Intelligent adapter

In one aspect the present invention provides an AC/DC or DC/DC adapter, comprising circuitry to generate a signal proportional to the maximum adapter current. In another aspect, the present invention provides a portable electronic device, comprising circuitry to receive a signal proportional to the maximum current supplied to the portable electronic device and a charger controller. Still another aspect of the present invention provides an adapter topology system, comprising an AC/DC or DC/DC adapter comprising circuitry to generate a signal proportional to the maximum adapter current; and a portable electronic device adapted to receive power from said adapter and to receive said signal proportional to the maximum adapter current.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to adapter topologies, and more particularly, to adapter topologies that generate information related to available or maximum adapter current and to electronic devices configured to receive this information. Particular utility for the present invention is in portable electronic devices, however, the present invention is equally applicable to any device that uses an adapter to derive power.

2. Description of Related Art

Most portable electronic devices (e.g., portable computers, cell phones, PDAs, etc.) in use today utilize an AC/DC or DC/DC adapter that can be plugged into a wall outlet or cigarette lighter, etc., used to power the device, and possibly charge the batteries simultaneously. A typical adapter simply supplies power, and provides no information to the charger circuit as to the maximum available power that can be delivered by the adapter. To control the power delivered to the batteries (for charging) and to the device, a charger circuit is provided which regulates the flow of current from the adapter. An example of charger topologies are provided in U.S. Pat. Nos. 6,246,215 and 6,329,796; and U.S. patent application Ser. No. 09/948,828, titled “Voltage Mode High Accuracy Battery Charger”, all assigned to 02Micro International Limited, and incorporated by reference herein in their entirety. Such charger topologies dynamically allocate available adapter current between the batteries and the device.

FIG. 1depicts a conventional topology that includes an adapter1and mobile equipment2. The terms “mobile equipment” or “portable electronic device” as used herein mean a portable computer, cell phone, PDA, and/or any other device that uses an adapter to derive power. The adapter1generates a signal90indicative of the type of adapter used. This signal only has two states, and is used as an identification (ID) signal that represents the type of adapter used. The adapter1ofFIG. 1can be of two types: a high power adapter (e.g., 70W) or a low power adapter (e.g., 45W). The high power type of adapter generates no signal90, while the low power adapter generates a signal90having a predetermined value. The mobile equipment is adapted with a switch4, whose conduction state determines the type of adapter (low power or high power) present. Assuming that high power adapter is present, switch4is OFF. If a low power adapter is present, signal90turns switch4ON. Signal90is a signal representing the type of adapter present (low or high), and may be used by power management processors or charger circuits. Note that this topology only has two states representing the presence of a low power adapter or high power adapter, and thus cannot generate information related to the maximum or available power provided by the adapter. Note also that this topology requires that the adapter and mobile equipment be matched, such that the adapter could not be used with other mobile equipment and vice-versa.

Thus, there exists a need to provide an adapter topology that provides information related to maximum adapter current, which may be utilized by a charger to accurately allocate available current to batteries (for charging) and a device (for operation). There also exists a need for an adapter topology that permits the adapter to be used with a wide range of devices so that the adapter is can be used with many types of mobile equipment devices.

SUMMARY OF THE INVENTION

Accordingly, in one aspect the present invention provides an AC/DC or DC/DC adapter, comprising circuitry to generate a signal proportional to the maximum adapter current.

In another aspect, the present invention provides a portable electronic device, comprising circuitry to receive a signal proportional to the maximum current supplied to said portable electronic device and a charger controller.

Still another aspect of the present invention provides an adapter topology system, comprising an AC/DC or DC/DC adapter comprising circuitry to generate a signal proportional to the maximum adapter current; and a portable electronic device adapted to receive power from said adapter and to receive said signal proportional to the maximum adapter current.

It will be appreciated by those skilled in the art that although the following Detailed Description will proceed with reference being made to preferred embodiments and methods of use, the present invention is not intended to be limited to these preferred embodiments and methods of use. Rather, the present invention is of broad scope and is intended to be limited as only set forth in the accompanying claims.

Other features and advantages of the present invention will become apparent as the following Detailed Description proceeds, and upon reference to the Drawings, wherein like numerals depict like parts, and wherein:

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

As a broad overview, the adapter topology system embodiments ofFIGS. 2–7generate an identification signal (ID) proportional to the maximum or available adapter current. Also, the topologies disclose electronic device configured to receive the signal proportional to the maximum or available adapter current. The system comprises both the adapter and the portable device, but the present invention is also directed to the adapter and the portable device independent of each other. A battery charger controller, associated with the portable electronic device (and such as provided in the aforementioned U.S. Patents) may be adapted to utilize this signal to dynamically allocate power between the batteries (for charging) and the mobile equipment (for operating power). Such battery charger controllers generally operate to give the mobile equipment power, and will use any remaining current to charge the batteries. The present invention is not limited to a particular charger controller, and a charge controller is not necessary for an understanding of the present invention.

FIG. 2depicts one exemplary adapter topology system100of the present invention. In this embodiment, the adapter5includes an embedded current limit encoder6that generates a signal50indicative of the maximum current provided by the adapter5. The encoder6may comprise, for example, serial code generating circuitry, current-to-frequency coding circuitry and/or other coding circuitry known in the art. Of course, the adapter supplies power to the device7(via the +/− power lines), as well as signal50. The mobile equipment7is adapted with current limit decoding circuitry8that decodes signal50. The decoding circuitry8is appropriately matched to the coding circuitry6to code and decode signal50. The decoding circuitry8generates a voltage signal16(VID) that is proportional to the adapter current limit IAD—lim, i.e., VID=k×IAD—lim. Note that in this exemplary embodiment, the voltage signal16can represent changes in the adapter current. In other words, signal16changes with changes in the adapter current limit. In this example, signal16changes linearly, however the present invention equally contemplates a nonlinear relationship between the maximum adapter current signal and signal16. Signal16is sent to a charger circuit (or other power management device) that can adjust power delivered to both batteries and the device based on the value of signal16.

FIG. 3depicts another exemplary adapter topology system110of the present invention. In this exemplary embodiment, the adapter9includes a current sense encoder10that generates a digital coded signal54indicative of the maximum current limit of the adapter9. The coded signal54is sent (via a conventional and/or proprietary digital channel) to a keyboard controller12(or any other type of microcontroller) associated with the mobile device. The keyboard controller12is a conventional device found in portable computers, and may be appropriately adapted to generate an SMBus serial communications signal56(designated as SMBus_Clk and SMBus_Data56in the Figure). Signal56is an SMBus digital signal representing the maximum current limit of the adapter9.

The charger circuit15is of the type that can be externally programmed with a signal indicative of the maximum current limit. Charger15includes an SMBus converter13that essentially comprises a DAC circuit to convert digital signal56into an analog signal58. A sense comparator14generates a signal indicative of the total current delivered by the adapter (across sense resistor Rsense) and generates a measured adapter current value Imeas. Imeas and signal58are compared in comparator16that generates a signal indicative of the difference between the maximum available adapter current (signal58) and the measured current supplied by the adapter. This value is used by other components in the charger (not shown and not necessary for an understanding of the present invention, but fully disclosed in the aforementioned patents) to dynamically allocate power delivered to the batteries and the mobile equipment.

FIG. 4depicts another exemplary adapter topology system120of the present invention. In this embodiment, the adapter17includes an embedded identification resistor RID18that is connected in series with the adapter voltage (+) and the mobile device. RIDis fixed for a given adapter, and generates a fixed voltage drop. The mobile equipment19includes a reference resistor Rref20connected to the identification resistor and to ground (−). RIDand Rref, taken together, comprise a voltage divider, and it follows that VIDis based on RID, Rref, and the adapter voltage. The adapter voltage, VID, across the reference resistor represents the adapter current capability, with a scale factor as a function of the value of the sense resistor Rsense, Rref and the charger current gain (k). If portability of the adapter17is desirable, this scale factor may be standardized by providing a standardized value for Rref. As with the previous embodiments, VIDmay be utilized by the charger circuitry to dynamically allocate power available from the adapter17based on the known value of the maximum or available power available.

FIG. 5depicts another exemplary adapter topology system130of the present invention. Topology130is similar to topology120ofFIG. 4, except the identification voltage, VID, is independent of the adapter voltage. This embodiment also depicts some details of the charger circuitry25(although not necessary for an understanding of the present invention). In this embodiment, the adapter21includes an embedded identification resistor RIDconnected to the adapter ground and to the mobile equipment23(via, for example, the power cord (+/−) of the adapter). The mobile equipment includes an embedded pull-up resistor Rref24that is coupled between signal line62and a regulated low voltage source LV (e.g., 5V, 3.3V, etc.), thus forming a voltage divider defined by RIDand Rref. Identification signal62, then, is a proportional voltage signal VID=k×IAD—limindicative of the maximum or available adapter current; where IAD—limis the adapter current limit and k is a proportionality constant. Note that VIDdepends only on RIDand Rref, and is independent of the adapter voltage.

FIG. 5also provides more detailed structure of an exemplary charger controller25. The charger25includes a current sense amplifier28and an error amplifier26. The current sense amplifier generates a signal (IAC—meas) indicative of the actual adapter current generated across the current sense resistor Rsense27. Error amplifier compares IAC—measwith VID(the voltage signal representing the maximum available adapter current) to generate a control signal used by the power regulating feedback loop of the charger controller25. Again, the details of the charger controller are not necessary for an understanding of the present invention, and are being provided herein only as an example of how one skilled in the art may utilize the maximum current signal. Accordingly, the present invention is not limited to the exemplary charger controller circuitry described herein.

FIG. 6depicts another exemplary adapter topology system140. This embodiment generates a normalized adapter current signal. This embodiment also depicts some elements of the charger controller circuit. In this embodiment, the adapter29includes an embedded current sense resistor (Rsense)30and a current sense amplifier31. These components might typically be associated with a charger controller. The amplifier31provides a normalized current signal64that is proportional to the adapter current (IAD×s). The gain of the amplifier31is selected to provide a standardized output when the adapter reaches its maximum current level. In other words, amplifier31has a set upper gain. The normalized current signal64is a value indicative of a percentage of maximum current.

The mobile equipment32in this embodiment includes an embedded resistor33Rsys coupled between the normalized current signal64and ground. Embedding Rsys in this manner eliminates error generated by the parasitic voltage drop of the adapter. The voltage drop across Rsys is indicative of the percentage of maximum current of the adapter, and is expressed as VIAD=Rsys×IAD×s. More precisely, the voltage VIADrepresents the actual adapter current as a percentage of the rated adapter current. Error amplifier compares this value to a value indicative of 100% of the adapter current (VIAD—lim) and generates a control signal used by the power regulation feedback loop of the charger controller.

FIG. 7depicts yet another exemplary adapter topology system150. This embodiment is similar to the topology ofFIG. 3, except that the DAC13is replaced with an SMBus programmable interface36and a multiplexed DAC37. The DAC37receives the output of the SMBus interface36and generates a plurality of programmable analog signals used by the charger controller15, as will be understood in the art. Examples of such programmable signals include the charging current reference IDAC38, the charging voltage reference VDAC39and the adapter current limit IACLIM.

The current limit encoder10embedded in the adapter9sends data representing the adapter maximum current to the keyboard controller (KBC)12(or any other microcontroller) in the mobile equipment11. The KBC12issues appropriate SMBus commands representing the adapter current limit, the battery charging voltage IDAC and the battery charging current VDAC to the charger15via SMBus communication protocols. The charger15uses the SMBus programmable interface36to decode the SMBus commands. The decoded values are sent to the multiplexed DAC37, one by one, and are converted to analog signals on the different outputs38,39and40. The signals (voltages) are used as reference signals for error amplifiers within the charger, such as error amplifier16depicted.

In all of the embodiments described herein the identification signal generated by the adapter represents a dynamic indication of the maximum available power for the particular adapter, and can change linearly with changes in available adapter current (power). Although the drawings generally depict a separate signal line between the adapter and the mobile equipment, those skilled in the art will recognize that numerous other communication methodologies could be employed to communicate information between the adapter and the mobile equipment. For example, the embodiments ofFIGS. 2,3and7may be adapted to include wireless communication (e.g., RF, IR, etc) between the adapter and the mobile equipment to communicate maximum or available adapter current information from the adapter to the mobile equipment. Likewise,FIG. 6could be similarly modified and further modified with a programmable current source (not shown) embedded in the mobile equipment. This programmable current source could be coupled to Rsys and programmed to generate the proportional adapter current value (IAD×s). Alternatively, such information could be communicated over the existing power lines (+ and/or −) using modulation/demodulation techniques known in the art to communicate available power data over the existing power lines.

Further modifications will become apparent to those skilled in the art, and all such modifications are deemed within the spirit and scope of the present invention as defined by the appended claims.