Patent Description:
A power supply apparatus (such as a personal computer, an AC-USB adapter, or the like) that includes a USB (Universal Serial Bus) interface can supply power, via a USB cable, to an electronic device that includes a USB interface. <CIT> discloses a method of setting a switch connected between an external power source and a load to a disconnected state when the voltage of the external power source is an overvoltage.

A power supply apparatus conforming to USB Power Delivery (USB PD) standard can supply power of a maximum of <NUM> W (<NUM> A, <NUM> V) to an electronic device through a USB interface. Hence, depending on the state or the arrangement of the power supply apparatus, an excessive voltage exceeding the maximum value of voltage that can be applied from the power supply apparatus to the electronic device may be applied to a VBUS terminal of the electronic device. If such an excessive voltage is applied to the VBUS terminal of the electronic device, it may cause internal circuitry connected to the VBUS terminal of the electronic device to break down. Furthermore, document <CIT> discloses cable quality detection and power consumer devices. Document <CIT> discloses power supply and over voltage protection apparatus and over voltage protection method.

According to an aspect of the embodiments, an electronic device or a control method more improved than the electronic device or control method described above is provided.

According to an aspect of the embodiments, internal circuitry of the electronic device can be protected from an excessive voltage.

The present invention in its first aspect provides an electronic device as specified in claims <NUM> to <NUM>.

The present invention in its second aspect provides a method as specified in claim <NUM>.

The present invention in its third aspect provides a computer program as specified in claim <NUM>.

Further aspects of the embodiments will become apparent from the following embodiments.

Exemplary embodiments, features, and aspects of the disclosure will be described below with reference to the drawings. However, aspects of the disclosure are not limited to the following embodiments.

An example of components of an electronic device <NUM> according to the first embodiment will be described first with reference to <FIG> is a block diagram for illustrating components of the electronic device <NUM> according to the first embodiment. The electronic device <NUM> is an electronic device capable of acting as an image capture apparatus or a mobile device.

As shown in <FIG>, the electronic device <NUM> includes a connector <NUM>, a pull-down resistor <NUM>, a communication unit <NUM>, a determination unit <NUM>, a control unit <NUM>, a switch <NUM>, a switch control unit <NUM>, a load unit <NUM>, and a battery (not shown). The battery can be removed from the electronic device <NUM> by the user.

The connector <NUM> is a USB Type-C connector (receptacle) to which a plug <NUM> of a USB Type-C cable <NUM> is connected. In this specification, a connector conforming to USB (Universal Serial Bus) Type-C standard will be referred to as a USB Type-C connector, and a cable conforming to the USB Type-C standard will be referred to as a USB Type-C cable. A power supply apparatus <NUM> is connected to the connector <NUM> via the USB Type-C cable <NUM>. The connector <NUM> receives power supplied from the power supply apparatus <NUM> via the USB Type-C cable <NUM>.

The connector <NUM> includes at least a CC (Configuration Channel) terminal 101a, a VBUS terminal 101b, and a GND terminal 101c. The CC terminal 101a is used to perform predetermined communication (to be referred to as predetermined USB PD communication) conforming to USB PD (Power Delivery) standard with the power supply apparatus <NUM>. The CC terminal 101a is used for determining the power supply capability of the power supply apparatus <NUM> by a method conforming to the USB Type-C standard. The VBUS terminal 101b is used to supply power from the power supply apparatus <NUM> to the electronic device <NUM>. The GND terminal 101c is connected to a ground line. The connector <NUM> has a pin assignment as that shown in <FIG> is a view for illustrating the pin assignment of the connector <NUM>. The connector <NUM> has a point-symmetric pin assignment as shown in <FIG>.

One end of the pull-down resistor <NUM> is connected to the ground line via the switch <NUM>. The voltage of the ground line is, for example, <NUM> V. The other end of the pull-down resistor <NUM> is connected to the CC terminal 101a and communication unit <NUM> via a node <NUM>. The resistance of the pull-down resistor <NUM> is defined by the USB Type-C standard. The pull-down resistor <NUM> is used to change the voltage of the CC terminal 101a.

The communication unit <NUM> is connected to the CC terminal 101a via the node <NUM>. The communication unit <NUM> performs the predetermined USB PD communication with the power supply apparatus <NUM> via the CC terminal 101a and determines whether the communication unit <NUM> can perform the predetermined USB PD communication with the power supply apparatus <NUM>. The control unit <NUM> is notified by the communication unit <NUM> as to whether the communication unit <NUM> is capable of performing the USB PD communication with the power supply apparatus <NUM>.

The determination unit <NUM> is connected to the VBUS terminal 101b. The determination unit <NUM> determines whether a first condition expressed as <MAT> is satisfied, and a second condition expressed as <MAT> is satisfied. If one of the first condition and the second condition is not satisfied, the determination unit <NUM> supplies, to the control unit <NUM>, a signal indicating that the voltage applied from the power supply apparatus <NUM> to the VBUS terminal 101b is excessive. Note that arrangement examples of the determination unit <NUM> will be described later (see <FIG> and <FIG>).

ΔV of inequality (<NUM>) is a voltage variation per unit time of the VBUS terminal 101b. A of inequality (<NUM>) is the maximum allowable value (corresponding to the maximum value of the voltage variation ΔV allowed by the VBUS terminal 101b) of the voltage variation ΔV per unit time. A of inequality (<NUM>) is determined based on, for example, a voltage Vreq of inequality (<NUM>). The first embodiment and the other embodiments will describe a case in which the voltage Vreq is, for example, <NUM> V and A is, for example, <NUM> mV/µs. Note that it is possible to determine A based on the USB PD standard.

V of inequality (<NUM>) is the voltage of the VBUS terminal 101b. The voltage Vreq (corresponding to a predetermined voltage) of inequality (<NUM>) is the voltage that the electronic device <NUM> requests the power supply apparatus <NUM> to apply to the VBUS terminal 101b. B of inequality (<NUM>) is determined based on the voltage Vreq. Vreq × B indicates the maximum allowable voltage (corresponding to the maximum value of voltage allowed to be applied to the VBUS terminal 101b) of the VBUS terminal 101b. The first embodiment and the other embodiments will describe a case in which the voltage Vreq is, for example, <NUM> V and B is, for example, <NUM>. Note that it is possible to determine B based on the USB PD standard.

The control unit <NUM> includes a memory storing programs for controlling the components of the electronic device <NUM> and a processor (e.g., a hardware processor) that controls the components of the electronic device <NUM> by executing the corresponding programs stored in the memory.

The switch <NUM> is a switch for switching whether to connect the pull-down resistor <NUM> to the ground line. When the switch <NUM> is set to an ON state (corresponding to a conductive state), the pull-down resistor <NUM> is connected to the ground line, and the voltage of the CC terminal 101a is pulled down until it is at the level of the pull-down voltage. Note that the pull-down voltage suffices to be a voltage (for example, <NUM> V or lower) conforming to the USB Type-C standard. When the switch <NUM> is set to an OFF state (corresponding to a nonconductive state), the pull-down resistor <NUM> is cut off from the ground line, and the voltage of the CC terminal 101a changes to a voltage (for example, <NUM> V) higher than the pull-down voltage. Note that the first embodiment and the other embodiments will describe an example in which the switch <NUM> is arranged between the pull-down resistor <NUM> and the ground line, but the arrangement of the switch <NUM> is not limited to this. For example, the switch <NUM> may be arranged between the node <NUM> and the pull-down resistor <NUM>.

The switch control unit <NUM> controls the switch <NUM> so that the switch <NUM> will be set to the ON state or the OFF state. The switch control unit <NUM> controls the switch <NUM> based on a control signal supplied from the control unit <NUM>. If the determination unit <NUM> determines that one of the first condition expressed by inequality (<NUM>) and the second condition expressed by inequality (<NUM>) is not satisfied, the control unit <NUM> supplies the control signal to the switch control unit <NUM> to set the switch <NUM> in the OFF state. The switch control unit <NUM> sets the switch <NUM> in the OFF state based on the control signal supplied from the control unit <NUM>. When the switch <NUM> is set to the OFF state, the voltage of the CC terminal 101a changes to a voltage (for example, <NUM> V) higher than the pull-down voltage. When the voltage of the CC terminal 101a changes to a voltage (for example, <NUM> V) higher than the pull-down voltage, the power supply apparatus <NUM> determines that the power supply apparatus <NUM> has been disconnected from the electronic device <NUM>. If it is determined that the power supply apparatus <NUM> has been disconnected from the electronic device <NUM>, the power supply apparatus <NUM> stops applying the voltage to the VBUS terminal 101b. Note that it may be set so that the control unit <NUM> will supply, after a predetermined time has elapsed since the control signal for setting the switch <NUM> to the OFF state has been supplied to the switch control unit <NUM>, the control signal for setting the switch <NUM> to the ON state. The predetermined time suffices to be a time enough for the power supply apparatus <NUM> to determine that the power supply apparatus <NUM> has been disconnected from the electronic device <NUM> based on the voltage change in the CC terminal 101a.

The load unit <NUM> is connected to the VBUS terminal 101b. The load unit <NUM> includes components to provide a user with functions that serve as an image capture apparatus or a mobile device. The load unit <NUM> operates by power supplied from the power supply apparatus <NUM> or the battery. The power supplied from the power supply apparatus <NUM> is supplied to the load unit <NUM> via the VBUS terminal 101b.

The power supply apparatus <NUM> operates as an external power source apparatus that supplies power to the electronic device <NUM> via the USB Type-C cable <NUM>. The power supply apparatus <NUM> operates, for example, as an AC-USB adapter. The power supply apparatus <NUM> includes at least a plug <NUM> which is connected to an AC power source (not shown), a conversion unit (not shown) that converts AC voltage into DC voltage, and a connector (not shown) to which the USB Type-C cable <NUM> is connected. Note that the power supply apparatus <NUM> is not limited to the AC-USB adapter. For example, the power supply apparatus <NUM> may be a personal computer or a portable battery.

<FIG> is a flowchart for illustrating an example of the operation of the electronic device <NUM> according to the first embodiment.

When the plug <NUM> of the USB Type-C cable <NUM> is inserted to the connector <NUM> of the electronic device <NUM>, the process of step S301 is started. In step S301, the control unit <NUM> supplies, to the switch control unit <NUM>, the control signal for setting the switch <NUM> to the ON state. The switch control unit <NUM> sets the switch <NUM> to the ON state based on the control signal supplied from the control unit <NUM>. As a result, the pull-down resistor <NUM> is connected to the ground line, and the voltage of the CC terminal 101a is pulled down to the pull-down voltage.

In step S302, the control unit <NUM> determines whether the power supply apparatus <NUM> conforms to the USB PD standard based on whether the communication unit <NUM> can perform the predetermined USB PD communication with the power supply apparatus <NUM>. If the communication unit <NUM> can perform the predetermined USB PD communication with the power supply apparatus <NUM> (YES in step S302), the control unit <NUM> determines that the power supply apparatus <NUM> conforms to the USB PD standard. If it is determined that the power supply apparatus <NUM> conforms to the USB PD standard, the control unit <NUM> proceeds to step S303. On the other hand, if the communication unit <NUM> cannot perform the predetermined USB PD communication with the power supply apparatus <NUM> (NO in step S302), the control unit <NUM> determines that the power supply apparatus <NUM> does not conform to the USB PD standard. If it is determined that the power supply apparatus <NUM> does not conform to the USB PD standard, the switch <NUM> is maintained in the ON state. In this case, power conforming not to the USB PD standard, but to the USB Type-C standard will be supplied from the power supply apparatus <NUM> to the electronic device <NUM>.

In step S303, the communication unit <NUM> requests the power supply apparatus <NUM> via the CC terminal 101a to increase the voltage applied by the power supply apparatus <NUM> to the VBUS terminal 101b to the voltage Vreq. The first embodiment and the other embodiments will describe an example in which the voltage Vreq is, for example, <NUM> V.

In step S304, the control unit <NUM> requests the determination unit <NUM> to execute a determination operation. The determination unit <NUM> starts the determination operation. As a result, the monitoring of the voltage of the VBUS terminal 101b is started by the determination unit <NUM>.

In step S305, the determination unit <NUM> detects the voltage of the VBUS terminal 101b and determines whether it satisfies the first condition expressed by inequality (<NUM>). For example, the determination unit <NUM> determines, based on the difference between the voltage of the VBUS terminal 101b previously detected by the determination unit <NUM> and the voltage of the VBUS terminal 101b most recently detected by the determination unit <NUM>, whether the voltage variation ΔV per unit time of the VBUS terminal 101b is less than <NUM> mV/µs (less than a first predetermined value). If the voltage variation ΔV per unit time of the VBUS terminal 101b is less than <NUM> mV/µs (YES in step S305), the determination unit <NUM> determines that the first condition is satisfied. In a case in which it is determined that the first condition is satisfied, the control unit <NUM> proceeds to step S306. On the other hand, if the voltage variation ΔV per unit time of the VBUS terminal 101b is equal to or more than <NUM> mV/µs (equal to or more than the first predetermined value) (NO in step S305), the determination unit <NUM> determines that the first condition is not satisfied. In a case in which it is determined that the first condition is not satisfied, the determination unit <NUM> supplies, to the control unit <NUM>, a signal indicating that the voltage applied from the power supply apparatus <NUM> to the VBUS terminal 101b is excessive, and the control unit <NUM> proceeds to step S309.

In step S309, the control unit <NUM> determines that the voltage applied from the power supply apparatus <NUM> to the VBUS terminal 101b is excessive. In addition, the control unit <NUM> controls the determination unit <NUM> to stop the determination operation, and supplies, to the switch control unit <NUM>, the control signal for setting the switch <NUM> to the OFF state. The switch control unit <NUM> sets the switch <NUM> to the OFF state based on the control signal supplied from the control unit <NUM>. The pull-down resistor <NUM> is cut off from the ground line when the switch <NUM> is set to the OFF state, and the voltage of the CC terminal 101a changes to a voltage (for example, <NUM> V) higher than the pull-down voltage. If the voltage of the CC terminal 101a changes to a voltage (for example, <NUM> V) higher than the pull-down voltage, the power supply apparatus <NUM> determines that the power supply apparatus <NUM> has been disconnected from the electronic device <NUM>. If it is determined that the power supply apparatus <NUM> has been disconnected from the electronic device <NUM>, the power supply apparatus <NUM> stops applying the voltage to the VBUS terminal 101b. As a result, the electronic device <NUM> can protect the internal circuitry (the load unit <NUM> or the like) connected to the VBUS terminal 101b of the electronic device <NUM> from an excessive voltage.

In step S306, the determination unit <NUM> detects the voltage of the VBUS terminal 101b and determines whether it satisfies the second condition expressed by inequality (<NUM>). For example, the determination unit <NUM> determines whether the voltage of the VBUS terminal 101b is lower than <NUM> V (corresponding to a second predetermined value). If the voltage of the VBUS terminal 101b is lower than <NUM> V (YES in step S306), the determination unit <NUM> determines that the second condition is satisfied. If it is determined that the second condition is satisfied, the control unit <NUM> proceeds to step S307. On the other hand, if the maximum allowable voltage of the VBUS terminal 101b is equal to or higher than <NUM> V (NO in step S306), the determination unit <NUM> determines that the second condition is not satisfied. If it is determined that the second condition is not satisfied, the determination unit <NUM> supplies, to the control unit <NUM>, a signal indicating that the voltage applied from the power supply apparatus <NUM> to the VBUS terminal 101b is excessive, and the control unit <NUM> proceeds to step S309. Note that the determination unit <NUM> will also determine that the second condition is not satisfied in a case in which the repetition of the processes of steps S305, S306, and S307 has exceeded a predetermined count.

In step S307, the communication unit <NUM> determines whether it has been able to receive a voltage change completion signal from the power supply apparatus <NUM> via the CC terminal 101a. The voltage change completion signal contains information indication the completion of the operation to increase the voltage applied to the VBUS terminal 101b to the voltage Vreq. The control unit <NUM> is notified by the communication unit <NUM> as to whether the communication unit <NUM> has been able to receive the voltage change completion signal from the power supply apparatus <NUM> via the CC terminal 101a. If the communication unit <NUM> has been able to receive the voltage change completion signal from the power supply apparatus <NUM> via the CC terminal 101a (YES in step S307), the control unit <NUM> determines that the operation to increase the voltage applied to the VBUS terminal 101b to the voltage Vreq has been completed, and proceeds to step S308. If the communication unit <NUM> has not been able to receive the voltage change completion signal from the power supply apparatus <NUM> via the CC terminal 101a (NO in step S307), the control unit <NUM> returns to step S305.

In step S308, the control unit <NUM> requests the determination unit <NUM> to stop the determination operation. The determination unit <NUM> accordingly stops the determination operation. Even when the determination unit <NUM> has stopped the determination operation, the switch <NUM> is maintained in the ON state. By maintaining the switch <NUM> in the ON state, the power supply from the power supply apparatus <NUM> to the electronic device <NUM> is maintained even after step S308.

<FIG> and <FIG> are timing charts for illustrating examples of the changes in the states of the CC terminal 101a, the VBUS terminal 101b, and the determination unit <NUM>. First, an example of the changes in the states of the CC terminal 101a, the VBUS terminal 101b, and the determination unit <NUM> in a case in which the first condition expressed by inequality (<NUM>) is not satisfied will be described with reference to <FIG>.

T401 indicates the point at which the plug <NUM> of the USB Type-C cable <NUM> has been inserted to the connector <NUM> of the electronic device <NUM> in a state in which the power supply apparatus <NUM> and the USB Type-C cable <NUM> are connected. At T401, the voltage of the CC terminal 101a is a voltage (for example, <NUM> V) higher than the pull-down voltage. Since the power supply apparatus <NUM> will determine that the power supply apparatus <NUM> is not connected to the electronic device <NUM> when the voltage of the CC terminal 101a is a voltage (for example, <NUM> V) higher than the pull-down voltage, the power supply apparatus <NUM> will not apply the voltage to the VBUS terminal 101b. Hence, at T401, the voltage of the VBUS terminal 101b is, for example, <NUM> V.

When the plug <NUM> of the USB Type-C cable <NUM> is inserted to the connector <NUM> of the electronic device <NUM>, the process of step S301 is started. In step S301, the control unit <NUM> supplies, to the switch control unit <NUM>, the control signal to set the switch <NUM> to the ON state. The switch control unit <NUM> sets the switch <NUM> to the ON state based on the control signal supplied from the control unit <NUM>. As a result, the pull-down resistor <NUM> is connected to the ground line, and the voltage of the CC terminal 101a is pulled down to the pull-down voltage (for example, <NUM> V). When the voltage of the CC terminal 101a has changed to the pull-down voltage, the power supply apparatus <NUM> determines that the power supply apparatus <NUM> has been connected to the electronic device <NUM>, and applies, to the VBUS terminal 101b, a voltage (for example, <NUM> V) higher than the pull-down voltage.

When a voltage (for example, <NUM> V) higher than the pull-down voltage is applied to the VBUS terminal 101b, the communication unit <NUM> performs USB PD communications <NUM>, <NUM>, and <NUM> with the power supply apparatus <NUM> via the CC terminal 101a. The USB PD communications <NUM>, <NUM>, and <NUM> each are communications conforming to the USB PD standard.

In the USB PD communication <NUM>, the power supply apparatus <NUM> transmits a list of usable voltages to the electronic device <NUM>. The communication unit <NUM> receives the list of usable voltages from the power supply apparatus <NUM> via the CC terminal 101a and notifies the control unit <NUM> of the received list. If the control unit <NUM> is notified of the list of usable voltages from the communication unit <NUM> before the elapse of a predetermined time from the start of the USB PD communication <NUM>, the control unit <NUM> will determine that the communication unit <NUM> has been able to perform the USB PD communication with the power supply apparatus <NUM>. In this case, the control unit <NUM> will determine that the power supply apparatus <NUM> conforms to the USB PD standard (YES in step S302). On the other hand, if the control unit <NUM> is not notified of the list of usable voltages from the communication unit <NUM> before the elapse of a predetermined time from the start of the USB PD communication <NUM>, the control unit <NUM> will determine that the communication unit <NUM> has not been able to perform the USB PD communication with the power supply apparatus <NUM>. In this case, the control unit <NUM> will determine that the power supply apparatus <NUM> does not conform to the USB PD standard (NO in step S302).

After it is determined that the power supply apparatus <NUM> conforms to the USB PD standard, the communication unit <NUM> performs the USB PD communication <NUM> with the power supply apparatus <NUM>. In the USB PD communication <NUM>, the communication unit <NUM> requests the power supply apparatus <NUM> via the CC terminal 101a to increase the voltage applied by the power supply apparatus <NUM> to the VBUS terminal 101b to the voltage Vreq (for example, <NUM> V) (step S303).

After requesting the power supply apparatus <NUM> via the CC terminal 101a to increase the voltage applied by the power supply apparatus <NUM> to the VBUS terminal 101b to the voltage Vreq (for example, <NUM> V), the communication unit <NUM> performs the USB PD communication <NUM> with the power supply apparatus <NUM>. In the USB PD communication <NUM>, the power supply apparatus <NUM> transmits, to the electronic device <NUM>, an acceptance signal that includes information indicating that it has accepted the request to increase the voltage applied to the VBUS terminal 101b to the voltage Vreq. The communication unit <NUM> determines whether it has been able to receive the acceptance signal from the power supply apparatus <NUM> via the CC terminal 101a. The control unit <NUM> is notified by the communication unit <NUM> as to whether the communication unit <NUM> has been able to receive the acceptance signal from the power supply apparatus <NUM> via the CC terminal 101a.

After the communication unit <NUM> has received the acceptance signal from the power supply apparatus <NUM> via the CC terminal 101a, the control unit <NUM> requests the determination unit <NUM> to start the determination operation described above (step S304). T402 indicates the point at which the determination operation is started by the determination unit <NUM>.

When the power supply apparatus <NUM> applies the voltage Vreq (for example, <NUM> V) to the VBUS terminal 101b, the voltage of the VBUS terminal 101b gradually increases as shown by reference numeral <NUM>. In a period from T402 until the above-described voltage change completion signal is received, the determination unit <NUM> repetitively determines whether both the first condition expressed by inequality (<NUM>) and the second condition expressed by inequality (<NUM>) are satisfied.

T403 indicates the point at which the voltage variation ΔV per unit time of the VBUS terminal 101b is, for example, equal to or more than <NUM> mV/µs. At T403, the determination unit <NUM> determines that the first condition expressed by inequality (<NUM>) is not satisfied (NO in step S305). When it is determined that the first condition expressed by inequality (<NUM>) is not satisfied, the determination unit <NUM> supplies, to the control unit <NUM>, a signal indicating that the voltage applied from the power supply apparatus <NUM> to the VBUS terminal 101b is excessive. Then, in step S309, the control unit <NUM> controls the determination unit <NUM> to stop the determination operation and supplies a control signal, to the switch control unit <NUM>, to set the switch <NUM> to the OFF state. In addition, in step S309, the switch control unit <NUM> sets the switch <NUM> to the OFF state based on the control signal supplied from the control unit <NUM>. After the switch <NUM> is set to the OFF state, the pull-down resistor <NUM> is cut off from the ground line, and the voltage of the CC terminal 101a increases to a voltage (for example, <NUM> V) higher than the pull-down voltage.

T404 indicates the point at which the voltage of the CC terminal 101a has increased to a voltage (for example, <NUM> V) higher than the pull-down voltage. At T404, the power supply apparatus <NUM> detects that the voltage of the CC terminal 101a has become a voltage (for example, <NUM> V) higher than the pull-down voltage and determines that the power supply apparatus <NUM> has been disconnected from the electronic device <NUM>. When it is determined that the power supply apparatus <NUM> has been disconnected from the electronic device <NUM>, the power supply apparatus <NUM> stops applying the voltage to the VBUS terminal 101b. When applying the voltage from the power supply apparatus <NUM> to the VBUS terminal 101b is stopped, the voltage of the VBUS terminal 101b changes to <NUM> V. As a result, the electronic device <NUM> can protect the internal circuitry (the load unit <NUM> or the like) connected to the VBUS terminal 101b of the electronic device <NUM> from an excessive voltage.

Next, an example of the changes in the states of the CC terminal 101a, the VBUS terminal 101b, and the determination unit <NUM> in a case in which the second condition expressed by inequality (<NUM>) is not satisfied will be described with reference to <FIG>. The processes from T401 to T402 of <FIG> are same as those from T401 to T402 of <FIG>, and thus a description will be omitted.

When the power supply apparatus <NUM> applies the voltage Vreq (for example, <NUM> V) to the VBUS terminal 101b, the voltage of the VBUS terminal 101b gradually increases as shown by a reference numeral <NUM>. In a period from T402 until the above-described voltage change completion signal is received, the determination unit <NUM> repetitively determines whether both the first condition expressed by inequality (<NUM>) and the second condition expressed by inequality (<NUM>) are satisfied.

T405 indicates the point at which the voltage of the VBUS terminal 101b has reached, for example, Vreq × B = <NUM> V. At T405, the determination unit <NUM> determines that the second condition expressed by inequality (<NUM>) is not satisfied (NO in step S306). When it is determined that the second condition is not satisfied, the determination unit <NUM> supplies, to the control unit <NUM>, a signal indicating that the voltage applied from the power supply apparatus <NUM> to the VBUS terminal 101b is excessive. Then, in step S309, the control unit <NUM> controls the determination unit <NUM> to stop the determination operation and supplies a control signal, to the switch control unit <NUM>, to set the switch <NUM> to the OFF state. In addition, in step S309, the switch control unit <NUM> sets the switch <NUM> to the OFF state based on the control signal supplied from the control unit <NUM>. After the switch <NUM> is set to the OFF state, the pull-down resistor <NUM> is cut off from the ground line, and the voltage of the CC terminal 101a increases to a voltage (for example, <NUM> V) higher than the pull-down voltage.

T404 indicates the point at which the voltage of the CC terminal 101a has changed to a voltage (for example, <NUM> V) higher than the pull-down voltage. At T404, the power supply apparatus <NUM> detects that the voltage of the CC terminal 101a has changed to a voltage (for example, <NUM> V) higher than the pull-down voltage, and determines that the power supply apparatus <NUM> has been disconnected from the electronic device <NUM>. When it is determined that the power supply apparatus <NUM> has been disconnected from the electronic device <NUM>, the power supply apparatus <NUM> stops applying the voltage to the VBUS terminal 101b. When applying the voltage from the power supply apparatus <NUM> to the VBUS terminal 101b is stopped, the voltage of the VBUS terminal 101b changes to <NUM> V. As a result, the electronic device <NUM> can protect the internal circuitry (the load unit <NUM> or the like) connected to the VBUS terminal 101b of the electronic device <NUM> from an excessive voltage.

<FIG> is a block diagram for illustrating an example of components of the determination unit <NUM>. As shown in <FIG>, the determination unit <NUM> includes an AD conversion unit <NUM> and a processing unit <NUM>. The operation of the processing unit <NUM> is controlled by the control unit <NUM>, and the operation of the AD conversion unit <NUM> is controlled by the processing unit <NUM>.

The AD conversion unit <NUM> is connected to the VBUS terminal 101b. The AD conversion unit <NUM> converts the voltage of the VBUS terminal 101b into a digital signal. The generated digital signal is supplied from the AD conversion unit <NUM> to the processing unit <NUM>. A known AD conversion unit may be used as the AD conversion unit <NUM>. The AD conversion unit <NUM> may be, for example, a successive approximation AD conversion unit or a sigma-delta AD conversion unit. Note that the voltage of the VBUS terminal 101b may be divided by a voltage dividing resistor before it is applied to the AD conversion unit <NUM>.

The processing unit <NUM> determines, based on the digital signal supplied from the AD conversion unit <NUM>, whether both the first condition expressed by inequality (<NUM>) and the second condition expressed by inequality (<NUM>) are satisfied. The processing unit <NUM> supplies a timing signal to the AD conversion unit <NUM> at an arbitrary timing (e.g., periodic timing). The AD conversion unit <NUM> generates a digital signal indicating the voltage of the VBUS terminal 101b in accordance with the timing signal supplied from the processing unit <NUM>, and supplies the generated signal to the processing unit <NUM>. As a result, a digital signal is periodically supplied from the AD conversion unit <NUM> to the processing unit <NUM>. The processing unit <NUM> includes a memory <NUM>. The memory <NUM> stores a digital signal indicating the voltage of the VBUS terminal 101b most recently supplied from the AD conversion unit <NUM> and a digital signal indicating the voltage of the VBUS terminal 101b previously supplied from the AD conversion unit <NUM>. The processing unit <NUM> determines whether the first condition expressed by inequality (<NUM>) is satisfied based on a difference between the two digital signals stored in the memory <NUM> and A = <NUM> mV/µs. In addition, the processing unit <NUM> determines whether the second condition expressed by inequality (<NUM>) is satisfied based on the most recent voltage V of the VBUS terminal 101b stored in the memory <NUM>, Vreq = <NUM>, and B = <NUM>.

In the above-described step S305, the processing unit <NUM> calculates the voltage variation ΔV per unit time of the VBUS terminal 101b based on the difference between two digital signals stored in the memory <NUM>. The voltage variation ΔV per unit time of the VBUS terminal 101b is calculated based on <MAT> where Vx is the previous voltage of the VBUS terminal 101b stored in the memory <NUM>, Vx+<NUM> is the most recent voltage of the VBUS terminal 101b stored in the memory <NUM>, and t corresponds to a time interval from the point at which the previous voltage of the VBUS terminal 101b has been detected to the point at which the most recent voltage of the VBUS terminal 101b has been detected (alternatively, the time interval at which a digital signal is supplied from the AD conversion unit <NUM> to the processing unit <NUM>).

After the voltage variation ΔV per unit time of the VBUS terminal 101b has been calculated, the processing unit <NUM> determines, based on the calculated voltage variation ΔV, whether the first condition expressed by inequality (<NUM>) is satisfied. For example, the processing unit <NUM> compares the calculated voltage variation ΔV with <NUM> mV/µs. If the calculated voltage variation ΔV is lower than <NUM> mV/µs (YES in step S305), the determination unit <NUM> determines that the first condition is satisfied. If the first condition is satisfied, the control unit <NUM> proceeds to step S306. If the calculated voltage variation ΔV equal to or higher than <NUM> mV/µs (NO in step S305), the determination unit <NUM> determines that the first condition is not satisfied. If the first condition is not satisfied, the determination unit <NUM> supplies, to the control unit <NUM>, a signal indicating that the voltage applied from the power supply apparatus <NUM> to the VBUS terminal 101b is excessive, and the control unit <NUM> proceeds to step S309.

In the above-described step S306, the processing unit <NUM> determines whether the second condition expressed by inequality (<NUM>) is satisfied based on the digital signal indicating the most recent voltage of the VBUS terminal 101b detected by the AD conversion unit <NUM>. For example, the processing unit <NUM> compares the most recent voltage detected by the AD conversion unit <NUM> with Vreq × B = <NUM> V. If the most recent voltage detected by the AD conversion unit <NUM> is lower than <NUM> V (YES in step S306), the determination unit <NUM> will determine that the second condition is satisfied. When the second condition is satisfied, the control unit <NUM> proceeds to step S307. If the most recent voltage detected by the AD conversion unit <NUM> is equal to higher than <NUM> V (NO in step S306), the determination unit <NUM> will determine that the second condition is not satisfied. When the second condition is not satisfied, the determination unit <NUM> supplies, to the control unit <NUM>, the signal indicating that the voltage applied from the power supply apparatus <NUM> to the VBUS terminal 101b is excessive, and the control unit <NUM> proceeds to step S309.

In this manner, in a case in which the determination unit <NUM> determines that one of the first condition and the second condition described above is not satisfied, the signal indicating that the voltage of the VBUS terminal 101b is excessive is supplied from the processing unit <NUM> to the control unit <NUM>. In this case, the control unit <NUM> supplies, to the switch control unit <NUM>, the control signal for setting the switch <NUM> to the OFF state. The switch control unit <NUM> sets the switch <NUM> to the OFF state based on the control signal supplied from the control unit <NUM> (step S309).

<FIG> is a block diagram for illustrating another example of components of the determination unit <NUM>. As shown in <FIG>, the determination unit <NUM> includes a comparator <NUM>, a ramp wave generating circuit <NUM>, and a reference voltage generating circuit <NUM>. The operations of the comparator <NUM>, the ramp wave generating circuit <NUM>, and the reference voltage generating circuit <NUM> are controlled by the control unit <NUM>.

The comparator <NUM> is a three-input comparator that includes a first input terminal Vin+, a second input terminal Vin-<NUM>, and a third input terminal Vin-<NUM>. The first input terminal Vin+ of the comparator <NUM> is connected to the VBUS terminal 101b, and the voltage of the VBUS terminal 101b is applied to the first input terminal Vin+. The second input terminal Vin-<NUM> of the comparator <NUM> is connected to the ramp wave generating circuit <NUM>, and the ramp wave generated by the ramp wave generating circuit <NUM> is input to the second input terminal Vin-<NUM>. The third input terminal Vin-<NUM> of the comparator <NUM> is connected to the reference voltage generating circuit <NUM>, and a reference voltage generated by the reference voltage generating circuit <NUM> is applied to the third input terminal Vin-<NUM>. In a case in which the voltage of the VBUS terminal 101b is lower than the voltage of the ramp wave supplied from the ramp wave generating circuit <NUM> and is lower than the reference voltage supplied from the reference voltage generating circuit <NUM>, the comparator <NUM> outputs a signal OUT at low level. In a case in which the voltage of the VBUS terminal 101b is equal to or higher than the voltage of the ramp wave supplied from the ramp wave generating circuit <NUM> or is equal to or higher than the reference voltage supplied from the reference voltage generating circuit <NUM>, the comparator <NUM> outputs the signal OUT at high level. The signal OUT output from the comparator <NUM> is input to the control unit <NUM>. The signal OUT output from the comparator <NUM> at high level means that one of the first condition expressed by inequality (<NUM>) and the second condition expressed by inequality (<NUM>) is not satisfied. When the signal OUT output from the comparator <NUM> is changed from low level to high level, the control unit <NUM> supplies, to the switch control unit <NUM>, the control signal to set the switch <NUM> to the OFF state. When a first control signal CTL1 supplied from the control unit <NUM> to the comparator <NUM> is at high level, the comparator <NUM> performs a comparison operation. When the first control signal CTL1 supplied from the control unit <NUM> to the comparator <NUM> is at low level, the comparator <NUM> does not perform the comparison operation.

The ramp wave generating circuit <NUM> generates a ramp wave (corresponding to the reference signal) which is a ramp-shaped analog signal. The ramp wave output from the ramp wave generating circuit <NUM> is input to the second input terminal Vin-<NUM> of the comparator <NUM>. In a case in which the voltage Vreq is, for example, <NUM> V, the ramp wave generating circuit <NUM> outputs a ramp wave corresponding to <NUM> mV/µs. When a second control signal CTL2 supplied from the control unit <NUM> to the ramp wave generating circuit <NUM> is at high level, the ramp wave generating circuit <NUM> starts the ramp wave output. When the second control signal CTL2 supplied from the control unit <NUM> to the ramp wave generating circuit <NUM> is at low level, the ramp wave generating circuit <NUM> stops the ramp wave output.

The reference voltage generating circuit <NUM> includes a first resistor <NUM> which is a fixed resistor and a second resistor <NUM> which is a variable resistor, and the reference voltage generating circuit generates a reference voltage corresponding to Vreq × B. One end of the first resistor <NUM> is connected to, for example, the power source (the battery or the like) of the electronic device <NUM>. The other end of the first resistor <NUM> is connected to one end of the second resistor <NUM> and the third input terminal Vin-<NUM> of the comparator <NUM> via a node <NUM>. The other end of the second resistor <NUM> is connected to the ground line. In this manner, the reference voltage generating circuit <NUM> generates the reference voltage by dividing the voltage supplied from the power source of the electronic device <NUM> by the first resistor <NUM> and the second resistor <NUM>. The reference voltage generated by the reference voltage generating circuit <NUM> is applied to the third input terminal Vin-<NUM> of the comparator <NUM>. The reference voltage generated by the reference voltage generating circuit <NUM> is changed when the control unit <NUM> controls the resistance value of the second resistor <NUM>. In a case in which the voltage Vreq is, for example, <NUM> V and B is, for example, <NUM>, the reference voltage is <NUM> V. The control unit <NUM> can control the resistance value of the second resistor <NUM> to change the value of the reference voltage to a value depending on the voltage Vreq.

Note that the voltage of the VBUS terminal 101b may be divided by a voltage dividing resistor before it is applied to the first input terminal Vin+ of the comparator <NUM>. For example, it may be set so that a voltage which is a times (a < <NUM>) the voltage of the VBUS terminal 101b will be applied to the first input terminal Vin+ of the comparator <NUM>. In such a case, the ramp wave generating circuit <NUM> will output a ramp wave corresponding to a × <NUM> mV/µs. Also, in such a case, the reference voltage generating circuit <NUM> will generate a reference voltage of a × Vreq × <NUM> V.

In the above-described step S305, the comparator <NUM> compares the voltage (corresponding to the voltage of the VBUS terminal 101b) of the first input terminal Vin+ and the voltage (corresponding to, for example, <NUM> mV/µs) of the second input terminal Vin-<NUM>. If the voltage of the first input terminal Vin+ is lower than the voltage of the second input terminal Vin-<NUM> (YES in step S305), the determination unit <NUM> will determine that the first condition expressed by inequality (<NUM>) is satisfied. If the first condition is satisfied, the control unit <NUM> proceeds to step S306. If the voltage of the first input terminal Vin+ is equal to or higher than the voltage of the second input terminal Vin-<NUM> (NO in step S305), the determination unit <NUM> will determine that the first condition expressed by inequality (<NUM>) is not satisfied. If the first condition is not satisfied, the determination unit <NUM> supplies, to the control unit <NUM>, a signal indicating that the voltage applied from the power supply apparatus <NUM> to the VBUS terminal 101b is excessive, and the control unit <NUM> proceeds to step S309.

In the above-described step S306, the comparator <NUM> compares the voltage (corresponding to the voltage of the VBUS terminal 101b) of the first input terminal Vin+ and the voltage (corresponding to, for example, <NUM> V) of the third input terminal Vin-<NUM>. If the voltage of the first input terminal Vin+ is lower than the voltage of the third input terminal Vin-<NUM> (YES in step S306), the determination unit <NUM> will determine that the second condition expressed by inequality (<NUM>) is satisfied. If the second condition is satisfied, the control unit <NUM> proceeds to step S307. If the voltage of the first input terminal Vin+ is equal to or higher than the voltage of the third input terminal Vin-<NUM> (NO in step S306), the determination unit <NUM> will determine that the second condition is not satisfied. If the second condition is not satisfied, the determination unit <NUM> supplies, to the control unit <NUM>, a signal indicating that the voltage applied from the power supply apparatus <NUM> to the VBUS terminal 101b is excessive, and the control unit <NUM> proceeds to step S309.

In a case in which it is determined that one of the first condition and the second condition is not satisfied, a signal indicating that the voltage of the VBUS terminal 101b is excessive is supplied from the comparator <NUM> to the control unit <NUM>. In this case, the control unit <NUM> supplies, to the switch control unit <NUM>, the control signal for setting the switch <NUM> to the OFF state. The switch control unit <NUM> sets the switch <NUM> to the OFF state based on the control signal supplied from the control unit <NUM>.

In this manner, according to the first embodiment in case in which one of the first condition expressed by inequality (<NUM>) and the second condition expressed by inequality (<NUM>) is not satisfied, the control unit <NUM> will determine that the voltage applied from the power supply apparatus <NUM> to the VBUS terminal 101b is excessive, and will set the switch <NUM> to the OFF state. Since the voltage of the CC terminal 101a will change to a voltage (for example, <NUM> V) higher than the pull-down voltage when the switch <NUM> is set in the OFF state, the power supply apparatus <NUM> will determine that the power supply apparatus <NUM> has been disconnected from the electronic device <NUM>. As a result, the power supply apparatus <NUM> stops the voltage application to the VBUS terminal 101b. Therefore, according to the first embodiment, the electronic device <NUM> can protect the internal circuitry (the load unit <NUM> or the like) connected to the VBUS terminal 101b of the electronic device <NUM> from an excessive voltage.

Note that the embodiments of the disclosure are not limited to the first embodiment as described above. The embodiments of the disclosure include the first embodiment that has been changed or modified without departing from the scope of the disclosure.

Various kinds of functions, processes, or methods described in the first embodiment can be implemented by a personal computer, a microcomputer, a CPU (Central Processing Unit), a processor, or the like by using corresponding programs. In the second embodiment, a personal computer, a microcomputer, a CPU (Central Processing Unit), a processor, or the like will be referred to as a "computer X" hereinafter. Also, in the second embodiment, a program for controlling the computer X, that is, a program for implementing one of the various kinds of functions, processes, or methods described in the first embodiment will be referred to as a "program Y".

Each of the various kinds of functions, processes, or methods described in the first embodiment is implemented by the computer X executing the program Y. In this case, the program Y is supplied to the computer X via a computer-readable storage medium. The computer-readable storage medium according to the second embodiment includes at least one of a hard disk device, a magnetic storage device, an optical storage device, a magneto-optical storage device, a memory card, a volatile memory, a nonvolatile memory, or the like. The computer-readable storage medium according to the second embodiment is a non-transitory storage medium.

Note that the embodiments of the disclosure are not limited to the second embodiment as described above. The embodiments of the disclosure include the second embodiment that has been changed or modified without departing from the scope of the disclosure.

While aspects of the disclosure are described with reference to exemplary embodiments, it is to be understood that the aspects of the disclosure are not limited to the exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all modifications and equivalent structures.

Claim 1:
An electronic device (<NUM>) comprising:
a monitoring means (<NUM>) configured to monitor a voltage of a first terminal (101b) that receives power supplied from a power supply apparatus (<NUM>);
a second terminal (101a) configured to communicate with the power supply apparatus;
a communication means (<NUM>) configured to perform a communication with the power supply apparatus (<NUM>) via the second terminal (101a),
wherein the power supply apparatus (<NUM>) conforms to a universal serial bus power delivery (USB PD) standard and the communication means performs USB PD communication with the power supply apparatus (<NUM>); and
a control means (<NUM>) configured to request, via the communication means (<NUM>), the power supply apparatus (<NUM>) to apply a predetermined voltage to the first terminal (101b),
wherein the the communication means (<NUM>) is configured to receive first information indicating an acceptance of the request in response to the request and receive second information indicating a completion of the application of the predetermined voltage,
wherein the control means (<NUM>) is configured to perform a detection that a voltage increase per unit time of the first terminal (101b) is not less than a first predetermined value and to perform a detection that the voltage of the first terminal (101b) is not less than a second predetermined value in a period from a reception of the first information from the power supply apparatus (<NUM>) via the communication means (<NUM>) until a reception of the second information from the power supply apparatus (<NUM>) via the communication means (<NUM>),
wherein the control means (<NUM>) is configured to perform control so as to stop the power supply from the power supply apparatus (<NUM>) if it is detected that the voltage increase per unit time of the first terminal (101b) is not less than the first predetermined value and to stop the power supply from the power supply apparatus (<NUM>) if it is detected that the voltage of the first terminal (101b) is not less than the second predetermined value.