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`
`Case/Docket No. TRANS59
`Express Mail No.EF338698854US
`
`THE HONORABLE COMMISSIONER OF PATENTS AND TRADEMARKS
`Washington, D.C. 20231
`
`Sir:
`
`Transmitted herewith for filing is the patent application of:
`
`Inventors: Andrew Read, Sameer Halepete, and Keith Klayman
`
`For: STATIC POWER CONTROL
`
`Enclosed are:
`XXX
`XXX
`XXX
`XXX
`
`Two (21 sheet(s) of Formal Drawing(s) including three (5) figures.
`An Assignment of the invention to: Transmeta Corporation on
`A Declaration and Power of Attorney.
`A Verified Statement to establish Small Entity Status under 37 CFR 1.9 and
`37 CFR 1.27.
`Return addressed stamped postcard.
`
`, 2000.
`
`The Filing Fee has been calculated as shown below:
`
`(Col. I)
`No. Filed
`
`-
`
`(Col.2)
`No. Extra
`
`-
`
`SMALL ENTITY
`FEE
`RATE
`-
`
`$355.00
`
`OTHER THAN A
`SMALL ENTITY
`RATE
`FEE
`
`-
`
`For:
`
`Basic Fee:
`Total
`Claims:
`Indep.
`Claims:
`
`-13
`
`-2
`
`-0-
`
`-0-
`
`□ Multiple Dep. Claim(s) Presented
`
`* If the difference in (Col. 1) is less than
`zero, enter "0" in (Col. 2)
`
`x$9.00
`
`X $40.00
`
`+ $135.00
`
`X $18.00
`
`X $80.00
`
`+ $270.00
`
`Total:
`
`$355.00
`
`Total:
`
`$.00
`
`$710.00
`
`-0-
`
`-0-
`
`-0-
`
`XXX
`
`A check in the amount of $355.00 is enclosed to cover the filing fee.
`
`Date:
`
`30 Sweetbay Road
`Rancho Palos Verdes, California 90275
`(310) 377-5073
`
`Express Mail No.EF338698854US
`
`m t&it&i iii HUJl!MBUlilllZ!illEiiiiLiiMiii IHiiMlnilbH&ki&L
`
`MICROCHIP TECHNOLOGY INC. EXHIBIT 1004
`Page 1 of 491
`
`

`

`Applicant or Patentee:
`Serial or Patent No.:
`Filed or Issued:
`
`TRANSMETA CORPORATION
`
`Attorney's
`Docket No.
`
`TRANS59
`
`For: STATIC POWER CONTROL
`
`VERIFIED STATEMENT (DECLARATION) CLAIMING SMALL ENTITY STATUS
`37 CFR 1.9 (f) and 1.27(c) - - SMALL BUSINESS CONCERN
`I hereby declare that I am an official of the small business concern empowered to act on behalf of the
`concern identified below:
`
`TRANSMETA CORPORATION
`NAME OF CONCERN:
`ADDRESS OF CONCERN:
`3940 FREEDOM CIRCLE, SANTA CLARA, CALIFORNIA 95054
`
`I hereby declare that the above identified small business concern qualifies as a small business concern
`as defined in 13 CFR 121.3-18, and reproduced in 37 CFR 1.9(d), for purposes of paying reduced fees
`under Section 41(a) and (b) of Title 35, United States Code, in that the number of employees of the
`concern, including those of its affiliates, does not exceed 500 persons. For purposes of this statement,
`( 1) the number of employees of the business concern is the average over the previous fiscal year of
`the concern of the persons employed on a full-time, part-time or temporary basis during each of the
`pay periods of the fiscal year, and (2) concerns are affiliates of each other when either, directly or
`indirectly, one concern controls or has the power to control the other, or a third party or parties controls
`or has the power to control both.
`
`I hereby certify that to the best of my knowledge and belief rights under contract or law have been
`conveyed to and remain with the small business concern identified above with regard to the invention
`entitled STATIC POWER CONTROL,
`
`by inventor(s) Andrew Read, Sameer Halepete, and Keith Klayman,
`described in
`[ _X_] the application for United States patent, the specification of which was filed on June
`16, 2000, and assigned Serial No. 09/595, 196,
`
`and I have reviewed the document that evidences the conveyance of those rights. That
`document
`[ _X_]
`
`is being filed herewith.
`
`( __ ] Small Business Concern
`
`[ __ ] Non-Profit Organization
`
`If the rights held by the above-identified small business concern are not exclusive, each individual,
`concern or organization having rights to the invention is listed below and no rights to the invention
`are held by any person, other than the inventor. who could not qualify as a small business
`concern under 37 CFR 1.9(d) or by any concern which would not qualify as a small business
`concern under 347 CFR 1.9(d) or a non-profit organization under 37 CFR 1.9(e). NOTE:
`Separate verified statements are required from each named person, concern or organization having
`rights to the invention averring to their status as small entities. (37 CFR 1.27)
`NAME:
`ADDRESS:
`( __ ] Individual
`NAME:
`ADDRESS:
`[ __ } Individual
`
`[ __ l Small Business Concern
`
`[ __ ] Non-Profit Organization
`
`I acknowledge the duty to file, in this application or patent, notification of any change in status resulting
`in loss of entitlement to small entity status prior to paying, or at the time of paying, the earliest of the
`issue fee or any maintenance fee due after the date on which status as a small entity is no longer
`appropriate. (37 CFR 1.28(b)).
`
`Page 1 of 2
`
`::. m :: a::a , : m 11 111 a a z 11
`
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`
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`
`MICROCHIP TECHNOLOGY INC. EXHIBIT 1004
`Page 2 of 491
`
`

`

`I hereby declare that all statements made herein of my own knowledge are true and that all statements
`made on information and belief are believed to be true; and further that these statements were made
`with the knowledge that willful false statements and the like so made are punishable by fine or
`imprisonment, or both, under Section 1001 of Title 18 of the United States Code, and that such willful
`false statements may jeopardize the validity of the application, any patent issuing thereon, or any
`patent to which this verified statement is directed.
`
`NAME OF PERSON SIGNING: MARK ALLEN
`TITLE OF PERSON OTHER THAN OWNER: PRESIDENT AND COO
`ADDRESS OF PERSON SIGNING: 3940 FREEDOM WAY, SANTA CLARA CALIFORNIA 95054
`SIGNATURE: ___________ DATE:
`
`Page 2 of 2
`
`;;; 1,,ana1 ·111
`
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`
`MICROCHIP TECHNOLOGY INC. EXHIBIT 1004
`Page 3 of 491
`
`

`

`METHOD AND APPARATUS FOR REDUCING STATIC POWER LOSS
`
`BACKGROUND OF THE INVENTION
`
`Field Of The Invention
`
`This invention relates to computer systems and, more particularly, to
`
`5
`
`apparatus and methods for reducing power use by a computer system
`
`during intervals in which processing is stopped.
`
`History Of The Prior Art
`
`As computer processors have increased in ability, the number of
`
`transistors utilized has increased almost exponentially. This increase in
`
`circuit elements has drastically increased the power requirements of
`
`such processors. As the need of power increases, the temperature at
`
`which a computer operates increases and the battery life of portable
`
`computers decreases. The loss of battery life with modern portable
`
`computers greatly reduces the time during which the computer can
`
`function as a portable device. In fact, the power usage has become so
`
`great that even with significant reduction in the process size utilized, a
`
`plethora of techniques have been implemented to reduce power usage to
`
`maintain the efficacy of portable computers.
`
`One of these techniques monitors the use of the various devices within
`
`20
`
`the computer and disables those devices that have not been utilized for
`
`some period. Because the processor utilizes a significant amount of the
`
`power (e.g., 50%) used by a portable computer, this technique is utilized
`
`to disable the processor itself when its processing requirements are
`
`unused for some interval. In the typical case, disabling the processor is
`
`1
`
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`
`MICROCHIP TECHNOLOGY INC. EXHIBIT 1004
`Page 4 of 491
`
`

`

`accomplished by terminating the system clocks furnished to the
`
`processor. When processor clocks have been disabled, controlling
`
`circuitry (typically a portion of the "Southbridge" circuitry of an X86-
`
`processor-based computer) remains enabled to detect interrupts
`
`5
`
`requiring processor operation. The receipt of such an interrupt causes
`
`the controlling circuitry to once again enable clocks to the processor so
`
`that the processor may take whatever steps are necessary to handle the
`
`basis of the interrupt.
`
`The technique of disabling the processor reduces significantly the
`
`dissipation of power caused by the operation of the processor even at a
`
`low frequency. In fact, the technique works quite well; and it is
`
`estimated that with many portable computers the processor is placed in
`
`the state in which system clocks are disabled during approximately
`
`ninety percent of the operation of the computer. However, use of this
`
`technique emphasizes another aspect of power loss using advanced
`
`processors. When system clocks for a processor are disabled, the
`
`processor must remain in a state (sometimes called "deep sleep") in
`
`which it is capable of rapidly responding to interrupts. Such a state
`
`requires the application of core voltage to the various circuits. The
`
`20
`
`application of this voltage generates a power dissipation referred to in
`
`this specification as "static power" usage because the processor is in its
`
`static state in which clocks are disabled. To date there has been little
`
`attention paid to this static power usage. However, the usage is very
`
`significant when a processor functions in the deep sleep mode as much
`
`25
`
`as ninety percent of the time. As process technologies continue to shrink
`
`2
`
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`MICROCHIP TECHNOLOGY INC. EXHIBIT 1004
`Page 5 of 491
`
`

`

`in dimension and lower operating voltages, this static power increases
`
`due to lower threshold voltages and thinner gate oxides.
`
`It is desirable to furnish apparatus and methods for reducing the power
`
`use of a processor in the state in which its clocks are disabled.
`
`5
`
`Summary Of The Invention
`
`The present invention is realized by a method for re_ducing power utilized
`
`by a processor including the steps of determining that a processor is
`
`transitioning from a computing mode to a mode in which system clock to
`
`the processor is disabled, and reducing core voltage to the processor to a
`
`value sufficient to maintain state during the mode in which system clock
`
`is disabled.
`
`These and other features of the invention will be better understood by
`
`reference to the detailed description which follows taken together with
`
`the drawings in which like elements are referred to by like designations
`
`throughout the several views.
`
`Brief Description Of The Drawings
`
`Figure 1 is a diagram illustrating current-voltage characteristics of
`
`CMOS transistor devices utilized in microprocessors.
`
`Figure 2 is another diagram illustrating current-voltage characteristics of
`
`20
`
`CMOS transistor devices utilized in microprocessors.
`
`Figure 3 is a circuit diagram illustrating a first circuit designed in
`
`accordance with the present invention for reducing static power usage.
`
`3
`
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`
`MICROCHIP TECHNOLOGY INC. EXHIBIT 1004
`Page 6 of 491
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`

`

`Figure 4 is a circuit diagram illustrating a second circuit designed in
`
`accordance with the present invention for reducing static power usage.
`
`Figure 5 is another circuit diagram illustrating a circuit designed in
`
`accordance with the present invention for reducing static power usage.
`
`5
`
`Detailed Description
`
`Figure 1 is a first diagram displaying a number of curves illustrating the
`
`current-voltage characteristics of CMOS transistor devices utilized in the
`
`circuits of a microprocessor. This first diagram utilizes a linear scale for
`
`both current and voltage. As may be seen, each of the curves illustrates
`
`that the drain-to-source current of a transistor is essentially nonexistent
`
`until the voltage at the gate terminal of the transist~::>r is raised to a
`
`threshold voltage. Once the threshold voltage of the transistor is
`
`reached, drain-to-source current increases either linearly or
`
`quadratically depending on whether the transistor is in the linear region
`
`or saturation region of operation.
`
`Although the diagram of Figure 1 appears to illustrate that current
`
`flowing below the threshold value of the gate voltage is insignificant, this
`
`is not the case in some situations. Figure 2 illustrates current versus
`
`voltage curves of the typical transistor device below the threshold voltage
`
`20
`
`with the voltage being plotted on a log scale. As may be seen, current in
`
`fact flows below the threshold voltage. If a transistor functions in the
`
`state below the threshold voltage for ninety percent·of computer
`
`processor operation, then this current has a significant affect on power
`
`usage by the processor.
`
`4
`
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`MICROCHIP TECHNOLOGY INC. EXHIBIT 1004
`Page 7 of 491
`
`

`

`Since a processor is not capable of computing in the mode in which its
`
`clocks are disabled, it would at first glance appear that the solution
`
`would be to terminate the application of voltage to the processor.
`
`However, as suggested above, it is necessary that the processor be
`
`5
`
`maintained in a condition in which it can respond rapidly to interrupts
`
`provided by the circuitry that controls application of the system clocks.
`
`To do this, the processor must maintain state sufficient to immediately
`
`return to an operating condition. Thus, prior art processors have been
`
`provided sufficient voltage to maintain such state and to keep their
`
`10
`
`transistors ready to immediately respond to interrupts. In general, this
`
`has been accomplished by maintaining the processor core voltage at the
`
`same level as the operating voltage. With most prior art processors, the
`
`core voltage used by a processor is selected by use of motherboard
`
`switches or setup software at a level sufficient to provide the highest
`
`"15
`
`frequency operations specified for the particular processor. For example,
`
`many processors provide 1.8 volts as a core voltage. On the other hand,
`
`the voltage required to maintain state in a deep sleep mode may be
`
`significantly less, e.g., one volt or less. Since such processors function at
`
`the same voltage whether in a computing or a deep sleep mode, a
`
`20
`
`significant amount of unnecessary power may be expended. In one
`
`typical state of the art X86 processor, the power usage averages
`
`approximately one-half watt in the deep sleep state because of the
`
`leakage illustrated by the diagram of Figure 2.
`
`The present invention reduces the voltage applied to the processor
`
`25
`
`significantly below the lowest voltage normally furnished as a core
`
`voltage for the processor during the mode in which system clocks are
`
`5
`
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`MICROCHIP TECHNOLOGY INC. EXHIBIT 1004
`Page 8 of 491
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`

`

`disabled thereby reducing the power utilized by the processor in the deep
`
`sleep state.
`
`Figure 3 is a circuit diagram illustrating a first embodiment of the
`
`invention. In the circuit 10 illustrated, a switching voltage regulator 11
`
`5
`
`receives an input signal at a terminal 12 which determines its output
`
`voltage value. Most modern processors utilize a voltage regulator which
`
`is capable of furnishing a range of core voltages for operating transistors;
`
`a typical regulator may furnish a range of voltages between 2 and 0.925
`
`volts from which a particular core voltage may be selected for operation.
`
`Typically, a binary signal is provided a the terminal 12 which selects the
`
`particular output voltage level to be furnished by the regulator 11; in
`
`such a case, a number of individual pins may be utilized as the terminal
`
`12.
`
`Recently, a new power saving technique has been utilized which
`
`dynamically adjusts both the voltage and operating frequency to a level
`
`;:5s
`
`sufficient to maintain computing operations being conducted by a
`
`processor. The technique which offers significant power savings is
`
`described in detail in U.S. Patent application Serial No. 09/484,516,
`
`filed January 18, 2000, entitled Adaptive Power Control, assigned to the
`
`20
`
`assignee of the present invention. A processor which utilizes this
`
`technique monitors operations within the processor to determine the
`
`frequency level at which the processor should operate. Depending on the
`
`particular operations being carried out by the processor, the value
`
`furnished at the terminal 12 of a regulator functioning in such a system
`
`25
`
`will cause the regulator to produce an output voltage at some level
`
`6
`
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`MICROCHIP TECHNOLOGY INC. EXHIBIT 1004
`Page 9 of 491
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`

`

`between the high and low values necessary for the particular processor
`
`to carry out computing functions.
`
`In the circuit of Figure 3, input to the terminal 12 is furnished via a
`
`circuit 13 such as a multiplexor that is capable of providing one or more
`
`5
`
`input values. In the embodiment illustrated, a value is provided at a first
`
`input 14 to the circuit 13 by the processor (or other circuitry) which
`
`determines the operating condition of the processor in its computing
`
`range; and a second value is provided at a second input 15 which is
`
`selected especially for the deep sleep condition. Either of these input
`
`values may be selected by a control signal provided at a control terminal
`
`16 of the circuit 13. In one embodiment, a system control signal
`
`normally utilized to signal entry into the deep sleep condition (a stop
`
`clock signal) is used as the control signal to be furnished at the control
`
`terminal 16. This control signal selects the input value furnished at the
`
`input 15 which is especially chosen to cause a typical prior art regulator
`
`11 to produce a voltage output for operating the processor in the deep
`
`sleep mode. In one embodiment of the invention, the value furnished for
`
`deep sleep mode is chosen to cause the regulator 11 to produce the
`
`lowest voltage possible in its range of output voltages. In one exemplary
`
`20
`
`processor that utilizes the technique described in the above-mentioned
`
`patent application, the processor is specified as capable of conducting
`
`computing operations in a core voltage range from a low voltage of 1.2
`
`volts to a high voltage of 1.6 volts. On the other hand, the processor
`
`when operating in deep sleep mode has no problem maintaining that
`
`25
`
`state necessary to resume computing even though functioning at a core
`
`voltage of 0.925 volts, the lowest voltage which the regulator can provide.
`
`7
`
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`MICROCHIP TECHNOLOGY INC. EXHIBIT 1004
`Page 10 of 491
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`

`

`Thus, although the voltage regulator 11 may typically provide a range of
`
`varying output voltage levels, the lowest voltage at which a processor is
`
`specified for conducting computing operations is typically significantly
`
`above the lowest value which the regulator is capable of furnishing.
`
`5
`
`In order to reduce power usage in one embodiment of the present
`
`invention, in response to a control signal indicating that the processor is
`
`about to go into the deep sleep state, the value at the input 15 is
`
`furnished by the circuit 13 to the regulator causing the regulator 11 to
`
`generate its lowest possible output voltage level for the deep sleep
`
`condition. In one exemplary embodiment, the high and low voltages
`
`generated in a computing mode are 1.6 volts and 1.2 volts while the deep
`
`sleep voltage is 0. 925 volts.
`
`Although the voltage level furnished by the regulator 11 for the deep
`
`sleep mode of the processor might appear to be only slightly lower than
`
`;:~5
`
`~ :::i:
`
`that furnished in the lowest operating condition for the exemplary
`
`processor, the reduction in power usage is quite significant. Because
`
`both the voltage and the leakage current are reduced, the reduction in
`
`power is approximately equal to the ratio in voltage levels raised to the
`
`power of about three to four. Over any period of processor use involving
`
`20
`
`the deep sleep state, such a reduction is quite large.
`
`One problem with this approach to reducing power is that it does not
`
`reduce the voltage level as far as might be possible and, thus, does not
`
`conserve as much power as could be saved. This approach only reduces
`
`the voltage level to the lowest level furnished by the regulator. This
`
`25
`
`voltage is significantly greater than appears to be necessary for a
`
`8
`
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`MICROCHIP TECHNOLOGY INC. EXHIBIT 1004
`Page 11 of 491
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`

`

`processor which also dynamically regulates voltage furnished during
`
`computing operations to save power. Two criteria control the level to
`
`which the core voltage may be reduced in deep sleep. The level must be
`
`sufficient to maintain state that the processor requires to function after
`
`5
`
`returning from the deep sleep state. The level must be one that can be
`
`reached during the times allowed for transition to and from the deep
`
`sleep mode.
`
`The first criterion is met so long as values of state stored are not lost
`
`during the deep sleep mode. Tests have shown that a core voltage
`
`significantly below one-half volt allows tl;le retention of the memory state
`
`of a processor. Thus, using this criterion, it would be desirable to reduce
`
`the core voltage to a value such as one-half volt or lower.
`
`However, depending on system configuration, the time allowed to
`
`transition to and from deep sleep in an X86 processor can be as low as
`
`i,'~5
`ft~
`
`50 microseconds. Depending on the capacitive load of the particular
`
`circuitry, a voltage variation of about 0.5 to 0.6 volts may take place
`
`during this time in one exemplary configuration.
`
`Thus, if the exemplary processor is operating at its lowest processing
`
`core voltage of 1.2 volts, its core voltage may be lowered in the time
`
`20
`
`available to 0.6 - 0.7 volts. On the other hand, if the processor is
`
`operating at a processing core voltage of 1.5 volts, its core voltage may
`
`only be lowered in the time available to 0.9 - 1 volts. Consequently, it is
`
`desirable that the core voltage furnished during deep sleep be lowered to
`
`a level which may be below the level provided by a typical voltage
`
`9
`
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`MICROCHIP TECHNOLOGY INC. EXHIBIT 1004
`Page 12 of 491
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`

`

`regulator but which varies depending on the core operating voltage from
`
`which it transitions.
`
`This desirable result may be reached utilizing a circuit such as that
`
`described in Figure 4. The circuit of Figure 4 includes a feedback
`
`5
`
`network 41 for controlling the level of voltage at the output of the
`
`regulator 11. Prior art regulators such as the Maxim 1 711 provide a
`
`feedback terminal and describe how that terminal may be utilized with a
`
`resistor-voltage-divider network joined between the output terminal and
`
`ground to raise the output voltage level.
`
`The embodiment of the present invention illustrated in Figure 4 utilizes
`
`the same feedback terminal and a similar resistor-voltage-divider
`
`network but joins the divider between the output terminal and a source
`
`of voltage 42 higher than the normal output voltage of the regulator to
`
`force the output voltage level to a lower value rather than a higher level.
`
`The particular source voltage and the particular resistor values may be
`
`selected to cause the voltage level at the output of the regulator to drop
`
`from a particular output value to a desired value such as 0.6 volts when
`
`transitioning from a computing level of 1.2 volts.
`
`By appropriate choice of the resistor values of the divider network 41 and
`
`20
`
`the source 42, the voltage drop provided by such a divider network
`
`accomplishes the desired result of providing an output voltage for the
`
`deep sleep mode of operation that varies from the previous processor
`
`computing core voltage by an amount attainable during the transition
`
`period available. In one embodiment, resistor 43 was chosen to be 1
`
`25
`
`Kohms, resistor 45 to be 2.7 Kohms, and source 42 to be 3.3 volts. Such
`
`10
`
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`MICROCHIP TECHNOLOGY INC. EXHIBIT 1004
`Page 13 of 491
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`

`

`values cause the voltage drop into deep sleep mode to be between 0.5
`
`and 0.6 volts whether beginning at core voltages of 1.2 or 1.6 volts. On
`
`the other hand, by using a higher value of voltage at source 45 and
`
`adjusting the values of resistors 41 and 43, the increments of voltage
`
`5
`
`drop reached from different starting voltages to final deep sleep voltage
`
`values at the terminal 12 may be brought closer to one another.
`
`It should be noted that the circuitry of Figures 3 and 4 may be combined
`
`so that both input selection and output adjustment are both used to
`
`adjust the core voltage value produced by a voltage regulator for deep
`
`sleep mode in particular instances where the load capacitance is
`
`relatively low.
`
`Prior art voltage regulators function in at least two different modes of
`
`operation. A first mode of operation is often ref erred to as "low noise" or
`
`"continuous" mode. In this mode, the regulator responds as rapidly as
`
`possible to each change in voltage thereby maintaining the output
`
`voltage at the desired output level as accurately as possible. In order to
`
`maintain this mode of rapid response, regulators consume a certain
`
`amount of power. When a regulator is supplying a significant amount of
`
`power to the load, the power required to operate in continuous mode is
`
`20
`
`relatively small. But, when a regulator is supplying a small amount of
`
`power to the load, the power used to operate the regulator in continuous
`
`mode becomes significant, and reduces the efficiency of the regulator
`
`significantly. It is common for regulators operating in the continuous
`
`mode to transfer charge from the supply capacitors back into the power
`
`25
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`source when the output voltage is changed from a higher voltage to a
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`11
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`MICROCHIP TECHNOLOGY INC. EXHIBIT 1004
`Page 14 of 491
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`lower voltage. The regulator can later transfer that charge back to the
`
`regulator output capacitors. Thus, most of the charge is not wasted.
`
`A second mode of operation by voltage regulators is often ref erred to as
`
`"high efficiency," "burst," or "skip" mode. In this mode, a regulator
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`5
`
`detects the reduction in load requirements (such as that caused by a
`
`transition into the deep sleep state) and switches to a mode whereby the
`
`regulator corrects the output voltage less frequently. When there is an
`
`increase in load requirements, the regulator switches back to the
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`continuous mode of regulation during which more rapid correction
`
`occurs. This has the positive effect of reducing the power consumed by
`
`the regulator during deep sleep thereby increasing the regulator
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`efficiency and saving system power. But, as a result of reducing the
`
`regulator response rate, there is more noise on the regulator output.
`
`It is common for regulators operating in the high efficiency mode to drain
`
`the charge on the supply capacitors during a high to low voltage
`
`transition on the power supply output or to allow the load to drain the
`
`charge. Thus, the charge is wasted during high to low voltage
`
`transitions.
`
`It is typical to operate a voltage regulator in the high efficiency mode.
`
`20
`
`Consequently, there is some waste of power whenever a regulated
`
`processor goes into the lower voltage deep sleep mode. If the processor is
`
`constantly being placed in deep sleep mode, then the loss of power may
`
`be quite high. Different operating systems may increase the waste of
`
`power by their operations. For example, an operating system that
`
`25
`
`detects changes in operation through a polling process must constantly
`
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`MICROCHIP TECHNOLOGY INC. EXHIBIT 1004
`Page 15 of 491
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`bring a processor out of deep sleep to determine whether a change in
`
`operating mode should be implemented. For many such systems, such a
`
`system causes an inordinate amount of power waste if a processor would
`
`otherwise spend long periods in the deep sleep mode. On the other
`
`5
`
`hand, an operating system that remains in deep sleep until an
`
`externally-generated interrupt brings it out of that state wastes power
`
`through operating the regulator in the high efficiency mode only when
`
`the processor is placed in the deep sleep state.
`
`The present invention utilizes the ability of regulators to function in both
`
`the high efficiency mode and the continuous mode to substantially
`
`reduce power wasted by transitioning between a computing and a lower
`
`voltage deep sleep mode. Although regulators have not been dynamically
`
`switched between high efficiency and continuous modes, in one
`
`embodiment of the invention, an additional controlling input 50 as
`
`5
`
`shown in Figure 5 is added to the regulator for selecting the mode of
`
`operation of the regulator based on whether the processor being
`
`regulated is transitioning between states. If the regulator receives a
`
`control signal 51 indicating that the processor is to be placed into the
`
`deep sleep mode, for example, then a regulator operating in the high
`
`20
`
`efficiency mode immediately switches to the continuous mode during the
`
`voltage transition. Assuming that the regulator returns the charge to the
`
`battery during continuous mode, this has the effect of reducing the waste
`
`of power caused during the transition. Once the transition has
`
`completed, the regulator switches back to the high efficiency state for
`
`25
`
`operation during the deep sleep mode of the processor.
`
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`MICROCHIP TECHNOLOGY INC. EXHIBIT 1004
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`For regulators that do not conserve capacitive charge by transferring the
`
`charge to the battery, a circuit for accomplishing this may be
`
`implemented or a capacitor storage arrangement such as a charge pump
`
`53 for storage may be added. Alternatively, when transitioning to deep
`
`5
`
`sleep, the regulator could switch to a mode where the regulator does not
`
`actively drive the voltage low but allows the capacitor charge to drain
`
`through the load. The selection of power savings modes is dependent on
`
`the processor leakage current, the voltage drop between the operating
`
`and deep sleep voltages, and the efficiency of the regulator in transferring
`
`10
`
`charge from the capacitors to the power source and then back. If the
`
`leakage current is not sufficient to bring the voltage down more than (1 -
`
`efficiency)* (deep sleep voltage drop) during the deep sleep interval, then
`
`it is more advantageous to use the load to drain the charge on the
`
`capacitors. Otherwise, the charge on the capacitors should be
`
`transferred back to the power source.
`
`The control signal utilized may be the same control signal (stop clocks)
`
`that signals the transition into the deep sleep state if the method is to be
`
`used only for transitions between operating and deep sleep states.
`
`Alternatively, a control signal generated by a particular increment of
`
`20
`
`desired change may be utilized for voltage changes within the computing
`
`range of the processor as well as the transition to deep sleep mode.
`
`Although the present invention has been described in terms of a
`
`preferred embodiment, it will be appreciated that various modifications
`
`and alterations might be made by those skilled in the art without
`
`25
`
`departing from the spirit and scope of the invention. The invention
`
`should therefore be measured in terms of the claims which follow.
`
`14
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`MICROCHIP TECHNOLOGY INC. EXHIBIT 1004
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`What Is Claimed Is:
`
`Claim 1.
`
`A method for reducing power utilized by a processor
`
`comprising the steps of:
`
`determining that a processor is transitioning from a computing mode to a
`
`mode is which system clock to the processor is disabled, and
`
`reducing core voltage to the processor to a value sufficient to maintain
`
`state during the mode in which system clock is disabled.
`
`Claim 2.
`
`A method as claimed in Claim 1 in which the step of
`
`determining that a processor is transitioning from a computing mode to a
`
`mode is which system clock to the processor is disabled comprising
`
`monitoring a stop clock signal.
`
`Claim 3.
`
`A method as claimed in Claim 1 in which the step of
`
`reducing core voltage to the processor to a value sufficient to maintain
`
`state during the state in which system clock is disabled comprises
`
`furnishing an