude of the DC voltage and current produced by
`the secondary circuit 210 are monitored by the secondary
`feedback circuit 230. The primary feedback circuit 140 and
`the secondary feedback circuit 230 are magnetically coupled
`by coils positioned on another core 23 to provide a feedback
`signal to the controller 150. In response to the feedback
`signal, the controller alters the relative phase between the
`two driver signals 152 and 154 to obtain the desired mag
`nitude of the voltage and current. Since the secondary coil
`212 is located at a summing point on the core of the ?ux
`from the two primary coils, as the phase between the driving
`signals 1'52 and 154 to the two primary coils alters, the
`magnitude of the current and voltage induced in the sec
`ondary coil will vary. This will permit control of the sec
`ondary circuit 210 output voltage and current, thereby
`providing a readily controlled output voltage.
`FIG. 3 shows a more detailed schematic of an embodi~
`ment of the invention. A standard AC plug may be coupled
`to input nodes 111, 112 to a ?rst ?lter coil L1 that is coupled
`to a full wave recti?er bridge 113, which may be a
`MDAl06G. Filtering capacitors C1, C2, C7, C8 are also
`coupled to the bridge 113 and one side of the bridge is
`coupled to AC ground.
`The other side of the bridge is coupled to the primary coils
`122 and 132 of the ?rst and second primary circuits 120, 130
`respectively. The other terminal of the primary coils 122,
`132 are coupled to the remainder of the primary circuits 120
`and 130. Each of these primary circuits 120, 130 also
`comprise a drive ?eld effect 124, 134, which may be a
`MTP6N60 and a capacitor 126, 136. The coils 122, 132,
`transistors 124, 134 and capacitors 126, 136 are selected so
`that the resonant frequency of the circuits 120, 130 is at
`about the frequency of the drive signals 152, 154 to maxi
`mize the e?iciency of the power supply. In this embodiment,
`the drive signal frequency is about one Megahertz, though
`other frequencies may be used.
`The drive signals 152 and 154 are supplied by a controller
`150 such as a a Unitrode UC3875QP or other similar
`product. The controller 150 receives the biasing power at
`pins 28 and 1 from the primary power supply circuit 160.
`Each of the coils 122 and 132 induce a varying magnetic
`?eld in the outer legs of the core 20. The secondary coil 212,
`which has a center tap 213, is coupled to a half wave recti?er
`bridge 214, which may comprise an MBRD66OCT, and then
`is coupled to a ?ltering circuit 216 comprised of a capacitor
`218, an inductor 220, and capacitors 222 and 224 to provide
`a DC regulated output 226.
`
`15
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`25
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`30
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`35
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`40
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`50
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`4
`The regulation is provided through feeding back to the
`controller 150 a signal modulated by a current sensing
`circuit 232 and a voltage sensing circuit 240 comprising the
`feedback circuit 230. To provide the carrier for modulation,
`a further secondary carrier coil 242 is coupled to one of the
`outer legs of the core 20. One of the legs of this transformer
`coil 242 is coupled to an isolation feedback transformer T2.
`The current sensing circuit takes the output of the center
`tap of the secondary coil 212 and provides a voltage drop
`across resistor R9 that is provided to a compressing circuit
`234. The output of the compressing circuit 234 is added to
`a voltage dropped across R13 and is provided to an ampli?er
`244 in the voltage sensing circuit 240. The other input in the
`voltage sensing circuit is a reference voltage developed by
`the zener reference diode 246 and also provided as a biasing
`level to the compressing circuit 234. The output of the
`ampli?er 244 is provided to the base of bipolar transistor Q3,
`which may be a MMBT2907T, con?gured in a common base
`con?guration, to amplitude modulate the current through the
`secondary side coil 246.
`The primary side coil 156 of feedback transformer T2 is
`magnetically coupled to the secondary side coil of 246 and
`generates an amplitude modulated signal that is envelope
`detected and integrated to provide a feedback voltage at
`input 22 of the controller 150.
`As a result, as the amplitude of the envelope of the
`modulated signal increases, the voltage at input 22 of the
`controller 150 increases. When the controller 150 deter
`mines that the voltage has exceeded a predetermined limit,
`indicating that either the current or voltage at the output has
`increased beyond the predetermined maximum, the relative
`phase difference of driver signals 152 and 154 is increased.
`If the amplitude at input 22 decreases below a predetermined
`threshold indicating that the voltage or the current is below
`the desired levels, the relative phase of signals 152 and 154
`is decreased towards zero to increase the voltage or current.
`Due to the summing effect of the magnetic ?ux at secondary
`coil 212, a highly e?icient control or regulation of the power
`supply circuit is obtained.
`Because of the high e?iciency that is attained with this
`circuit, heat dissipation is much less and it is possible to
`reduce the size of power supply to a much smaller form
`factor. In particular, each of the electrical components in
`FIG. 2 other than the transformer may be mounted using
`surface mount devices on a printed circuit board. Further,
`each of the inductors and transformer cores are low pro?le
`planar cores mounted through cutouts formed by the printed
`circuit board. The coils of the inductors and transformers are
`provided by wiring traces on the circuit board that wrap
`around the portion of the appropriate core penetrating the
`circuit board. As a result, an extremely compact form factor
`may be obtained. FIG. 4 shows a top planar view of such a
`printed circuit board with each inductor L1, L2 and trans
`former cores T1 and T2 identi?ed.
`Notwithstanding the smaller size of the form factor, heat
`dissipation is not a serious problem due to the increased
`ef?ciency of the power supply according to the disclosed
`embodiments. Therefore, with all the components
`assembled on a printed circuit board as described above, the
`assembled printed circuit board may be housed within a
`housing formed from an injection molded plastic dimen
`sioned 2.75" by 4.5" by 0.75" without undue: heating of the
`housing. For example, with such a housing, surface tem
`peratures on the housing should not exceed one hundred
`twenty degrees Fahrenheit. A normal electrical plug such as
`a phased, three-prong plug, is coupled by an input cable (not
`
`Sorias Exhibit 2003, Page 7
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`5,479,331
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`20
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`
`5
`shown) through a hole formed in the housing and an output
`cable (not shown) having a connector (not shown) coupled
`to the printed circuit.board and to an output connector.
`Alternatively, the three-prong plug (not shown) may be
`formed within the housing with the prongs projecting from
`the housing to avoid the opening for a cable. Also, the plug
`may be of a pivotable type (not shown) mounted on the
`surface of the housing and rotate between a recessed posi
`tion in a cutout formed within the housing and an in use
`position projecting at ninety degrees from the surface of the
`housing.
`Although the disclosed embodiment shows only one
`regulated DC voltage being supplied (for example + 5 volts
`DC), it would readily be understood by those of ordinary
`skill in the ?eld that other regulated or unregulated voltages
`may also be supplied with minor modi?cations to the
`disclosed embodiment. For unregulated voltages, additional
`secondary coils (not shown) with the appropriate number of
`windings to provide the voltage may be magnetically
`coupled to any of the legs of the transformer core 120. The
`appropriate circuitry must then be provided for rectifying
`and ?ltering the output of this additional secondary coil.
`Similarly, an additional regulated voltage may be supplied
`by providing a feedback control circuit such as the type
`described above that provides the appropriate feedback.
`Thus, a small, highly e?icient form factor power supply
`has been disclosed that may be readily mounted within a
`small container. Regulation of the output voltage may be
`readily attained. Alternatively, with appropriate heat transfer
`components, the disclosed power supply may actually be
`mounted within a notebook or even a subnotebook-size
`computer. Still further, the secondary coil can be positioned
`where the magnetic ?ux induced in the core from the two
`primary coils destructively interfere with each other and
`where the phase of the two driving signals is approximately
`one hundred eighty degrees out of phase. Other alternatives
`will be readily apparent to those of skill in the art. Resort to
`the true scope of the invention should be had by resort to the
`claims.
`I claim:
`1. A power supply circuit, the circuit comprising:
`a magnetic core;
`?rst and second primary coals electromagnetically
`coupled to the core to induce magnetic ?ux in the core;
`and
`a secondary coil electromagnetically coupled to the core
`to generate an electromotive force based upon the
`magnetic ?ux in the core, wherein the secondary coil is
`positioned relative to the primary coils such that the
`?ux generated by the primary coils constructively inter
`fere;
`driving circuitry coupled to each of the primary coils to
`provide a separate driving signal to each primary coil
`and each driving signal having a phase a phase rela
`tionship existing between the driving signals;
`a recti?er coupled to the secondary coil to provide a
`regulated DC signal and
`a feedback means coupled between the output of the
`recti?er and the driving circuitry to alter the phase
`relationship between the driving signals to regulate the
`DC signal.
`_
`2. The power supply circuit of claim 1, wherein the
`feedback means includes:
`
`35
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`
`6
`a current sensing circuit coupled to the secondary coil to
`sense current ?ow through the secondary coil;
`a voltage sensing circuit coupled to the regulated DC
`signal;
`an amplitude modulation circuit to amplitude modulate a
`signal based upon the sensed voltage and current ?ow;
`and
`a feedback transformer coupled to the amplitude modu
`lation circuit.
`3. The power supply circuit of claim 1, wherein the core
`is an E block type and each primary coil is mounted on an
`outer leg of the core and the secondary coil is mounted on
`an inner leg.
`4. The power supply circuit of claim 2, wherein the core
`is an E block type and each primary coil is mounted on an
`outer leg of the core and the secondary coil is mounted on
`an inner leg of the core.
`5. The power supply circuit of claim 1, wherein the core
`is a low pro?le magnetic core.
`6. A method for providing a regulated power supply
`providing a regulated direct current output signal having at
`least one parameter at a prede?ned level, the method com
`prising:
`providing a ?rst and second driving signal each having a
`phase, a controllable phase relationship existing
`between the signals;
`providing a ?rst magnetic core with a plurality of primary
`coils magnetically coupled to the core to produce
`magnetic ?ux therein and at least a secondary coil
`magnetically coupled to the core such that the second
`ary coil is positioned at a point where the magnetic ?ux
`from the two primary coils constructively interfere so
`that the secondary coil has a current induced therein
`when the primary coils are driven;
`providing the direct current output signal based upon the
`current induced in the secondary coil,
`sensing at least one parameter of the output signal;
`providing a feedback signal based upon the sensed param
`eter; and
`altering the controllable phase relationship exists between
`the driving signals to keep the parameter of the output
`signal within a predetermine range of the level.
`7. The method of claim 6, wherein the parameter is
`current.
`8. The method of claim 6, wherein the parameter is
`voltage.
`9. The method of claim 6, wherein each primary coil is
`part of a separate resonant circuit.
`10. The method of claim 9, wherein the frequencies of the
`drive signals are substantially at the resonant frequency of
`the resonant circuit.
`11. The method of claim 6, wherein the providing of the
`feedback signal comprises:
`inducing a feedback current based upon the magnetic ?ux
`induced in the core; and
`amplitude modulating the feedback current based upon
`the parameter.
`12. A power supply circuit, the circuit comprising:
`a magnetic core;
`?rst and second primary coils electromagnetically
`coupled to the core to induce magnetic ?ux in the core;
`and
`
`Sorias Exhibit 2003, Page 8
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`5,479,331
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`7
`a secondary coil electromagnetically coupled to the core
`to generate an electromotive force based upon the
`magnetic flux in the core, wherein the secondary coil is
`positioned relative to the primary coils such that the
`?ux generated by the primary coils destructively inter
`fere:
`driving circuitry coupled to each of the primary coils to
`provide a separate driving signal to each primary coil
`and each driving signal having a phase, a phase rela
`
`8
`tionship existing between the driving signals;
`a recti?er coupled to the secondary coil to provide a
`regulated DC signal; and
`a feedback means coupled between the output of the
`recti?er and the driving circuitry to alter the phase
`relationship between the driving signals to regulate the
`DC signal.
`
`Sorias Exhibit 2003, Page 9
`Prong, Inc. v. Sorias, Trial No. IPR2015-01317