PATENT DOCUMENT

Publication Number: US-10719110-B2
Application Number: US-201715826314-A
Country: US
Kind Code: B2

Title: In-system power usage measurement

Abstract:
Systems and methods are provided for performing an in-system measurement of power consumption without exclusive use of an in-line current-sense resistor. Indeed, these systems and methods may take advantage of existing parasitic resistances in an electronic device—such as resistances that might vary over time and under different operating conditions. To perform an in-system measurement, a digital value of a first voltage caused by an unknown amount of current flowing into a power-consuming component over an unknown resistance may be measured. Before or afterward, a current source may be activated to add or subtract a known amount of current to the unknown amount of current, resulting in a second voltage over the unknown resistance, and a digital value of the second voltage over the unknown resistance may be measured. The power consumption by the power-consuming component can then be calculated from these values.

Claims:
What is claimed is: 
     
       1. An electronic device comprising:
 a power supply; 
 an electronic display configured to be supplied with power by the power supply via at least one conductor between an electronic display power source input in the electronic display and the power supply, wherein the at least one conductor has a first resistance; 
 a selectively activatable current source coupled to the at least one conductor, wherein the selectively activatable current source is configured to cause an amount of current flowing across the first resistance of the at least one conductor to change by a first current difference when the selectively activatable current source is activated; and 
 voltage measurement circuitry configured to measure a digital value of a first voltage difference across the first resistance while the selectively activatable current source is activated and to measure a digital value of a second voltage difference across the first resistance while the selectively activatable current source is not activated, thereby enabling a calculation of power consumption by the electronic display based at least in part on the digital value of the first voltage difference, the digital value of the second voltage difference, and a digital value of the first current difference. 
 
     
     
       2. The electronic device of  claim 1 , wherein the selectively activatable current source comprises a switch and a resistor coupled in series between the at least one conductor and a reference voltage. 
     
     
       3. The electronic device of  claim 1 , wherein the selectively activatable current source comprises a switch and a current mirror coupled in series between the at least one conductor and a reference voltage node. 
     
     
       4. The electronic device of  claim 1 , wherein the selectively activatable current source is coupled to the at least one conductor between a resistance and the electronic display power source input in the electronic display. 
     
     
       5. The electronic device of  claim 1 , wherein the first resistance comprises a parasitic resistance on the at least one conductor. 
     
     
       6. The electronic device of  claim 1 , wherein the power supply is disposed on a logic board coupled to the electronic display via a flexible cable and wherein the first resistance comprises a flex resistance of the flexible cable. 
     
     
       7. The electronic device of  claim 1 , wherein the power supply is disposed on a logic board that includes a power transistor configured to selectively provide the power to the electronic display, wherein the first resistance comprises a switching resistance of the power transistor. 
     
     
       8. The electronic device of  claim 1 , wherein the first resistance comprises a ferrite resistance on the electronic display. 
     
     
       9. The electronic device of  claim 1 , wherein the first resistance is configured to vary depending on a current operating condition of the electronic device. 
     
     
       10. The electronic device of  claim 9 , wherein the current operating condition comprises a temperature of the at least one conductor. 
     
     
       11. The electronic device of  claim 1 , comprising routing circuitry configured to cause the selectively activatable current source to couple to a different at least one conductor that is disposed between the power supply and a second power-consuming component of the electronic device, wherein the different at least one conductor has a second resistance, wherein the routing circuitry is configured to cause the voltage measurement circuitry to couple to the different at least one conductor to measure a digital value of a different first voltage difference across the second resistance while the selectively activatable current source is activated and to measure a digital value of a different second voltage difference across the second resistance while the selectively activatable current source is not activated, thereby enabling a calculation of power consumption by the second power-consuming component of the electronic device based at least in part on the digital value of the different first voltage difference, the digital value of the different second voltage difference, and a digital value of a different current difference that is applied to the different at least one conductor when the selectively activatable current source is activated. 
     
     
       12. A method comprising:
 supplying electrical power from a power supply of an electronic device to a power-consuming component of the electronic device over at least a first resistance; 
 measuring a digital value of a first voltage over the first resistance; 
 activating a current source, wherein activating the current source causes an amount of current flowing across the first resistance to change by a first amount of current and therefore causes the first voltage over the first resistance to change to a second voltage over the first resistance; 
 measuring a digital value of the second voltage over the first resistance; and 
 calculating power consumption by the power-consuming component of the electronic device using data processing circuitry in the electronic device based at least in part on the digital value of the first voltage, the digital value of the second voltage, and a digital value of the first amount of current. 
 
     
     
       13. The method of  claim 12 , comprising determining the digital value of the first amount of current at least in part by calculating an amount of current flowing through the current source when the current source is activated. 
     
     
       14. The method of  claim 13 , wherein the amount of current flowing through the current source when the current source is activated is calculated by determining a voltage difference over the current source and dividing the voltage difference over the current source by a known resistance value of a resistor of the current source. 
     
     
       15. The method of  claim 12 , comprising determining the digital value of the first amount of current at least in part by accessing from a memory a digital value of an electrical current drawn by a current mirror of the current source. 
     
     
       16. The method of  claim 12 , wherein the digital value of the first voltage and the digital value of the second voltage are measured by a first analog-to-digital converter configured to measure the digital value of the first voltage and the digital value of the second voltage. 
     
     
       17. The method of  claim 12 , wherein the digital value of the first voltage is measured at least in part by:
 measuring a first digital value using a first analog-to-digital converter; 
 measuring a second digital value using a second analog-to-digital converter; and 
 calculating a difference between the first digital value and the second digital value to obtain the digital value of the first voltage. 
 
     
     
       18. The method of  claim 12 , wherein the power consumption by the power-consuming component of the electronic device is calculated at least in part by:
 determining the digital value of the first amount of current; 
 calculating a value of the first resistance by taking a difference between the first voltage and the second voltage to obtain a voltage difference and dividing the voltage difference by the first amount of current; 
 calculating a component current value flowing into the power-consuming component of the electronic device by dividing the first voltage by the value of the first resistance; and 
 calculating the power consumption based at least in part on the component current value and the first voltage. 
 
     
     
       19. An article of manufacture comprising one or more tangible, non-transitory, machine-readable media comprising instructions to:
 measure a digital value of a first voltage over a first resistance occurring between a power supply of an electronic device and power-consuming component of the electronic device; 
 cause an amount of current flowing across the first resistance to change by a defined or calculable first amount of current and therefore cause the first voltage over the first resistance to change to a second voltage over the first resistance; 
 measure a digital value of the second voltage over the first resistance; and 
 calculate power consumption by the power-consuming component of the electronic device based at least in part on the digital value of the first voltage, the digital value of the second voltage, and a digital value of the first amount of current. 
 
     
     
       20. The article of manufacture of  claim 19 , wherein the instructions to cause the amount of current flowing across the first resistance to change by the defined or calculable first amount of current comprises instructions to issue a control signal to a switch that, when activated, closes a circuit between an input of the power-consuming component of the electronic device and a reference voltage node to add or subtract the defined or calculable first amount of current. 
     
     
       21. The article of manufacture of  claim 19 , wherein the instructions to measure the first voltage over the first resistance comprise instructions to measure the first voltage between an initial voltage output by the power supply and a load voltage at an input of the power-consuming component of the electronic device.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     Under 35 U.S.C. § 120, this application is a Non-Provisional application claiming priority to U.S. Provisional Application No. 62/543,214, entitled “IN-SYSTEM POWER USAGE MEASUREMENT,” filed Aug. 9, 2017, which is incorporated herein by reference in its entirety for all purposes. 
    
    
     BACKGROUND 
     This disclosure relates to measuring power consumption by a component of an electronic device without necessarily adding an always-on, power-consuming in-line current-sense resistor. 
     This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present techniques, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
     Electronic devices have become ubiquitous features of the modern world. Computers, mobile phones, televisions, smart home devices, and cars represent some of these electronic devices. These electronic devices—namely, the various components of the electronic devices—consume power during operation. In one example, electronic displays may consume comparatively large amounts of power. Tracking and measuring how much power electronic displays or other components consume within an electronic device would be useful for debugging and/or monitoring overall power consumption. 
     Many methods for measuring the amount of power consumed by a component of an electronic device may have severe drawbacks. In one example, a current-sense resistor having a known resistance may be placed in series from a power supply of the electronic device to the component of the electronic device. A voltage may be measured across that resistor. Because the resistance of the current-sense resistor is known, the current through the resistor can subsequently be calculated. Multiplying the measured voltage by the calculated current gives the value of the amount of power consumed by the component. An in-line current-sense resistor, however, constantly dissipates additional power in the form of heat any time the component of the electronic device is consuming power, regardless of whether power is currently being measured. Losing additional power and increasing the amount of ambient heat, however, are undesirable in an electronic device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which: 
         FIG. 1  is a schematic block diagram of an electronic device, in accordance with an embodiment; 
         FIG. 2  is a perspective view of a notebook computer representing an embodiment of the electronic device of  FIG. 1 , in accordance with an embodiment; 
         FIG. 3  is a front view of a hand-held device representing another embodiment of the electronic device of  FIG. 1 , in accordance with an embodiment; 
         FIG. 4  is a front view of another hand-held device representing another embodiment of the electronic device of  FIG. 1 , in accordance with an embodiment; 
         FIG. 5  is a front view of a desktop computer representing another embodiment of the electronic device of  FIG. 1 , in accordance with an embodiment; 
         FIG. 6  is a front view of a wearable electronic device representing another embodiment of the electronic device of  FIG. 1 , in accordance with an embodiment; 
         FIG. 7  is a schematic block diagram of circuitry for an in-system power measurement of a component of an electronic device, in accordance with an embodiment; 
         FIG. 8  is a flowchart of a method for measuring power usage of a component of an electronic device, in accordance with an embodiment; 
         FIG. 9  is a block diagram of a system for measuring power consumed by an electronic display, in accordance with an embodiment; 
         FIG. 10  is a block diagram of another system for measuring power consumed by an electronic display, in accordance with an embodiment; 
         FIG. 11  is a block diagram of another system for measuring power consumed by an electronic display, in accordance with an embodiment; and 
         FIG. 12  is a block diagram of another system for measuring power consumed by an electronic display, in accordance with an embodiment. 
     
    
    
     SUMMARY 
     A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below. 
     An efficient method for measuring the power usage of a target load within an electronic device—not only during prototyping and development stages, but also in commercial or mass production—may provide immense value. Such an in-system power measurement may be used to more accurately how power is consumed by various components of an electronic device in real-world use. This could provide valuable feedback to improve power efficiency as well as provide more accurate estimates of battery life. In another example, a specific component may be determined to be malfunctioning if an uncharacteristically high amount of power is measured. 
     In this disclosure, an in-system power measurement system is described, which may efficiently obtain power measurements without exclusively using an in-line current-sense resistor. As mentioned above, an in-line current-sense resistor for measuring power consumption by a particular electronic component will dissipate some power as heat any time the electronic component is consuming power. Thus, over the lifetime of the electronic device, such an in-line current-sense resistor could, on its own, consume a significant amount of power. This is especially true when considering the total number of electronic devices that would have a widely deployed current-sense resistor if included in the electronic devices in mass production. 
     Rather than exclusively use an in-line, always-on current-sense resistor, the systems and methods of this disclosure may measure power consumption using a switchable current source that can be turned off when not in use for measuring power consumption based on resistances that may already be present in an electronic device (though an additional current-sense resistor, of possibly lower resistance, may be added if desired). The switchable current source may draw a known (defined) or calculable amount of current. By measuring a first voltage difference over a resistance when the switchable current source is off and by measuring a second voltage difference over the resistance when the switchable current source is on, an estimate of power may be calculated. Moreover, the resistance over which the first and second voltages are measured may or may not be additional resistances of some well-known value. Indeed, resistances that are already in the electronic device (e.g., a parasitic resistance) may also be used for measuring the voltage differences, even if these resistances vary depending on current operating conditions like temperature. 
     DETAILED DESCRIPTION 
     One or more specific embodiments of the present disclosure will be described below. These described embodiments are only examples of the presently disclosed techniques. Additionally, in an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but may nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
     When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. 
     Within electronic devices, certain electronic components may consume variable amounts of power during operation. Monitoring the different levels of power usage of electronic components of the electronic devices may facilitate the debugging and design of the electronic devices. Rather than exclusively use an in-line, always-on current-sense resistor, the systems and methods of this disclosure may measure power consumption using a switchable current source that can be turned off when not in use for measuring power consumption. 
     With this in mind,  FIG. 1  represents an electronic device  10  that may employ such in-system power-measurement systems and methods. The electronic device  10  may include, among other things, one or more processor(s)  12 , memory  14 , nonvolatile storage  16 , a display  18  input structures  22 , an input/output (I/O) interface  24  and a power source  26 . The various functional blocks shown in  FIG. 1  may include hardware elements (e.g., including circuitry), software elements (e.g., including computer code stored on a computer-readable medium) or a combination of both hardware and software elements. It should be noted that  FIG. 1  is merely one example of a particular implementation and is intended to illustrate the types of components that may be present in the electronic device  10 . 
     By way of example, the electronic device  10  may represent a block diagram of the notebook computer depicted in  FIG. 2 , the handheld device depicted in either of  FIG. 3  or  FIG. 4 , the desktop computer depicted in  FIG. 5 , the wearable electronic device depicted in  FIG. 6 , or similar devices. It should be noted that the processor(s)  12  and/or other data processing circuitry may be generally referred to herein as “data processing circuitry.” Such data processing circuitry may be embodied wholly or in part as software, firmware, hardware, or any combination thereof. Furthermore, the data processing circuitry may be a single contained processing module or may be incorporated wholly or partially within any of the other elements within the electronic device  10 . 
     In the electronic device  10  of  FIG. 1 , the processor(s)  12  and/or other data processing circuitry may be operably coupled with the memory  14  and the nonvolatile storage  16  to perform various algorithms. Such programs or instructions, including those for carrying out the techniques described herein, may be executed by the processor(s)  12  or other data processing circuitry and may be stored in any suitable article of manufacture that includes one or more tangible, computer-readable media at least collectively storing the instructions or routines, such as the memory  14  and the nonvolatile storage  16 . The memory  14  and the nonvolatile storage  16  may include any suitable articles of manufacture for storing data and executable instructions, such as random-access memory, read-only memory, rewritable flash memory, hard drives, and optical discs. Also, programs (e.g., e.g., an operating system) encoded on such a computer program product may also include instructions that may be executed by the processor(s)  12  to enable the electronic device  10  to provide various specific functionalities. 
     In certain embodiments, the display  18  may be a liquid crystal display (e.g., LCD) or an organic light emitting diode (OLED) display, which may allow users to view images generated on the electronic device  10 . In some embodiments, the display  18  may include a touch screen, which may allow users to interact with a user interface of the electronic device  10 . Furthermore, it should be appreciated that, in some embodiments, the display  18  may include one or more light emitting diode (e.g., μLED or OLED) displays, or some combination of LCD panels and LED panels. 
     The input structures  22  of the electronic device  10  may enable a user to interact with the electronic device  10  (e.g., e.g., pressing a button to increase or decrease a volume level). The I/O interface  24  may enable electronic device  10  to interface with various other electronic devices. The I/O interface  24  may include various types of ports that may be connected to cabling. These ports may include standardized and/or proprietary ports, such as USB, RS232, Apple&#39;s Lightning® connector, as well as one or more ports for a conducted RF link. The I/O interface  24  may also include, for example, interfaces for a personal area network (e.g., PAN), such as a Bluetooth network, for a local area network (e.g., LAN) or wireless local area network (e.g., WLAN), such as an 802.11x Wi-Fi network, and/or for a wide area network (e.g., WAN), such as a 3rd generation (e.g., 3G) cellular network, 4th generation (e.g., 4G) cellular network, or long term evolution (e.g., LTE) cellular network. The I/O interface  24  may also include interfaces for, for example, broadband fixed wireless access networks (e.g., WiMAX), mobile broadband Wireless networks (e.g., mobile WiMAX), and so forth. 
     As further illustrated, the electronic device  10  may include a power source  26 . The power source  26  may include any suitable source of power, such as a rechargeable lithium polymer (e.g., Li-poly) battery and/or an alternating current (e.g., AC) power converter. The power source  26  may be removable, such as replaceable battery cell. 
     In certain embodiments, the electronic device  10  may take the form of a computer, a portable electronic device, a wearable electronic device, or other type of electronic device. Such computers may include computers that are generally portable (e.g., such as laptop, notebook, and tablet computers) as well as computers that are generally used in one place (e.g., such as conventional desktop computers, workstations and/or servers). In certain embodiments, the electronic device  10  in the form of a computer may be a model of a MacBook®, MacBook® Pro, MacBook Air®, iMac®, Mac® mini, or Mac Pro® available from Apple Inc. By way of example, the electronic device  10 , taking the form of a notebook computer  30 A, is illustrated in  FIG. 2  in accordance with one embodiment of the present disclosure. The depicted notebook computer  30 A may include housing or enclosure  32 , a display  18 , input structures  22 , and ports of the I/O interface  24 . In one embodiment, the input structures  22  (e.g., such as a keyboard and/or touchpad) may be used to interact with the notebook computer  30 A, such as to start, control, or operate a GUI or applications running on notebook computer  30 A. For example, a keyboard and/or touchpad may allow a user to navigate a user interface or application interface displayed on display  18 . 
       FIG. 3  depicts a front view of a handheld device  30 B, which represents one embodiment of the electronic device  10 . The handheld device  34  may represent, for example, a portable phone, a media player, a personal data organizer, a handheld game platform, or any combination of such devices. By way of example, the handheld device  34  may be a model of an iPod® or iPhone® available from Apple Inc. of Cupertino, Calif. 
     The handheld device  30 B may include an enclosure  36  to protect interior components from physical damage and to shield them from electromagnetic interference. The enclosure  36  may surround the display  18 , which may display indicator icons  39 . The indicator icons  39  may indicate, among other things, a cellular signal strength, Bluetooth connection, and/or battery life. The I/O interfaces  24  may open through the enclosure  36  and may include, for example, an I/O port for a hard wired connection for charging and/or content manipulation using a connector and protocol, such as the Lightning connector provided by Apple Inc., a universal serial bus (e.g., USB), one or more conducted RF connectors, or other connectors and protocols. 
     Input structures  40  and  42 , in combination with the display  18 , may allow a user to control the handheld device  30 B. For example, the input structure  40  may activate or deactivate the handheld device  30 B, one of the input structures  42  may navigate user interface to a home screen, a user-configurable application screen, and/or activate a voice-recognition feature of the handheld device  30 B, while other of the input structures  42  may provide volume control, or may toggle between vibrate and ring modes. The input structures  42  may also include a microphone may obtain a user&#39;s voice for various voice-related features, and a speaker to allow for audio playback and/or certain phone capabilities. The input structures  42  may also include a headphone input to provide a connection to external speakers and/or headphones. 
       FIG. 4  depicts a front view of another handheld device  30 C, which represents another embodiment of the electronic device  10 . The handheld device  30 C may represent, for example, a tablet computer, or one of various portable computing devices. By way of example, the handheld device  30 C may be a tablet-sized embodiment of the electronic device  10 , which may be, for example, a model of an iPad® available from Apple Inc. of Cupertino, Calif. 
     Turning to  FIG. 5 , a computer  30 D may represent another embodiment of the electronic device  10  of  FIG. 1 . The computer  30 D may be any computer, such as a desktop computer, a server, or a notebook computer, but may also be a standalone media player or video gaming machine. By way of example, the computer  30 D may be an iMac®, a MacBook®, or other similar device by Apple Inc. It should be noted that the computer  30 D may also represent a personal computer (e.g., PC) by another manufacturer. A similar enclosure  36  may be provided to protect and enclose internal components of the computer  30 D such as the dual-layer display  18 . In certain embodiments, a user of the computer  30 D may interact with the computer  30 D using various peripheral input devices, such as input structures  22 , which may connect to the computer  30 D via a wired and/or wireless I/O interface  24 . 
     Similarly,  FIG. 6  depicts a wearable electronic device  30 E representing another embodiment of the electronic device  10  of  FIG. 1  that may be configured to operate using the techniques described herein. By way of example, the wearable electronic device  30 E, which may include a wristband  43 , may be an Apple Watch® by Apple, Inc. However, in other embodiments, the wearable electronic device  30 E may include any wearable electronic device such as, for example, a wearable exercise monitoring device (e.g., e.g., pedometer, accelerometer, heart rate monitor), or other device by another manufacturer. The display  18  of the wearable electronic device  30 E may include a touch screen (e.g., e.g., LCD, OLED display, active-matrix organic light emitting diode (e.g., AMOLED) display, and so forth), which may allow users to interact with a user interface of the wearable electronic device  30 E. 
     Any of the devices  30  described above may store one or more multi-frame assets on the memory  14  and/or nonvolatile storage  16 , for example, or on the cloud that may be accessed via the I/O interface  24 . The techniques described below may be used to convert or compress a selected multi-frame asset into a single image for humorous or artistic purposes, for example. These techniques may be embodied in any suitable combination of hardware, firmware, and/or software which may be stored and executed on the devices  30 , using the processor(s)  12 , memory  14 , and/or nonvolatile storage  16 , for example. Furthermore, these techniques may be used on any multi-frame asset such as video, time-lapse photography, panoramic images, fast-burst images, etc. 
       FIG. 7  is a block diagram of a circuit  50  with the electronic device  10  that may include a power supply  52 , a parasitic resistance  54 , and a load  56 . The power supply  52  supplies power to the circuit  50 . The power for the power supply  52  may originate from the power source  26 . The power supply  52  may, for example, be a power management integrated circuit (PMIC) and/or a battery. The power from the power supply  52  creates an input voltage  58  (VINPUT) at the connection, or node, between the power supply  52  and the parasitic resistance  54  of the circuit  50 . The parasitic resistance  54  represents the variety of unwanted resistances that may exist within the circuit  50  between the power supply  52  and the load  56 . The parasitic resistance  54  introduces power loss into the circuit  50 . 
     The load  56  represents an electronic component of the electronic device to which the power supply  52  may be supplying power. In other words, the load  56  consumes power that the power supply  52  provides to the circuit  50 . A load voltage  60  (V LOAD ), which can be measured, forms at the node between the load  56  and the parasitic resistance  54 . 
     A voltage difference measurement device  62  (e.g., analog-to-digital converter) may measure voltage differences that can be used to calculate the power usage of the load  56 . The voltage difference measurement device  62  measures the difference between the input voltage  58  and the load voltage  60  and communicates this to the electronic device  10 . The voltage difference measurement device  62  may connect to the input voltage  58  and the load voltage  60  in order to determine the difference in voltage across the parasitic resistance  54 . Measuring the difference in voltage across the parasitic resistance  54  only once, however, may not provide enough information to calculate the power usage of the load  56 . 
     As such, the difference in voltage across the parasitic resistance  54  may be measured in conjunction with a test current  64  from a current source  66 . The current source  66  may be any one of a variety of devices that produces in an appropriately precise current through the connection from the load  56  node to a reference voltage  68  (e.g., a known resistor and a switch, a current mirror and a switch, and so forth). The application of the load  56  may determine the appropriately precise current for the electronic device  10  and what specific device to use for the current source  66 . Regardless of application specification for the current source  66 , a control signal  70  may enable or disable the current source  66 . 
     When the current source  66  is enabled by the control signal  70 , the test current  64  transmits from the load  56  node to the reference voltage  68 . The test current  64  results from the voltage difference between the load voltage  60  and the reference voltage  68 . The most appropriate voltage for the reference voltage  68  may depend on the application of the circuit  50 . The test current  64  may exist with or without the voltage difference measurement device  62  connected to the same node between the parasitic resistance  54  and the load  56 . 
     Any suitable data processing circuitry of the electronic device  10  may calculate the test current  64  by dividing the difference between the load voltage  60  measured and the reference voltage  68  by the known resistance of the current source  66 . The voltage difference between the input voltage  58  and the load voltage  60  combined with the value of the test current  64  from the current source  66  lead to the calculation of the power usage of the load  56 . A power usage calculation method  80  is described further in  FIG. 8 . 
     The power usage calculation method  80  in  FIG. 8  includes the enabling of the power usage measurement function (process block  82 ), measuring the initial voltage difference across the parasitic resistance (process block  84 ), enabling the control signal (process block  86 ), measuring the voltage across the parasitic resistance (process block  88 ), calculating the test current through the current source (process block  90 ), calculating the parasitic resistance (process block  92 ), and calculating the power usage of the electric load (process block  94 ). 
     To elaborate, once enabled, in an embodiment, the voltage difference measurement device  62  may perform the initial voltage difference measurement. The voltage difference measurement device  62  may perform the initial voltage difference measurement by measuring the difference between the input voltage  58  and the load voltage  60  on either connecting ends of the parasitic resistance  54  (process block  84 ). The initial voltage difference measurement may be expressed as follows:
 
Δ V   INITIAL   =V   INPUT.INITIAL   −V   LOAD.INITIAL   EQ. 1
 
     The initial voltage difference measurement may be taken before enabling the control signal  70  or after disabling the control signal  70 . The initial voltage difference measurement acts as a calibration that may protect against variances within the circuit  50  affecting measurement accuracy. The initial measurement acts to mathematically reset the voltage baseline before the control signal is enabled. This measurement baseline may be taken before each power calculation to compensate for variation in the components of the circuit  50  (e.g., variations resulting from changes in process, voltage, and/or temperature) and/or may be taken during manufacturing in a controlled environment. Resetting the baseline of the voltage comparison by taking the initial voltage difference measurement allows for any variations in the components to be inherent to the baseline each time a new power usage measurement is made. Once the voltage difference measurement device  62  makes the initial voltage difference measurement (process block  84 ), the control signal  70  may enable (process block  86 ). 
     When the control signal  70  enables (process block  86 ), the current source  66  is activated to cause the test current  64  through the current source  66 . The addition of the test current  64  to the circuit  50  may cause the values of the input voltage  58  and the load voltage  60  to change. To accommodate the change, the power usage measurement may involve measuring an additional voltage difference across the parasitic resistance  54  (process block  88 ). 
     The voltage difference measurement device  62  may make the additional voltage difference measurement across the parasitic resistance (process block  88 ). The voltage difference measurement is taken after the current source  66  is enabled. The voltage difference measurement device  62  may perform the final voltage difference measurement by measuring the difference between the value of the input voltage  58  and the value of the load voltage  60 . The final voltage difference measurement may be expressed as follows:
 
Δ V   FINAL   =V   INPUT.FINAL   −V   LOAD.FINAL   EQ. 2
 
     Using a measurement of the final load voltage  60 , the electronic device may calculate the test current  64  (process block  90 ). Following the physical relationship provided by Ohm&#39;s Law, the electronic device  10  may calculate the test current  64  by dividing the final load voltage  60  by the known resistance of the current source  66 . The test current  64  calculation may be expressed as such: 
     
       
         
           
             
               
                 
                   
                     I 
                     TEST 
                   
                   = 
                   
                     
                       V 
                       
                         LOAD 
                         . 
                         FINAL 
                       
                     
                     
                       R 
                       T 
                     
                   
                 
               
               
                 
                   EQ 
                   . 
                   
                       
                   
                   ⁢ 
                   3 
                 
               
             
           
         
       
     
     To complete the power usage measurement, the electronic device  10  may calculate the parasitic resistance  54  (process block  92 ). The electronic device  10  may calculate the parasitic resistance  54  by dividing the difference between the initial voltage difference measurement and the voltage difference measurement by the test current  64 . The parasitic resistance  54  calculation may be expressed as such: 
     
       
         
           
             
               
                 
                   
                     R 
                     PARASITIC 
                   
                   = 
                   
                     
                       
                         Δ 
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         
                           V 
                           INITIAL 
                         
                       
                       - 
                       
                         Δ 
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         
                           V 
                           FINAL 
                         
                       
                     
                     
                       I 
                       TEST 
                     
                   
                 
               
               
                 
                   EQ 
                   . 
                   
                       
                   
                   ⁢ 
                   4 
                 
               
             
           
         
       
     
     To calculate the power usage of the load  56  (process block  94 ), divide the product of the final load voltage  60  and the difference between the between the initial voltage difference measurement and the final voltage difference measurement by the parasitic resistance  54  to calculate the power usage of the load  56 . The power usage of the load  56  calculation may be expressed as such: 
     
       
         
           
             
               
                 
                   
                     P 
                     LOAD 
                   
                   = 
                   
                     
                       
                         V 
                         
                           LOAD 
                           . 
                           INITIAL 
                         
                       
                       * 
                       
                         ( 
                         
                           Δ 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           
                             V 
                             INITIAL 
                           
                         
                         ) 
                       
                     
                     
                       R 
                       PARASITIC 
                     
                   
                 
               
               
                 
                   EQ 
                   . 
                   
                       
                   
                   ⁢ 
                   5 
                 
               
             
           
         
       
     
     Some applications may benefit from determining the power usage of the display  18  of the electronic device  10 .  FIG. 9  shows an example of an electronic display circuit  100  in which the power usage of the display  18  is measured. 
       FIG. 9  shows an electronic display circuit  100 , which may include a main logic board (MLB)  102 , a display  104 , and a flexible connection  106 . In this example, the MLB  102  connects to the display  104  through the flexible connection  106 . The MLB  102  may include a first PMIC/battery  108  and a load switch  110 . The first PMIC/battery  108  may act as the power supply  52  to the circuit. The first PMIC/battery  108  connects to the load switch  110 . The load switch  110  acts to disconnect or connect the power supply  52  to the attached load  56 . The load switch  110  may have a non-negligible internal resistance R LOADSW , which introduces losses into the electronic display circuit  100 . The MLB  102  may connect to the display  104  through the flexible connection  106 . The flexible connection  106  has a flexible connection internal resistance  112  (R FLEX ) which also introduces losses into the electronic display circuit  100 . 
     The display  104  may include a display internal resistance  114  (R DISPLAY ), a second PMIC  116 , and a load current  118  (I LOAD ). The display  104  may have the display internal resistance  114 . The display internal resistance  114  represents the total of the internal resistances to the display  104  (e.g., ferrite resistors, transmission line impedances). The second PMIC  116  may control the power usage of the display  104 . In this embodiment, the load current  118  transmits from the first PMIC/battery  108  to the second PMIC  116 . The load current  118  value may vary based on the power usage use of the second PMIC  116 . The varied power usage of the second PMIC  116  may be based on how long and in what capacity the display  104  is used in. For this example, the power usage of the display  104  is of interest, so the components involved with the power usage calculation method  80  are placed in relation to the second PMIC  116  as to make such measurements within the electronic display circuit  100 . Components involved with the power usage calculation method  80  include a test resistance  120 , a switch  122 , a controller  124  or other circuitry of the electronic device  10 , a reference ground voltage  126 , and an analog-to-digital converter  128 . 
     To implement the power usage calculation method  80 , the analog-to-digital converter  128  may make the initial voltage measurement across the parasitic resistance  54  (process block  84 ), assuming power usage measurement is enabled in the controller  124  or other circuitry of the electronic device  10  (process block  82 ). The specific application of the circuit  50  determines the appropriate value of the parasitic resistance  54 . Different applications may involve different resistances to account for differences in operating voltages, so the parasitic resistance  54  may be sized appropriately for the application. In this embodiment, the display internal resistance  114  represents the parasitic resistance  54 . 
     To make the initial voltage measurement across the parasitic resistance  54 , the analog-to-digital converter  128  uses a negative input terminal  130  to connect to the node between the display internal resistance  114  and the second PMIC  116 . A positive input terminal  132  on the analog-to-digital converter  128  connects on the opposite end of the display internal resistance  114 . This connection allows for the analog-to-digital converter  128  to measure the initial voltage across the display internal resistance  114 . The controller  124  or other circuitry of the electronic device  10  stores the measurement made by the analog-to-digital converter  128  for future calculation. 
     Once the controller  124  or other circuitry of the electronic device  10  stores the initial voltage measurement, the controller  124  or other circuitry of the electronic device  10  enables the switch  122  with a control signal  134 . The closing of the switch  122  allows for a test current  136  (I TEST ) to transmit from the reference ground voltage  126  to the node between the display internal resistance  114  and the second PMIC  116 . Once the switch  122  is closed and the complete connection is made, the analog-to-digital converter  128  may measure the voltage across the display internal resistance  114 . The controller  124  or other circuitry of the electronic device  10  may store the voltage measurement made by the analog-to-digital converter  128 . The controller  124  or other circuitry of the electronic device  10  may calculate the test current  136  by dividing the final load voltage measured by the negative input terminal  130  by the test resistance  120 . 
     Once the controller  124  or other circuitry of the electronic device  10  calculates the test current  136 , the controller  124  or other circuitry of the electronic device  10  may calculate the parasitic resistance  54  (process block  92 ) without directly measuring the value of the parasitic resistance  54 . The controller  124  or other circuitry of the electronic device  10  may calculate the parasitic resistance  54  by dividing the difference between the initial voltage difference measurement and the voltage difference measurement by the test current  136 . The calculated resistance is used to calculate the power usage of the power usage of the display  104  through measuring the power usage of the second PMIC  116  (process block  94 ). The controller  124  or other circuitry of the electronic device  10  may divide the product of the final load voltage  60  and the difference between the initial voltage difference measurement and the voltage difference measurement by the parasitic resistance  54  to calculate the power usage of the load  56 . 
     Suppose the display internal resistance  114  were insufficient value of parasitic resistance  54  for the load current of the second PMIC  116 . To solve this, an increased value of the parasitic resistance  54  may facilitate in making the proper power usage of the load measurement. Solving this problem by only physically adding an additional source of resistance would be inefficient, however, as it would result in additional loss to the electronic display circuit  100 . Reconnecting the voltage difference measurement device  62  to include additional parasitic resistance  54  inherent to the electronic display circuit  100  may provide a better solution and one that relies less on additional sources of resistance. In other words, leveraging existing resistances within the circuit to increase the parasitic resistance  54  may solve the problem of insufficient value of the parasitic resistance  54  without adding additional losses to the electronic display circuit  100 . 
     This is possible since the power usage calculation method  80  works independent of knowing the exact value of the parasitic resistance  54 . Since the power usage calculation method  80  works independent of the exact value of the parasitic resistance  54 , the parasitic resistance  54  may equate to a combination of available resistances within the electronic display circuit  100  as long as they are of sufficient rating for the application. Both  FIG. 10  and  FIG. 11  show variations to the parasitic resistance  54  that are used for in-system power measurements within the electronic display circuit  100 . 
       FIG. 10  shows a second electronic display circuit  140  for measuring in-system power consumption with a different parasitic resistance  54 . Here, the flexible connection internal resistance  112  internal to the flexible connection  106  may join the MLB  102  to the display  104  in the second electronic display circuit. This additional resistance may be used to increase the value of the parasitic resistance  54  (e.g., as may be valuable when a single source of resistance is not sufficient). To include the flexible connection internal resistance  112  with the display internal resistance  114  in the creation of the parasitic resistance  54 , the positive input terminal  132  of the analog-to-digital converter  128  may intersect at the node between the load switch  110  and the flexible connection internal resistance  112 . This change of connection point translates into the analog-to-digital converter  128  reading the voltage difference over both the flexible connection internal resistance  112  and the display internal resistance  114 . The combination of the flexible connection internal resistance  112  and the display internal resistance  114  make the parasitic resistance  54  in this embodiment. 
       FIG. 11  shows another example of circuitry for in-system power measurement via a third electronic display circuit  150 . Here, the positive input terminal  132  of the analog-to-digital converter  128  connects at a node between the first PMIC/battery  108  and the load switch  110 . This change of connection point translates into the analog-to-digital converter  128  reading the voltage difference over the internal resistance of the load switch  110 , the flexible connection internal resistance  112 , and the display internal resistance  114 . The combination of the internal resistance of the load switch  110 , the flexible connection internal resistance  112 , and the display internal resistance  114  make the parasitic resistance  54  in this embodiment. 
       FIG. 12  shows another example of circuitry for in-system power measurement via a fourth electronic display circuit  160 . The electronic display circuit  160  includes the analog-to-digital converter  128  and a second analog-to-digital converter  164 . The analog-to-digital converter  128  connects the negative input terminal  130  to the reference ground voltage  126  and the positive input terminal  132  to the node connecting the display internal resistance  114  to the second PMIC  116 . The second analog-to-digital converter  164  connects a second negative input terminal  168  to a second reference ground voltage  170  and a second positive input terminal  166  to the node connecting the first PMIC/battery  108  to the load switch  110 . The combination of the two analog-to-digital converters makes an effective voltage difference measurement. 
     Additionally or alternatively, a single analog-to-digital converter  128  may be used to make power usage calculations for different loads. For example, the circuit  50  may be used to measure the power usage of multiple loads by switching device(s) that may switch which load is currently being measured. By way of example, one or more multiplexers may selectively route the power measurement circuitry to measure the power consumption of different loads on command. Using such switching device(s) may allow the positive input terminal  132  and the negative input terminal  130  of the voltage difference measurement device  62  to transition between measuring loads, and may be controlled by the controller  124  or other circuitry of the electronic device  10 . 
     Because the voltage difference measurement device  62  to measure voltages outside the measurement range of the voltage difference measurement device  62  may lead to unreliable and incorrect power calculations, an additional component, designed to increase the input voltage  58  and the load voltage  60  measured into a more appropriate range (e.g., differential amplifier) for the voltage difference measurement device  62 , may be added in series with the positive and negative terminals of the voltage difference measurement device  62  at the node of measurement if desired. Furthermore, any of the examples discussed above may be used to measure power consumption by another electronic component of the electronic device  10 , and it should be appreciated that an electronic display is provided by way of example. 
     Thus, the technical effects of the present disclosure include a method for measuring the power usage of one or more target loads. This may be performed without introducing additional unwanted resistances into the circuits by leveraging other resistances (e.g., parasitic resistances) to calculate power usage through use of a current source and a voltage difference measurement device. 
     The specific embodiments described above have been shown by way of example, and it should be understood that these embodiments may be susceptible to various modifications and alternative forms. It should be further understood that the claims are not intended to be limited to the particular forms disclosed, but rather to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure.

Metadata:
Filing Date: 20171129
Publication Date: 20200721
Grant Date: 20200721
Priority Date: 20170809
Inventors: SLIECH, Kevin W.
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F1/26", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/26", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/26", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 65274173