Abstract:
One embodiment of a disclosed cable protection device connected between the positive and negative wires of the cable that provides an efficient method of protection from overheating of the device due to changes in temperatures with minimal power dissipation. The cable protection device includes a temperature monitoring device that continuously senses the temperature of the cable and device to check for overheating. A controller connected to the temperature monitor sends out an alarm message and a control signal to either an actuator circuit or a crowbar function circuit. The actuator circuit can send out current pulses to the adapter indicating the adapter to lower its current limit, so that the device can still keep charging and is not over heated. The crowbar function circuit causes the adapter to turn off power to the cable in order to provide burning of the device or connector due to overheating.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present disclosure relates to a power supply cable protection device for preventing a thermal runaway when connected to a portable device. 
         [0003]    2. Description of the Related Art 
         [0004]    Charging cables such as USB cables are widely used to connect AC adapter to a portable device for the purpose of charging the device battery. The current supplied to the charging cable is high and creates a risk of the cable and connector overheating and burning out. A protection device is embedded in the charging cable but the available protection devices shut off the power supply to the cable in case of a minor increase in the cable temperature. The protection devices are typically connected in series with the current path resulting in a high dissipation of power. Additionally the protection devices are large, expensive, and slow leading to an inefficient protection device. 
       SUMMARY 
       [0005]    A cable protection device connected between the positive and negative wires of the cable provides an efficient method of protection from overheating of the device due to changes in temperatures with minimal power dissipation. The cable protection device includes a temperature monitoring device that continuously senses the temperature of the cable and device to check for overheating. A controller connected to the temperature monitor sends out an alarm message and a control signal to either an actuator circuit or a crowbar function circuit. The actuator circuit can send out current pulses to the adapter indicating the adapter to lower its current limit, so that the device can still keep charging and is not over heated. The crowbar function circuit causes the adapter to turn off power to the cable in order to prevent burning of the device or connector due to overheating. 
         [0006]    The features and advantages described in the specification are not all inclusive and, in particular, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings and specification. Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The teachings of the embodiments of the present disclosure can be readily understood by considering the following detailed description in conjunction with the accompanying drawings. 
           [0008]    Figure (FIG.)  1  is a block diagram illustrating a portable device charging environment including a cable protection device, according to one embodiment. 
           [0009]      FIG. 2  is a block diagram illustrating the components of the cable protection device of  FIG. 1 , according to one embodiment. 
           [0010]      FIG. 3  is a flowchart illustrating the operation of a cable protection device of  FIG. 1 , according to one embodiment. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0011]    The Figures (FIG.) and the following description relate to preferred embodiments of the present disclosure by way of illustration only. It should be noted that from the following discussion, alternative embodiments of the structures and methods disclosed herein will be readily recognized as viable alternatives that may be employed without departing from the principles of the present disclosure. 
         [0012]    Reference will now be made in detail to several embodiments of the present disclosure, examples of which are illustrated in the accompanying figures. It is noted that wherever practicable similar or like reference numbers may be used in the figures and may indicate similar or like functionality. The figures depict embodiments of the present disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the embodiments described herein. 
         [0013]    Figure (FIG.)  1  is a block diagram illustrating a portable device charging environment including a cable protection device, according to one embodiment. The environment  100  includes an adapter  110 , a charging cable  125 , a cable protection device  120 , a connector  130  and a portable device  140 . The adapter plugs into the wall electrical socket, receives an AC power supply, converts it to a suitable DC voltage/current that the adapter may be rated for, and supplies the converted DC voltage to the charging cable  125 . The cable protection device  120  is connected between the positive and negative wires of the charging cable  125 . The cable protection device  120  is explained in detail below with reference to  FIG. 2 . 
         [0014]    The charging cable  125  is connected to a portable device charging connector  130 , for example, a USB connector, a mini-USB connector, USB type C connector or any other such connector. Each connector  130  has a set of electrical parameters including the maximum current rating that the connector  130  can handle. The connector  130  provides the required current for charging the portable device  140  via the connector pins  135 . The connector pins  135  may include a supply voltage, data pins and a ground reference pin. 
         [0015]    The portable device  140  includes one or more computing devices capable of receiving user input as well as transmitting and/or receiving data. In one embodiment, a portable device  140  is a smartphone, a tablet or a conventional computer system, such as a desktop or laptop computer. Alternatively, a portable device  140  may be a device having computer functionality that may access a set of mobile applications. The portable device  140  operates on a battery that is charged by the power supplied by the adapter  110  via the connector  130  connected by the charging cable  125 . 
         [0016]      FIG. 2  is a block diagram illustrating the components of the cable protection device of  FIG. 1 , according to one embodiment. The cable protection device  120  includes a temperature monitor  230 , a controller  220  that includes a crowbar switch and an actuator circuit  210 . The actuator is connected in parallel to the protection block of the adapter via control signals. The temperature monitor is connected to the connector attached to the charging cable that charges the portable device. 
         [0017]    The temperature monitor  230  continuously monitors the temperature of either, the material or the air pocket of the connector  130  when the portable device is set up for charging. Examples of temperature monitor include temperature sensors  242  and temperature detecting circuits including resistors and transistors. The temperature monitors may operate based on detecting the current temperature, or some circuits may periodically detect a difference in temperatures from a reference temperature. The monitored temperature is fed to the controller  220 . 
         [0018]    The controller  220  adjusts the current supply to the connector  130  and the portable device  140  in case there is a minor increase in the temperature of the connector  130  and sends control signals to shut off the power supply in case of a thermal runaway. The controller  220  receives the monitored temperature and compares it to a programmable first threshold (e.g. 90° F.) that is stored in the memory of the controller  220  and compares the monitored temperature to the programmed first threshold. 
         [0019]    If the monitored temperature is equal to or greater than the programmed first threshold, but less than a second threshold, the controller sends a control signal to the actuator  210  to send sink current pulses to the adapter  110 . The sink current pulses are recognized by a controller in the adapter  110 . The controller of the adapter may reduce its current limit to a current level of the incoming sink current pulses. Additionally, the sink current pulses may be sent in an audible frequency range to produce an alarm message notifying a user of the portable device  140  of overheating of the cable connector. The control signal remains active till the temperature is reduced to an acceptable level (e.g. below the first threshold). 
         [0020]    If the monitored temperature is equal to or greater than a programmed second threshold e.g. 110° F., although other thresholds may be used which can be based on a variety of factors such as the cable materials, the controller sends a signal to the actuator to activate the crowbar circuit by driving a short circuit or a low impedance path across the output voltage, thus shutting the power supply to the connector  130  and the portable device  140 . The control signal remains active till the temperature is reduced to an acceptable level (e.g. below the first threshold). 
         [0021]    The actuator circuit  210  is connected in parallel to the controller (the load) and to a protection block of the adapter  110  resulting in minimal power dissipation. The actuator circuit  210  generates sink current pulses or activates the crowbar circuit based on a control signal from the controller  220 . The sink current pulses may be of audible frequency and generate noise/alarm message to notify a user of a portable device  140  of overheating of the charging cable  125 . The activation of the crowbar circuit may cut off the power supply to the connector  130 . 
         [0022]    On receiving the sink current pulses, the controller at the adapter adjusts the current limit to the received current limit. Adjusting the current limit of the adapter will cause a reduction in the current supplied to the connector  130  via the charging cable  125 . This allows the portable device  140  to continue to be charged and will prevent burning of the charging cable  125  and the connector  130  due to overheating. 
         [0023]    On receiving the activation for the crowbar function, the adapter&#39;s over current protection circuit is triggered. The over protection circuit switches off the power supply to the charging cable by enabling a short circuit or a low resistance path across the output voltage. This stops the further rise of temperature at the connector, thus preventing a thermal runaway and in effect, prevents damage to the charging cable, connector and the portable device. The crowbar function is active until it receives further control signals from the actuator circuit  210  of the cable protection device  120 . 
         [0024]      FIG. 3  is a flowchart illustrating the operation of a cable protection device of  FIG. 1 , according to one embodiment. The cable protection device  120  monitors  310  the temperature of either, the material or the air pocket of the connector when connected to a portable device for charging the device. The monitored temperature is compared  320  against a second threshold temperature that is programmable. If the monitored temperature is equal to or greater than the second threshold, the cable protection device  120  sends control signals to activate  330  the crowbar circuit of the adapter to turn off the power supply to the charging cable  125  and the connector  130 . 
         [0025]    If the monitored temperature is not equal to or greater than the second threshold, the monitored temperature is compared  340  to a first threshold temperature. If the monitored temperature is equal to or greater than the first threshold temperature, the cable protection device  120  sends  350  sink current pulses that may be at an audible frequency to the adapter  110 . The sink current pulses enable the adapter to lower its current limit to the limit indicated by the sink current pulses, and the audible frequency may be used to notify the same to the user of the portable device via an alarm message. If the monitored temperature is less than the first threshold temperature, the cable protection device  120  continues monitoring  310  and comparing  320  the connector temperature. 
         [0026]    Reference in the specification to “one embodiment” or to “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least one embodiment. The appearances of the phrase “in one embodiment” or “an embodiment” in various places in the specification are not necessarily all referring to the same embodiment. 
         [0027]    Some portions of the detailed description are presented in terms of algorithms and symbolic representations of operations on data bits within a computer memory. These algorithmic descriptions and representations are the means used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. An algorithm is here, and generally, conceived to be a self-consistent sequence of steps (instructions) leading to a desired result. The steps are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical, magnetic or optical signals capable of being stored, transferred, combined, compared and otherwise manipulated. It is convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like. Furthermore, it is also convenient at times, to refer to certain arrangements of steps requiring physical manipulations or transformation of physical quantities or representations of physical quantities as modules or code devices, without loss of generality. 
         [0028]    However, all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise as apparent from the following discussion, it is appreciated that throughout the description, discussions utilizing terms such as “processing” or “computing” or “calculating” or “determining” or “displaying” or “determining” or the like, refer to the action and processes of a computer system, or similar electronic computing device (such as a specific computing machine), that manipulates and transforms data represented as physical (electronic) quantities within the computer system memories or registers or other such information storage, transmission or display devices. 
         [0029]    Certain aspects of the embodiments include process steps and instructions described herein in the form of an algorithm. It should be noted that the process steps and instructions of the embodiments can be embodied in software, firmware or hardware, and when embodied in software, could be downloaded to reside on and be operated from different platforms used by a variety of operating systems. The embodiments can also be in a computer program product which can be executed on a computing system. 
         [0030]    The embodiments also relate to an apparatus for performing the operations herein. This apparatus may be specially constructed for the purposes, e.g., a specific computer, or it may comprise a general-purpose computer selectively activated or reconfigured by a computer program stored in the computer. Such a computer program may be stored in a computer readable storage medium, such as, but is not limited to, any type of disk including floppy disks, optical disks, CD-ROMs, magnetic-optical disks, read-only memories (ROMs), random access memories (RAMs), EPROMs, EEPROMs, magnetic or optical cards, application specific integrated circuits (ASICs), or any type of media suitable for storing electronic instructions, and each coupled to a computer system bus. Memory can include any of the above and/or other devices that can store information/data/programs and can be transient or non-transient medium, where a non-transient or non-transitory medium can include memory/storage that stores information for more than a minimal duration. Furthermore, the computers referred to in the specification may include a single processor or may be architectures employing multiple processor designs for increased computing capability. 
         [0031]    The algorithms and displays presented herein are not inherently related to any particular computer or other apparatus. Various general-purpose systems may also be used with programs in accordance with the teachings herein, or it may prove convenient to construct more specialized apparatus to perform the method steps. The structure for a variety of these systems will appear from the description herein. In addition, the embodiments are not described with reference to any particular programming language. It will be appreciated that a variety of programming languages may be used to implement the teachings of the embodiments as described herein, and any references herein to specific languages are provided for disclosure of enablement and best mode. 
         [0032]    In addition, the language used in the specification has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter. Accordingly, the disclosure of the embodiments is intended to be illustrative, but not limiting, of the scope of the embodiments, which is set forth in the claims. 
         [0033]    While particular embodiments and applications have been illustrated and described herein, it is to be understood that the embodiments are not limited to the precise construction and components disclosed herein and that various modifications, changes, and variations may be made in the arrangement, operation, and details of the methods and apparatuses of the embodiments without departing from the spirit and scope of the embodiments as defined in the appended claims.