Patent Publication Number: US-10320219-B2

Title: Dynamic power control circuit

Description:
BACKGROUND 
     Many developments have been made to improve the way batteries are used in mobile devices. For instance, some charging circuits have been developed to enable a single battery charger to supply power for device operation while also providing an independent power source to charge the device batteries. Although there have been some improvements with respect to such circuits, there are many shortcomings and inefficiencies with respect to current technologies. For example, some current charging circuits have a limited number of mechanisms for addressing situations where a high level of current is needed for device operation. Such designs can lead to inefficiencies and/or prevent a device from using the full capacity of a power source. 
     The disclosure made herein is presented with respect to these and other considerations. It is with respect to these and other considerations that the disclosure made herein is presented. 
     SUMMARY 
     A dynamic power control circuit is provided and described herein. In some configurations, an apparatus can include a system circuit, one or more batteries, a control circuit, and a controlled resistor. The system circuit can include any circuit that creates a load, such as the main components of a mobile device, e.g., one or more processors, memory, display screen, and radio. The apparatus is configured to receive power from two different outputs of an external power source: a system output coupled to the system circuit via a first node, and a charge output coupled to the batteries via a second node. The control circuit can detect one or more conditions of the device, such as an activation, e.g., utilization, of the external power source. In other examples, the control circuit can detect a voltage difference between the first node and the second node, or detect a level and/or a direction of current between components. As described herein, based at least in part on one or more detected conditions, e.g., an activation of the external power source and/or various voltage levels, the control circuit can cause the controlled resistor to adjust a level of impedance between the first node and the second node. The controlled impedance between the first node and the second node enables the system circuit to dynamically utilize power supplied by the external power source as well as power supplied by the batteries. The controlled impedance can create a more direct path between the system circuit and the batteries when one or more conditions are present. The techniques disclosed herein provide a design that can mitigate inefficiencies by reducing a resistive path between the batteries and the system circuit. 
     It should be appreciated that the above-described subject matter may also be implemented as part of an apparatus, system, or as part of an article of manufacture. These and various other features will be apparent from a reading of the following Detailed Description and a review of the associated drawings. 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended that this Summary be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a schematic diagram of an apparatus comprising a dynamic power control circuit. 
         FIGS. 2A-2C  show schematic diagrams of an apparatus comprising a switch having a single logical input. 
         FIG. 3  shows a schematic diagram of an apparatus comprising a dynamic power control circuit in a use scenario. 
         FIG. 4  shows a schematic diagram illustrating details of a controlled resistor controlled by a dynamic power control circuit. 
         FIG. 5  illustrates a flow chart implementing an example method in accordance with techniques disclosed herein. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, reference is made to the accompanied drawings, which form a part hereof, and which is shown by way of illustration, specific example configurations of which the concepts can be practiced. These configurations are described in sufficient detail to enable those skilled in the art to practice the techniques disclosed herein, and it is to be understood that other configurations can be utilized, and other changes may be made, without departing from the spirit or scope of the presented concepts. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the presented concepts is defined only by the appended claims. 
     Throughout the specification and claims, the following terms take the meanings explicitly associated herein, unless the context clearly dictates otherwise. The meaning of “a,” “an,” and “the” includes plural reference, the meaning of “in” includes “in” and “on.” The term “connected” means a direct electrical connection between the items connected, without any intermediate devices. The term “coupled” means a direct electrical connection between the items connected, or an indirect connection through one or more passive or active intermediary devices and/or components. The terms “circuit” and “component” means either a single component or a multiplicity of components, either active and/or passive, that are coupled to provide a desired function. The term “signal” means at least a wattage, current, voltage, or data signal. The terms, “gate,” “drain,” and “source,” can also mean a “base,” “collector” and “emitter,” and/or equivalent parts. 
     Referring to  FIG. 1 , an apparatus  100  can include a system circuit  101 , one or more batteries  103 , a control circuit  105 , and a controlled resistor  107 . The system circuit  101  can, for example, include the components of a device, e.g., a processor, memory, and radio, or any other components that create a load. The apparatus  100  is configured to receive power from at least two different outputs of an external power source  109 : (1) a system output (SYS OUT ) coupled to the system circuit  101  via a first node  150  (V SYS ), and (2) a charge output (CHG OUT ) coupled to the batteries  103  via a second node  151  (V PACK ). The control circuit  105  can detect one or more conditions, such as the activation of the external power source  109 . The one or more conditions can also include a voltage difference between the first node  150  and the second node  151 . In other examples, the control circuit  105  can also detect one or more current levels and/or current directions between selected nodes. As will be described in more detail below, based at least in part on the detected conditions, the control circuit  105  can control the connectivity, e.g., a level of impedance, between the first node  150  and the second node  151 . Controlled connectivity between the first node  150  and the second node  151  enables the system circuit  101  to dynamically utilize power supplied by the external power source  109  as well as power supplied by the batteries  103  by the use of a controlled path of impedance that can react to one or more detected conditions. 
     To illustrate aspects of the techniques disclosed herein,  FIGS. 2A-2C  show several use scenarios of an apparatus  200  comprising a switch  113  having a single logical input. In this example, the switch  113  controls the connectivity between one or more batteries  103  and a system circuit  101 . As shown in  FIG. 2A , when the system circuit  101  is in use without the activation of an external power source, the switch  113  connects the first node  150  and the second node  151  to enable the system circuit  101  to utilize power from the batteries  103 . 
     As shown in  FIG. 2B , when the external power source  109  is connected to the apparatus  200 , power is received from the two different outputs. The system output (SYS OUT ) is coupled to the first node  150  supplying power to the system circuit  101 , and the charge output (CHG OUT ) is coupled to the second node  151  supplying power to the batteries  103 . In this example, when the external power source  109  is connected, the switch  113  creates a high impedance path or an open circuit between the first node  150  and the second node  151  allowing the two outputs of the external power source  109  to independently supply power to the system circuit  101  and the batteries  103 . 
     In some configurations, the switch  113  comprises an input enabling one or more components to control with switch  113  with a logical signal indicating that the external power source  109  is active or inactive. The one or more components generating the logical signal can include the power supply. The logical signal can also be generated by other components such as a universal serial bus component, or any other suitable component for indicating the utilization of the external power source  109 . As indicated by the dashed lines, when the external power source  109  is active, the current flows from the external power source  109  to the batteries  103  and the system circuit  101 . 
     In some use scenarios, the system circuit  101  may draw a high level of current that exceeds the capabilities of the external power source  109 . In such scenarios, the batteries  103  may supplement the external power source  109  by supplying power to the system circuit  101 . This scenario is illustrated in  FIG. 2C , where the dashed lines show that current flows from the batteries  103 , through the external power source  109 , eventually reaching the system circuit  101 . As illustrated by the representative resistors (R), such a configuration may cause inefficiencies as the path from the batteries  103  to the system circuit  101  may be lengthy. In addition, such a path can create a high level of resistance which in turn causes unwanted power loss as well as a reduction in the amount of current the batteries  103  can supply to the system circuit  101 . The configuration shown in  FIGS. 2A-2C  illustrate a need for a dynamic control circuit that can react to a wide range of such use scenarios. 
     Referring now to  FIG. 3 , illustrative examples of several use scenarios for a dynamic power control circuit that is capable of detecting and reacting to one or more conditions of an apparatus  100  are shown and described below. In one illustrative example, the system circuit  101  comprises a positive lead for receiving power at the first node  150  from the first output of the external power source  109 . The batteries  103  comprise a positive lead for receiving power at a second node  151  from a second output of the external power source  109 . It can be appreciated that this example is provided for illustrative purposes and is not to be construed as limiting. The apparatus  100  can include any number and/or suitable arrangement of components, including any number of system circuits  101  and any number of batteries  103 . 
     The controlled resistor  107  comprises a first lead coupled to the first node  150  and a second lead coupled to the second node  151 . The controlled resistor  107  causes a high impedance path between the first node  150  and the second node  151  when the controlled resistor  107  is “off,” and the controlled resistor  107  causes a low impedance path between the first node  150  and the second node  151  when the controlled resistor  107  is “on.” The controlled resistor  107  further comprises an input for turning the controlled resistor  107  “on” or “off.” 
     The control circuit  105  includes a first input coupled to the first node  150 , a second input coupled to the second node  151 , a logical input coupled to a third node  152 , and an output (also referred to as a “control output”) coupled to the input of the controlled resistor  107 . The control circuit  105  can receive signals at the first node  150  and the second node  151  to detect one or more conditions. For example, the control circuit  105  can be configured to determine a voltage at the first node  150  and a voltage at the second node  151 . The control circuit  105  can also be configured to detect one or more current levels between at least two components. 
     In addition, the control circuit  105  can be configured to detect a direction of a current between two or more components. To enable such capabilities, one or more coils can be wrapped around a conductor, such as a conductor coupling the external power source  109  and the system circuit  101  and/or a conductor coupling the external power source  109  and the batteries  103 . The coils can be coupled to the first input and/or the second input to enable the control circuit  105  to detect one or more current levels and/or one or more current directions. 
     The one or more components for generating a logical signal indicating that the external power source  109  is active or inactive can be a part of the external power source  109 , a connector for the external power source  109 , or any other component for detecting the presence and/or use of the external power source  109 . The logical signal indicating that the external power source  109  is active or inactive can be communicated through a third node  152  that is independent of the first node  150  and the second node  151 . The logical signal indicating that the external power source  109  is active or inactive can also be communicated through the first node  150  and/or the second node  151 . In such configurations, a logical signal can be communicated to the first input and/or the second input of the control circuit  105 . 
     The control circuit  105  can be configured to cause the controlled resistor  107  to be “on” when the logical signal at the logical input indicates that the external power source is inactive. For illustrative purposes, the external power source  109  “active” when providing power to one or more components of the apparatus  100 , and “inactive” when the external power source  109  is disconnected or not providing power to one or more components of the apparatus  100 . Thus, when the external power source  109  is not providing power to one or more components of the apparatus  100 , the controlled resistor  107  provides a short circuit or a low impedance path between the first node  150  and the second node  151 , allowing the system circuit  101  to operate from the batteries  103 . 
     The control circuit  105  can be configured to cause the controlled resistor  107  to be “off” when the logical signal at the logical input indicates that the external power source is active, and when the voltage at the first node  150  and the voltage at the second node  151  are within a threshold of one another. Such a configuration allows the two outputs of the external power source  109  to independently provide power to the system circuit  101  and the batteries  103 . 
     The control circuit  105  can be configured to cause the controlled resistor  107  to be “on” when the logical signal at the logical input indicates that the external power source is active, and when the voltage at the first node  150  is less than the voltage at the second node  151  by the threshold. For example, while the external power source is active, if the threshold is 40 millivolts, the voltage at the first node  150  is 4.0 volts and the voltage at the second node  151  is 5.0 volts, the control circuit  105  will cause the controlled resistor  107  to be “on.” Such a configuration allows the batteries  103  to supplement the power provided by the external power source  109  while using a path of resistance that is shorter and more efficient than the path shown in  FIG. 2C . 
     In some examples, the threshold can be within a range of zero volts to one hundred millivolts. In another illustrative example, the threshold can be approximately forty millivolts, or within a range between thirty-five millivolts and forty-five millivolts. These examples are provided for illustrative purposes and are not to be construed as limiting as any suitable threshold can be utilized with the techniques disclosed herein. 
     These examples are provided for illustrative purposes, as other conditions and/or criteria can be used to cause the controlled resistor  107  to react to different scenarios. In another example, the control circuit  105  can be configured to cause the controlled resistor  107  to be “off” when the logical signal at the logical input indicates that the external power source is active, and when a first signal at the first input and a second signal at the second input fulfill a first criteria. The control circuit  105  can be configured to cause the controlled resistor  107  to be “on” when the logical signal at the logical input indicates that the external power source is active, and when the first signal at the first input and the second signal at the second input fulfill a second criteria. 
     The criteria for controlling the controlled resistor  107  can be based on current measurement at the first node  150  leading into the system circuit  101 . In such an example, the first criteria can be fulfilled when a current between the external power source  109  and the system circuit  101  is below a threshold. The second criteria can be fulfilled when the current between the external power source  109  and the system circuit  101  is above the threshold. 
     In some configurations, the first criteria can be fulfilled when a current between the external power source  109  and the at least one battery  103  is flowing in a first direction, e.g., toward the battery  103 . In such an example, the second criteria can be fulfilled when the current between the external power source  109  and the at least one battery  103  is flowing in a second direction, e.g., away from the battery  103 . 
     In some configurations, the control circuit  107  can be configured to cause the controlled resistor  107  to vary the level of impedance between the first node  150  and the second node  151  to maintain a predetermined voltage difference between the voltage at the first node  150  and the voltage at the second node  151 . Such a configuration can also be implemented with criteria, e.g., the logical signal indicates that the external power source is active and/or when the voltage at the first node  150  is outside of a threshold of the voltage at the second node  151 . 
     In some configurations, when the voltage across the controlled resistor  107  is reverse biased, the controlled resistor  107  is “off” and the impedance through the controlled resistor  107  is high, e.g., an open circuit. In some configurations, when the voltage across the controlled resistor  107  exceeds a threshold voltage, e.g., a range around 30 mV, in a forward direction, the controlled resistor  107  is “on,” and the impedance of the controlled resistor  107  is controlled such that the voltage between the first node  150  and the second node  151  is regulated to a threshold voltage difference. In one illustrative example, the threshold voltage difference can be 30 mV. The threshold voltage difference can be at other levels depending on design needs. For illustrative purposes such configurations can be referred to herein as a “linear region,” where the controlled resistor  107  is regulating the forward voltage to a desired level, e.g., about 30 mV. If the current through the controlled resistor  107  is so high that the controlled resistor  107  is fully turned “on,” then it acts as an switch that is turned on with resistance and the voltage across the controlled resistor  107  is (I*R), which can be greater than the 30 mV set point. 
     Referring now to  FIG. 4 , aspects of the controlled resistor  107  are shown and described below. In some configurations, the controlled resistor  107  comprises a transistor  111 , such as a field-effect transistor  111 . The gate of the transistor  111  is coupled to the output of the control circuit. The source of the transistor  111  is coupled to the first node  150  and the drain of the transistor  111  is coupled to the second node  151 . Such configurations, and other configurations, enable the control circuit  105  to cause the controlled resistor  107  to gradually transition the level of impedance between the first node  150  and the second node  151  from a high impedance path to a low impedance path as a difference between the voltage of the first signal and the voltage of the second signal increases. The control circuit  105  can also cause the controlled resistor  107  to gradually transition the level of impedance between the first node  150  and the second node  151  from a low impedance path to a high impedance path as a difference between the voltage of the first signal and the voltage of the second signal decreases. A high impedance path can also be an open circuit and a low impedance path can be a closed circuit. 
     The controlled resistor  107  can also include other components, such as a pFET or an ideal diode. Any suitable component or combination of components can be used, including a mechanical switch or a combination of parts that include one or more diodes and an Op-amp. In such configurations, a controlled resistor  107  having a forward bias voltage drop close to zero can work with the techniques disclosed herein. 
       FIG. 5  illustrates a flow chart implementing a method  500  in accordance with techniques disclosed herein. Other logical flows can be implemented using the circuits described herein, the logical disclosed herein is provided for illustrative purposes and is not to be construed as limiting. The logical flow described herein can be implemented by an apparatus  100  having a system circuit  101 , one or more batteries  103 , a control circuit  105 , and a controlled resistor  107 . 
     The logical flow starts at block  501 , where the control circuit  105  receives a signal from the first node  150  coupled to a positive lead of a system circuit  101  (“load circuit”) and the first output of an external power source  109 . At block  503 , the control circuit  105  receives a signal from the second node  151  coupled to a positive lead of at least one battery  103  and the second output of an external power source  109 . At block  505 , the control circuit  105  receives a logic signal from the external power source  109 . The logic signal can include any type of signal indicating activation or deactivation of the external power source  109 . 
     Next, at block  505 , the control circuit  105  and the controlled resistor  107  control an impedance path between the first node  150  and the second node  151 . As described herein, the impedance path between the first node  150  and the second node  151  can be adjusted in a number of ways depending on a desired outcome. For example, the impedance path can be a short circuit or a low impedance path when the external power source  109  is not active. The impedance path can be an open circuit or a high impedance path when the logical signal at the logical input indicates that the external power source  109  is active, and when the voltage at the first node  150  and the voltage at the second node  151  are within a threshold of one another. In addition, the impedance path can be a short circuit or a low impedance path when the logical signal indicates that the external power source  109  is active, and when the voltage at the first node  150  is less than the voltage at the second node  151  by a threshold amount. In some configurations, the impedance path can be dynamically adjusted to maintain a predetermined voltage difference between the first node  150  and the second node  151 . 
     It should be understood that the operations of the methods disclosed herein are not necessarily presented in any particular order and that performance of some or all of the operations in an alternative order(s) is possible and is contemplated. The operations have been presented in the demonstrated order for ease of description and illustration. Operations may be added, omitted, and/or performed simultaneously, without departing from the scope of the appended claims. It also should be understood that the illustrated methods can be ended at any time and need not be performed in its entirety. 
     The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.