Power system and method

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.

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.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Referring initially toFIG. 1, a block diagram of a processor-based electronic device or system, generally designated by reference numeral10, is illustrated. The system10may be any of a variety of types such as a computer, pager, cellular phone, personal organizer or the like. In a processor-based device, a processor12, such as a microprocessor, may control the operation of system functions and requests. The processor12may be coupled to various types of memory devices to facilitate its operation. For example the processor12may be connected to a volatile memory26and a non-volatile memory28. The volatile memory26may comprise a variety of memory types, such as static random access memory (“SRAM”) or dynamic random access memory (“DRAM”) or the like. The non-volatile memory28may comprise various types of memory such as electrically programmable read only memory (“EPROM”), and/or flash memory or the like.

The system10includes a power 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 the processor12depending on the functions that the system10performs. For example, an input device16may be coupled to the processor12to receive input from a user. The input device16may 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 or video display18may also be coupled to the processor12to provide information to the user.

A communications port22may be adapted to provide a communication interface between the electronic device10and peripheral devices24. The peripheral24may include a docking station, expansion bay or other external component. Furthermore, an RF sub-system/baseband processor20may be coupled to the processor12to provide wireless communication capability.

FIG. 2illustrates a schematic diagram of a power system in accordance with an embodiment of the present invention. The power system is generally referred to by the reference numeral32. An adaptor38comprises output terminals37and39. The adaptor38may be either an AC or DC power adaptor. A converter stage40(shown in dashed lines) includes a capacitor46, a switch48, a diode50, an inductor52, and a capacitor54, which are positioned on a circuit board33. Various other components may be included in the converter stage, depending upon design considerations such as the desired output voltage and the like. The capacitor46is connected across the adaptor outputs37and39. The terminal37is additionally connected to the switch48, which may be a 30-volt MOSFET switch, or any other suitable switching component. The switch48is connected between the cathode of a diode50and a terminal of an inductor52. The anode of the diode50is connected to a ground or circuit of lower potential. The inductor52is also connected to the DC—DC component42and the capacitor54.

A current sense circuit, such as a current sense resistor56is connected between the converter stage40and a common connection to a first battery34and a second battery36. The current sense resistor56provides feedback regarding and amount of current that is flowing to or from the batteries34and36. The battery34comprises a switch58and a switch62, which are connected in series to a battery cell stack64. The battery36comprises a switch60and a switch66, which are connected in series to a battery cell stack68.

If the adaptor38is connected to a power source, power from the adaptor38will flow through the converter stage40to the DC—DC component42and the batteries34and36. The converter stage40regulates the output through the switch48and maintains a voltage level sufficient to ensure the power distributor or DC—DC component42is able to operate efficiently. In this mode, the batteries34and36can charge. By placing the switches58and62in the battery34in a back-to-back configuration, current flows into the battery cell stack64when the switches58and62are turned “on.” The same is true for the switches60and66, which control the flow of current to the battery cell stack68. Conversely, when the battery34or the battery36is charged, the switches58and62(for the battery34), and switches60and66(for the battery36) may be turned “off” to block current from flowing to the respective batteries.

Alternatively, if the adaptor38is not providing power, the switches58and62(for the battery34) or the switches60and66for the battery36may be turned “on” to power the system10(FIG.1). In this situation, each battery34or36blocks the in-flow of current to prevent one of the batteries34or36at a higher voltage from charging the other. This adaptation enables the DC—DC component42to 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 which battery34or36will 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 the switch48enables the use of switches with lower voltages ratings than would otherwise be possible for the switches58,60,62and66. As an example, such regulation enables the batteries34and36, 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 the switches58,60,62and66, 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. 3illustrates 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 the reference 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 the power system32A.

A first feedback component is connected across the battery cell stack64and a second feedback component72is connected across the battery cell stack68. The outputs of the two feedback components70and72are combined to form an input to an interface component74, which provides input to the switch48. The first feedback component70, the second feedback component72, and/or the interface component74may be internal or external to the respective batteries.

The interface component74controls the operation of the switch48, including the current flow through the switch48, based on the input it receives from the feedback components70and72. This input is influenced by various factors, such as the status of the batteries34and36and whether the adaptor38is supplying power. For instance, if neither battery34nor36needs to be charged or if the adaptor38is not supplying power, then the interface component74does not send control signals to the switch48to adjust the current flow. However, if the batteries34or36require charging, then the switch48is used to regulate the charging process. The charging process is regulated by using signals from the battery feedback components70and72to the interface component74to adjust the current flow into the batteries34and36. If the current flow through the switch48is to be increased or decreased, then the interface component74transmits the appropriate signal to the switch48.

FIG. 4illustrates 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 the reference numeral100, corresponds to each of the feedback components70and72(FIG.3). The feedback circuit100is connected across a battery cell stack78, which corresponds to one of the battery cell stacks64or68(FIG.3). The battery cell stack78comprises a plurality of cells, such as lithium ion cells or the like. As shown inFIG. 4, a feedback resistor84, a feedback resistor86and a feedback resistor94are connected in series across a first terminal80and a second terminal82of the battery cell stack78. A current sense resistor96is connected between the second terminal82and ground.

The resistor84is connected between the terminal80and an input to an amplifier88, which has a feedback capacitor90connected thereto. The resistor86is connected between the same input of the amplifier88and a first terminal (cathode) of a diode92. The resistor94is connected between the first terminal (cathode) of the diode92and the terminal82of the battery cell stack78. The second terminal (anode) of diode92is connected to the output of amplifier102.

A resistor98is connected across the second terminal82and an input of the amplifier102, which also has a grounded capacitor101connected thereto. The other input of the amplifier102is connected to a grounded resistor108and a feedback capacitor104. The other end of capacitor104is connected to the output of the amplifier102. The resistor106is connected across a reference signal input105and resistor108, so resistor108is used to set a reference voltage for the amplifier102. The reference signal input105is connected to an input of the amplifier88.

If a current received at the amplifier102is higher than an expected value or range, then the output voltage signal from the amplifier102increases. This increase may turn “on” the feedback diode92, which results in current being fed through the resistor94. As the current flows through the resistor94, the voltage across the feedback diode92may increase, which causes the output voltage of the amplifier88to decrease. In this manner, the charge current delivered by the converter stage40(FIG. 3) is regulated. The use of a feedback circuit such as the feedback circuit100eliminates the need for a sense resistor, such as the current sense resistor56(FIG.3).

A connection point112functions 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 the batteries34and36(FIG.3). The analog feedback terminal or connection point112is connected to an input of comparator110. The other input of comparator110receives an oscillation signal input109, which may include a sawtooth wave signal, a sine wave signal or other suitable signal. The feedback input signal or oscillation signal input109is used along with the output of the amplifier88to produce a digital signal from the output of the comparator110, such as a digital feedback terminal or connection point114. The digital feedback terminal114includes signals that are generally a rectangle waveform, a pulse train, or other suitable signal.

The digital feedback terminal114or the analog feedback terminal112is connected to the converter stage40(FIG.3), DC—DC component42(FIG.3), a microprocessor, or any other control system within the device10. For instance, the analog feedback terminal or connection point112is connected to the switch48(FIG. 3) to increase or decrease the current delivered by the converter stage40. Depending on the signal received by the switch48(FIG.3), the converter stage40stops the charging process. Thus, the signal feedback supplies the appropriate signal to the power system32to manage the current and voltage distribution.

The output of the feedback circuit100is used to facilitate the operation of the switches58,60,62, and66(FIG. 3) to start or end the charging of the batteries34and36(FIG.3). For instance, when the battery cell stack78is charging and the charging voltage is above an expected range or value, the resistor84conducts current into the first input terminal of the amplifier88, and the output of amplifier88decreases. This changes the signals on the connection points112and/or114, which in turn controls the operation of the switch48of FIG.3. This acts to reduce the voltage across battery 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 the reference numeral132, begins at block131. At block134, output power for the operation of an electronic device is produced. An adaptor, such as the38(FIG. 2orFIG. 3) may be the source of this power. As shown at block136, the power output is delivered to a converter stage, such as the converter stage40(FIG. 2or FIG.3).

As discussed above with regard to the converter stage, the output power is processed into a regulated power or regulated output, as shown at block138. 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. At block140, the regulated output is delivered to a DC—DC component, such as the DC—DC component42ofFIG. 2or FIG.3and to one or more batteries, such as the batteries34and36of FIG.2and FIG.3. The process ends at block142.