Automatic role reversal prevention for dual-role ports

Abstract

Aspects of the present disclosure provide a circuit (102). In at least some examples, the circuit includes a dual-role port (124) for transferring power to and from the circuit. The circuit also includes a microprocessing unit (114). The microprocessing unit is configured to control the circuit to operate as a sink device to receive power from a source device via the dual-role port when the power supply includes a first amount of stored energy, detect a change in a termination resistance of the source device at the dual-role port, and control the circuit to limit power transfer from the circuit to the power supply via the dual-role port when the power supply changes state from a source state to a sink state.

Description

Technical Field

[0001] Universal Serial Bus (USB) communication occurs between a host having a downstream facing port (DFP) and a device having an upstream facing port (UFP). The DFP and UFP are sometimes implemented by a single port called a dual role port (DRP) that can be controlled to operate as either the DFP or the UFP. In some USB technologies such as USB Type-C (USB-C), a single DRP port can be both a source and a sink of power. The DRP port can also dynamically or automatically change roles between the DFP and UFP and / or between a source of power and a sink of power, automatically based on one or more monitored conditions. This dynamic or automatic change can sometimes be a drawback.

Summary of the Invention

[0002] Various aspects of the present disclosure provide a circuit. In at least some examples, the circuit includes a dual role port for transferring power to and from the circuit. The circuit also includes a microprocessing unit. The microprocessing unit is configured to detect a change in the termination resistance of a source device at the dual role port such that when the power supply includes a first amount of stored energy, the circuit is controlled to operate as a sink device for receiving power from the source device via the dual role port, and to control the circuit to limit power transfer from the circuit to the power supply via the dual role port when the power supply changes the situation from a sourcing state to a sinking state.

[0003] Other aspects of the disclosure provide a system. In at least one example, the system includes a power bank configured to act as a source device. The power bank includes a battery, dual-role bus voltage terminals for transferring power to and from the battery, and a microprocessing unit. The microprocessing unit is configured to control the battery to source power to a sink device via the dual-role bus voltage terminals when the battery includes a first amount of stored energy, and to inhibit power transfer from the sink device to the battery via the dual-role port when the battery includes less energy than the first amount of stored energy.

[0004] Other aspects of the disclosure provide a computer program product including a computer-readable storage medium including program instructions. In at least one example, the program instructions are executable by a microprocessing unit to cause a device communicatively coupled to the microprocessing unit to receive power from a source device via a dual-role port capable of non-parallel operation as both an input terminal and an output terminal, where the source device terminates a communication channel coupling the source device and the dual-role port to a pull-up signal on the source side of the communication channel while the source device is outputting power. Executing the program instructions further causes the microprocessing unit to detect removal of the pull-up signal on the source side of the communication channel and, when removal of the pull-up signal is detected, to start a timer. Executing the program instructions further causes the microprocessing unit to detect that a pull-down signal terminates communication on the source side of the communication channel and, when detection that the pull-down signal terminates communication on the source side of the communication channel occurs before the timer expires, to inhibit power transfer to the source device via the dual-role port.

[0005] Next, for a detailed description of various examples, reference is made to the accompanying drawings.

Brief Description of the Drawings

[0006]

Figure 1

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Figure 2

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Figure 3

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Figure 4A

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Figure 4B

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DETAILED DESCRIPTION OF THE INVENTION

[0013] In the present disclosure, a source device refers to a device having a finite power source (e.g., a power bank including a rechargeable battery, a portable computing device having a rechargeable battery, etc.) that discharges to charge another device. Further in the present disclosure, a sink device refers to a device coupled to the source device to receive power from the source device for operation and / or charging of the sink device. The source device and the sink device each have the ability to reverse roles (e.g., the source acting as a sink and vice versa). When a source device such as a rechargeable battery pack (e.g., a power bank) is electrically coupled to a sink device such as a mobile phone, a tablet device, a wearable device, a portable computer, etc., it is often intended to charge the sink device using the power stored in the source device. Energy waste can occur in the form of transmission losses and can be counterproductive to the desired result of charging when the source device and the sink device reverse roles during charging.

[0014] When the source device and the sink device are each Universal Serial Bus (USB) Type-C (USB-C) devices that utilize a dual-role port (DRP), the port can dynamically reverse its role based on the charging states of the source device and the sink device. For example, when the source device is coupled to the sink device and has accumulated more charge than the sink device, power is transferred from the source device to the sink device. During this time, the source device is in the sourcing state or operating mode. When the power accumulated by the source device is consumed, in at least some instances, the source device presents itself as a sink device (e.g., to an initial sink device, etc.). During this time, the source device is in the sinking state or operating mode at that point. Due to the dynamic role-reversal capability of the DRP, if the sink device enters the sourcing state or operating mode, the sink device can initiate recharging of the source device's battery. In at least some situations, this role reversal is undesirable because energy is lost due to heat and other transfer-related losses, and the amount of power available for further charging may decrease. In certain situations, this role reversal is even more undesirable because the sink device that the user is attempting to charge by coupling the source device to it may be charged and then discharged again, leaving little or no additional time for the user to use the sink device. For example, when the user couples an external rechargeable battery to a laptop computer via the DRP, the laptop computer's internal rechargeable battery can be charged based on the energy received from the external rechargeable battery. When little or no energy remains in the external rechargeable battery, charging stops. However, next, the laptop computer then treats the discharged external rechargeable battery as a device for charging, similar to when a discharged mobile phone is coupled to the laptop computer. Thus, the laptop computer can automatically initiate the transfer of energy from its internal rechargeable battery to the external rechargeable battery.In cases where there is no user present to observe this automatic role change, such as when charging is being performed unattended, the internal rechargeable battery and the external rechargeable battery can continue to transfer energy back and forth. In at least some examples, this role reversal can continue and be repeated until all available energy is consumed due to losses and until there is no energy remaining for charging or operating the laptop computer. Therefore, in at least some situations, it is desirable to prevent the automatic role reversal of DRP in the source and / or sink device.

[0015] At least some aspects of the present disclosure provide a mechanism for the automatic role reversal of DRP. Further, at least some aspects of the present invention suppress the power transfer from the sink device to the source device from which the sink device received power in other ways. Some implementations are at least partially mechanically implemented, such as via switches, buttons, or plugging and replugging of connections. For example, when the switch is in the first position, DRP is controlled to source power but not sink power. When the switch is in the second position, DRP is controlled to sink power but not source power. The switch is actuated by the user based on the desired DRP operation of the user at a given time. Therefore, the mechanical implementations of the present disclosure require some form of user input. Alternatively, role reversal is prevented until the connection between the two devices is disconnected and later reconnected. Other implementations can be at least partially implemented via software. For example, the software implementation is timer-based. In other examples, the software implementation is based on one or more alerts or messages that can warn of an impending role reversal of DRP and provide an input for the user to permit or deny the role reversal of DRP. In at least some examples, the software implementation further utilizes user input, such as preventing role reversal until the user provides a user input that commands operation in the sourcing mode.

[0016] Next, referring to FIG. 1, a block diagram of an exemplary USB system 100 is shown. In one example, the USB system includes a source device 102, a USB cable 104, and a sink device 106. In at least one example, the source device 102 is a device that provides signals to the sink device 106 via the USB cable 104, and the sink device 106 is configured to pull current from the source device 102 via the USB cable 104. In some examples, at least a portion of the current received from the source device 102 by the sink device 106 is stored in a battery (not shown) by the sink device 106, and the battery is charged. In some implementations, the source device 102 includes a power supply 108, a USB Power Delivery (PD) controller 110, and a voltage control circuit 112. The power supply 108 is, for example, a power supply capable of providing an output signal with an adjustable voltage level that is adjusted based on a control signal received by the power supply 108. In at least some examples, the power supply 108 is or includes a rechargeable battery.

[0017] Power supply 108 receives a control signal from voltage control circuit 112. In some examples, power supply 108 receives the control signal from voltage control circuit 112 via optical communication (e.g., an optocoupler). In other examples, power supply 108 receives the control signal from voltage control circuit 112 via a physical coupling between power supply 108 and voltage control circuit 112. In yet other examples, power supply 108 itself is not adjustable, but an external component coupled to or configured to couple to the output of power supply 108 adjusts the value of the signal output by power supply 108. For example, the output of power supply 108 can be a signal having a substantially constant voltage value, and this voltage value is manipulated to output one or more other signals having voltage values different from the output of power supply 108. For example, the output of power supply 108 can be manipulated by a power converter (not shown), such as a buck converter, a boost converter, or a buck-boost converter, and the output of the power converter can be provided to node 118. In at least some examples, the power converter is controlled by voltage control circuit 112 to manipulate the output of power supply 108 to form one or more other signals. In at least one example, USB PD controller 110 is a microcontroller having processing capabilities. In other examples, USB PD controller 110 is any processing element capable of receiving one or more inputs and generating one or more outputs based on rules, analysis, or other processing applied to at least some of the inputs.

[0018] The voltage control circuit 112 is any circuit capable of adjusting and / or controlling the value of the signal present at node 118. For example, the voltage control circuit 112 is any circuit capable of receiving a reference voltage (VREF) from the USB PD controller 110 and controlling the power supply 108 according to VREF to control the value of the bus voltage (VBUS) signal present at node 118. For example, the voltage control circuit 112 controls the power supply 108 according to VREF so that the signal present at node 118 has a relationship with the value of VREF that is approximately equal to, proportional to, or otherwise related, where the scope is not limited in this specification.

[0019] In at least some examples, the USB PD controller 110 includes and / or implements at least a portion of the microprocessing unit 114. In various examples, the microprocessing unit 114 is a processor, a microprocessor, a field programmable gate array (FPGA), a component suitable for implementing or capable of implementing a state machine, or any other suitable component or device having processing capabilities. For example, when the USB PD controller 110 is a microcontroller, at least a portion of the microprocessing unit 114 is implemented as specific programming within the USB PD controller 110 to perform at least some of the operations disclosed herein. For example, the microprocessing unit 114 executes or implements software or other code to prevent automatic role reversal of the DRP port of the source device 102. The DRP port is, in at least one example, the VBUS terminal 122. For example, the VBUS terminal 122 can be a DRP port capable of providing power to the sink device 106 via the USB cable 104 or receiving power from the sink device 106 via the USB cable 104. In some examples, the source device 102 further includes a transistor 116 operable as a switch to control the output of the VBUS signal via the VBUS terminal 122 and a receptacle 124 configured to receive a plug to provide a communicable coupling with the source device 102. The transistor 116 can be any suitable technology including at least a p-type field effect transistor (FET) or an n-type FET.

[0020] In at least one exemplary architecture, the output of the power supply 108 is coupled to node 118, and the input of the voltage control circuit 112 is coupled to node 118. The first terminal of the microprocessing unit 114 is coupled to or configured to couple to node 118, and the first terminal (drain terminal) of the transistor 116 is coupled to node 118. The first input of the voltage control circuit 112 is coupled to the VREF output of the USB PD controller 110, and the first output of the voltage control circuit 112 is coupled to the cathode (CATH) input of the USB PD controller 110. The first terminal of the USB PD controller 110 is coupled to the gate terminal of the transistor 116, the second terminal of the USB PD controller 110 is coupled to node 120, the second terminal (e.g., source terminal) of the transistor 116 is coupled to node 120, and the VBUS terminal 122 is coupled to node 120. The second terminal of the microprocessing unit 114 is configured to couple to the configuration channel (CC) 1 terminal 132, and the third terminal of the microprocessing unit 114 is configured to couple to the CC2 terminal 134. In various examples, CC1 and CC2 are each configurable to couple to the connection voltage (VCONN) terminal 138 of the USB cable 104 or the CC terminal 136 of the USB cable 104, depending on the orientation in which the plug 126 is inserted into the receptacle 124. In some examples, the VBUS terminal 122, the CC1 terminal 132, and the CC2 terminal 134 are housed within the receptacle 124, are part of the receptacle 124, or otherwise interact with the receptacle 124 to communicatively couple the source device 102 to the USB cable 104.

[0021] In at least one example, the USB cable 104 includes a plug 126 configured to interact with a receptacle 124 to communicatively couple the USB cable 104 to the source device 102. The plug 126 houses, includes, or otherwise interacts with VBUS terminals 140, CC terminals 136, and VCONN terminals 138, each configured to communicatively couple the USB cable 104 to the source device 102.

[0022] The sink device 106 is any device suitable for coupling to the USB cable 104 to receive power from and / or communicate data with the source device 102, and the scope, hardware architecture, or operating mode of the sink device 106 is not limited herein. In at least some examples, the sink device 106 also implements a USB controller substantially similar to the USB PD controller 110 and / or includes functionality substantially similar to the microprocessing unit 114.

[0023] In one example of the operation of the system 100, when the sink device 106 is connected to the source device 102 via the USB cable 104, after the source device 102 (e.g., the USB PD controller 110) determines, the USB PD controller 110 controls the power supply 108 to output a signal having a voltage level specified by a control signal received by the power supply 108. The USB PD controller 110 controls the power supply 108 to output a signal, for example, by controlling a voltage control circuit 112.

[0024] In at least some examples, the USB PD controller 110 applies pull-up signals to both the CC1 terminal 132 and the CC2 terminal 134 and monitors the values of the signals present at each of the CC1 terminal 132 and the CC2 terminal 134. In some examples, the pull-up signals are applied by coupling the CC1 terminal 132 and the CC2 terminal 134 to a voltage supply 150 via a pull-up termination register (Rp) 142. In at least some examples, the voltage supply 150 outputs a signal having a voltage value different from that of the power supply 108. For example, in at least some implementations, the voltage supply 150 outputs a signal having a voltage of about 5V, about 3.3V, or another suitable voltage. The voltage of the signal output by the voltage supply 150 is, in some examples, based on the signal output by the power supply 108 (e.g., the output of a regulator or converter that receives the output of the power supply 108 as an input to generate the voltage provided by the voltage supply 150). In some examples, each of the pull-up signals has substantially the same voltage level. In other examples, each of the pull-up signals has a different voltage level. For example, the USB PD controller 110 compares the value of the signal present at each of the CC1 terminal 132 and the CC2 terminal 134 with a threshold to determine whether it is less than the value of the pull-up signal (or a corresponding amount of the values of the pull-up signals). In various implementations, the source device 102 monitors the CC1 terminal 132 and / or the CC2 terminal 134 for the presence of an open state, an Rd-attached state, or an Ra-attached state. The open state exists for a CCx terminal (e.g., either the CC1 terminal 132 or the CC2 terminal 134) when the value of the signal present at that CCx terminal exceeds a first threshold (in one example, 1.6V). The Rd-attached state exists for a CCx terminal when the signal present at that CCx terminal is below the first threshold and above a second threshold (in one example, 0.25V). The Rp-attached state exists for a CCx terminal when the signal present at that CCx terminal is below the second threshold.In at least some examples, a CCx or CCy terminal (e.g., either CC1 terminal 132 or CC2 terminal 134, which is not the CCx terminal) determined to be in an Rd attached state is terminated by a sink device 106 comprising a pull - down termination resistor (Rd) coupled to a ground node 152.

[0025] In some examples, the USB PD controller 110 ignores the presence of the USB cable 104 when the sink device 106 is not coupled to the USB cable 104 (and thereby the source device 102). For example, when the CCx terminal is in an Ra attached state and the CCy terminal is in an open state, the USB PD controller 110 ignores the presence of the USB cable 104 and does not communicate with the USB cable 104. In other examples, the USB PD controller 110 communicates with the USB cable 104 (such as when the USB cable 104 includes an electronic marker) when the CCx terminal is in an Ra attached state and the CCy terminal is in an open state.

[0026] In at least some examples, when the USB PD controller 110 detects the presence of the sink device 106, the USB PD controller 110 applies a signal to the VBUS terminal 122, for example, by controlling the power supply 108 to output VBUS. In some examples, the USB PD controller 110 detects the presence of the sink device 106 in one of two ways. First, when the CCx terminal is in the Rd-attached state and the CCy terminal is in the open state or the Ra-attached state, the USB PD controller 110 determines that the sink device 106 is coupled to the source device 102. Second, when the CCx terminal is in the open state or the Ra-attached state and the CCy terminal is in the Rd-attached state, the USB PD controller 110 also determines that the sink device 106 is coupled to the source device 102. The USB PD controller 110 determines that the CCx terminal or the CCy terminal is in the Rd-attached state based on, in at least some examples, the USB PD controller 110 terminating the CCx or CCy terminal with Rp142. The USB PD controller 110 terminates the CCx or CCy terminal with Rp142 by controlling the switches 144 and 146 to couple the CCx and CCy terminals to Rp142. In at least some examples, the switches 144 and 146 are each controlled by the microprocessing unit 114.

[0027] Similarly, when the source device 102 is coupled to the sink device 106 (e.g., via the USB cable 104 using the plug 126 and the receptacle 124), the sink device 106 loads or pulls down either the CC1 terminal 132 or the CC2 terminal 134 coupled to the CC terminal 136 (e.g., via approximately a 5.1 kiloohm resistor or the like). By pulling down one of the CC1 terminal 132 or the CC2 terminal 134, the value of the signal present on one of the CC1 terminal 132 or the CC2 terminal 134 coupled to the CC terminal 136 is decreased, putting one of the CC1 terminal 132 or the CC2 terminal 134 in the Rd-attached state.

[0028] The microprocessing unit 114 controls the provision of VBUS to the VBUS terminal 122 in at least some examples. For example, the microprocessing unit 114 controls the transistor 116 to couple the node 118 to the VBUS terminal 122. When the power supply 108 is discharged, the microprocessing unit 114 toggles the switch 144 and the switch 146 to couple the CCx or CCy terminal to the pull-down termination register (Rd) 148. When the sink device 106 performs a toggle from Rd to Rp and the CCx or CCy terminal of the source device 102 is considered to be terminated at Rd148, the sink device 106 transitions to become the new source device and the source device 102 transitions to become the new sink device. However, in at least some examples, the microprocessing unit 114 provides a signal indicating that the source device 102 and the sink device 106 should not reverse roles to the sink device 106 (e.g., as part or a component of a PD message or an alert message). When the sink device 106 receives a signal indicating that it should not reverse roles with the source device 102, in at least some examples, the sink device 106 implements a timer when the sink device 106 detects the disconnection of Rp at the source device 102. Thereafter, if the sink device 106 detects Rd at the source device 102 before the expiration of the timer, the sink device 106 does not reverse roles and becomes the new source device. However, if the sink device 106 detects Rd at the source device 102 after the expiration of the timer, the sink device 106 reverses roles, becomes the new source device, and provides power to the source device 102 acting as the new sink device.

[0029] In other examples, when the microprocessing unit 114 determines that the power level of the power supply 108 is at or below a pre-defined threshold, the microprocessing unit 114 communicates an alert or other message to the sink device 106. The pre-defined threshold can be a percentage of the maximum charge of the power supply 108, such as about 10% of the maximum charge remaining, 5% of the maximum charge remaining, or any other pre-defined threshold. The alert can be, for example, a notification of a charge drop in the power supply 108. In at least some examples, the alert further includes one or more interactive elements that can provide feedback to the user. For example, the interactive elements include an option to allow a role reversal between the source device 102 and the sink device 106, or an option to prevent a role reversal between the source device 102 and the sink device 106. In at least some examples, if the user does not respond to the alert within a pre-defined time period, the user's inactivity is assumed to be a negative response, and a role reversal between the source device 102 and the sink device 106 will be prevented.

[0030] In still other examples, the source device 102 includes a hardware switch 154. The hardware switch 154 disconnects Rd in at least some examples so that when the power supply 108 is exhausted, the CCx or CCy terminals are not terminated by either Rp142 or Rd148. In such examples, the user actuates the hardware switch 154 to prevent the source device 102 from terminating the CCx or CCy terminals with Rd. This prevention of termination, in at least some examples, prevents the sink device 106 from detecting the termination of Rd148 by the source device 102 and from reversing its role to source power from the sink device 106 to the source device 102. In at least some examples, based on the state of the hardware switch 154 (e.g., actuated or not actuated), the microprocessing unit 114 controls the switch 156 to separate Rd148 from switches 144 and 146.

[0031] In yet other examples, when sink device 106 detects the removal of the termination of Rp142 by source device 102, sink device 106 starts a timer. In some examples, the timer starts at a non-zero value and counts down towards zero, expiring when the count reaches zero. In other examples, the timer starts at zero and counts up, expiring when the count reaches a pre-defined non-zero value. When sink device 106 starts the timer, the sink device disables the dual-role function of sink device 106. If sink device 106 detects the termination of Rd148 by source device 102 before the expiration of the timer, sink device 106 maintains the disabled state of the dual-role function. For example, the dual-role function is maintained in the disabled state until a user input that commands sink device 106 to operate as a source device is received, or until the termination of Rd148 by source device 102 no longer exists. If sink device 106 detects the termination of Rd148 by source device 102 after the expiration of the timer, sink device 106 re-enables the dual-role function and starts operating in the sourcing mode to source power to source device 102 that is currently operating in the sinking mode.

[0032] In the above, the prevention of power transfer between sink device 106 and source device 102 has been discussed, but in at least some other examples, the power transfer is suppressed. In some examples, when the power transfer is suppressed, the power transfer is completely prevented. In other examples, when the power transfer is suppressed, the power transfer is permitted, but the rate is reduced. For example, when the power transfer is suppressed, the power transfer rate is lower than when the power transfer is not suppressed.

[0033] The CC1 terminal 132 is configured to be coupled to the CC terminal 136, and the CC2 terminal 134 is configured to be coupled to the VCONN terminal 138, as considered and shown in FIG. 1 herein, although in some instances such couplings are reversed. For example, at least some of the USB cables 104 are reversible, and depending on the orientation in which the plug 126 is inserted into the receptacle 124, the CC1 terminal 132 is configured to be coupled to one of the CC terminal 136 or the VCONN terminal 138, and the CC2 terminal 134 is configured to be coupled to the other of the CC terminal 136 or the VCONN terminal 138. Thus, although a coupling associated with one orientation of insertion of the plug 126 into the receptacle 124 is described herein, any orientation of insertion of the plug 126 into the receptacle 124 is contemplated and within the scope of the present disclosure. Thus, in at least some instances, the USB PD controller 110 is further configured to detect and / or determine which of the CC1 terminal 132 or the CC2 terminal 134 is coupled to the VCONN terminal 138 (or, the CC terminal 136) in order to determine which of the CC1 terminal 132 or the CC2 terminal 134 to couple to the node 118.

[0034] Turning now to FIG. 2, a flowchart of an exemplary method 200 for controlling power transfer is shown. In at least some instances, method 200 is implemented by a microprocessing unit, such as microprocessing unit 114, within a second device operating as a sink device that initially receives power from a first device operating as a source device, but that may later change roles and operate as a source device. In at least some particular instances, method 200 is implemented by a microprocessing unit, such as microprocessing unit 114, implemented within a sink device, such as sink device 106, each of which was considered above with respect to FIG. 1.

[0035] In operation 202, the second device determines that Rp is no longer detected. For example, the second device determines that Rp is no longer detected when the first device stops causing Rp to be present on the CC line that couples the first and second devices. In some examples, it is determined that Rp no longer exists by comparing the value of the voltage present on the CC line to a threshold value. For example, when Rp is present, the voltage present on the CC line exceeds the threshold value. When Rp is not present, the voltage present on the CC line is less than the threshold value. In at least some examples, the fact that Rp is no longer detected indicates that power is no longer being conveyed from the first device to the second device.

[0036] In operation 204, the second device detects the presence of Rd on the CC line that couples the first and second devices. In some examples, it is determined that Rd is present by comparing the value of the voltage present on the CC line to a threshold value. For example, when Rd is present, the voltage present on the CC line can be between a pair of threshold values. When Rd is not present, the voltage present on the CC line can be outside a pair of threshold values. When Rd is not detected, the method remains at operation 206. In at least some implementations, the presence of Rd on the CC line indicates that the first device is operating as a sink device. When the second device detects Rd on the CC line, in at least some examples, the second device starts sourcing power back to the first device. However, as previously described herein, such actions can result in undesirable operation of the first and second devices. Accordingly, before the second device sources power to the first device, the second device proceeds to operation 206.

[0037] In operation 206, the second device determines whether Rd is detected within a predetermined time period during which Rp is no longer detected. For example, when Rd is detected within a predetermined time period during which Rp is no longer detected, this may indicate that the first device has been discharged but remains coupled to the second device. In such an example, when the first and second devices are coupled via the DRP, an undesirable reverse transfer of charge from the second device to the first device can occur. For example, when the power supply of the first device discharges, in some examples, the terminals of the first device are terminated by Rd. This termination occurs within about 10 milliseconds (ms) in at least some examples. In other examples, the termination occurs between about 10 ms and about 100 ms. When the first device is separated from the second device and then re-coupled to the second device, the terminals of the first device are still terminated by Rd. However, the physical actions of separating and re-coupling the first and second devices can potentially exceed the amount of time spent terminating the terminals of the first device when the power supply of the first device discharges. For example, the physical actions of separating and re-coupling the first and second devices can take about 100 ms or more. In this way, the second device can distinguish between a first device whose power supply has discharged but which remains coupled to the second device and a device that is coupled to the second device with the intention of the second device sourcing power to a newly coupled device.

[0038] When Rd is detected within a predetermined time period, method 200 proceeds to operation 208. In at least some examples, determining whether Rd is detected within a predetermined time period includes starting or otherwise initiating a counter or timer when Rp is no longer detected in operation 202. When Rd is detected in operation 204, the value of the counter or timer is compared to a timer threshold to determine whether the timer value exceeds the timer threshold. In at least some examples, the timer threshold is configurable. For example, the timer threshold is configured to expire after about 10 ms, about 50 ms, about 100 ms, about 200 ms, or any other suitable amount of time.

[0039] In operation 308, the second device disables the DRP function of the second device. In at least some examples, disabling the DRP function prevents the second device from presenting Rp on the CC line and starting to operate as a source device to recharge the first device when the first device has Rd present on the CC line. Alternatively, in at least some examples, instead of disabling the DRP function in operation 208, the second device limits the power transfer tolerance such that power transfer is suppressed but not completely prevented.

[0040] In operation 210, the second device determines whether the user desires for the second device to operate as a source device. In at least some examples, the second device makes the determination based on input received from the user. In some examples, the input is received via a physical articulable input source such as, for example, a switch, a toggle, a button. In other examples, the input is received via a soft input source such as, for example, a software button, a graphical user interface button, a software setting toggle. In still other examples, the input is received by unplugging and plugging of the user between the first device and the second device. When the user does not desire for the second device to operate as a source device, method 200 remains at operation 210. When the user desires for the second device to operate as a source device, method 200 proceeds to operation 212.

[0041] In operation 212, the second device enables the DRP function of the second device. In at least some examples, enabling the DRP function allows the second device to present Rp on the CC line and begin operating as a source device to recharge the first device when the first device (or another device coupled to the second device) presents Rd on the CC line. After enabling the DRP function, method 200 proceeds to operation 214. Alternatively, when the second device does not disable the DRP function in operation 208 and instead suppresses power transfer, in operation 212, the second device removes the restrictions on the power transfer tolerance imposed in operation 208.

[0042] Returning now to operation 206, when Rd is not detected within a predetermined time period, it may indicate that the first device has been discharged and separated from the second device, but that the first device, or another device operating as a sink device, is coupled to the second device. In such examples, method 200 proceeds to operation 214.

[0043] In operation 214, the second device starts a power source to a device (which may be the first device) having Rd coupled to the second device. In at least some examples, the second device sources power via DRP that has previously received power from the first device before Rp is no longer detected in operation 202.

[0044] Turning now to FIG. 3, a table 300 of exemplary pseudo - code for implementing power transfer is shown. In at least some examples, the execution of the pseudo - code shown in table 300 implements at least some of the operations of method 200. The pseudo - code of table 300 is implemented, in at least some examples, by a microprocessing unit such as microprocessing unit 114 of FIG. 1 when the microprocessing unit is implemented within a sink device, as described elsewhere in this specification.

[0045] Table 300 shows the arithmetic routines of RpConnectionDetected, RpDisconnectDetected, and DisconnectHandler. In at least some examples, the routines shown in Table 300 are part of another software program or process such that the routines in Table 300 are subroutines of a software program or process that is called by a software program or process. For example, when a software program or process receives an input signal indicating that Rp has been detected, the software program or process calls the RpConnectionDetected routine to set the variable RpLossSignal to false. Similarly, when a software program or process receives an input signal indicating that Rp is no longer detected, the software program or process calls the RpDisconnectDetected routine to set the variable RpLossSignal to true. Additionally, as shown in Table 300, the RpDisconnectDetected routine calls the DisconnectHandler routine as a result of failure to detect Rp. In other examples, after setting RpLossSignal to true, the RpDisconnectDetected routine returns to the software program or process that called the RpDisconnectDetected routine, and then that software program or process calls the DisconnectHandler routine.

[0046] As shown in the DisconnectHandler routine, after the disconnection of Rp is detected, the DRP function is disabled by calling the routine DisableDRPConfiguration. After disabling the DRP function, the variable DisconnectTimeOut is initialized to zero and incremented by one unit per millisecond until 200 ms elapses or the user provides an input to override the timer delay, as long as RpLossSignal remains true. For example, when the user indicates that the device implementing the pseudo-code of Table 300 should operate as the source device (such that the variable OperateAsSourceDevice has a value of true set by another routine or subroutine), the DisconnectHandler stops incrementing the counter and enables the DRP function. Additionally, in some examples, when 200 ms has elapsed since the initialization of DisconnectTimeOut, the DisconnectHandler stops incrementing the counter and enables the DRP function. In at least some examples, the DRP function is enabled by calling the routine EnableDRPConfiguration.

[0047] Table 300 shows pseudo-code that includes certain variables, operations, functions, and process flows, but there are various other programming implementations of method 200. The pseudo-code of Table 300 is not intended to exclude these other programming implementations from the scope of the present disclosure. Rather, the pseudo-code of Table 300 simply shows one exemplary implementation while holding other programming implementations of method 200 within the scope of the present disclosure.

[0048] Next, turning to FIGS. 4A and 4B, a flowchart of an exemplary method for controlling power transfer is shown. In at least some examples, the method is implemented by a pair of devices coupled to each other via a DRP, one of which operates as a source device and one of which operates as a sink device. For example, the method is at least partially implemented by a microprocessing unit, such as microprocessing unit 114, in a first device operating as a source device that initially operates as a sink device but later changes roles to operate as a source device and provides power to a second device. The method is further at least partially implemented by another microprocessing unit, such as microprocessing unit 114, in the second device. In at least some particular examples, the method is partially implemented by a microprocessing unit, such as microprocessing unit 114, in a source device, such as source device 102 described above with respect to FIG. 1, and a sink device, such as sink device 106 also described above with respect to FIG. 1.

[0049] For example, this method includes a first portion 405 and a second portion 410. The first portion 405 is implemented in a first device that initially operates as a source device in at least some examples. The second portion 410 is implemented in a second device that initially operates as a sink device in at least some examples. In operation 415, the first device determines whether the remaining charge of the power supply of the first device is less than about 5% of the maximum capacity. When the remaining charge is not less than 5% of the maximum capacity, the first portion 405 remains at operation 415. When the remaining charge is less than 5% of the maximum capacity, the first portion proceeds to operation 420. In other examples, an alert message is sent based on another threshold of the remaining charge, such as about 10%, about 20%, about 2%, or any other suitable remaining charge amount. In at least some examples, the alert message is sent based on the discharge rate of the power supply of the first device such that the alert message is sent when a specific amount of charging time remains at a specific current draw (e.g., the alert message is sent about 5 minutes before charging ends). In at least some examples, the alert message is a PD message or is sent as a component of a PD message.

[0050] In operation 420, the first device transmits an alert message. In at least some examples, the alert message includes the status of the first device and indicates the remaining charge of the power supply of the first device. For example, in some implementations, the power supply of the first device is a battery and the status of the first device indicates the remaining charge in the battery. The alert message is transmitted to the second device in at least some examples when the second device is coupled to the first device and receives power from the first device.

[0051] In operation 425, the second device receives an alert message. In at least some examples, the alert message is received from the first device. For example, in at least some implementations, the alert message received in operation 425 is the alert message transmitted by the first device in operation 420. In other examples, the alert message received by the second device in operation 425 is received from any suitable source not limited in scope herein, such that the second part 410 of this method is separable and independent from the first part 405 of this method. In at least some examples, the alert message indicates the status of a device operating as a source device to provide power to the second device. For example, the status includes the remaining charge of the power supply of a source device such as a battery.

[0052] In operation 430, the second device disables the DRP function of the second device. In at least some examples, disabling the DRP function prevents the second device from presenting Rp on the CC line that couples the second device to the first device and starting to operate as a source device to recharge the first device when the first device has Rd present on the CC line. Alternatively, in at least some examples, instead of disabling the DRP function in operation 430, the second device limits the tolerance of power transfer such that power transfer is suppressed but not completely prevented.

[0053] In operation 435, the second device determines whether the user desires for the second device to operate as a source device. The second device makes the determination based on input received from the user in at least some instances. In some instances, the input is received via a physical articulable input source such as a switch, toggle, button, etc. In other instances, the input is received via a soft input source such as a software button, a graphical user interface button, a software setting toggle, etc. When the user does not desire for the second device to operate as a source device, the first part 410 of this method remains at operation 435. When the user desires for the second device to operate as a source device, the second part 410 of this method proceeds to operation 440.

[0054] In operation 440, the second device enables the DRP function of the second device. In at least some instances, enabling the DRP function allows the second device to present Rp on the CC line and begin operating as a source device to recharge the first device when the first device (or another device coupled to the second device) presents Rd on the CC line. Alternatively, when the second device did not disable the DRP function in operation 430 and instead suppressed power transfer, in operation 440, the second device removes the restrictions on the power transfer tolerance imposed in operation 430.

[0055] Next, turning to FIG. 5, a table 505 and a table 510 of exemplary pseudocode for implementing power transfer are shown. In at least some examples, the execution of the pseudocode shown in table 505 implements at least some of the operations of the method of FIGS. 4A and 4B, such as the operations included in the first portion 405 of the method of FIGS. 4A and 4B. Similarly, in at least some examples, the execution of the pseudocode shown in table 510 implements at least some of the operations of the method of FIGS. 4A and 4B, such as the operations included in the second portion 410 of the method of FIGS. 4A and 4B. In at least some examples, the pseudocode of table 505 is implemented by a microprocessing unit, such as microprocessing unit 114 of FIG. 1, when the microprocessing unit is implemented within a source device, as described in other portions of this specification. In at least some examples, the pseudocode of table 510 is implemented by a microprocessing unit, such as microprocessing unit 114 of FIG. 1, when the microprocessing unit is implemented within a sink device, as described in other portions of this specification.

[0056] As shown by the pseudocode of table 505, the first device continuously monitors the charge to determine whether the charge level is lower than an alarm threshold. In at least some examples, the charge level is that of a power supply, such as a battery of the first device, and the alarm threshold is a percentage of the maximum charge remaining, the amount of remaining time until the charge is complete, or any other suitable threshold. When the charge level is lower than the alarm threshold, an alarm message is sent.

[0057] As shown by the pseudocode of Table 510, when the second device has not received an alarm message, the second device calls the Delay subroutine that implements a delay for a predetermined time period before returning to re-determine whether an alarm message has been received. When the second device receives an alarm message, the second device disables the DRP function by calling the routine DisableDRPConfiguration. After disabling the DRP function, the second device monitors for user input and delays until input is received. In some examples, the user input takes the form of user unplugging and replugging the connection between the first device and the second device. For example, when the user indicates that the second device should operate as a source device (such that the variable OperateAsSourceDevice has a true value set by another routine or subroutine), the second device enables the DRP function. In at least some examples, the DRP function is enabled by calling the routine EnableDRPConfiguration.

[0058] Tables 505 and 510 show pseudocode that includes certain variables, operations, functions, and process flows, but there are various other programming implementations for FIGS. 4A and 4B. The pseudocode of Tables 505 and 510 is not meant to exclude these other programming implementations from the scope of the present disclosure. Rather, the pseudocode of Tables 505 and 510 simply shows one exemplary implementation while holding other programming implementations of the methods of FIGS. 4A and 4B within the scope of the present disclosure.

[0059] Turning now to FIG. 6, a flowchart of an exemplary method 600 for power transfer is shown. In at least some examples, method 600 is implemented by a microprocessing unit, such as microprocessing unit 114, in either a source device, such as source device 102, or a sink device, such as sink device 106.

[0060] In operation 602, power is transferred from the source device and the sink device. The power is transferred, for example, from the source device to the sink device. While the power is being transferred from the source device to the sink device, the source device is in a sourcing state or operating mode and terminates the connection to the pull-up termination between the source device and the sink device. Similarly, while the power is being transferred from the source device to the sink device, the sink device is in a sinking state or operating mode and terminates the connection to the pull-down termination between the source device and the sink device.

[0061] In operation 604, power transfer from the sink device to the source device is suppressed. By suppressing the power transfer, in some examples, power transfer is prevented until a user input that commands power transfer is received. In other examples, suppressing the power transfer allows the occurrence of power transfer but reduces the transfer rate (e.g., when compared to the transfer rate when not suppressed).

[0062] There are a number of suitable processes for suppressing power transfer. In at least one example, in one implementation, the source device sends a warning message to the sink device indicating the charge remaining within the power supply of the source device. Based at least in part on this warning message, the sink device suppresses the reverse transfer of power from the sink device to the source device. The power transfer is suppressed, at least in some examples, until a timer expires and / or a user input is received. The user input can include the user unplugging and replugging the connection between the source device and the sink device, the user pressing a hardware or software button, the user toggling a switch, etc.

[0063] In another example, when the power supply of the source device is exhausted, the source device changes its charging state or changes its mode from sourcing to sinking. This change is achieved by the source device removing the pull-up termination of the connection between the source device and the sink device and providing a pull-down termination to the connection between the source device and the sink device. The sink device detects the removal of the pull-up termination and starts a timer. When the sink device detects the pull-down termination of the connection between the source device and the sink device, the sink device suppresses reverse power transfer to the source device. For example, the sink device permits power transfer at a low rate or prevents power transfer. In at least some examples, the suppression of power transfer continues until a user input is received that commands the sink device to transfer power to the source device.

[0064] In the foregoing discussion, the terms "including" and "comprising" are used in an open-ended fashion and should be interpreted to mean "including but not limited to." The term "coupled" is used throughout the specification. This term may encompass a connection, communication, or signal path that enables a functional relationship consistent with the description of the present disclosure. For example, if device A generates a signal to control device B to perform a certain action, in a first example, device A is coupled to device B, or in a second example, when intervening component C does not substantially change the functional relationship between device A and device B, device A is coupled to device B via intervening component C such that device B is controlled by device A via the control signal generated by device A. A device "configured to" perform a certain task or function may be configured (e.g., programmed and / or hardwired) by a manufacturer at the time of manufacture to perform that function, and / or may be configurable (or reconfigurable) by a user after manufacture to perform the function and / or other additional or alternative functions. Such configuration may be accomplished via the firmware and / or software programming of the device, via the construction and / or layout of the hardware components and the interconnections of the device, or a combination thereof. Also, a circuit or device said to include certain components may instead be configured to couple to those components to form the described circuit elements or devices. For example, one or more semiconductor elements (such as transistors), one or more passive elements (resistors, capacitors, and / or inductors), and / or one or more sources (such as voltage and / or current sources) may instead include only semiconductor elements within a single physical device (e.g., a semiconductor die and / or an integrated circuit (IC) package), and may be configured to couple to at least some of the passive elements and / or sources to form the described structure, either at the time of manufacture or after manufacture by an end user and / or a third party.

[0065] In this specification, although a certain component is described as being of a particular process technology (e.g., FET, metal-oxide semiconductor FET (MOSFET), n-type, p-type, etc.), these components can be replaced with components of other process technologies (e.g., replacing a FET and / or MOSFET with a bipolar junction transistor (BJT), replacing n-type with p-type or vice versa, etc.), and the circuit including the replaced components can be reconfigured to provide a desired function that is at least partially similar to the function available before the component replacement. A component shown as a register generally represents any one or more elements connected in series and / or in parallel to provide the amount of impedance represented by the shown register, unless otherwise specified. Additionally, the use of the phrase "ground potential" in the above discussion is intended to include chassis ground, earth ground, floating ground, virtual ground, digital ground, common ground, and / or any other form of ground connection applicable or appropriate to the teachings of this disclosure. Unless otherwise specified, "about," "approximately," or "substantially" preceding a value means + / - 10 percent of the shown value.

[0066] The above discussion is meant to illustrate the principles and various examples of this disclosure. Those skilled in the art will recognize numerous variations and modifications once the above disclosure is fully understood. This disclosure is intended to embrace all such variations and modifications.

Claims

1. A circuit comprising: a transistor having first and second current terminals and a control terminal; a controller having a user controllable input, a control output coupled to the control terminal, a configuration terminal, a power supply terminal coupled to the first current terminal, and a device power terminal coupled to the second current terminal; transferring power from the device power terminal to the power supply terminal at a first rate in response to a first signal at the configuration terminal; in response to a second signal at the configuration terminal; transferring power from the power supply terminals to the device power terminals at the first rate when the user controllable input is in a first state; limiting the transfer of power from the power supply terminal to the device power terminal by (a) prohibiting the transfer of power from the power supply terminal to the device power terminal when the user controllable input is in a second state, or (b) transferring power from the power supply terminal to the device power terminal at a second rate that is lower than the first rate; The controller configured to: The circuit includes:

2. The circuit of claim 1, each of the first signal and the second signal indicating a respective termination state of a device coupled to the device power terminal and the configuration terminal; The circuit, wherein the termination state comprises one of an open state, a pull-up termination state, or a pull-down termination state.

3. The circuit according to claim 2, The controller: transferring power from the device power terminal to the power supply terminal at the first rate in response to the first signal indicating the pull-up termination status; starting a timer in response to a third signal at the configuration terminal indicating a change from the pull-up termination state; limiting the transfer of power from the power supply terminal to the device power terminal if the second signal indicates the pull-down termination state before the timer expires; transferring power from the power supply terminal to the device power terminal at the first rate if the second signal indicates the pull-down termination state after the timer expires; The circuit is further configured as follows.

4. 4. The circuit of claim 3, The controller: limiting the transfer of power from the power supply terminal to the device power terminal based on receiving the second signal indicating the pull-down termination condition before the timer expires; removing restriction on the transfer of power from the power supply terminals to the device power terminals based on the user controllable input having the first state. The circuit is further configured as follows.

5. The circuit of claim 1, The controller: (a) a power supply of a device coupled to said device power terminal has a power level below a threshold; or (b) limiting the transfer of power from the power supply terminals to the device power terminals; the power supply terminal is connected to the device power terminal, the power supply terminal being connected to the device power terminal; 6. The circuit of claim 1, further comprising a termination circuit coupled to the configuration terminal; The controller: placing the termination circuit in a pull-up termination state to transfer power from the power supply terminal to the device power terminal; placing the termination circuit in a pull-down termination state to transfer power from the device power terminal to the power supply terminal; placing the termination circuit in an open state or in the pull-down termination state to inhibit the transfer of power from the power supply terminal to the device power terminal; The circuit is further configured as follows.

7. The circuit of claim 1, the configuration terminals and the device power terminals are adapted to be coupled to a device via a Type C Universal Serial Bus (USB); The circuit, wherein the controller is at least part of a Type-C Universal Serial Bus (USB) power supply controller.

8. 1. A system comprising: a transistor having first and second current terminals and a control terminal; a controller having a first control input, a first control output coupled to the control terminal, a power supply terminal coupled to the first current terminal, and a device power terminal coupled to the second current terminal; Determining the total amount of stored energy in the power supply; transferring power from the power supply terminals to the device power terminals at a first rate in response to determining that the power source has a first stored energy; In response to determining that the power source has less energy than the first stored energy, inhibiting the transfer of power from the device power terminal to the power supply terminal by: (a) prohibiting the transfer of power from the device power terminal to the power supply terminal; or (b) transferring power from the device power terminal to the power supply terminal at a second rate that is less than the first rate. The controller configured to: Including, the system.

9. The system according to claim 8, the controller further having a second control output and further configured to inhibit transfer of power from the device power terminal to the power supply terminal by sending a message via the second control output indicating at least one of: (a) the power source has less energy than the first stored energy; or (b) transfer of power from the device power terminal to the power supply terminal is inhibited.

10. The system of claim 8, the controller further having a configuration terminal; the system further includes a termination circuit coupled to the configuration terminal; The controller: placing the termination circuit in a pull-up termination state to transfer power from the power supply terminal to the device power terminal; placing the termination circuit in an open state or in a pull-up termination state to inhibit the transfer of power from the device power terminal to the power supply terminal; placing the termination circuit in a pull-down termination state to transfer power from the device power terminal to the power supply terminal; The system further comprises:

11. The system of claim 10, The system, wherein the device power terminals and the configuration terminals are adapted to be coupled to a device via a Type C Universal Serial Bus (USB) port.

12. 9. The system of claim 8, The controller further has a user controllable input, and in response to determining that the power source has less energy than the first stored energy: transferring power from the device power terminal to the power supply terminal at the first rate when the user controllable input has a first state; inhibiting the transfer of power from the device power terminals to the power supply terminals when the user controllable input has a second state; The system further comprises:

13. The system of claim 12, The system, wherein the user-controllable input is adapted to be coupled to an input device, and the first and second states of the user-controllable input are selectable by the input device.

14. A tangible, non-transitory computer-readable storage medium, comprising: When executed by a controller, the controller receiving a first signal at a configuration terminal of the controller; in response to the first signal, causing power to be transferred from a device power terminal of the controller to a power supply terminal of the controller; receiving a second signal at the configuration terminal; determining a state of a user controllable input of said controller; In response to the second signal, causing power to be transferred from the power supply terminals to the device power terminals at a first rate when the user controllable input has a first state; a computer-readable storage medium comprising instructions for, when the user-controllable input is in a second state, causing the transfer of power to be limited by: (a) prohibiting the transfer of power from the power supply terminal to the device power terminal; or (b) transferring power from the power supply terminal to the device power terminal at a second rate that is lower than the first rate.

15. The computer-readable storage medium of claim 14, each of the first signal and the second signal indicating a respective state of a termination of a device coupled to the device power terminal and the configuration terminal, the state of the termination including one of an open state, a pull-up termination state, and a pull-down termination state; The computer-readable storage medium, when executed by the controller, causes the controller to: Responsive to the first signal indicating the pull-up termination status, causing power to be transferred from the device power terminal to the power supply terminal at the first rate; starting a timer in response to a third signal at the configuration terminal indicating a change from the pull-up termination state; limiting the transfer of power from the power supply terminal to the device power terminal if the second signal indicates the pull-down termination state before the timer expires; causing power to be transferred from the power supply terminal to the device power terminal at the first rate if the second signal indicates a pull-down termination state after the timer expires; A computer-readable storage medium further comprising instructions.

16. 16. The computer-readable storage medium of claim 15, When executed by the controller, the controller limiting the transfer of power from the power supply terminal to the device power terminal based on receiving the second signal indicating the pull-down termination condition before the timer expires; and based on the user controllable input having the first state, causing a restriction on the transfer of power from the power supply terminals to the device power terminals to be lifted. A computer-readable storage medium further comprising instructions. Medium.

17. The computer-readable storage medium of claim 14, The computer-readable storage medium further includes instructions that, when executed by the controller, cause the controller to limit the transfer of power from the power supply terminal to the device power terminal in response to receiving a message indicating at least one of: (a) a power source has a power level below a threshold; or (b) transfer of power from the power supply terminal to the device power terminal is limited.

18. The computer-readable storage medium of claim 17, the configuration terminal is coupled to a termination circuit; The computer-readable storage medium, when executed by the controller, causes the controller to: placing the termination circuit in a pull-up termination state to transfer power from the power supply terminal to the device power terminal; causing the termination circuit to be in a pull-down termination state to transfer power from the device power terminal to the power supply terminal; placing the termination circuit in an open state or in the pull-down termination state to inhibit the transfer of power from the power supply terminal to the device power terminal; A computer-readable storage medium further comprising instructions.

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