US20050162123A1 - Power system and method - Google Patents

Abstract

The disclosed embodiments relate to power systems and methods. One such power system includes an adapter that produces a power output. A converter stage receives the power output and in turn provides a regulated output. The regulated output is delivered to a battery and to a DC-DC component.

Description

BACKGROUND OF THE RELATED ART
• Portable computing devices may derive power from internal batteries, which may be charged by being connected to an external source of AC or DC power. When charged, the battery may be used to power the portable computing device when no source of AC or DC power is readily available. Additionally, the battery may function as back-up power when there is a disruption to AC or DC power used to power the portable device. When the portable device is operating on AC or DC power, the battery may be recharging for later use as a primary supply of power.
• In designing the power system of personal computing devices, the configuration and layout of components may affect the operation and efficiency of the device. For instance, improper placement of components may result in problems, such as increasing potential damages to batteries, decreasing efficiency, or reducing the amount of time that the battery is able to provide power for the portable device.
• Standards relating to the design of power systems for portable computing devices exist. One such standard is the Smart Battery System v1.1. Other standards include the Intelligent Battery Architecture, version 2 (“IBA”) and the Constant Power Adapter (“CPA”) method. These standards may inhibit efficiency in power systems.
SUMMARY
• In one embodiment of the present invention, a power system for a processor-based electronic system comprises a power adapter for producing a power output. A converter stage receives the power output and generates a regulated power. The regulated output is delivered to a battery and to a DC-DC component.
• Another embodiment relates to a method of operation for a power system. The method comprises producing a power output, delivering the power output to a converter, regulating the power output, delivering the regulated output to a DC-DC component and a battery. The battery charges from the regulated output, while the DC-DC component adjusts the regulated output into a plurality of voltages for a plurality of circuits.
BRIEF DESCRIPTION OF THE DRAWINGS
• The foregoing and other advantages of the invention may become apparent upon reading the following detailed description and upon reference to the drawings in which
• FIG. 1 illustrates a block diagram of a processor-based system in accordance with an embodiment of the present invention;
• FIG. 2 illustrates a schematic diagram of a power system in accordance with an embodiment of the present invention;
• FIG. 3 illustrates a schematic diagram of a power system with a control circuit in accordance with an embodiment of the present invention;
• FIG. 4 illustrates a schematic diagram of a feedback circuit in accordance with an embodiment of the present invention; and
• FIG. 5 illustrates a flow diagram in accordance with an embodiment of the present invention.
DESCRIPTION OF SPECIFIC EMBODIMENTS
• Referring initially toFIG. 1, a block diagram of a processor-based electronic device or system, generally designated byreference numeral10, is illustrated. Thesystem10 may be any of a variety of types such as a computer, pager, cellular phone, personal organizer or the like. In a processor-based device, aprocessor12, such as a microprocessor, may control the operation of system functions and requests. Theprocessor12 may be coupled to various types of memory devices to facilitate its operation. For example theprocessor12 may be connected to avolatile memory26 and anon-volatile memory28. Thevolatile memory26 may comprise a variety of memory types, such as-static random access memory (“SRAM”) or dynamic random access memory (“DRAM”) or the like. Thenon-volatile memory28 may comprise various types of memory such as electrically programmable read only memory (“EPROM”), and/or flash memory or the like.
• Thesystem10 includes apower supply14, which may comprise a battery or batteries, an AC power adapter and/or a DC power adapter. Various other devices may be coupled to theprocessor12 depending on the functions that thesystem10 performs. For example, aninput device16 may be coupled to theprocessor12 to receive input from a user. Theinput device16 may comprise a user interface and may include buttons, switches, a keyboard, a light pen, a mouse, a digitizer and/or a voice recognition system or the like. An audio orvideo display18 may also be coupled to theprocessor12 to provide information to the user.
• Acommunications port22 may be adapted to provide a communication interface between theelectronic device10 andperipheral devices24. The peripheral24 may include a docking station, expansion bay or other external component. Furthermore, an RF sub-system/baseband processor20 may be coupled to theprocessor12 to provide wireless communication capability.
• FIG. 2 illustrates a schematic diagram of a power system in accordance with an embodiment of the present invention. The power system is generally referred to by thereference numeral32. Anadaptor38 comprisesoutput terminals37 and39. Theadaptor38 may be either an AC or DC power adaptor. A converter stage40 (shown in dashed lines) includes acapacitor46, aswitch48, adiode50, aninductor52, and acapacitor54, which are positioned on acircuit board33. Various other components may be included in the converter stage, depending upon design considerations such as the desired output voltage and the like. Thecapacitor46 is connected across theadaptor outputs37 and39. Theterminal37 is additionally connected to theswitch48, which may be a 30-volt MOSFET switch, or any other suitable switching component. Theswitch48 is connected between the cathode of adiode50 and a terminal of aninductor52. The anode of thediode50 is connected to a ground or circuit of lower potential. Theinductor52 is also connected to the DC-DC component42 and thecapacitor54.
• Acurrent sense resistor56 is connected between theconverter stage40 and a common connection to afirst battery34 and asecond battery36. Thecurrent sense resistor56 provides feedback regarding the amount of current that is flowing to or from thebatteries34 and36. Thebattery34 comprises aswitch58 and aswitch62, which are connected in series to abattery cell stack64. Thebattery36 comprises aswitch60 and aswitch66, which are connected in series to abattery cell stack68.
• If theadaptor38 is connected to a power source, power from theadaptor38 will flow through theconverter stage40 to the DC-DC component42 and thebatteries34 and36. Theconverter stage40 regulates the output through theswitch48 and maintains a voltage level sufficient to ensure the power distributor or DC-DC component42 is able to operate efficiently. In this mode, thebatteries34 and36 can charge. By placing theswitches58 and62 in thebattery34 in a back-to-back configuration, current flows into thebattery cell stack64 when theswitches58 and62 are turned “on.” The same is true for theswitches60 and66, which control the flow of current to thebattery cell stack68. Conversely, when thebattery34 or thebattery36 is charged, theswitches58 and62 (for the battery34), and switches60 and66 (for the battery36) may be turned “off” to block current from flowing to the respective batteries.
• Alternatively, if theadaptor38 is not providing power, theswitches58 and62 (for the battery34) or theswitches60 and66 for thebattery36 may be turned “on” to power the system10 (FIG. 1). In this situation, eachbattery34 or36 blocks the in-flow of current to prevent one of thebatteries34 or36 at a higher voltage from charging the other. This adaptation enables the DC-DC component42 to continue to receive an uninterrupted supply of power to operate the system10 (FIG. 1). In another embodiment, a microcontroller circuit or other similar circuit is used to determine whichbattery34 or36 will provide power to the DC-DC component42. Such a circuit operates by measuring voltage differential between the two batteries.
• The regulation of the power output from theswitch48 enables the use of switches with lower voltages ratings than would otherwise be possible for theswitches58,60,62 and66. As an example, such regulation enables thebatteries34 and36, as well as the DC-DC component42, to be configured to receive a maximum of about 16.8 volts DC. This enables the use of 20-volt switches for theswitches58,60,62 and66, and also in the DC-DC component42, where more robust and expensive switches would otherwise be needed. The use of MOSFET switches with lower voltage additionally saves power by reducing the voltage drop across the switches relative to switches with higher voltage ratings.
• FIG. 3 illustrates a schematic diagram of a power system with a control circuit in accordance with an embodiment of the present invention. The control circuit, which is generally referred to by thereference numeral32A, incorporates feedback components and an interface component into the control circuit32 (FIG. 2). The feedback components are utilized to control the voltage or current at various components throughout thepower system32A.
• A first feedback component is connected across thebattery cell stack64 and asecond feedback component72 is connected across thebattery cell stack68. The outputs of the twofeedback components70 and72 are combined to form an input to aninterface component74, which provides input to theswitch48. Thefirst feedback component70, thesecond feedback component72, and/or theinterface component74 may be internal or external to the respective batteries.
• Theinterface component74 controls the operation of theswitch48, including the current flow through theswitch48, based on the input it receives from thefeedback components70 and72. This input is influenced by various factors, such as the status of thebatteries34 and36 and whether theadaptor38 is supplying power. For instance, if neitherbattery34 nor36 needs to be charged or if theadaptor38 is not supplying power, then theinterface component74 does not send control signals to theswitch48 to adjust the current flow. However, if thebatteries34 or36 require charging, then theswitch48 is used to regulate the charging process. The charging process is regulated by using signals from thebattery feedback components70 and72 to theinterface component74 to adjust the current flow into thebatteries34 and36. If the current flow through theswitch48 is to be increased or decreased, then theinterface component74 transmits the appropriate signal to theswitch48.
• FIG. 4 illustrates a schematic diagram of a feedback circuit in accordance with an embodiment of the present invention. The feedback circuit, which is generally referred to by thereference numeral100, corresponds to each of thefeedback components70 and72 (FIG. 3). Thefeedback circuit100 is connected across abattery cell stack78, which corresponds to one of the battery cell stacks64 or68 (FIG. 3). Thebattery cell stack78 comprises a plurality of cells, such as lithium ion cells or the like. As shown inFIG. 4, afeedback resistor84, afeedback resistor86 and afeedback resistor94 are connected in series across afirst terminal80 and asecond terminal82 of thebattery cell stack78. Acurrent sense resistor96 is connected between thesecond terminal82 and ground.
• Theresistor84 is connected between the terminal80 and an input to anamplifier88, which has afeedback capacitor90 connected thereto. Theresistor86 is connected between the same input of theamplifier88 and a first terminal (cathode) of adiode92. Theresistor94 is connected between the first terminal (cathode) of thediode92 and theterminal82 of thebattery cell stack78. The second terminal (anode) ofdiode92 is connected to the output ofamplifier102.
• Aresistor98 is connected across thesecond terminal82 and an input of theamplifier102, which also has a groundedcapacitor101 connected thereto. The other input of theamplifier102 is connected to a groundedresistor108 and afeedback capacitor104. The other end ofcapacitor104 is connected to the output of theamplifier102. Theresistor106 is connected across areference signal input105 andresistor108, soresistor108 is used to set a reference voltage for theamplifier102. Thereference signal input105 is connected to an input of theamplifier88.
• If a current received at theamplifier102 is higher than an expected value or range, then the output voltage signal from theamplifier102 increases. This increase may turn “on” thefeedback diode92, which results in current being fed through theresistor94. As the current flows through theresistor94, the voltage across thefeedback diode92 may increase, which causes the output voltage of theamplifier88 to decrease. In this manner, the charge current delivered by the converter stage40 (FIG. 3) is regulated. The use of a feedback circuit such as thefeedback circuit100 eliminates the need for a sense resistor, such as the current sense resistor56 (FIG. 3).
• A connection point112 functions as an analog feedback terminal that may allow the converter stage40 (FIG. 3) to receive an analog signal for use in controlling the charging of thebatteries34 and36 (FIG. 3). The analog feedback terminal or connection point112 is connected to an input ofcomparator110. The other input ofcomparator110 receives anoscillation signal input109, which may include a sawtooth wave signal, a sine wave signal or other suitable signal. The feedback input signal oroscillation signal input109 is used along with the output of theamplifier88 to produce a digital signal from the output of thecomparator110, such as a digital feedback terminal orconnection point114. Thedigital feedback terminal114 includes signals that are generally a rectangle waveform, a pulse train, or other suitable signal.
• Thedigital feedback terminal114 or the analog feedback terminal112 is connected to the converter stage40 (FIG. 3), DC-DC component42 (FIG. 3), a microprocessor, or any other control system within thedevice10. For instance, the analog feedback terminal or connection point112 is connected to the switch48 (FIG. 3) to increase or decrease the current delivered by theconverter stage40. Depending on the signal received by the switch48 (FIG. 3), theconverter stage40 stops the charging process. Thus, the signal feedback supplies the appropriate signal to thepower system32 to manage the current and voltage distribution.
• The output of thefeedback circuit100 is used to facilitate the operation of theswitches58,60,62, and66 (FIG. 3) to start or end the charging of thebatteries34 and36 (FIG. 3). For instance, when thebattery cell stack78 is charging and the charging voltage is above an expected range or value, theresistor84 conducts current into the first input terminal of theamplifier88, and the output ofamplifier88 decreases. This changes the signals on the connection points112 and/or114, which in turn controls the operation of theswitch48 ofFIG. 3. This acts to reduce the voltage acrossbattery cell stack78.
• Referring toFIG. 5, a flow diagram in accordance with embodiments of the present invention is illustrated. The process illustrated in the diagram, which is generally referred to by thereference numeral132, begins atblock131. Atblock134, output power for the operation of an electronic device is produced. An adaptor, such as the38 (FIG. 2 orFIG. 3) may be the source of this power. As shown atblock136, the power output is delivered to a converter stage, such as the converter stage40 (FIG. 2 orFIG. 3).
• As discussed above with regard to the converter stage, the output power is processed into a regulated power or regulated output, as shown atblock138. For instance, the power is converted into a regulated DC power output, from either an AC or DC input source. The converter is designed to produce regulated power within a predefined range. Atblock140, the regulated output is delivered to a DC-DC component, such as the DC-DC component42 ofFIG. 2 orFIG. 3 and to one or more batteries, such as thebatteries34 and36 ofFIG. 2 andFIG. 3. The process ends atblock142.

Claims (10)

1-12. (canceled)

6. An electronic device comprising:

a processor;

a memory capable of storing data to be accessed by the processor; and

a power system comprising:

a power adapter capable of producing a power output;

a converter stage coupled to receive the power output and generate a regulated output;

a DC-DC component coupled to receive the regulated output; and

a battery removably coupled to receive the regulated output.

7. The power system set forth inclaim 6, comprising a video adapter operatively coupled to the processor to create an image signal.

8. The power system set forth inclaim 7, comprising a monitor to receive the image signal and display a corresponding image to a user.

9. The power system set forth inclaim 8, comprising a user input device to receive input from a user.

10. The power system set forth inclaim 6, comprising a feedback circuit to provide feedback from the battery to the converter stage to manage the charging of the battery.

11. The power system set forth inclaim 10, wherein the battery comprises:

a first switch connected to a terminal of the battery; and

a second switch connected between the first switch and the feedback circuit, wherein the first and second switches enable the charging of the battery.

12. The power system set forth inclaim 6, wherein the DC-DC component adjusts the regulated output into different voltages to be applied to other circuits connected to the power system.

13. The power system set forth inclaim 6, comprising a battery circuit to monitor current and voltage levels at the battery to regulate charging of the battery.

14-26. (canceled)

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