Patent Publication Number: US-11385696-B2

Title: Electronic apparatus, control method in electronic apparatus, and apparatus

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a technique for controlling power (current) in an electronic apparatus having a plurality of external connection interfaces. 
     Description of the Related Art 
     Conventionally, as an interface that connects an electronic apparatus as an information processing apparatus and a peripheral apparatus, the interface of the USB (Universal Serial Bus) standard has prevailed widely. The USB standard specifies as part of the specifications thereof that it is possible to supply a power current, as bus power, to a target peripheral apparatus from an electronic apparatus (information processing apparatus), other than data communication. 
     Then, in a case where power (current) is supplied by the USB interface in conformity with the standard, in an electronic apparatus, in order to guarantee the operation of a peripheral apparatus, a power source capable of supplying a current (rated current) in accordance therewith is included. However, even in a case where a power source is included by supposing peripheral apparatuses to be connected, there are a variety of peripheral apparatuses and depending on the peripheral apparatus that is connected, there is a possibility that a current larger than or equal to a permitted value flows (that is, a possibility that an overcurrent occurs). Consequently, in order to protect the electronic apparatus from the overcurrent, normally, a circuit for suppressing an overcurrent (that is, overcurrent control circuit) is included. 
     Further, in recent years, in general, a plurality of USB ports is included as the USB interface in an electronic apparatus, and in such a case, a USB hub IC is mounted on the electronic apparatus and further, an overcurrent control circuit is incorporated in the USB hub IC that is mounted. For example, Japanese Patent Laid-Open No. 2013-109461 has disclosed a device that protects an electronic apparatus from an overcurrent by mounting a signal that detects an overcurrent and a signal necessary for controlling an overcurrent (for example, power enable signal and the like) on the USB hub IC as an overcurrent control circuit for each USB port. 
     However, in a case where an overcurrent control circuit (in more detail, signal for controlling an overcurrent) is incorporated in the USB hub IC as in the device of Japanese Patent Laid-Open No. 2013-109461, it is necessary to include pins (terminals) and a circuit, and therefore, there is such a problem that the manufacturing cost is raised. The present invention has been made in view of the above-described conventional problem and an object thereof is to protect an electronic apparatus from an overcurrent while suppressing the manufacturing cost of the electronic apparatus. 
     SUMMARY OF THE INVENTION 
     In order to achieve the above-described object, the present invention is an electronic apparatus including a plurality of external interfaces and capable of supplying a current to an external device connected via the external interface, the electronic apparatus including: a power source control unit allocated to each of the plurality of external interfaces and configured to output whether or not an overcurrent supplied to the external device is detected as an overcurrent detection signal, as well as controlling supply or shutoff of a current for the external device; a control unit configured to output a power source control signal for controlling supply or shutoff of a current for the external device to the power source control unit; a logical product circuit that outputs a logical product of the overcurrent detection signal output from each of the power source control units as an external interrupt signal to the control unit; and an interface control unit configured to output external interface information specifying an external interface at which the overcurrent has occurred to the control unit in a case where the overcurrent detection signal is received and one of the overcurrent detection signals is asserted, and the control unit, in a case where the external interrupt signal is asserted, outputs the power source control signal to the power source control unit having detected the overcurrent so as to shut off supply of power for the external device, as well as acquiring the external interface information. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram showing a configuration of a conventional electronic apparatus; 
         FIG. 2  is a block diagram showing a configuration of a VBUS control unit of the conventional electronic apparatus; 
         FIG. 3  is a block diagram showing a configuration of a USB hub IC of the conventional electronic apparatus; 
         FIG. 4  is a block diagram showing a configuration of an electronic apparatus according to the present embodiment; 
         FIG. 5  is a block diagram showing a configuration of a VBUS control unit of the electronic apparatus according to the present embodiment; 
         FIG. 6  is a block diagram showing a configuration of a USB hub IC of the electronic apparatus according to the present embodiment; 
         FIG. 7  is a timing chart relating to power source control of the electronic apparatus according to the present embodiment; and 
         FIG. 8  is a flowchart showing a procedure of processing relating to power source control of the electronic apparatus according to the present embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     In the following, preferred embodiments of the present invention are explained in detail with reference to the attached drawings. The following embodiments are not intended to limit the present invention and all combinations of features explained in the present embodiments are not necessarily indispensable to the solution of the present invention. 
     First, before explaining the embodiments of the present invention, a power source control configuration of a conventional electronic apparatus is explained.  FIG. 1  is a block diagram showing a general hardware configuration including a plurality of USB ports (that is, connection ports of the USB interface). In  FIG. 1 , explanation is given by using an image forming apparatus  10  including three USB ports as a general hardware configuration (electronic apparatus) including a plurality of USB ports. 
     The image forming apparatus  10  is a multi function peripheral (MFP) including a plurality of functions, such as a copy function and a fax function, and for example, configured as follows. An SOC (System on a Chip)  101  is a main unit internally mounting a CPU (Central Processing Unit) and configured to control the entire image forming apparatus  10 , and includes a controller for controlling each unit. The SOC  101  is connected with each unit via various interfaces possessed by the SOC  101 . 
     A ROM (Read Only Memory)  102  is a memory storing a program for activating the SOC  101 , various kinds of setting information and so on. A RAM (Random Access Memory)  103  is a work memory for the SOC  101  to operate. The RAM  103  is used to save (store) image data for which image processing has been performed by execution of the operation, such as loading of various programs, storing of arithmetic operation processing results, printing, and scanning. 
     A storage device  104  is a nonvolatile memory for storing programs and data whose data size is large. The storage device  104  includes, for example, an HDD (Hard Disk Drive), an SSD (Solid State Drive), a flash memory and so on. 
     A printer unit  105  is a unit configured to operate by performing transmission and reception of image data and control signals with the SOC  101  and includes various devices relating to the printing operation, such as a photoconductor drum, a laser oscillator, a toner fixing unit, and a motor. A scanner unit  106  is a unit configured to operate by performing transmission and reception of control signals relating to the reading operation with the SOC  101  and includes various devices, such as a document detection sensor, a reading sensor, and a motor. 
     A LAN communication unit  107  includes a network controller and a wired LAN interface and performs network communication by connecting with an external apparatus by a LAN (Local Area Network) cable. A USB communication unit  108  includes a controller of a USB device apparatus and an interface (for example, Type B) of a USB device apparatus. The USB communication unit  108  performs communication of the USB standard by connecting with an interface (for example, Type A) of a USB host possessed by an external personal computer by a USB cable. The USB communication unit  108  is a communication unit configured to perform communication by the same USB standard as that of USB interfaces connected with a USB hub IC  110 , to be described later, but those USB interfaces are different in that whether the image forming apparatus  10  corresponds to the host side or the device side, and the USB communication unit  108  corresponds to the communication unit on the device side. 
     An operation unit  109  receives image data for display from the SOC  101  and displays the image data on a screen and in addition, receives the operation of a user via a touch panel, a key and so on, and transmits a control signal corresponding to the operation to the SOC  101 . Upon receipt of the control signal from the operation unit  109 , the SOC  101  changes the image data that is displayed and performs a predetermined function (for example, copy and the like) based on the control signal. 
     The USB hub IC  110  is connected with the SOC  101  by the USB standard and extends the USB interface on the host side to a plurality of ports. In  FIG. 1 , the interface of the USB host possessed by the SOC  101  is only one port and a configuration is shown in which the interface is increased (extended) up to three ports by using the USB hub IC  110 . 
     In  FIG. 1 , the communication of the USB standard between the SOC  101  and the USB hub IC  110  is indicated as a USB upstream signal  111 . Further, the communication of the USB standard between the USB hub IC  110  and USB ports branched from the USB hub IC  110  is indicated as USB downstream signals  112 ,  123 , and  129 . 
     The USB hub IC  110  detects a device that is connected, controls the communication speed, and controls power supply to VBUS control units  114 ,  124 , and  130  (specifically, controls enable/disable signal), in addition to increasing ports by distributing signals. In addition, signals that are output from the USB hub IC  110  and which control power supply to the VBUS control units  114 ,  124 , and  130  are indicated as USB power source control signals  113 ,  121 , and  127  in  FIG. 1 . 
     The VBUS control units  114 ,  124 , and  130  are blocks that control on or off of power that is supplied from a power source unit  115  to USB ports  118 ,  125 , and  131 . The power source unit  115  converts input AC power into DC power and supplies the converted DC power to each unit of the image forming apparatus  10 . 
     In the configuration shown in  FIG. 1 , power supplied to the USB ports is indicated by USB upstream power  116  on the input sides of the VBUS control units  114 ,  124 , and  130  and USB downstream power  117 ,  133 , and  134  on the output sides. The VBUS control units  114 ,  124 , and  130  respectively control the supply (on or off) of power to the USB ports  118 ,  125 , and  131  based on the USB power source control signals  113 ,  121 , and  127  transmitted from the USB hub IC  110 . For example, upon detecting that the USB power source control signals  113 ,  121 , and  127  are changed to the enable side, the VBUS control units  114 ,  124 , and  130  perform control so as to turn on the internal connection and supply power to the USB downstream power  117 ,  133 , and  134 . In addition, power supplied to units other than the VBUS control units  114 ,  124 , and  130  is not the main purpose of the present invention, and therefore, it is not shown schematically and explanation thereof is also omitted. 
     The USB ports  118 ,  125 , and  131  are USB connectors (Type A) for connecting an external device having a USB interface to the image forming apparatus  10 . USB device apparatuses  119 ,  126 , and  132  are USB device apparatuses capable of connecting to the USB connector (Type A). The USB device apparatuses  119 ,  126 , and  132  are, for example, USB memories, USB card readers, portable HDDs connected via a USB cable, or the like. 
     Here, these USB device apparatuses consume a current that basically satisfies the standard of the image forming apparatus  10 , but provided that the USB interface is possessed, it is possible to connect any USB device apparatus, and therefore, there is a case where a nonstandard USB device apparatus is connected. Then, in such a case, there is a possibility that the current (power) that is supplied enters an overcurrent state where a current larger than or equal to a permitted value of the current that the power source unit  115  can supply flows. 
     Consequently, also in the conventional power source control configuration, the VBUS control units  114 ,  124 , and  130  not only control on or off of power that is supplied as their function but also detect an overcurrent in a case of the occurrence thereof and notify the USB hub IC  110  of that as an error signal. This error signal is indicated as VBUS error signals  120 ,  122 , and  128  in  FIG. 1 . Upon receipt of the VBUS error signals  120 ,  122 , and  128 , the USB hub IC  110  shuts off the power supply from the VBUS control units  114 ,  124 , and  130  by performing control so as to make the USB power source control signals  113 ,  121 , and  127  disable. Further, in general, the threshold value of an overcurrent detected in the VBUS control units  114 ,  124 , and  130  is designed so as to satisfy the rated current and in the conventional power source control configuration, the threshold value is set to 500 mA. In addition, the VBUS control units  114 ,  124 , and  130  perform detection of an error other than detection of an overcurrent, shutoff of power and so on as their function, as will be explained in detail in  FIG. 2 . 
     Next, the internal configuration of the VBUS control unit  114  in the conventional power source control configuration is explained in detail by using  FIG. 2 . The VBUS control units  124  and  130  have the same internal configuration as that of the VBUS control unit  114 , and therefore, explanation thereof is omitted here. 
     A switch unit  200  is a circuit that controls conduction between the USB upstream power  116  and the USB downstream power  117  based on a control signal from a switch control unit  201 . The switch unit  200  includes, for example, a switching element, such as an FET (Field Effect Transistor). 
     The switch control unit  201  is a circuit that generates a signal for controlling conduction of the switch unit  200  and includes, for example, a charge pump circuit and a gate logic circuit. In more detail, the switch control unit  201  controls conduction of the switch unit  200  in accordance with notifications from a low-voltage malfunction prevention unit  202 , an overcurrent detection unit  203 , and an overheating shutoff unit  205 , to be described later, and the USB power source control signal  113 . Further, in a case of performing control so as to bring the switch unit  200  into the nonconduction state, the switch control unit  201  performs discharge control of the USB downstream power  117  by notifying an output discharge unit  206  of that. 
     The low-voltage malfunction prevention unit  202  is a circuit that notifies, in a case where the voltage of the USB upstream power  116  is lower than or equal to a predetermined voltage value, the switch control unit  201  of that. Upon receipt of the notification that the voltage of the above-described USB upstream power  116  is lower than or equal to a predetermined voltage value from the low-voltage malfunction prevention unit  202 , the switch control unit  201  performs control so as to bring the switch unit  200  into the nonconduction state. 
     The overcurrent detection unit  203  is a circuit that notifies, in a case where the current value of the current flowing as the USB upstream power  116  or the USB downstream power  117  is a current value larger than or equal to a predetermined threshold value, the switch control unit  201  and an overcurrent detection notification unit  204  of that. Upon receipt of the notification that a current larger than or equal to the above-described threshold value is flowing from the overcurrent detection unit  203 , the switch control unit  201  limits the current flowing as the USB downstream power  117  by bringing the switch unit  200  into a semi-conduction state. As a supplement, bringing into a semi-conduction state means limiting the overcurrent supplied to the USB device apparatuses  119 ,  126 , and  132  to less than the threshold value that is detected as an overcurrent. 
     The overcurrent detection notification unit  204  is a circuit that outputs the VBUS error signal  120  to the USB hub IC  110  upon receipt of the notification that a current larger than or equal to the above-described threshold value is flowing from the overcurrent detection unit  203  and includes, for example, an open drain FET and the like. 
     The overheating shutoff unit  205  is a circuit that notifies, in a case where the temperature of the VBUS control unit  114  becomes higher than or equal to a predetermined temperature, such as a case where an overcurrent limit state continues, the switch control unit  201  of that. Upon receipt of the notification that the temperature of the above-described VBUS control unit  114  has become higher than or equal to a predetermined temperature from the overheating shutoff unit  205 , the switch control unit  201  performs control so as to bring the switch unit  200  into the nonconduction state. Upon receipt of the notification from the switch control unit  201 , the output discharge unit  206  performs control so as to discharge the output power in the USB downstream power  117  and includes, for example, a switching element, such as an FET. 
     Next, the internal configuration of the USB hub IC  110  in the conventional power source control configuration is explained in detail by using  FIG. 3 . A USB port unit  300  is an interface circuit in conformity with the USB standard and configured so as to be capable of upstream communication. To the USB port unit  300 , as shown in  FIG. 3 , the USB upstream signal  111  is connected. 
     A TT unit  301  is a circuit called a transaction translator and performs transaction conversion processing in a case where the speed mode on the upstream side and the speed mode on the downstream side are different. Here, the speed mode refers to the High Speed mode or the Full Speed mode specified by the USB standard. 
     A repeater unit  302  is a circuit that controls data transfer between the upstream side and the downstream side in a case where the speed mode on the upstream side and the speed mode on the downstream side are the same. A routing unit  303  performs control so that with which DS port unit of DS port units  304 ,  305 , and  306 , data communication is performed for the USB port unit  300  (that is, performs route control). The DS port units  304 ,  305 , and  306  are interface circuits in conformity with the USB standard and configured so as to be capable of downstream communication. As shown in  FIG. 3 , to the DS port units  304 ,  305 , and  306 , the USB downstream signals  112 ,  123 , and  129  are connected, respectively. 
     DS port power source control units  307 ,  308 , and  309  are circuits that generate the USB power source control signals  113 ,  121 , and  127  transmitted to the VBUS control units  114 ,  124 , and  130  connected to the downstream side. Specifically, the DS port power source control unit  307  performs control so as to make the USB power source control signal  113  enable or disable in accordance with a request of the SOC  101  on the upstream side. The DS port power source control units  308  and  309  similarly control the USB power source control signals  121  and  127 . 
     Further, it is possible for the DS port power source control units  307 ,  308 , and  309  to perform control so as to make the USB power source control signals  113 ,  121 , and  127  disable without intervention of software control in accordance with the overcurrent occurrence notifications by the VBUS error signals  120 ,  122 , and  128 . Further, upon receipt of the overcurrent occurrence notifications by the above-described VBUS error signals  120 ,  122 , and  128 , the DS port power source control units  307 ,  308 , and  309  notify the SOC  101  of the occurrence of an overcurrent as information via the USB upstream signal  111 . 
     An MPU unit  310  is a circuit that sets and controls each block making up the USB hub IC  110  and includes a ROM and a RAM. As above, by using  FIG. 1  to  FIG. 3 , the conventional power source control configuration is explained. Consequently, in the following, an electronic apparatus (power source control apparatus) according to the embodiment of the present invention is explained by using  FIG. 4  to  FIG. 8 . 
       FIG. 4  is a block diagram showing a configuration of an electronic apparatus according to the present embodiment. As a general electronic apparatus including a plurality of external interfaces (that is, USB ports), it is possible to suppose a PC (Personal Computer) and the like, but in  FIG. 4 , explanation is given by using an image forming apparatus  40  including three USB ports. 
     The image forming apparatus  40  is a multi function peripheral (MFP) including a plurality of functions, such as a copy function and a fax function, and for example, configured as follows. A SOC  401  is a main unit internally mounting a CPU and configured to control the entire image forming apparatus  40 , and includes a controller for controlling each unit. The SOC  401  is connected with each unit via various interfaces possessed by the SOC  401 . Further, the SOC  401  includes general-purpose ports for outputting USB power source control signals  453 ,  454 , and  455 , to be described later. 
     A ROM  402  is a memory storing a program for activating the SOC  401 , various kinds of setting information and so on. A RAM  403  is a work memory for the SOC  401  to operate. The RAM  403  is used to save (store) image data for which image processing has been performed by execution of the operation, such as loading of various programs, storing of arithmetic operation processing results, printing, and scanning. 
     A storage device  404  is a nonvolatile memory for storing programs and data whose data size is large. The storage device  404  includes, for example, an HDD, an SSD, a flash memory and so on. A printer unit  405  is a unit configured to operate by performing transmission and reception of image data and control signals with the SOC  401  and includes various devices relating to the printing operation, such as a photoconductor drum, a laser oscillator, a toner fixing unit, and a motor. A scanner unit  406  is a unit configured to operate by performing transmission and reception of control signals relating to the reading operation with the SOC  401  and includes various devices, such as a document detection sensor, a reading sensor, and a motor. 
     A LAN communication unit  407  includes a network controller and a wired LAN interface and performs network communication by connecting with an external apparatus by a LAN cable. A USB communication unit  408  includes a controller of a USB device apparatus and an interface (for example, Type B) of a USB device apparatus. The USB communication unit  408  performs communication of the USB standard by connecting with an interface (for example, Type A) of a USB host possessed by an external personal computer by a USB cable. The USB communication unit  408  is a communication unit configured to perform communication by the same USB standard as that of the USB interface connected with a USB hub IC  410 , to be described later, but those USB interfaces are different in that whether the image forming apparatus  40  corresponds to the host side or the device side, and the USB communication unit  408  corresponds to the communication unit on the device side. 
     An operation unit  409  receives image data for display from the SOC  401  and displays the image data on a screen and in addition, receives the operation of a user via a touch panel, a key and so on, and transmits a control signal corresponding to the operation to the SOC  401 . Upon receipt of the control signal from the operation unit  409 , the SOC  401  changes the image data that is displayed and performs a predetermined function (for example, copy and the like) based on the control signal. 
     The USB hub IC  410  is connected with the SOC  401  by the USB standard and extends the USB interface on the host side to a plurality of ports. In  FIG. 4 , the interface of the USB host possessed by the SOC  401  is only one port and a configuration is shown in which the interface is increased (extended) up to three ports by using the USB hub IC  410 . 
     In  FIG. 4 , the communication of the USB standard between the SOC  401  and the USB hub IC  410  is indicated as a USB upstream signal  411 . Further, the communication of the USB standard between the USB hub IC  410  and the USB ports branched from the USB hub IC  410  is indicated as USB downstream signals  412 ,  423 , and  429 . The USB hub IC  410  is an interface controller (that is, interface control unit) and detects a device that is connected and controls the communication speed, in addition to increasing ports by distributing signals. 
     VBUS control units  414 ,  424 , and  430  are blocks that control on or off of power that is supplied from a power source unit  415  to USB ports  418 ,  425 , and  431 . The power source unit  415  converts input AC power into DC power and supplies the converted DC power to each unit of the image forming apparatus  40 . 
     In the configuration shown in  FIG. 4 , power supplied to the USB ports is indicated by USB upstream power  416  on the input sides of the VBUS control units  414 ,  424 , and  430  and USB downstream power  417 ,  433 , and  434  on the output sides. The VBUS control units  414 ,  424 , and  430  respectively controls the supply (on or off) of power to the USB ports  418 ,  425 , and  431  based on the USB power source control signals  453 ,  454 , and  455  connected to the output port of the SOC  401 . For example, upon detecting that the USB power source control signals  453 ,  454 , and  455  are changed to the enable side, the VBUS control units  414 ,  424 , and  430  perform control so as to turn on the internal connection and supply power to the USB downstream power  417 ,  433 , and  434 . In addition, power supplied to units other than the VBUS control units  414 ,  424 , and  430  is not the main purpose of the present invention, and therefore, it is not shown schematically and explanation thereof is also omitted. For example, the VBUS control units  414 ,  424 , and  430  include high-side switch circuits and the like. 
     The USB ports  418 ,  425 , and  431  are USB connectors (Type A) for connecting an external device having a USB interface to the image forming apparatus  40 . USB device apparatuses  419 ,  426 , and  432  are USB device apparatuses capable of connecting to the USB connector (Type A). The USB device apparatuses  419 ,  426 , and  432  are, for example, keyboards, USB memories, USB card readers, portable HDDs connected via a USB cable, or the like. 
     Here, these USB device apparatuses consume a current that basically satisfies the standard of the image forming apparatus  40 , but provided that the USB interface is possessed, it is possible to connect any USB device apparatus, and therefore, there is a case where a nonstandard USB device apparatus is connected. Then, in such a case, there is a possibility that the current (power) that is supplied enters an overcurrent state where a current larger than or equal to a permitted value of the current that the power source unit  415  can supply flows. 
     Consequently, in the electronic apparatus according to the present embodiment, the VBUS control units  414 ,  424 , and  430  not only control on or off of power that is supplied as their function but also detect an overcurrent in a case of the overcurrent thereof and notify the USB hub IC  410  of that as an error signal. This error signal is an overcurrent detection signal indicating where or not an overcurrent is detected and in  FIG. 4 , indicated as VBUS error signals  420 ,  422 , and  428 . Upon receipt of the VBUS error signals  420 ,  422 , and  428 , the USB hub IC  410  notifies the SOC  401  of the USB port at which the overcurrent has occurred or the occurrence of the overcurrent and the USB port at which the overcurrent has occurred via the USB upstream signal  411 . Further, in general, the threshold value of an overcurrent that is detected in the VBUS control units  414 ,  424 , and  430  is designed so as to satisfy the rated current and in the present embodiment, the threshold value is set to 500 mA. 
     An AND logic gate  451  is a logical product circuit and notifies the SOC  401  of an AND logic signal of the VBUS error signals  420 ,  422 , and  428  as a VBUS error interrupt signal  452  (that is, notifies the SOC  401  of an AND logic signal as an external interrupt signal). The SOC  401  checks the USB port at which the overcurrent has occurred as information, which is notified via the USB upstream signal  411 , with the VBUS error interrupt signal  452  as a trigger. The SOC  401  makes disable the signal corresponding to the VBUS control unit having detected the overcurrent of the USB power source control signals  453 ,  454 , and  455  in accordance with the information specifying the USB port at which the overcurrent has occurred. In addition, the VBUS control units  414 ,  424 , and  430  perform detection of an error other than detection of an overcurrent, shutoff of power and so on as their functions, as will be explained in detail in  FIG. 5 . 
     As above, by using the image forming apparatus  40  as the electronic apparatus according to the present embodiment, the power source control configuration thereof is explained, but the electronic apparatus is not limited to this and any apparatus having a USB host interface may be used. Consequently, the electronic apparatus may be, for example, a personal computer and the like. 
     Next, the internal configuration of the VBUS control unit  414  in the electronic apparatus according to the present embodiment is explained in detail by using  FIG. 5 . The VBUS control units  424  and  430  have the same internal configuration as that of the VBUS control unit  414 , and therefore, explanation thereof is omitted here. 
     A switch unit  500  is a circuit that controls conduction between the USB upstream power  416  and the USB downstream power  417  based on a signal from a switch control unit  501 . The switch control unit  501  includes, for example, a switching element, such as an FET. 
     The switch control unit  501  is a circuit that generates a signal for controlling conduction of the switch unit  500  and includes, for example, a charge pump circuit and a gate logic circuit. In more detail, the switch control unit  501  controls conduction of the switch unit  500  in accordance with notifications from a low-voltage malfunction prevention unit  502 , an overcurrent detection unit  503 , and an overheating shutoff unit  505 , to be described later, and the USB power source control signal  453 . Further, in a case of performing control so as to bring the switch unit  500  into the nonconduction state, the switch control unit  501  performs discharge control of the USB downstream power  417  by notifying an output discharge unit  506  of that. 
     The low-voltage malfunction prevention unit  502  is a low voltage detection unit and is a circuit that notifies, in a case where the voltage of the USB upstream power  416  (that is, input voltage) becomes lower than or equal to a predetermined voltage value, the switch control unit  501  of that. Upon receipt of the notification that the voltage of the above-described USB upstream power  416  is lower than or equal to a predetermined voltage value from the low-voltage malfunction prevention unit  502 , the switch control unit  501  performs control so as to bring the switch unit  500  into the nonconduction state. 
     The overcurrent detection unit  503  is a circuit that notifies, in a case where the current value of the current flowing as the USB upstream power  416  or the USB downstream power  417  is a current value larger than or equal to a predetermined threshold value, the switch control unit  501  and an overcurrent detection notification unit  504  of that. Upon receipt of the notification that a current larger than or equal to the above-described threshold value is flowing from the overcurrent detection unit  503 , the switch control unit  501  limits the current flowing as the USB downstream power  417  by bringing the switch unit  500  into a semi-conduction state. As a supplement, bringing into a semi-conduction state means limiting the overcurrent supplied to the USB device apparatuses  419 ,  426 , and  432  to less than the threshold value that is detected as an overcurrent. 
     The overcurrent detection notification unit  504  is a circuit that outputs the VBUS error signal  420  to the USB hub IC  410  upon receipt of the notification that a current larger that or equal to the above-described threshold value is flowing from the overcurrent detection unit  503  and includes, for example, an open drain FET and the like. 
     The overheating shutoff unit  505  is an overheating detection unit and is a circuit that notifies, in a case where the temperature of the VBUS control unit  414  becomes higher than or equal to a predetermined temperature, such as a case where an overcurrent limit state continues, the switch control unit  501  of that. Upon receipt of the notification that the temperature of the above-described VBUS control unit  414  has become higher than or equal to a predetermined temperature from the overheating shutoff unit  505 , the switch control unit  501  performs control so as to bring the switch unit  500  into the nonconduction state Upon receipt of the notification from the switch control unit  501 , the output discharge unit  506  performs control so as to discharge the output power in the USB downstream power  417  and includes, for example, a switching element, such as an FET. 
     Next, the internal configuration of the USB hub IC  410  in the electronic apparatus according to the present embodiment is explained in detail by using  FIG. 6 . A USB port unit  600  is an interface circuit in conformity with the USB standard and configured so as to be capable of upstream communication. To the USB port unit  600 , as shown in  FIG. 6 , the USB upstream signal  411  is connected. 
     A TT unit  601  is a circuit called a transaction translator and performs transaction conversion processing in a case where the speed mode on the upstream side and the speed mode on the downstream side are different. Here, the speed mode refers to the High Speed mode or the Full Speed mode specified by the USB standard. 
     A repeater unit  602  is a circuit that controls data transfer between the upstream side and the downstream side in a case where the speed mode on the upstream side and the speed mode on the downstream side are the same. A routing unit  603  performs control so that with which DS port unit of DS port units  604 ,  605 , and  606 , data communication is performed for the USB port unit  600  (that is, performs route control). The DS port units  604 ,  605 , and  606  are interface circuits in conformity with the USB standard and configured so as to be capable of downstream communication. As shown in  FIG. 6 , to the DS port units  604 ,  605 , and  606 , the USB downstream signals  412 ,  423 , and  429  are connected, respectively. 
     DS port overcurrent notification reception units  607 ,  608 , and  609  receive overcurrent occurrence notifications by the VBUS error signals  420 ,  422 , and  428 . Upon receipt of the overcurrent occurrence notifications as signals, the DS port overcurrent notification reception units  607 ,  608 , and  609  notify the SOC  401  of the USB port at which the overcurrent has occurred as information via the USB upstream signal  411 . An MPU unit  610  is a circuit that sets and controls each block making up the USB hub IC  410  and includes a ROM and a RAM. 
       FIG. 7  is a timing chart relating to the power source control of the electronic apparatus according to the present embodiment and specifically, is a diagram showing processing from the occurrence of an overcurrent until the USB power source control signal is made disable by the SOC  401  as a timing chart. In  FIG. 7 , explanation is given on the assumption that an overcurrent has occurred at the USB port  431 . 
     In a case where an overcurrent occurs at the USB port  431 , the VBUS control unit  430  performs control so as to change the VBUS error signal  428  to the Low level (that is, asserts the VBUS error signal  428 ) ( 700 ). That is, the VBUS control unit  430  notifies the USB hub IC  410  that an overcurrent has occurred as a signal. In a case where the VBUS error signal  428  is output at the Low level, in accordance with the change in the level of the VBUS error signal  428 , the VBUS error interrupt signal  452 , which is the output of the AND logic gate  451 , changes to the Low level (that is, the VBUS error interrupt signal  452  is asserted) ( 701 ). 
     On the other hand, upon receipt of the overcurrent occurrence notification by the VBUS error signal  428 , the USB hub IC  410  notifies the SOC  401  of the USB port at which the overcurrent has occurred, that is, the USB port  431 , as information via the USB upstream signal  411  ( 702 ). Further, the SOC  401  acquires overcurrent port information ( 702 ) with the change in the level of the VBUS error interrupt signal  452  ( 701 ) as a trigger. Although described later in  FIG. 8 , in a case where the SOC  401  is not notified of the overcurrent port information ( 702 ) by the USB hub IC  410  at the timing of the SOC  401  trying to acquire the overcurrent port information ( 702 ), the SOC  401  tries again to acquire the overcurrent port information ( 702 ). 
     In a case of acquiring the overcurrent port information ( 702 ) and recognizing (determining) that an overcurrent has occurred at the USB port  431 , the SOC  401  shuts off the USB downstream power  434  by making disable the USB power source control signal  455  ( 703 ). After this, by the USB downstream power  434  being shut off, the USB port  431  returns from the overcurrent state, and therefore, the VBUS control unit  430  cancels the overcurrent notification in the VBUS error signal  428  ( 704 ). 
       FIG. 8  is a flowchart showing a procedure of processing relating to the power source control of the electronic apparatus according to the present embodiment and specifically, a flowchart showing a procedure of processing in a case where the SOC  401  detects a change in the level of the VBUS error interrupt signal  452 . 
     Upon detecting a change in the level of the VBUS error interrupt signal  452 , the SOC  401  checks the USB upstream signal  411  in order to acquire overcurrent port information with the detection as a trigger (S 801 ). Based on the results of the check of the USB upstream signal  411 , the SOC  401  determines whether or not it has been possible to acquire the overcurrent port information (S 802 ). 
     In a case where the SOC  401  tries to acquire the overcurrent port information before the USB hub IC  410  reports the overcurrent port information via the USB upstream signal  411 , it is not possible for the SOC  401  to acquire the overcurrent port information. Because of this, the SOC  401  returns the processing to step S 801 . On the other hand, in a case where it has been possible to acquire the overcurrent port information, the SOC  401  makes disable the signal corresponding to the VBUS control unit having detected the overcurrent of the USB power source control signals  453 ,  454 , and  455  in accordance with the overcurrent port information (S 803 ). 
     As above, according to the present embodiment, in a case where an overcurrent occurs at one of the USB ports, it is possible for the SOC to check the overcurrent port information (external interface information) via the USB upstream signal with the VBUS error interrupt signal as a trigger. By the SOC making disable the signal corresponding to the VBUS control unit having detected the overcurrent of the SUB power source control signals in accordance with the overcurrent port information, it is possible to protect the electronic apparatus from the overcurrent. 
     Further, without including a function (circuit) necessary for controlling an overcurrent in the USB hub IC (that is, while suppressing the manufacturing cost of the USB hub IC), it is possible to protect the electronic apparatus from an overcurrent for each USB port by the SOC including a general-purpose port. 
     OTHER EMBODIMENTS 
     Embodiment(s) of the present invention can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a ‘non-transitory computer-readable storage medium’) to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like. 
     According to the present invention, while suppressing the manufacturing cost of an electronic apparatus, it is possible to protect the electronic apparatus from an overcurrent. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2017-236937, filed Dec. 11, 2017, which is hereby incorporated by reference wherein in its entirety.