Abstract:
A power supply for a portable computer comprises a power adapter case that houses an AC power adapter circuit and a battery charging circuit. A portable computer using this power supply includes a rechargeable battery but does not require a conventional battery charging circuit. In another implementation, the power supply includes a signal line connecting the AC power adapter circuit to the battery charging circuit, wherein if the AC power adapter circuit is about to overload, the AC power adapter circuit transmits a signal over the first signal line. The battery charging circuit, upon receiving the signal, may cease recharging the batteries. In addition, the portable computer may do one or more of isolating the AC power adapter circuit, commencing a shut down of the portable computer, reducing display brightness, reducing CPU speed, entering a sleep mode, shutting down wireless communications, or shutting down unnecessary peripherals.

Description:
BACKGROUND  
       [0001]     Portable computers, such as laptops and notebook computers, generally include an on-board rechargeable battery to provide a power supply for the portable computer when an alternating current (AC) power source, such as an AC power outlet, is unavailable. When an AC power source is available, the portable computer may use an AC power adapter to connect to the AC power source. The AC power source may then power the portable computer as well as recharge the on-board battery.  
         [0002]     The portable computer generally includes a battery charger that receives power from the AC power source and directs that power to the rechargeable battery as needed. When the battery is being recharged, the battery charger tends to dissipate quite a bit of power (e.g., 3-4 Watts), depending on the battery charge status and the charge acceptance capability. This power is generally dissipated as heat energy that increases the temperature within the portable computer. An increase in the internal temperature of the portable computer may lead to a decrease in device reliability and potential device failure. Furthermore, the battery charger tends to have a large footprint on the printed circuit board (e.g., the motherboard) of the portable computer. This increases the size of the portable computer and/or takes space away from other components.  
         [0003]     In addition to the heat dissipation issues, as conventional portable computers become more demanding of power, conventional AC adapters become more likely to experience an overload which may lead to failure of the adapter. Failure of the AC adapter may cause a relatively instant power loss to the portable computer, possibly resulting in loss or corruption of data.  
         [0004]     Accordingly, improved portable computer and AC adapter designs are necessary to improve the reliability and performance of portable computers.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]      FIG. 1  illustrates a generic portable computer power scheme.  
         [0006]      FIG. 2  illustrates a portable computer power scheme in accordance with the invention.  
         [0007]      FIG. 3  illustrates a first conventional power scheme for a portable computer and an AC power adapter.  
         [0008]      FIG. 4  illustrates one implementation of a power scheme for a portable computer and its associated AC power adapter in accordance with the invention.  
         [0009]      FIG. 5  illustrates a second conventional power scheme for a portable computer and an AC power adapter.  
         [0010]      FIG. 6  illustrates another implementation of a power scheme for a portable computer and its associated AC power adapter in accordance with the invention.  
         [0011]      FIG. 7  illustrates an implementation of an AC adapter in communication with a portable computer to address or prevent overload problems.  
     
    
     DETAILED DESCRIPTION  
       [0012]     Described herein are systems and methods of providing power to a portable computer and increasing its reliability and performance. In the following description, various aspects of the illustrative implementations will be described using terms commonly employed by those skilled in the art to convey the substance of their work to others skilled in the art. However, it will be apparent to those skilled in the art that the present invention may be practiced with only some of the described aspects. For purposes of explanation, specific numbers, materials and configurations are set forth in order to provide a thorough understanding of the illustrative implementations. However, it will be apparent to one skilled in the art that the present invention may be practiced without the specific details. In other instances, well-known features are omitted or simplified in order not to obscure the illustrative implementations.  
         [0013]     Various operations will be described as multiple discrete operations, in turn, in a manner that is most helpful in understanding the present invention, however, the order of description should not be construed to imply that these operations are necessarily order dependent. In particular, these operations need not be performed in the order of presentation.  
         [0014]      FIG. 1  illustrates a generic portable computer power scheme. A portable computer system  100  is shown having a system load  102 . The system load  102  represents the power demands of the portable computer  100  from components that include, but are not limited to, a central processing unit (CPU), a hard disk drive, a random access memory (RAM), a read only memory (ROM), a CD-ROM drive, a DVD drive, a keyboard, a mouse, a monitor, a wireless communications device or platform, as well as other components that are well known to those of ordinary skill in the art. An alternating current (AC) adapter  104  receives power from an AC power source (not shown), such as a standard electrical outlet, and provides that power to the portable computer  100  to supply the power demands of the system load  102 . The power is also supplied to a battery changer  106  that uses the power to recharge one or more on-board batteries  108 . The batteries  108  provide power to the portable computer  100  when an AC power source is unavailable.  
         [0015]     As described above, the battery charger  106  often dissipates a substantial amount of heat energy when it is charging the batteries  108 . This heat dissipation increases the internal temperature of the portable computer  100  and therefore decreases the reliability and stability of the portable computer  100 . In addition, the battery charger  106  has a large footprint that takes up space within the portable computer  100  that may be used to house other components or that may be eliminated to reduce the size of the portable computer  100 .  
         [0016]     Therefore, in accordance with an implementation of the invention,  FIG. 2  illustrates a power scheme for a portable computer  200  that addresses these drawbacks. The portable computer  200  utilizes a novel power adapter  202  that houses both an AC power adapter  202 A, such as an AC power adapter circuit, and a battery charger  202 B, such as a battery charger circuit. The portable computer  200  still houses the on-board batteries  108  but no longer houses its own battery charger  106 .  
         [0017]     The implementation shown in  FIG. 2  is possible because the battery charger  106  can only operate if the AC adapter  104  is connected and in use. The battery charger  106  needs power from the AC adapter  104  to charge the batteries  108 . When the AC adapter  104  is not connected and the portable computer  100  is being powered by the batteries  108 , the battery charger  106  serves no function. Since the battery charger  106  can only be used with the AC adapter  104 , moving the battery charger  106  outside the portable computer  100  and coupling it to the AC adapter  104  does not hinder the performance of the portable computer  100 .  
         [0018]     With the battery charger  202 B housed in the novel power adapter  202 , the heat dissipation is moved outside of the portable computer  200 . This increases the reliability and stability of the portable computer  200 . This also allows the heat to dissipate more quickly since the heat will not be trapped within the body of the portable computer  200 . Additionally, surface area within the portable computer  200  that was previously consumed by the battery charger  106  now becomes available to other components. Alternatively, the portable computer  200  may have a smaller form factor with the removal of the battery charger  106 .  
         [0019]      FIG. 3  illustrates a first conventional power scheme for a portable computer  300  and an AC power adapter  302 . This first conventional power scheme is used by portable computers with multi-battery pack support, for instance, one battery pack  308  in the main portable computer system  300  and a second battery pack (not shown) in a device-bay, such as a DVD-drive bay or a floppy disk drive bay. As shown, the AC power adapter  302  sources power to a battery charger  304  and a power path switch  306 . The battery charger  304  is used to recharge on-board batteries  308  via a charger path switch  310 . The charger path switch  310  is used in multi-battery pack systems to provide a mechanism by which the battery packs can be isolated from each other, from the AC power adapter  302 , from the battery charger  304 , or from the rest of the portable computer  300 .  
         [0020]     The power path switch  306  is used to direct the flow of power within the portable computer  300 . For instance, the power path switch  306  may direct power from the AC power adapter  302  to the system load  102  via a DC/DC converter  312 . Alternately, the power path switch  306  may direct power from the batteries  308  to the system load  102  via the DC/DC converter  312 .  FIG. 3  also illustrates a V DC  node that denotes the main power bus that supplies power to the system  300 .  
         [0021]     The portable computer  300  further includes a system management controller (SMC)  314 . The SMC  314  has many functions that are well known in the art. For instance, the SMC  314  can communicate with the batteries  308  (e.g., via a smart battery specification such as SMBus) to gather information such as whether the batteries  308  need to be recharged and how much capacity or run time is left in the batteries. The SMC  314  can use this information to help the portable computer  300  determine where power should be directed and which power sources to use.  
         [0022]     In the conventional power scheme shown of  FIG. 3 , when the AC power adapter  302  is connected, power is directed from the AC adapter  302  to both the battery charger  304  and the power path switch  306  where the power may be supplied to the system load  102 . If the batteries  308  need to be recharged, the battery charger  304  can supply power to the batteries  308 . In systems that have multi-battery pack support, the battery charger  304  can also supply power to a second battery that is docked in a device-bay.  
         [0023]     The battery charger  304  in the conventional power scheme shown in  FIG. 3  suffers from the same drawbacks of the system  100  shown in  FIG. 1 . Namely, the battery charger  304  dissipates a substantial amount of heat while it is supplying power to the batteries  308  and/or the battery in the device-bay. For example, the battery charger  304  may dissipate three to four watts of power while it is recharging the batteries. The battery charger  304  also has a sizable footprint within the portable computer  300 . Finally, the battery charger  304  can only be used when the AC adapter  302  is connected. When the AC power adapter  302  is not connected, the battery charger  304  serves no function.  
         [0024]      FIG. 4  illustrates a novel power scheme for a portable computer  400  and its associated power adapter  402  that is designed in accordance with an implementation of the invention. The power scheme of  FIG. 4  is for use in portable computers based on the first conventional power scheme described in  FIG. 3 .  
         [0025]     The portable computer  400  utilizes a novel power adapter  402  that houses both an AC power adapter  402 A and a battery charger  402 B. The portable computer  400  still houses on-board batteries  308  but no longer houses the battery charger  304 . The portable computer  400  may also house a battery pack (not shown) in a device-bay. Again, this implementation is possible because the battery charger cannot be used without the AC adapter  402  being connected. As such, moving the battery charger outside of the portable computer  400  and housing it with the AC adapter  402 A does not hinder the performance of the portable computer  400 .  
         [0026]     With the battery charger  402 B housed in the novel power adapter  402 , heat dissipation is moved outside of the portable computer  400 , thereby increasing the reliability and stability of the portable computer  400 . The heat may dissipate more quickly in this design. Additionally, the footprint within the portable computer  400  previously consumed by the battery charger  304  becomes available to either house other components or to decrease the form factor of the computer  400 .  
         [0027]     As shown in  FIG. 4 , the novel power adapter  402  has two traces back to the portable computer  400 . A first trace  404  is a power supply line to provide power to address the system load  102 . For instance, this may be a normal 19 volt input that conventional portable computers use. A second trace  406  is a power supply line that is the output of the battery charger  402 B and provides power to the batteries  308  for recharging. Although not shown, another trace may be included between the novel power adapter  402  and the portable computer  400  for grounding purposes.  
         [0028]      FIG. 5  illustrates a second conventional power scheme for a portable computer  500  and an AC power adapter  502 . This second conventional power scheme is known in the art as a “narrow V DC ” (NV DC ) scheme, which is a design technique to reduce the voltage range of the V DC  node. In known power schemes, the AC adapter delivers power in at a voltage that typically ranges up to approximately 19 volts. This voltage range is then provided on the V DC  node. In an NV DC  power scheme, however, the voltage range is reduced down prior to being delivered to the V DC  node. In one implementation, for instance, the power range may be reduced down to about 9 to 12.6 volts. The NV DC  power scheme reduces design complexity because the voltage range can be reduced to match the voltage range being used by the components within a portable computer. For example, a generic lithium-ion battery pack with a 3-series configuration/stack operates in the 9 to 12.6 voltage range, so the NV DC  power scheme can reduce the incoming voltage range down to 9 to 12.6 volts. Future components or battery packs may operate at different voltage ranges, and as such, the NV DC  power scheme may reduce the incoming voltage range down to the appropriate voltage range. The NV DC  power scheme also improves the performance of the various DC-DC converters  312  in the portable computer  500 .  
         [0029]     The NV DC  power scheme is implemented using a system charger/voltage regulator (SCVR)  504 , shown in  FIG. 5 . The up to approximately 19 volts of the AC power adapter  502  is isolated from the portable computer  500  by the SCVR  504  so its voltage never reaches the V DC  node. The SCVR  504  acts as a gateway that receives the higher input voltage from the AC power adapter  502  (i.e., 19 volts) and then regulates that power down to a lower voltage output (i.e., 9 to 12.6 volts). The SCVR  504  then directs that power to components of the portable computer  500 . As such, the V DC  node voltage range is only 9 to 12.6 volts.  
         [0030]     In addition to regulating the incoming voltage, the SCVR  504  may function as the battery charger  304  described above. The SCVR  504  can therefore direct power to recharge the on-board batteries  308  when receiving power from the AC power adapter  502 . The SCVR  504  also delivers power to the DC/DC converters  312  where the power is used to address the system load  102 .  
         [0031]     The SCVR  504  in the NV DC  power scheme shown in  FIG. 5  suffers from the same drawbacks of the system  100  shown in  FIG. 1  and the system  300  shown in  FIG. 3 . The SCVR  504  dissipates a substantial amount of heat while it is performing all of its functions, such as regulating down the voltage, supplying power to the system load  102 , and supplying power to the batteries  308 . For example, the SCVR  504  may dissipate five to eight watts of power while carrying out these functions. The SCVR  504  has a sizable footprint inside the portable computer  500 . And as described above, the SCVR  504  can only be used when the AC adapter  502  is connected. When the AC power adapter  502  is not connected, the SCVR  504  serves no function.  
         [0032]      FIG. 6  illustrates a novel power scheme for a portable computer  600  and its associated power adapter  602  that is designed in accordance with an implementation of the invention. The power scheme of  FIG. 6  is for use in portable computers based on the NV DC  power scheme described in  FIG. 5 .  
         [0033]     The portable computer  600  utilizes a novel power adapter  602  that houses both an AC power adapter  602 A and an SCVR  602 B. The portable computer  600  still houses on-board batteries  308  but no longer houses the SCVR  504 . Once again, this implementation is possible because the SCVR  602 B can only be used if the AC power adapter  602 A is also in use. As such, moving the SCVR  602 B outside of the portable computer  600  and housing it with the AC adapter  602 A does not hinder the performance of the portable computer  600 .  
         [0034]     With the SCVR  602 B housed in the novel power adapter  602 , heat dissipation is moved outside of the portable computer  600 , thereby increasing the reliability and stability of the portable computer  600 . The heat may dissipate more quickly in this design. Additionally, the footprint within the portable computer  600  previously consumed by the SCVR  504  becomes available to either house other components or to decrease the form factor of the computer  600 .  
         [0035]     As shown in  FIG. 6 , the novel power adapter  602  includes a trace  604  back to the portable computer  600 . This trace  604  is a power supply line that provides the 9 to 12.6 volt input that portable computers using an NV DC  power scheme use. The trace  604  from the SCVR  602 B provides power to address the system load  102  and provides power to the batteries  308  for recharging. Power from the AC adapter  602 A is provided only to the SCVR  602 B for voltage regulation. The AC adapter  602 A does not supply power to the portable computer  600  directly. In one implementation, a trace  606  may also be included to couple the SCVR  602 B to the SMC  314 . Although not shown, another trace may be included between the novel power adapter  602  and the portable computer  600  for grounding purposes.  
         [0036]     It has been observed that power ratings for AC adapters are rising because of the higher power demands of conventional portable computer systems due to ever increasing system loads and from the need to recharge battery packs. This results in even greater heat dissipation within a conventional portable computer system that uses an on-board battery charger. If the AC adapter cannot meet the increasing power demand, the AC adapter may overload and/or fail. Overloading the AC adapter, combined with increasing the internal temperature due to increased heat dissipation, may cause the portable computer system to become less reliable and may lead to system failure.  
         [0037]     To address this issue,  FIG. 7  illustrates an implementation of the invention consisting of a power adapter  700  that is in communication with a portable computer system  702  to address or prevent overload problems. The power adapter  700  is an AC adapter as described above. The portable computer system  702  includes a battery charger  704  that may be mounted within the portable computer  702 . In alternate implementations, the battery charger  704  may be housed within the power adapter  700 , similar to implementations of the invention described above. The system  702  also includes an SMC  706 .  
         [0038]     In this implementation, an adapter overload (ADP_OL) signal line  708  is provided that couples the power adapter  700  to the portable computer  702  through, for instance, the battery charger  704 . An adapter down (ADP_DOWN) signal line  710  is also provided that couples the battery charger  704  to the SMC  706 .  
         [0039]     When the power adapter  700  determines that the power demand of the portable computer  702  is too great and an overload of the power adapter  700  is occurring or is imminent, the power adapter  700  can send an “ADP_OL” signal to the battery charger  704  over the signal line  708 . The battery charger  704  may then shut down the battery charging circuit to reduce the power demand from the power adapter  700 . This action alone may avert a potential overload of the power adapter  700 .  
         [0040]     The battery charger  704  may also send a “ADP_DOWN” signal to the SMC  706  over the signal line  710 . The SMC  706  may then take action to protect the portable computer  702  as it deems necessary. In one implementation, the SMC  706  may isolate the output of the power adapter  700  from the portable computer  702  using, for instance, an adapter isolation circuit  712 . In further implementations, the SMC  706  or other components within the portable computer  702  may take further steps towards reducing the load on the battery charger  704 , including but not limited to reducing display brightness setting, reducing the CPU speed, entering a sleep or hibernation mode, shutting down wireless communications, or shutting down unnecessary peripherals. The portable computer  702  may continue to operate using the batteries  108  and may undergo a sequential shut down method to preserve data prior to a complete shut down.  
         [0041]     In some implementations, the “ADP_OL” signal on line  708  may be a bidirectional signal, thereby allowing the portable computer  702  to send data to the power adapter  700 . In an implementation, the portable computer  702  may communicate its desired voltage level and the power adapter  700  may adjust its output voltage. Once this voltage level is acknowledged and met by the power adapter  700 , if the voltage level delivered by the power adapter  700  changes from the desired voltage level, the portable computer  702  may determine that a power issue has developed within the power adapter  700 , for instance broken wires or an imminent overload. The portable computer  702  may decide to isolate the output of the power adapter  700  and perform a safe sequential shut down prior to a complete power adapter  700  malfunction.  
         [0042]     The implementations described with reference to  FIG. 7  provide a method by which the power adapter  700  may communicate with the portable computer  702  to alert the portable computer  702  of possible power delivery issues, such as an overload of the power adapter  700 . This provides the portable computer  702  with an opportunity to perform a sequential and safe shut down prior to the corruption or loss of data.  
         [0043]     The above description of illustrated implementations of the invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed. While specific implementations of, and examples for, the invention are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize.  
         [0044]     These modifications may be made to the invention in light of the above detailed description. The terms used in the following claims should not be construed to limit the invention to the specific implementations disclosed in the specification and the claims. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.