US20080122290A1

US20080122290A1 - Adapter power for mobile devices

Info

Publication number: US20080122290A1
Application number: US11/564,803
Authority: US
Inventors: Peter T. Li; Don J. Nguyen; Andrew W. Keates
Original assignee: Intel Corp
Current assignee: Intel Corp
Priority date: 2003-07-18
Filing date: 2006-11-29
Publication date: 2008-05-29
Also published as: TWI344977B; CA2532461A1; EP1648970A2; JP2011092935A; WO2005010109A2; DE602004011673T2; US7767750B2; JP2007523966A; KR101067082B1; ATE385513T1; DE602004011673D1; TW200510481A; ES2300821T3; EP1648970B1; US20080125540A1; WO2005010109A3; KR20060119858A; JP5102490B2

Abstract

Method and apparatus for efficiently utilizing adapter power. By utilizing a control line in the system, the system is able to condition the battery while an external adapter is being used as the source of the system power.

Description

BACKGROUND INFORMATION

Computer systems are becoming increasing pervasive in our society, including everything from small handheld electronic devices, such as personal data assistants and cellular phones, to application-specific electronic devices, such as set-top boxes, digital cameras, and other consumer electronics, to medium-sized mobile systems such as notebook, sub-notebook, and tablet computers, to desktop systems, servers and workstations. Computer systems typically include one or more processors. A processor manipulates and controls the flow of data in a computer by executing instructions.
To provide more powerful computer systems for consumers, processor designers strive to continually increase the operating speed of the processor. Unfortunately, as processor speed increases, the power consumed by the processor tends to increase as well. Historically, the power consumed by a computer system has been limited by two factors. First, as power consumption increases, the computer tends to run hotter, leading to thermal dissipation problems. Second, the power consumed by a computer system may tax the limits of the power supply used to keep the system operational, reducing battery life in mobile systems and diminishing reliability while increasing cost in larger systems.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features of the invention will be apparent from the following description of preferred embodiments as illustrated in the accompanying drawings, in which like reference numerals generally refer to the same parts throughout the drawings. The drawings are not necessarily to scale, the emphasis instead being placed upon illustrating the principles of the inventions.

FIG. 1 illustrates a block diagram of a computer system in accordance with an embodiment.

FIG. 2 is a flow chart of an adaptive charge rate according to an embodiment.

FIG. 3 is a schematic of an adapter power rating identification in accordance with one embodiment.

FIG. 4 is a schematic of an adapter power rating identification in accordance with a second embodiment.

FIG. 5 is a flow chart of one method to maximize adapter output power.

DETAILED DESCRIPTION

In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular structures, architectures, interfaces, techniques, etc. in order to provide a thorough understanding of the various aspects of the invention. However, it will be apparent to those skilled in the art having the benefit of the present disclosure that the various aspects of the invention may be practiced in other examples that depart from these specific details. In certain instances, descriptions of well-known devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.
FIG. 1 illustrates a block diagram of a computer system 100 in accordance with an embodiment. The computer system 100 includes a computing device 102 and a power adapter 104 (e.g., to supply electrical power to the computing device 102). The computing device 102 may be any suitable computing device such as a laptop (or notebook) computer, a personal digital assistant, a desktop computing device (e.g., a workstation or a desktop computer), a rack-mounted computing device, and the like.
Electrical power may be provided to various components of the computing device 102 (e.g., through a computing device power supply 106) from one or more of the following sources: one or more battery packs, an alternating current (AC) outlet (e.g., through a transformer and/or adaptor such as a power adapter 104), automotive power supplies, airplane power supplies, and the like. In one embodiment, the power adapter 104 may transform the power supply source output (e.g., the AC outlet voltage of about 110 VAC to 240 VAC) to a direct current (DC) voltage ranging between about 7 VDC to 12.6 VDC. Accordingly, the power adapter 104 may be an AC/DC adapter.
The computing device 102 also includes one or more central processing unit(s) (CPUs) 108 coupled to a bus 110. In one embodiment, the CPU 108 is one or more processors in the Pentium® family of processors including the Pentium® II processor family, Pentium® III processors, Pentium® IV processors available from Intel® Corporation of Santa Clara, Calif. Alternatively, other CPUs may be used, such as Intel's Itanium®, XEON™, and Celeron® processors. Also, one or more processors from other manufactures may be utilized. Moreover, the processors may have a single or multi core design.
A chipset 112 is also coupled to the bus 110. The chipset 112 includes a memory control hub (MCH) 114. The MCH 114 may include a memory controller 116 that is coupled to a main system memory 118. The main system memory 118 stores data and sequences of instructions that are executed by the CPU 108, or any other device included in the system 100. In one embodiment, the main system memory 118 includes random access memory (RAM); however, the main system memory 118 may be implemented using other memory types such as dynamic RAM (DRAM), synchronous DRAM (SDRAM), and the like. Additional devices may also be coupled to the bus 110, such as multiple CPUs and/or multiple system memories.
The MCH 114 may also include a graphics interface 120 coupled to a graphics accelerator 122. In one embodiment, the graphics interface 120 is coupled to the graphics accelerator 122 via an accelerated graphics port (AGP). In an embodiment, a display (such as a flat panel display) may be coupled to the graphics interface 120 through, for example, a signal converter that translates a digital representation of an image stored in a storage device such as video memory or system memory into display signals that are interpreted and displayed by the display. The display signals produced by the display device may pass through various control devices before being interpreted by and subsequently displayed on the display.
A hub interface 124 couples the MCH 114 to an input/output control hub (ICH) 126. The ICH 126 provides an interface to input/output (I/O) devices coupled to the computer system 100. The ICH 126 may be coupled to a peripheral component interconnect (PCI) bus. Hence, the ICH 126 includes a PCI bridge 128 that provides an interface to a PCI bus 130. The PCI bridge 128 provides a data path between the CPU 108 and peripheral devices. Additionally, other types of I/O interconnect topologies may be utilized such as the PCI Express™ architecture, available through Intel® Corporation of Santa Clara, Calif.
The PCI bus 130 may be coupled to an audio device 132 and one or more disk drive(s) 134. Other devices may be coupled to the PCI bus 130. In addition, the CPU 108 and the MCH 114 may be combined to form a single chip. Furthermore, the graphics accelerator 122 may be included within the MCH 114 in other embodiments.
Additionally, other peripherals coupled to the ICH 126 may include, in various embodiments, integrated drive electronics (IDE) or small computer system interface (SCSI) hard drive(s), universal serial bus (USB) port(s), a keyboard, a mouse, parallel port(s), serial port(s), floppy disk drive(s), digital output support (e.g., digital video interface (DVI)), and the like, Hence, the computing device 102 may include volatile and/or nonvolatile memory.

Adaptive Charge Rate

Currently, a computer system 100 may not know the power rating of the adapter 104. Both an electrical load and a battery may demand power from the adapter 104, both simultaneously and individually. The power adapter 104 may supply power to the electrical load through V_DCand charge a battery through a battery charger. The battery charger usually starts to charge Li-Ion batteries with a constant current. Usually, the power required by the battery does not depend on the power consumption of the electrical load. This may cause problems if the electrical load does not obtain sufficient power from the adapter. The adapter 104 may shut down due to excessive power demand if its protection mechanism functions properly. However, if protection mechanisms do not function properly, the adapter may overheat, resulting in damages.
Current charging architectures for computers are designed to charge battery cells at a fixed (maximum) rate. Faster charge rates are generally a tradeoff with charge capacity, so the charge rate is capped at a level expected to ensure low battery wear during the charge process. However, with the advent of new battery cells capable of faster charging with little sacrifice of capacity allows for the opportunity to charge cells faster. This is accomplished by shifting the charge rate limitation from the battery itself to the capability of the charging power source, typically an AC adapter.
FIG. 2 is a flow chart of an adaptive charge rate method 200 in accordance with one embodiment. In method 200, the computing device 102 initially receives from the adapter 104, or other external power source, information regarding the amount of power available from the adapter, 202. Next, the device 102 determines its own power demand, 204. In step 206, method 200 determines if the available power output from the adapter is greater than the device's power output. If the adapter 104 power output is greater than the device's power demand than the method goes to step 202 where it continues to monitor the adapter's power capacity.
However, if at step 206, the adapter power output is greater than the device's power output, then the method continues to step 208. At step 208, the method 200 determines if the battery pack needs to be charged. If the battery does not need to be charged than the method goes to step 206. If the battery needs to be charged, the method 200 next determines if the battery temperature is safe to charge, 210. If the battery temperature is not safe to charge the method ends, 218.
If the battery temperature is safe to charge, the method 200 determines the battery's state of charge (SOC), 212. If the state of charge is safe enough to charge the batter, 214, the battery is charged fast 216. However, if the state of charge is not safe the method ends 218.
By monitoring usage of power by the computing device, and comparing it with the available power, the computing device deduces the amount of power available in excess of that needed to power the device. This excess power, available for charging the battery, is then compared to the maximum charge rate allowed by the battery pack. A charge rate is calculated and may charge the battery at the maximum rate the available power permits, up to a maximum rate indicated by the battery.
The method 200 controls the charge rate of batteries by calculating the current available for charging from the current level available from the power source and the current required at any given point in time to power the computing device. Advantageously, the above will result in the fastest possible charging of batteries within the limitations of the AC adapter and the batteries. This allows the battery to make optimal use of the power available in the adapter 104. During usage, this may decrease the charge time of batteries capable of faster charging.

Adapter Power Rating Identification

In current implementations, an adapter 104 notifies the computing device 102 of its power rating. Based on this power rating different bandgap reference voltages, V_REF, is required. This severely limits the number of adapter power ratings available since the number of the bandgap reference voltages for V_REFis limited to what the manufacture provides. However, this may be avoided by changing the resistor values in the circuit, various adapter power ratings maybe accommodated with one V_REFvalue.
The adapter power rating is identified by the voltage V_ADFCat the adapter feedback and control (ADFC) line. In general, the voltage V_ADFCis proportional to the power rating of the adapter. The voltage V_ADFCthat identifies the power rating of the adapter is derived from the reference voltage V_REF. The power to computing device 102 maybe controlled by adjusting the current I_ADFCinput to the power adapter 104 through the V_ADFCline.
The power adapter 104 not only supplies power to the platform but also functions as a battery charger to charge the battery. The adapter 104 output voltage (V_DCIN) may be controlled by the current (I_ADFC)provided from the platform through the V_ADFCline. By utilizing the V_ADFCline, the system is able to condition the battery while the external adapter 104 is being used as the source of system power.
FIG. 3 illustrates a schematic of a power adapter rating identification system 300 in accordance with one embodiment. The power adapter rating identification system 300 illustrates an embodiment of the power adapter 104 and portions of the computing device 102.
The power adapter 104 includes a reference voltage source (V_REF) 302 which provides a potential to a comparator 312. For FIG. 3, the adapter uses a lower reference voltage 302 than the V _ADFC 330. Here the V _REF 302 is equal to 1.225V. Therefore the value of V _ADFC 330 is higher than 1225V.
The comparator 312 may be any suitable comparator such as an operational amplifier. As illustrated in FIG. 3, the output of the comparator 312 may be fed back through various components of the power adapter 104 (not shown) to the positive voltage source V _DCIN 304. Moreover, the comparator 312 receives its non-inverting input from the positive voltage source 304 through resistors 314 (R1), 315 (R2), and 316 (R2). The resistors 314, 315, and 316 may have any suitable value. Also, the value of resistors 314, 3157 and 316 may be fixed in one embodiment.
As illustrated in FIG. 3, the resistors 314, 315, and 316 are coupled to a voltage V _ADFC 330. The V _ADFC 330 is coupled to a current source I_ADFC 338 in the computing device 102. When there is no voltage being injected to the adapter 104, the value 317 going into comparator 312 is the same as V _REF 302. However, if I_ADFC 338 is being input from the computing device 102 into a diode 318, then the V _ADFC 330 is going to be proportional to the values of the resistors, power rating, I_ADFC, V_ADFC, V_DCIN, etc.
Utilizing I_ADFC 338, V _ADFC 330 and the V _REF 302, the system 300 is able to identify the power rating of the adapter 312. The system 300 also illustrates a negative voltage pin 324, e.g., to provide a differential voltage source in conjunction with the positive voltage source 304. Accordingly, by changing the resistor values in the circuit, various adaptor power ratings may be accommodated with one V_REFvalue.
FIG. 4 illustrates a schematic of a power adapter rating identification system 400 in accordance with a second embodiment. The power adapter rating identification system 400 illustrates an embodiment of the power adapter 104 and portions of the computing device 102.
The power adapter 104 includes a reference voltage source (V_REF) 402 which provides a potential to a comparator 312. FIG. 4 is similar to FIG. 3 in most ways, except in system 400, the adapter uses a higher reference voltage 402 than the V _ADFC 330. Here the V _REF 402 is equal to 2.5V. Therefore the value of V _ADFC 330 is lower than 2.25V. Accordingly, by changing the resistor values in the circuit, various adaptor power ratings may be accommodated with one V_REFvalue.

Adapter Power Maximizer

In current implementations, the adapter 104 supplies power to the system and charges battery packs if needed. If the system power demand increases, the system usually lowers the adapter output voltage through the ADFC line. However, the power delivered from the adapter is proportional to its output voltage. The adapter output power may actually be decreased as its output voltage is lowered if its output current is not increased. If the battery is not discharged, the battery pack may be discharged to supply the balance of power to the system.
However, battery pack cannot supply power to the system if they are fully discharged. The adapter output current has to increase to maintain output power level as output voltage decreases. Higher adapter output current may lead to larger adapter size and more expensive adapters.
For example, assume for a 3-series lithium-ion battery, its output voltage is about 12.6V when fully charged, only 9V when fully discharged. This means that the adapter output current has to increase by 40% to have the same output at 9V as it does at 12.6V. Thus a need exists to maximize the adapter output power when battery packs in a notebook PC are fully discharged.
FIG. 5 is a flow chart of one method 500 to maximize adapter output power. In current systems, a mechanism exists to detect how much power and current is needed from the adaptor. This current is proportional to the V_ADFC. Initially, method 500 detects the adapter power and current limit 510.
If the current is not at the adapter's limit, method 500 determines if the battery is charging 520. If the battery is charging then method continues to 510 to continue detecting adapter power and current. If the battery is not charging, then the battery power switch is turned on 530. Once turned on, the method continues to 510.
If the current is at the adapter's limit, method 500 determines if the battery is fully discharged 540. If the battery is not fully discharged, then the method 500 lowers adapter output voltage 550.
If the battery is fully discharged, method 500 next determines if the battery is charging 560. If the battery is not charging then the system may raise adapter output voltage until an upper limit is reached 580.
However, if the battery is charging, then the battery power switch is turned off 570. Then method 500 raises the adapter output voltage until upper limit has been reached. This method 500 enables the system to increase adapter power.
Reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least an implementation. The appearances of the phrase “in one embodiment” in various places in the specification may or may not be all referring to the same embodiment.
Thus, although embodiments have been described in language specific to structural features and/or methodological acts, it is to be understood that claimed subject matter may not be limited to the specific features or acts described. Rather, the specific features and acts are disclosed as sample forms of implementing the claimed subject matter.

Claims

1. A method comprising:

comparing power output from system and adapter module;

determining battery state of charge; and

charging battery.

2. The method of claim 1 further comprising determining adapter power capacity and determining system power demand.

3. The method of claim 1, further comprising determining if battery needs charging.

4. The method of claim 3, further comprising determining if the battery temperature is safe to charge.

5. The method of claim 4 further comprising determining if the state of charge is safe for the battery.

6. The method of claim 5 wherein the charging of battery is performed quickly.

7. A method comprising:

determining if battery is fully discharged;

determining if battery is charging; and

modify adapter output voltage.

8. The method of claim 7 further comprising detecting adapter power and current.

9. The method of claim 8 further comprising determining if battery is charging.

10. The method of claim 9 wherein if battery is not charging, turning off battery switch.

11. The method of claim 10 raising the adapter output voltage until limit is reached.

12. The method of claim 11 wherein the limit is an upper limit.

13. The method of claim 8, further comprising lowering adapter output voltage if battery not discharging.

14. An apparatus comprising:

a power monitor module to modify an output power of a power adapter in accordance with a power consumption of a computing device.

15. The apparatus of claim 14, wherein the power monitor module is implemented in the computing device.

16. The apparatus of claim 14, wherein the power adapter is external to the computing device.

17. The apparatus of claim 14, wherein the power monitor module controls the output power of the power adapter.

18. The apparatus of claim 14, wherein the computing device comprises a battery pack capable of being charged by the power adapter.

19. The apparatus of claim 14, wherein the computing device is selected from a group comprising a laptop computer, a personal digital assistant, a desktop computing device, and a rack-mounted computing device.

20. The apparatus of claim 14, wherein the power adapter is an alternating current/direct current (AC/DC) power adapter.