USB port controller, electronic device

Abstract

To provide a system capable of starting power feeding in a short time after a source and a sink are connected.SOLUTION: A USB port controller 500 supports the USB (Universal Serial Bus) Type-C and is mounted on electronic equipment 400 operating as a sink. A capacitor C21 is connected with a power supply terminal VBUS. A discharge switch SW22 and a discharge resistor R21 are connected in series between the power supply terminal VBUS and the ground line. When a voltage VBUS is not supplied to the power supply terminal VBUS from a source, a discharge controller 520 turns on the discharge switch SW22.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a controller for USB Type-C.

Background Art

[0002] Battery-powered devices such as smartphones, tablet terminals, notebook computers, portable audio players, and digital cameras incorporate a rechargeable secondary battery and a charging circuit for charging the battery. Some charging circuits charge the secondary battery based on a DC voltage (bus voltage V BUS ) supplied from the outside via a USB cable or a DC voltage from an external AC adapter.

[0003] As a power supply system using USB, a standard called USB Power Delivery (hereinafter referred to as the USB-PD standard) has been established. In the USB-PD standard, the available power has increased significantly from 7.5W of the BC standard to a maximum of 100W. Specifically, in the USB-PD standard, as the USB bus voltage, supply of a voltage higher than 5V (specifically, 9V, 12V, 15V, 20V, etc.) is allowed, and the charging current is also allowed to be supplied in an amount larger than that of the BC standard (specifically, 2A, 3A, 5A, etc.). The USB-PD standard is also adopted in the USB Type-C standard.

[0004] FIG. 1 is a block diagram of a power supply system 100R. This power supply system 100R complies with the USB Type-C standard and includes a power supply device (also referred to as a source or host) 200 and a power receiving device (also referred to as a sink or device) 300 connected via a USB cable 106.

[0005] The power supply device 200 is mounted on the electronic device 102. The electronic device 102 may be an AC adapter. The power receiving device 300 is mounted on a battery-powered electronic device 400 such as a smartphone, a tablet terminal, a digital camera, a digital video camera, or a portable audio player.

[0006] The power supply device 200R includes a power supply circuit 202, a power supply side PD controller (hereinafter referred to as the power supply side controller) 204, and a bus switch SW1. A USB cable 106 is detachably connected to the receptacle 108 of the electronic device 400. There is also a charging adapter in which the receptacle 108 is omitted and the USB cable 106 is integrated with the electronic device 102.

[0007] The receptacle 108 includes a VBUS terminal for supplying the bus voltage V BUS a GND terminal for supplying the ground voltage V GND and a CC (Configuration Channel) port. Actually, two CC ports are provided, but in FIG. 1, they are simplified and shown as one. The power supply circuit 202 generates the bus voltage V BUS The power supply circuit 202 may include an AC / DC converter that receives AC100V from an external power supply (for example, a commercial AC power supply) not shown and converts it into a DC bus voltage V BUS The bus voltage V BUS generated by the power supply circuit 202 is supplied to the power receiving device 300R via the bus line of the USB cable 106 and the bus switch SW1.

[0008] The power supply side controller 204 and the power receiving side controller 310 are each port controllers related to USB Type-C, are connected to each other via the CC line, and provide a communication function. The power supply side controller 204 and the power receiving side controller 310 negotiate the voltage level of the bus voltage V BUS to be supplied by the power supply device 200R. The power supply side controller 204 controls the power supply circuit 202 so as to obtain the determined voltage level, and also controls the on / off of the bus switch SW1.

[0009] The electronic device 400 includes a battery 402, a receptacle 404, a load (system) circuit 406, and a power receiving device 300R. The battery 402 is a rechargeable secondary battery. The load circuit 406 includes a CPU, a memory, a liquid crystal display, an audio circuit, and the like. An electronic device 102 is detachably connected to the receptacle 404 via a USB cable 106.

[0010] The power receiving device 300R receives power from the electronic device 102 and charges the charging circuit 302. The power receiving device 300R includes a charging circuit 302, a power receiving side controller 310, and a bus switch SW2.

[0011] The charging circuit 302 receives a bus voltage V BUS (on the power receiving device 300R side, denoted as the bus voltage V BUS_SNK ) from the power supply device 200R via the USB cable 106 and the bus switch SW2, and charges the battery 402. The charging circuit 302 is composed of a step-down DC / DC converter, a linear regulator, or a combination thereof.

[0012] From the charging circuit 302 to the load circuit 406, a system voltage V BUS_SNK corresponding to at least one of the bus voltage V BAT and the voltage V SYS of the battery 402 is supplied. The load circuit 406 includes a multi-channel power supply including a power management IC (Integrated Circuit), a DC / DC converter, a linear regulator, etc., and a microcomputer, a liquid crystal display, a display driver, etc.

[0013] Data (PDO: Power Data Object) that defines the bus voltage V BUS required by the power receiving device 300R and the maximum current is defined in the power receiving side controller 310. When the electronic device 102 and the electronic device 400 are connected, the power supply side controller 204 and the power receiving side controller 310 perform negotiation, and based on the PDO, the bus voltage V BUSThe voltage level is determined. Also, the power receiving controller 310 controls the on / off state of the bus switch SW2.

[0014] FIG. 2 is an operation sequence diagram of the power supply system 100 in FIG. 1. When the power supply device 200R and the power receiving device 300R are connected via the USB cable 106, the power supply side controller 204 detects the connection based on the state of the CC port (S100). Specifically, the power receiving side controller 310 of the power receiving device 300R waits in a state where the CC port is pulled down by a pull-down resistor (termination resistor) Rd having a predetermined resistance value. When the power supply device 200R and the power receiving device 300R are connected, a voltage corresponding to the pull-down resistor Rd on the power receiving device 300R side and its own state is generated at the CC port of the power supply device 200R. With this, the power supply side controller 204 of the power supply device 200R can detect the connection of the power receiving device 300R (electronic device 400).

[0015] The power supply device 200R that has detected the connection of the power receiving device 300R turns on the bus switch SW1 (S102) on the condition that the voltage of its own VBUS terminal is lower than the voltage level called vSafe0V, and supplies the default 5V bus voltage V BUS When the bus switch SW1 is turned on, the power receiving side controller 310 becomes operable. vSafe0V is defined between 0.0 and 0.8V in the standard.

[0016] Subsequently, the power supply side controller 204 and the power receiving side controller 310 perform negotiation to determine the bus voltage V BUS (S104). The power supply side controller 204 changes the bus voltage V BUS from the initial voltage of 5V to the required voltage (S106).

[0017] The bus voltage V BUSWhen the change to the required voltage is completed, the power supply side controller 204 notifies the power receiving side controller 310 of this (S108). In response to this notification, the power receiving side controller 310 turns on the bus switch SW2 (S110). As a result, the bus voltage V is supplied to the charging circuit 302 and the load circuit 406 (S112). BUS is supplied.

Prior Art Documents

Patent Documents

[0018]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0019] The inventor has studied the reconnection of the source and sink of USB Type-C and has come to recognize the following problems.

[0020] FIG. 3 is a diagram for explaining the reconnection of the source and sink. V BUS_SRC is the voltage of the VBUS terminal on the source side, and V BUS_SNK is the voltage of the VBUS terminal on the sink side.

[0021] Before time t 0 the sink (power receiving device) 300R and the source (power supply device) 200R are connected by a USB cable, and a 5V bus voltage V BUS is supplied from the source 200R to the sink 300R.

[0022] At time t 0 when the USB cable is unplugged, the output switch SW1 of the source 200R turns off, a discharge path (not shown) conducts, and the capacitor C1 is discharged. As a result, the voltage V BUS_SRC decreases toward 0V. On the other hand, in the sink 300R, the switch SW2 turns off.

[0023] As shown in FIG. 1, a capacitor C2 is connected to the VBUS pin of the sink 300R. After the switch SW2 is turned off, the discharge path of the capacitor C2 is lost, so the voltage V of the VBUS terminal of the sink 300R BUS_SNK decreases very slowly.

[0024] At time t 1 the source 200R and the sink 300R are reconnected via a USB cable. The power supply side controller 204 detects that the sink 300R is connected based on the state of the CC port.

[0025] The charge of the capacitor C2 of the sink 300R is supplied to the VBUS pin of the source 200R, and the voltage V BUS_SRC rises. As a result, the voltage V BUS_SRC exceeds the threshold voltage vSafe0V.

[0026] After that, the voltages V BUS_SRC and V BUS_SNK decrease. When the voltage V 2 falls below the threshold vSafe0V at time t BUS_SRC , the power supply side controller 204 turns on the bus switch SW1. Thereby, the 5V voltage generated by the power supply circuit 202 is supplied to the sink 300R.

[0027] That is, in the power supply system 100R of FIG. 1, at time t 1 , a delay occurs between the time when the source 200R and the sink 300R are connected and the time t 2 when power supply starts. This delay becomes longer depending on the capacitance of the capacitor C2.

[0028] The present disclosure has been made in view of such problems, and an exemplary object of one of its aspects is to provide a system capable of starting power supply in a short time after connecting a source and a sink.

Means for Solving the Problems

[0029] One aspect of the present disclosure relates to a sink-side USB port controller compatible with USB (Universal Serial Bus) Type-C. The sink on which the USB port controller is mounted includes a power terminal, a capacitor connected to the power terminal, and a discharge resistor and a discharge switch connected in series between the power terminal and the ground line. The USB port controller includes a discharge control unit that turns on the discharge switch when no voltage is supplied from the source to the power terminal.

[0030] Another aspect of the present disclosure is an electronic device. This electronic device includes a USB (Universal Serial Bus) receptacle including a power terminal and a ground terminal, an internal circuit, a capacitor connected between the power terminal and the ground line, an input switch connected between the power terminal and the internal circuit, a discharge resistor and a discharge switch connected in series between the power terminal and the ground line, and a discharge control unit that turns on the discharge switch when no voltage is supplied from the source to the power terminal.

Advantages of the Invention

[0031] According to one aspect of the present disclosure, power supply can be started in a short time after connecting the source and the sink.

Brief Description of the Drawings

[0032]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

DETAILED DESCRIPTION OF THE INVENTION

[0033] (Overview of Embodiment) The overview of some exemplary embodiments of the present disclosure will be described. This overview is provided as a prelude to the detailed description to follow, and for the purpose of providing a basic understanding of the embodiments, simplifies and describes some concepts of one or more embodiments, and does not limit the scope of the invention or the disclosure. This overview is not an all-inclusive overview of all possible embodiments, nor is it intended to identify the important elements of all embodiments or to delineate the scope of some or all aspects. For convenience, "one embodiment" may be used to refer to one embodiment (example or modification) or a plurality of embodiments (examples or modifications) disclosed in this specification.

[0034] The USB port controller according to one embodiment is compatible with USB (Universal Serial Bus) Type-C. The sink on which the USB port controller is mounted includes a power terminal, a capacitor connected to the power terminal, and a discharge resistor and a discharge switch connected in series between the power terminal and the ground line. The USB port controller includes a discharge control unit that turns on the discharge switch when no voltage is supplied from the source to the power terminal.

[0035] When the source is not connected, the discharge switch provided in the sink is turned on, discharging the charge of the capacitor and reducing the voltage of the power supply terminal. Therefore, when the source is connected next, the residual charge of the capacitor is zero or very small, suppressing the rise in the voltage of the power supply terminal of the source. As a result, at the time of reconnection, the voltage of the power supply terminal of the source becomes lower than the threshold voltage, so that the bus switch (output switch) of the source immediately turns on, and power supply can be started in a short time.

[0036] In one embodiment, the discharge switch may be built into the USB port controller.

[0037] In one embodiment, the discharge resistor may be built into the USB port controller.

[0038] In one embodiment, the discharge switch may be a depletion-type transistor. When a voltage is supplied from the source to the power supply terminal, the discharge control unit may apply an off-level drive voltage to the control terminal of the discharge switch.

[0039] In one embodiment, the USB port controller may be integrally integrated on a single semiconductor substrate. "Integral integration" includes cases where all components of the circuit are formed on the semiconductor substrate and cases where the main components of the circuit are integrally integrated. Some resistors, capacitors, etc. may be provided outside the semiconductor substrate for adjusting circuit constants. By integrating the circuit on one chip, the circuit area can be reduced and the characteristics of the circuit elements can be kept uniform.

[0040] An electronic device according to an embodiment includes a USB (Universal Serial Bus) receptacle including a power supply terminal and a ground terminal, an internal circuit, a capacitor connected between the power supply terminal and the ground line, an input switch connected between the power supply terminal and the internal circuit, a discharge resistor and a discharge switch connected in series between the power supply terminal and the ground line, and a discharge control unit that turns on the discharge switch when no voltage is supplied from a source to the power supply terminal.

[0041] In one embodiment, the discharge switch is a depression-type transistor, and the discharge control unit may apply an off-level drive voltage to the control terminal of the discharge switch when a voltage is supplied from a source to the power supply terminal.

[0042] (Embodiment) Hereinafter, preferred embodiments will be described with reference to the drawings. The same or equivalent components, members, and processes shown in each drawing are denoted by the same reference numerals, and redundant descriptions will be omitted as appropriate. Also, the embodiments are illustrative and not restrictive of the disclosure and the invention, and not all features or combinations thereof described in the embodiments are necessarily essential to the disclosure and the invention.

[0043] In this specification, the state where "member A is connected to member B" means that in addition to the case where member A and member B are physically directly connected, member A and member B are indirectly connected via other members that do not substantially affect their electrical connection state or impair the functions and effects achieved by their combination.

[0044] Similarly, the state where "member C is connected (provided) between member A and member B" means that in addition to the case where member A and member C, or member B and member C are directly connected, they are indirectly connected via other members that do not substantially affect their electrical connection state or impair the functions and effects achieved by their combination.

[0045] FIG. 4 is a block diagram of a power supply system 100 according to an embodiment. The power supply system 100 complies with the USB Type-C standard and includes a power supply device (also referred to as a source) 200 and a power receiving device (also referred to as a sink) 300. The power supply device 200 and the power receiving device 300 are connected via a USB cable 106.

[0046] For example, the power supply device 200 is mounted on the electronic device 102. The electronic device 102 may be an AC adapter. The power receiving device 300 is mounted on a battery-powered electronic device 400 such as a smartphone, a tablet terminal, a digital camera, a digital video camera, or a portable audio player.

[0047] First, the configuration on the source side, that is, the electronic device 102 side, will be described.

[0048] The electronic device 102 includes a power supply device 200 and a receptacle 108. The power supply device 200 includes a power supply circuit 202, a power supply side PD controller (hereinafter referred to as a power supply side controller) 204, a bus switch SW1, and capacitors C11 and C12. The USB cable 106 is detachably connected to the receptacle 108 of the electronic device 400. There is also a charging adapter in which the receptacle 108 is omitted and the USB cable 106 is integrated with the electronic device 102.

[0049] The receptacle 108 includes a VBUS terminal for supplying a bus voltage V BUS a GND terminal for supplying a ground voltage V GND (0V), and a CC (Configuration Channel) port.

[0050] The power supply circuit 202 generates a bus voltage V BUS The power supply circuit 202 may include an AC / DC converter that receives AC 100V from an external power supply (for example, a commercial AC power supply) not shown and converts it into a DC bus voltage V BUS The bus voltage V BUSIt is supplied to the power receiving device 300 via the bus line and the bus switch SW1 of the USB cable 106.

[0051] The power supply side controller 204 is a port controller related to USB Type-C and USB-PD. The power supply side controller 204 and the USB port controller 500 are connected via the CC line. The power supply side controller 204 can detect the connection of the power receiving device 300 based on the state of the CC pin on the USB port controller 500 side. Also, the power supply side controller 204 and the USB port controller 500 can communicate via the CC line, and the power supply side controller 204 and the USB port controller 500 negotiate the voltage level of the bus voltage V BUS to be supplied by the power supply device 200. The power supply side controller 204 controls the power supply circuit 202 so as to obtain the determined voltage level, and also controls the on and off of the bus switch SW1.

[0052] In the USB Type-C standard, after detecting the connection of the power receiving device 300, the power supply side controller 204 turns on the bus switch SW1 on the condition that the bus voltage V BUS_SRC of the VBUS terminal is lower than a predetermined threshold value vSafe0V.

[0053] Subsequently, the configuration of the sink side, that is, the electronic device 400, will be described.

[0054] The electronic device 400 includes a battery 402, a receptacle 404, a load (system) circuit 406, and a power receiving device 300. The battery 402 is a rechargeable secondary battery. The load circuit 406 includes a CPU, a memory, a liquid crystal display, an audio circuit, and the like. The electronic device 102 is detachably connected to the receptacle 404 via the USB cable 106.

[0055] The power receiving device 300 receives power from the electronic device 102 and charges the charging circuit 302. The power receiving device 300 includes a charging circuit 302, a USB port controller 500, a bus switch SW21, capacitors C21 and C22, a discharge resistor R21, and a discharge switch SW22.

[0056] The charging circuit 302 receives the bus voltage V from the power supply device 200 via the USB cable 106 and the bus switch SW21 BUS and charges the battery 402. On the power receiving device 300 side, the bus voltage V BUS is also referred to as the input voltage and is denoted as V BUS_SNK . The charging circuit 302 is composed of a step - down DC / DC converter, a linear regulator, or a combination thereof.

[0057] From the charging circuit 302 to the load circuit 406, a system voltage V BUS_SNK corresponding to at least one of the bus voltage V BAT and the voltage V of the battery 402 SYS is supplied. The load circuit 406 includes a multi - channel power supply including a power management IC (Integrated Circuit), a DC / DC converter, a linear regulator, etc., a microcontroller, a liquid crystal display, a display driver, etc.

[0058] Capacitors C21 and C22 are connected to both ends of the bus switch SW21. Also, a discharge resistor R21 and a discharge switch SW22 are connected in parallel with the capacitor C21 between the VBUS terminal of the receptacle 404 and the ground line.

[0059] The USB port controller 500 includes a CC pin circuit 510, a discharge control unit 520, and a processor 530. The CC pin circuit 510 includes a pull - down resistor that pulls down the CC pin. When the power receiving device 300 is a dual power role (DPR) where the sink and source can be switched, the CC pin circuit 510 is configured to be switchable between a state of pulling down the CC pin (i.e., sink) and a state of pulling up (i.e., source).

[0060] As described above, the USB port controller 500 negotiates with the USB port controller 600 via the CC line. The transceiver for communication via the CC line is included in the CC pin circuit 510.

[0061] The USB port controller 500 has data (PDO: Power Data Object) that defines the bus voltage V BUS and the maximum current required by the power receiving device 300. When the electronic device 102 and the electronic device 400 are connected, the power supply side controller 204 and the USB port controller 500 negotiate, and the voltage level of the bus voltage V BUS is determined based on the PDO. Also, the USB port controller 500 controls the on / off of the bus switch SW2. The processor 530 executes a software program and executes negotiation with the power supply side controller 204. The processor 530 may be a microcontroller independent of the USB port controller 500.

[0062] The discharge control unit 520 monitors the voltage V BUS_SNK of the VBUS terminal of the receptacle 404. The discharge control unit 520 is configured to turn on the discharge switch SW22 when the bus voltage V BUS is not supplied from the electronic device 102 to the VBUS terminal. When the discharge control unit 520 detects that the bus voltage V BUS is supplied from the electronic device 102 to the VBUS terminal, it turns off the discharge switch SW22.

[0063] The above is the configuration of the power supply system 100. Next, its operation will be described.

[0064] FIG. 5 is a diagram for explaining the operation when the power supply device 200 and the power receiving device 300 in the power supply system 100 of FIG. 4 are reconnected.

[0065] Time t 0Previously, the power receiving device 300 and the power supply device 200 were connected by a USB cable 106, and a 5V bus voltage V BUS was supplied from the power supply device 200 to the power receiving device 300.

[0066] In this state, since the VBUS terminal of the receptacle 404 is supplied with the 5V bus voltage V BUS , the discharge control unit 520 turns off the discharge switch SW22.

[0067] At time t 0 , when the USB cable is unplugged, the bus switch SW1 of the power supply device 200 turns off, a discharge path (not shown) conducts, the capacitor C12 is discharged, and the voltage V BUS_SRC decreases toward 0V. The USB port controller 500 turns off the bus switch SW21.

[0068] When the USB cable is unplugged, the voltage V BUS_SNK on the power receiving device 300 side decreases. When the discharge control unit 520 detects the decrease in the voltage V 1 at time t BUS_SNK , it determines that the power supply of the bus voltage V BUS has stopped, and turns on the discharge switch SW22. As a result, the capacitor C21 is discharged, and the voltage V BUS_SNK rapidly decreases to 0V.

[0069] At time t 2 , the power supply device 200 and the power receiving device 300 are reconnected by the USB cable 106. The power supply side controller 204 of the power supply device 200 detects that the power receiving device 300 is connected based on the state of the CC port.

[0070] At time t 2 , since the charge of the capacitor C21 of the power receiving device 300 is zero, even if the power supply device 200 and the power receiving device 300 are connected, the voltage V BUS_SRC does not rise, and the voltage V BUS_SRC maintains a state lower than the threshold voltage vSafe0V.

[0071] At time t3 When the power supply side controller 204 detects that the voltage V BUS_SRC is lower than the threshold value vSafe0V, it turns on the bus switch SW1. As a result, the voltage V BUS_SRC and V BUS_SNK increases.

[0072] In the power receiving device 300, when the discharge control unit 520 detects that the bus voltage V BUS_SNK has been supplied, it turns off the discharge switch SW22. As a result, the discharge path including the discharge resistor R21 and the discharge switch SW22 is cut off.

[0073] The above is the operation of the power supply system 100.

[0074] According to this power supply system 100, when the power supply device 200 is not connected, the charge of the capacitor C21 is discharged by turning on the discharge switch SW22 provided in the power receiving device 300, and the voltage V BUS_SNK of the VBUS terminal decreases. Therefore, when the power supply device 200 is connected next time, the residual charge of the capacitor C21 is zero or very small, and the rise of the voltage V BUS_SRC of the VBUS terminal of the power supply device 200 can be suppressed. As a result, when reconnecting, since the voltage V BUS_SRC is lower than the threshold voltage vSafe0V, the bus switch SW1 of the power supply device 200 immediately turns on, and power supply can be started in a short time.

[0075] When the bus voltage V BUS is being supplied from the power supply device 200 to the power receiving device 300, since the discharge switch SW22 is off, it is possible to prevent wasteful power consumption in the discharge path.

[0076] Figure 6 is a circuit diagram showing a configuration example of the discharge switch SW22 and the discharge control unit 520. The discharge control unit 520 supplies the power supply voltage V BUSIt is necessary to turn on in a state where it is not supplied. The discharge switch SW22 includes a transistor M21. The transistor M21 is a depletion-type N-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor).

[0077] The discharge control unit 520 includes a driver 522. The driver 522 is inoperable when the power supply voltage V BUS is not supplied and outputs 0V. The depletion MOSFET is a normally-on type device and becomes on state by a gate voltage of 0V.

[0078] The driver 522 becomes operable when the power supply voltage V BUS is supplied. The driver 522 can switch and output a negative drive voltage V NEG in an operable state. The driver 522 may include a negative charge pump. By applying a negative voltage V NEG to the gate of the discharge switch SW22 of the depletion MOSFET, the discharge switch SW22 can be turned off.

[0079] The driver 522 may be configured to always output a negative voltage V BUS in an operable state where the power supply voltage V NEG is supplied. Alternatively, the driver 522 may be configured to be controllable in output between 0V and the negative voltage V NEG in an operable state. Also, the positions of the discharge switch SW22 and the discharge resistor R21 may be interchanged.

[0080] FIG. 7 is a circuit diagram showing a modified example of the discharge switch SW22 and the discharge control unit 520. In this modified example, the transistor M21, which is the discharge switch SW22, is integrated into the USB port controller 500. The USB port controller 500 includes a discharge pin DISCHG, and the transistor M21 is connected between the discharge pin DISCHG and the ground line. The discharge resistor R21 is connected between the discharge pin DISCHG of the USB port controller 500 and the VBUS terminal. According to this modified example, the number of external components can be reduced.

[0081] FIG. 8 is a circuit diagram showing a modified example of the discharge switch SW22 and the discharge control unit 520. In this modified example, in addition to the transistor M21, the discharge resistor R21 is integrated into the USB port controller 500. The USB port controller 500 includes a discharge pin DISCHG, and the transistor M21 and the discharge resistor R21 are connected between the discharge pin DISCHG and the ground line. The transistor M21 and the discharge resistor R21 may be interchanged. The discharge pin DISCHG of the USB port controller 500 is directly connected to the VBUS terminal. According to this modified example, the number of external components can be further reduced.

[0082] FIG. 9 is a circuit diagram showing another configuration example of the discharge switch SW22 and the discharge control unit 520. The discharge switch SW22 includes a transistor M22. The transistor M22 is a depletion-type P-channel MOSFET.

[0083] The discharge control unit 520 includes a pull-up resistor R22 connected between the gate and source of the transistor M22, and a driver 524 that controls the gate of the transistor M22. The output of the driver 524 becomes high impedance in an inoperative state where the power supply voltage V BUS is not supplied. At this time, since the gate-source of the transistor M22 is shorted by the pull-up resistor R22, the gate-source voltage becomes 0V, and the discharge switch SW22 turns on.

[0084] Driver 524 outputs a voltage higher than the power supply voltage V BUS when in an operable state where the power supply voltage V BUS is supplied. As a result, transistor M22 turns off.

[0085] In the case of FIG. 9, at least one of transistor M22, discharge resistor R21, and pull-up resistor R22 may be integrated into USB port controller 500.

[0086] It is understood by those skilled in the art that the embodiments are examples and that there are various variations in each component and combination of each processing process, and that such variations are also included in the scope of the present disclosure or the present invention.

Explanation of Reference Numerals

[0087] 100 Power supply system 102 Electronic device 106 USB cable 108 Receptacle 200 Power supply device 202 Power supply circuit 204 Power supply side controller SW1 Bus switch 400 Electronic device 402 Battery 404 Receptacle 406 Load circuit 300 Power receiving device 302 Charging circuit 310 Power receiving side controller SW21 Bus switch SW22 Discharge switch R21 Discharge resistor R22 Pull-up resistor C21,C22 Capacitor 500 USB port controller 510 CC pin circuit 520 Discharge control unit 522,524 Driver M21,M22,M23 Transistor 530 Processor

Claims

1. A sink - side USB port controller compatible with USB (Universal Serial Bus) Type - C, wherein the sink on which the USB port controller is mounted, has a power terminal, a capacitor connected to the power terminal, a discharge resistor and a discharge switch connected in series between the power terminal and the ground line, and is provided with, the USB port controller, is provided with a discharge control unit that turns on the discharge switch when no voltage is supplied from the source to the power terminal. A USB port controller.

2. The USB port controller according to claim 1, wherein the discharge switch is built in the USB port controller.

3. The USB port controller according to claim 1 or 2, wherein the discharge resistor is built in the USB port controller.

4. The discharge switch is a depletion - type transistor, and the discharge control unit applies a drive voltage of an off - level to the control terminal of the discharge switch when a voltage is supplied from the source to the power terminal. The USB port controller according to any one of claims 1 to 3.

5. The USB port controller according to any one of claims 1 to 4, which is integrally integrated on a single semiconductor substrate.

6. An electronic device comprising the USB port controller according to any one of claims 1 to 5.

7. A USB (Universal Serial Bus) receptacle including a power terminal and a ground terminal, an internal circuit, a capacitor connected between the power terminal and the ground line, an input switch connected between the power terminal and the internal circuit, a discharge resistor and a discharge switch connected in series between the power terminal and the ground line, and a discharge control unit that turns on the discharge switch when no voltage is supplied from the source to the power terminal. An electronic device comprising.

8. The discharge switch is a depletion - type transistor, and the discharge control unit applies a drive voltage of an off - level to the control terminal of the discharge switch when a voltage is supplied from the source to the power terminal. The electronic device according to claim 7.

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