Dynamic learning of voltage source capabilities

Abstract

Embodiments of the present application relate to dynamic learning of voltage source capabilities. A system may include a power supply (100) that may be configured to generate any one of a plurality of output voltages at a power supply output node. The system may also include a voltage auto-detection power distribution (PD) controller (120) coupled to the power supply (102). The voltage auto-detection PD controller (120) is configured to monitor input signals to detect the presence of a device (80) coupled to the system via a cable (90) and assert a combination of multiple control signals. For each combination of control signals, the voltage auto-detection PD controller (120) measures the value of the output voltage from the power supply (102), stores the measured value, and generates a plurality of packets for transmission to the device (80). Each packet contains a parameter indicating the measured output voltage.

Description

[0001] This application is a divisional application of the invention patent application with the application date of December 28, 2017, application number 201780066105.9, and invention name “Dynamic Learning of Voltage Source Capability”. Background Art

[0002] Some interconnect specifications define a power transfer protocol in which a first device advertises its power transfer capabilities (e.g., voltage and current) to a second device. The first device thus provides power and the second device receives power. In some embodiments, the power capabilities of the source device are hard-coded in a controller inside the source device. The source device accesses its preset configuration and advertises these specific power capabilities to the receiving device. The receiver selects one of the advertised power capabilities, and the source device configures its power supply according to the agreed-upon power capabilities. Summary of the invention

[0003] In one embodiment, a system may include a power supply that may be configured to generate any of a plurality of output voltages at a power supply output node. The system may also include a voltage auto-detection power distribution (PD) controller coupled to the power supply. The voltage auto-detection PD controller may be configured to monitor input signals to detect the presence of a device coupled to the system via a cable and assert a combination of a plurality of control signals. For each combination of control signals, the voltage auto-detection PD controller may measure a value of an output voltage from the power supply, store the measured value, and generate a plurality of packets for transmission to the device. Each packet includes a parameter indicating a measured output voltage.

[0004] In another embodiment, a system may include a power supply, a power switch, a voltage auto-detection power distribution (PD) controller, and a configurable resistor divider network. The power supply may be configurable to generate any one of a plurality of output voltages at a power supply output node. The power switch may be coupled between the power supply output node and a voltage bus and may be configured to couple the output voltage from the power supply output node to the voltage bus. The voltage auto-detection PD controller may be coupled to the power supply and coupled to the power switch via an enable signal. The voltage auto-detection PD controller may be configured to selectively control the power switch to be in an open state or a closed state. The configurable resistor divider network may be coupled to the voltage auto-detection PD controller. The voltage auto-detection PD controller may be configured to start a power supply output voltage learning mode upon detecting a receiving device coupled to the system via a cable. During the power supply output voltage learning mode, the voltage auto-detection PD controller may be configured to use the enable signal to configure the power switch to an open state and assert a combination of multiple control signals to the configurable resistor divider network. For each combination of control signals, the voltage auto-sensing PD controller may be configured to measure the value of the output voltage from the power source and generate a plurality of packets for transmission to the receiving device, wherein each packet includes parameters indicative of the measured output voltage.

[0005] In yet another embodiment, a method may include detecting attachment of a first device to a second device, and iteratively configuring a power supply of the second device to generate a plurality of output voltages. For each iteration, the method may include measuring each output voltage and storing a value indicative of each measured output voltage. The method may also include transmitting a communication packet to the first device. The communication packet may include the value indicative of the measured output voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] To describe various examples in detail, reference is now made to the accompanying drawings, in which:

[0007] Figure 1 An embodiment is shown in which a power supply device including a voltage auto-detecting power distribution (PD) controller is coupled to a receiving device via a cable according to various examples;

[0008] Figure 2 Showing various examples Figure 1 Embodiment of the power supply device;

[0009] Figure 3 Demonstrating embodiments of a voltage auto-sensing PD controller according to various examples;

[0010] Figure 4 Another embodiment of a voltage auto-detection PD controller according to various examples is presented;

[0011] Figure 5 Describing an embodiment in which a pull-up resistor on a communication channel conductor can be selectively disconnected by control of a voltage auto-sensing PD controller; and

[0012] Figure 6 Methods according to various embodiments are presented. DETAILED DESCRIPTION

[0013] Reference may be made herein to the Universal Serial Bus (USB) Power Delivery (PD) and Type-C specifications, but such references are for illustrative purposes only and do not limit the scope and claims of the present disclosure. The present disclosure also relates to other specifications. Various USB PD and Type-C specifications enable the transmission of higher power levels through USB cables and connectors. This technology creates a universal power plug for laptops, tablet computers, etc. that may require more than, for example, 5V. For example, the USB-PD specification defines a communication link between ports connected via a USB-PD cable. The communication can be half-duplex and packet-based. The communication contains information that enables the two ports to communicate and negotiate the voltage and current that the source port will provide to the port. The basic communication according to the USB PD specification can be bi-phase mark coding (BMC). Such communication occurs independently of normal USB communication through the same cable, although on different wires. USB-PD communication packets flow over different conductors (e.g., control channel (CC) conductors), rather than USB data conductors.

[0014] A power supply device (sometimes called a "source") can advertise its supply type in the form of a power data object (PDO), which is contained in a USB PD message called a source capability message. A fixed-power PDO contains a voltage and a maximum current; a variable-power PDO contains a maximum voltage, a minimum voltage, and a maximum current; and a battery-powered PDO contains a maximum voltage, a minimum voltage, and a maximum power. A source device can advertise multiple unique PDOs. A receiving device (sometimes called a "sink") can request one of the advertised power capabilities via a USB PD message called a request message. If the source can satisfy the sink's request, the source sends an accept message; otherwise the source can send a reject or wait message. After the source has adjusted its power supply, the source sends a PS_RDY message to notify the sink that the sink can begin receiving power at the agreed-upon level.

[0015] Before announcing its voltage capabilities, the source first detects that the receiver has been attached by means of a cable or other connection mechanism. The source may include a pull-up resistor on the CC conductor. The receiver includes a pull-down resistor or clamp on the CC conductor. The source detects the presence of the receiver by measuring the DC voltage on the CC conductor. At one voltage level or range of voltage, the source determines that the receiver is not attached, and at a different level or range of voltage, the source determines that the receiver is attached. The source can then verify that the voltage on the CC conductor is stable for a predetermined period of time (e.g., between 100ms and 200ms) for jitter elimination purposes. According to the applicable specification, the source then applies a predetermined voltage (e.g., 5V) to the power line of the cable (referred to as the voltage bus (VBUS) in the USB PD specification) within 475ms. Then, after applying the predetermined voltage (e.g., 5V), the source can send a communication message to announce its source power capabilities (e.g., using PDO as described above), such as which voltages can be provided and the current level of each corresponding voltage.

[0016] In the power supply output voltage learning mode, the source determines the voltage that the source's power supply can generate before the source can announce the voltage to the receiver. According to the disclosed embodiment, the voltage auto-detection PD controller in the source dynamically learns the voltage that the source's power supply can generate before announcing such power capabilities to the receiver. In this embodiment, the power capabilities of the power supply are not preconfigured into the PD controller of the source. Instead, the power distribution capabilities of the power supply are dynamically determined by the voltage auto-detection PD controller in the source. For power supply types characterized by minimum and maximum voltages (rather than just multiple discrete voltage levels), the voltage auto-detection PD controller can control the power supply to reach its maximum and minimum voltages individually, and then announce the voltage range. For power supply types characterized by a single voltage, the power supply has multiple voltage settings, any of which can be used. In this case, the auto-detection PD controller controls the power supply to reach each of its unique voltages, and then announces those unique voltages.

[0017] Figure 1An embodiment of a power supply device 100 coupled to a receiving device 80 via a cable 90 is described. The power supply device 100 can generate an operating voltage and current and provide it to the receiving device 80, which uses the voltage and current provided by the power supply device 100 to power a load 82 in the receiving device. The load 82 can include any type of circuit, such as a processor, memory, custom circuit, passive components, active components, etc. In some embodiments, the power supply device 100 may include a power "brick", which is a power adapter that converts AC mains power to a DC voltage and current for the receiving device 80. In other embodiments, the power supply device 100 can be a computing device or can be part of a computing device, such as a computer, a tablet computer device, etc. In addition, the power supply device 100 may be capable of dual-mode operation, that is, as a source device in which it generates power or a receiving device in which it receives power generated by another device. For some embodiments, the power supply and receiving devices 100 and 80 implement the USB PD and Type-C specifications, but other specifications and protocols may also be implemented.

[0018] The power supply device 100 includes a power supply 102, an output capacitor (C OUT ), a pull-up resistor 106 (which can be implemented as a current source integrated in an integrated circuit (IC) of a power supply device), and a voltage automatic detection power distribution (PD) controller 120. The power supply 102 receives an input AC mains voltage and converts it into one or more output DC voltages and currents, and outputs the output DC power via a voltage bus (V BUS ) 100 to the receiving device 80. The voltage auto-detection PD controller 120 of the power supply device 100 may interact with the PD controller 84 in the receiving device 80 (which may be the same or different from the voltage auto-detection PD controller 120) to negotiate which voltage levels the power supply 102 will generate and provide to the receiving device 80. The power supply 102 may be capable of generating output voltages at any of a plurality of different levels (e.g., 5V, 9V, 15V, 20V, etc.). In various embodiments, the power supply 102 may be capable of generating only a single output voltage, two different output voltages, three output voltages, etc. The voltage auto-detection PD controller 120 in the source device announces to the PD controller 84 in the receiving device 80 (e.g., by means of a message transmitted over a control channel (CC) conductor (e.g., wire, conductive trace, etc.) 104). The receiving device 80 may select one of the announced voltages, and the voltage auto-detection PD controller 120 responds by configuring the power supply 102 to supply the agreed voltage to the receiving device 80. In embodiments where the power source is characterized by a voltage range capability between a minimum voltage and a maximum voltage, the receiving device 80 may request a voltage between the minimum and maximum values ​​advertised by the voltage auto-detect PD controller 120 .

[0019] In addition to being used to transmit communication packets during the power negotiation process, the CC conductors 104 may also be used for an additional reason, which permits the voltage auto-detection PD controller 120 to detect when the receiving device 80 has been connected to the power supply device 100 by, for example, the cable 90. The pull-up resistor 106 is coupled between the CC conductors 104 within the power supply device 100, and the pull-down resistor 86 is coupled between the CC conductors 104 within the receiving device 80. Therefore, the voltage level on the CC conductors will be at a higher level if no receiving device 80 is connected to the power supply device 100 than if the receiving device 80 and its pull-down resistor 86 are connected to the power supply device via the cable 90. The voltage auto-detection PD controller 120 can therefore detect whether the receiving device 80 is connected to the voltage auto-detection PD controller by monitoring the voltage level on the CC conductors 104.

[0020] As mentioned above, the power supply 102 may be capable of generating any of a number of different voltages. According to the disclosed embodiments, the voltage auto-detection PD controller 120 performs a process by which the controller dynamically determines the specific voltage capability of the power supply 102 and notifies the receiving device 80 of the specific voltage. Therefore, the voltage auto-detection PD controller 120 does not need to be pre-configured for a specific voltage group and can therefore be used with a variety of power supplies. In addition, because the voltage auto-detection PD controller 120 learns the actual voltage that the power supply 102 can generate, the power supply 102 does not need to be designed for a specific precise voltage level. That is, when designing a power supply system, each actual power supply may have different characteristics that may cause its output voltage to be slightly different, but because the voltage auto-detection PD controller 120 measures the voltage that the power supply can actually generate, the design constraints and tolerances can be relaxed for the power supply design.

[0021] Figure 2 An example of a possible implementation of a power supply device 100 is shown. The source device 100 includes various components coupled together as shown to form a power supply 102. Some of the components may include a bridge rectifier 190, an isolation transformer 144, and a constant voltage constant current flyback controller 142. Various other passive components such as resistors, capacitors, etc. are also shown. The bridge rectifier 190 rectifies the incoming AC mains waveform. The flyback controller 142 provides a constant voltage using an optical coupler formed by a photodiode 111 and a photodetector 114.

[0022] The voltage auto-sensing PD controller 120 is shown with a pair of CC terminals labeled CC1 and CC2. The connector of the cable 90 may be symmetrical, meaning that the connector is not keyed and therefore may be connected in either orientation. Thus, there may be two CC conductors, and one conductor is used depending on the orientation of the conductor to which the cable is attached. The power supply 102 generates an output voltage which is Figure 21 and is the voltage on node 108. Node 108 is the output node of power supply 102 and is coupled to power switch (e.g., field effect transistor Q1) 116. Power switch 116 can be controlled to be in an on (closed) state or an off (open) state by a control signal GDen from a voltage auto-detection PD controller 120. Node 110 is coupled from node 108 to the opposite terminal of power switch 116, and the voltage on the node is provided to a voltage bus (VBUS) and provided to receiving device 80 through cable 90. When power switch 116 is on, the voltage on VBUS is almost the same as the VOUT voltage.

[0023] Voltage Auto-Detection PD controller 120 may include an analog-to-digital converter (ADC) that can be used to convert either or both of the VOUT or VBUS voltages into digital form. PWR The terminal provides the VOUT voltage to the voltage auto-detection PD controller 120, which provides the VBUS voltage to the V PWR terminals, as shown.

[0024] A configurable resistor divider network 130 may also be included and coupled to the voltage auto-sensing PD controller 120. Figure 2 In an embodiment of the present invention, the configurable resistor divider network 130 may include a pair of series-connected resistors coupled between the VOUT node 108 and ground. As shown, the resistors include resistor 112a (R FBU ) and resistor 112b (R FBL ). The node between resistors 112a and 112b is designated as resistor node 117. Voltage auto-sensing PD controller 120 includes a pair of control terminals, which are shown as CTL1 and CTL2 (and sometimes referred to as CTL1 signal and CTL2 signal). Configurable resistor divider network 130 also includes resistor 112c (R FBL1 ) and a resistor 112d (R FBL2). The CTL1 and CTL2 terminals can be open drain terminals. Therefore, the voltage automatic detection PD controller 120 can configure each CTL1 and CTL2 terminal to be disconnected or grounded. If the CTL1 terminal is pulled low, then its corresponding resistor 112c is coupled in parallel with the resistor 112b, thereby changing the resistance of a portion of the resistor divider network 130. However, if CTL2 remains disconnected, then the resistor 112c remains floating and is therefore not actually included in the resistor divider network. The same is true for the CTL2 terminal—pulling CTL2 low causes its corresponding resistor 112d to be placed in parallel with the resistor 112b; otherwise, the resistor 112d is not placed in parallel with the resistor 112b. Each combination of control signals CTL1 and CTL2 can configure the configurable resistor divider network differently from other combinations of control signals. In other embodiments, the power supply device 100, rather than the configurable resistor divider network, may include a programmable current source to change the amount of current in a controlled manner through the resistor 112a. In other embodiments, the auto-sensing PD controller may have circuitry capable of setting a different reference voltage using, for example, a digital-to-analog converter (DAC).

[0025] Current flows from Vout through the configurable resistor divider network 130 to ground. The magnitude of the current varies with the equivalent resistance of the resistor divider network 130, and therefore varies with whether each resistor 112c and 112d is coupled in parallel with resistor 112b through the operation of the CTL1 and CTL2 signals. By changing the amount of current passing through the resistor divider network 130 due to the operation of the CTL1 and CTL2 signals, the voltage across resistor 112a can be changed, and therefore the current through the photodiode 111 can be changed. The intensity of the light generated by the photodiode 111 can vary with the current through the photodiode. The light generated by the photodiode 111 is detected by the photodetector 114. Therefore, the combination of the photodiode 111 and the photodetector 114 forms an optical feedback signal to the flyback converter 142. The flyback converter 142 uses the optical feedback signal to adjust its output voltage VOUT.

[0026] The power supply 102 may be capable of generating a plurality of different voltages, and for each such voltage, VOUT is adjusted to track a particular voltage based on an optical feedback signal from the photodiode 111. In addition, the power supply 102 may be configured by the voltage auto-detection PD controller 120 to generate a particular output voltage VOUT by configuring the CTL1 and CTL2 signals. In this example, with two control signals (CTL1 and CTL2), four configurations are possible for the configurable resistor divider network 130. The four combinations differ from each other in whether resistors 112c and 112d are included in parallel with resistor 112b.

[0027] According to the disclosed embodiment, upon detecting the receiving device 80 (e.g., by monitoring the voltage level on the CC1 or CC2 conductors), the voltage auto-detection PD controller 120 begins the process of identifying the various voltages that the power supply 102 can generate. The voltage auto-detection PD controller 120 can perform this process by iteratively cycling through various combinations of CTL1 and CTL2 signals. For each combination of CTL1 and CTL2 control signals, the voltage auto-detection PD controller 120 measures the value of its output voltage VOUT and stores the measured value (e.g., in a non-volatile memory internal to the controller or otherwise accessible to the controller). The voltage auto-detection PD controller 120 can wait for a predetermined period of time to allow the VOUT voltage to stabilize before measuring using, for example, an ADC internal to the voltage auto-detection PD controller 120. After cycling through various combinations of CTL1 and CTL2, the voltage auto-detection PD controller 120 can notify the receiving device 80 of the measured voltage, as described above. For example, the voltage auto-detection PD controller 120 can generate multiple packets for transmission to the receiving device 80, each of which includes parameters indicating the measured output voltage. In some embodiments, such as with a programmable current source, an auto-detecting PD controller may measure excessive voltages in a reasonable amount of time, and in such embodiments, the controller may measure and advertise the maximum and minimum voltages to the receiving device.

[0028] When the voltage auto-detection PD controller 120 is performing the VOUT learning process, the voltage auto-detection PD controller 120 may configure the power switch 116 to be in the off state. Therefore, the various voltages generated by the power supply during the aforementioned learning process are not placed on the VBUS node 110 and are therefore not provided to the receiving device 80. The voltage measured by the voltage auto-detection PD controller 120 is the voltage on the VOUT node 108, wherein the power switch 116 is in the off (open) state.

[0029] However, in some implementations, the power supply device 100 should place a predetermined voltage on the VBUS node 110 within a preset amount of time after detecting the presence of the sink device 80. For example, for the USB PD specification, the power supply device 100 will place 5V on the VBUS within 475ms of detecting the sink device 80. Figure 2 In an embodiment, according to the USB PD specification, the time required to cycle through various CTL1 and CTL2 combinations, measure and record the VOUT voltage should be less than 475ms. Other embodiments for complying with this timing requirement are described below.

[0030] Figure 1Embodiments also include a load circuit 140 coupled between the VOUT node 108 and ground. The load circuit 140 in this example includes a resistor 142 connected in series with a solid-state switch 144. The gate of the solid-state switch 144 acts as an enable / disable terminal for the load circuit 140. The gate of the solid-state switch 144 can be driven by a discharge (DSCG1) signal from the voltage automatic detection PD controller 120. If the DSCG1 signal is in one logic state (e.g., high), then the switch 144 is in an on (closed) state, thereby allowing current to flow from the VOUT node 108 to ground. In the relative logic state of DSCG1, the switch 144 will be in an off (disconnected) state, thereby preventing current from flowing from the VOUT node 108 to ground. The voltage automatic detection PD controller 120 can use the DSCG1 signal to effectively apply a load to the VOUT node 108 to help stabilize the power supply output. In some embodiments, the load circuit 140 can be connected to the VOUT node 108 as shown in FIG. Figure 1 108, or the solid-state switch 144 may be integrated into the voltage auto-detection PD controller 120. The voltage auto-detection PD controller 120 also includes a discharge signal DSCG2 configured to permit current to flow from the VBUS node 110 through the resistor 119 and through the internal solid-state switch to ground. Thus, the voltage auto-detection PD controller 120 is configured to apply a load to either or both of the VOUT node 108 and the VBUS node 110.

[0031] After measuring the various VOUT voltages that the power supply 102 can generate, the voltage auto-detection PD controller 120 can also calculate the upper and lower voltage limits for each measured voltage. Such voltages thus define the acceptable range of the output voltage of the power supply and can therefore be used to implement under-voltage and over-voltage protection. In some embodiments, the voltage auto-detection PD controller 120 calculates the upper and lower voltage thresholds as:

[0032] V UPPER =V MEAS *aUPPER+O UPPER

[0033] V LOWER =V MEAS *aLOWER+O LOWER

[0034] Where V UPPER is the upper voltage limit, V MEAS is the measured voltage, α UPPER , α LOWER , O UPPER and O LOWER Contains the permissible supply tolerance and the permissible measurement tolerance. UPPER , αLOWER , O UPPER and O LOWER The parameters may be determined a priori and stored in memory in the voltage auto-detection PD controller 120. For each possible VOUT voltage that may be generated by the power supply 102 and determined by the voltage auto-detection PD controller 120, the voltage auto-detection PD controller 120 calculates a pair of upper and lower voltage thresholds and stores the calculated thresholds in memory. During operation, the voltage auto-detection PD controller 120 may measure the voltage on VBUS, compare the voltage to the thresholds for the applicable power supply voltage, and respond accordingly (e.g., turn off the power switch 116) if an overvoltage or undervoltage condition is detected.

[0035] In embodiments where the device 100 may be able to supply power to or receive power from another device, the voltage auto-detection PD controller 120 of the power device 100 may initialize itself into a "receive" mode, in which the device 100 is configured to receive operating voltages (rather than generate voltages) from other devices via the cable 90. However, when in receive mode, the voltage auto-detection PD controller 120 of the device 100 (now running as a power receiver) may perform the process described above to assert various combinations of control signals CTL1 and CTL2 and measure output voltage values ​​from its own power supply. The voltage auto-detection PD controller 120 may then send a USB PD message, called a PR_SWAP message, to the other device to notify the measured voltage. This technique permits the device 100 to have more time to measure its various possible voltages.

[0036] In another embodiment, the voltage auto-detection PD controller 120 may measure the VOUT voltage as a certain value, but round the measured value to a different value. For example, the voltage auto-detection PD controller may measure VOUT as 14.8V, but round the measured value to 15V and notify the receiving device 80 of 15V instead of the measured value of 14.8V. In such embodiments, the packet generated by the power supply device 100 and communicated to the receiving device 80 may include a combination of the actual measured voltage value and the rounded value. In either case, the voltage auto-detection PD controller 120 sends a packet to the receiving device 80 containing a parameter indicating the measured VOUT voltage value—the parameter is the actual measured value or its rounded corresponding value.

[0037] Figure 3A block diagram illustrating at least a portion of a voltage auto-detection PD controller 120. In this example, the voltage auto-detection PD controller 120 includes a state machine 150, a voltage multiplexer 152, and an ADC 154. The ADC 154 may be used to digitize the VOUT voltage or the VBUS voltage as selected by a control signal from the state machine 150 through the multiplexer 152. The state machine 150 may be implemented as a microcontroller executing machine instructions, a programmable logic device, or other suitable type of control circuit. The state machine 150 may include or be coupled to a memory 152 for storing parameters used to calculate the voltage thresholds mentioned above and for storing measured and / or rounded values ​​of the voltages.

[0038] Figure 4 Another embodiment of the power supply device 100 is described. The power supply 102 and the voltage automatic detection PD controller 120 in this embodiment are almost the same as those described above. Figure 2 However, compared to Figure 2 , Figure 4 There are several differences. Figure 2 The configurable resistor divider network 130 has been replaced by Figure 4 1. The configurable resistor divider network 170 in FIG. For the configurable resistor divider network 130, the configurable resistor divider network 170 includes a pair of series-connected resistors 172 and 174 coupled between the VOUT node 108 and ground. Another pair of resistors 176 and 178 are connected to a node 173 defined between the resistors 172 and 174. Resistors 172, 174 are coupled to ground via corresponding solid-state switches, rather than connecting the opposite terminals of resistors 172 and 174 to the CTL1 and CTL2 terminals of the voltage auto-sensing PD controller. Resistor 176 is thus connected between resistor node 173 and switch 180, while resistor 178 is connected between resistor node 173 and switch 182. The CTL1 and CTL2 signals are provided to the gates of switches 180 and 182 and can thus turn the switches on or off. When a given switch 180 , 182 is on, its corresponding resistor 176 , 178 is coupled in parallel to resistor 174 ; otherwise, the corresponding resistor remains floating and is therefore not coupled in parallel to resistor 174 .

[0039] Figure 4 The embodiment relative to Figure 2 Another difference in the embodiments of Figure 4An embodiment includes a DC to DC (DC / DC) converter 160. The DC / DC converter 160 is coupled between the power supply 102 and the VBUS node 110. Therefore, the input DC voltage to the DC / DC converter 160 is the VOUT voltage, and the output DC voltage from the DC / DC converter 160 is provided to the VBUS node 110. The output voltage from the DC / DC converter 160 can be the voltage that the power supply device will impose on the VBUS node 110 within a time period corresponding to the specification. In the above USB PD example, the power supply device 110 will place 5V on VBUS within 475ms. The output voltage generated by the DC / DC converter 160 can therefore be 5V in this example. The DC / DC converter 160 also includes a control terminal coupled to the voltage automatic detection PD controller 120 (for example, as Figure 4 102 ). The DCDCen signal may be selectively asserted by the voltage auto-detection PD controller 120 to enable or disable the operation of the DC / DC converter 160. In embodiments where the process of sequentially passing through the various possible voltages that may be generated by the power supply, measuring the voltages and storing them in memory takes longer than the allotted time period that the power supply must be configured to generate the desired voltage (e.g., 5V), the voltage auto-detection PD controller 120 may enable the DC / DC converter 160 to generate and / or provide its output voltage onto the VBUS node 110. The DC / DC converter 160 may be capable of generating a predetermined voltage (5V in this example) from any of the various voltages that may be generated by the power supply 102. Thus, the acceptable input voltage range of the DC / DC converter 160 is wide enough to include at least the various voltages that the power supply 102 may conceivably generate. In some embodiments, although the DC / DC converter 160 applies voltage to VBUS, the auto-detection PD controller 120 only announces 5V to the receiving device 80 and only provides a small amount of current. In such cases, the DC / DC converter 160 may be implemented as a relatively simple and inexpensive circuit.

[0040] The DC / DC converter 160 may be enabled by the voltage auto-sensing PD controller 120 to generate its output voltage for the VBUS node 110 , and does so while the power switch 116 remains off so that the voltage auto-sensing PD controller 120 may continue the process of ramping the various voltages that the power supply 102 may generate.

[0041] Figure 5 Shows something like Figure 1 An embodiment of an embodiment of an embodiment. Figure 5A technique is described to provide the voltage auto-detection PD controller of the source device with more time to measure and record the various voltages that may be produced by the power supply 102. In this example, the pull-up resistor 106 may be removed from the CC conductor 104 on the source device side of the cable by turning off the switch 180. The switch 180 may be controlled by a control signal from the voltage auto-detection PD controller 120. Turning off the switch 180 and actually removing the pull-up resistor from the circuit simulates a disconnection of the sink device 80. The voltage auto-detection PD controller 120 may perform a process to learn the power supply voltage and then open the switch 180.

[0042] Figure 6 A flow chart of a method 20 according to the disclosed embodiment is shown. The operations may be performed in the order shown or in a different order. In addition, the operations may be performed sequentially, or two or more of the operations may be performed simultaneously.

[0043] At 202, the method includes initializing the power supply device 100 to a low power state. While in this state, the power supply device (and specifically, for example, a voltage auto-sensing PD controller) operates in a power output voltage learning mode, wherein at least one function performed is to wait for and monitor the attachment of a receiving device 80, and to perform Figure 6 The remainder of the operation is shown in . In some embodiments, the voltage auto-detection PD controller 120 may perform this operation by comparing the voltage on the CC conductor (CC1 or CC2) to a predetermined voltage range—one voltage range may indicate no attachment of the receiving device 80, and another voltage range may indicate attachment of a receiving device. At 204, the method includes detecting attachment of the receiving device.

[0044] At 206, the method begins verifying the attached receiving device. Verifying the attached receiving device may include ensuring that the voltage on the CC conductor remains between a lower threshold and an upper threshold for a predetermined time period to guard against false positives when the receiving device is not actually attached. In some embodiments, the lower threshold is 0 volts. However, in one example, the lower and upper thresholds are 0.2V and 1.6V, respectively, and the predetermined time period is 150ms. The predetermined time period may be longer as desired, longer than the time to enable the voltage to VBUS for the required time period.

[0045] Operations 208 to 214 describe a repetitive loop in which the voltage auto-detection PD controller 120 of the power supply device learns the various voltages that the power supply can generate. At 208, the method includes setting the voltage auto-detection PD controller 120 to cause the power supply to generate a first output voltage (VOUT). In some embodiments, the voltage auto-detection PD controller may adjust the control signals CTL1 and CTL2 to thereby cause the power supply to generate a specific output voltage based on the optical feedback signal as described above. At 210, the method may include waiting for a specific time period before measuring (at 212) the output voltage (VOUT) from the power supply. The time period may help to allow the output voltage of the power supply to stabilize in order to make more accurate voltage measurements. In some embodiments, the time period is fixed and configured into the voltage auto-detection PD controller 120. In other embodiments, the time period may be based on continuous measurement. That is, a series of voltage measurements may be made in rapid succession (e.g., every 1 ms) after the power supply is configured for output voltage, and when the measured voltage stops changing more than a threshold amount between one such measurement and the next such measurement (e.g., the change from one measurement to a subsequent measurement is less than a threshold percentage), the series of measurements stops and the last measured voltage is used. At 212, the measured voltage may also be stored in, for example, an internal memory of the voltage automatic detection PD controller 120. The record may also include configuration settings of the CTL1 and CTL2 signals to cause the power supply to generate the measured voltage. In addition, the voltage automatic detection PD controller 120 may still also calculate the upper and lower voltage thresholds of the measured voltage (as explained in the above example) and also store the calculated voltage thresholds in the memory. Thus, a record of the measured voltage for a given configuration of the CTL1 / CTL2 signals and the corresponding upper and lower voltage thresholds is generated. In some embodiments, a record may be made to a non-volatile memory so that a learning process does not need to be performed each time a receiving device is attached. In other embodiments, the automatic detection PD controller 120 may store the record until the AC main power input is removed.

[0046] At 214, the voltage auto-detection PD controller 120 determines whether any more configurations of CTL1 / CTL2 are still to be used. If such a combination is still to be used, then at 216, the voltage auto-detection PD controller 120 controls the CTL1 and CTL2 signals accordingly, and the method loops back to operation 210. In some embodiments, according to the applicable specification (e.g., the USB PD specification), the power supply must be able to generate a predetermined voltage (e.g., 5V). Because the voltage is required, the voltage auto-detection PD controller 120 does not need to use the CTL1, CTL2 signals to implement the power supply to measure the voltage. Alternatively, the voltage auto-detection PD controller 120 implements the knowledge that the power supply 102 is able to generate the voltage. In some embodiments, the required voltage (e.g., 5V) can be the minimum voltage that can be generated by the power supply and corresponds to a specific combination of CTL1 and CTL2 signals (e.g., two signals high-drain remains open). During the power supply output voltage learning process, the specific combination of CTL1 / CTL2 signals can be omitted if necessary. In some embodiments, multiple voltages may be implemented that may make the predetermined CTL1, CTL2 signals known to generate the signals.

[0047] If the voltage auto-detect PD controller 120 has subjected the power source 102 to all relevant combinations of CTL1 and CTL2 signals, then at 218, the method includes completing verification of the attached receiving device 80 as explained above. In order to complete the receiver verification process, the CC voltage should remain between the thresholds for a certain amount of time, which may be relatively long compared to the time used in 206. A timer may be started in 206, and if more time is needed to ensure that the CC voltage has stabilized, the timer may be extended in 218. Intervention operations 208 to 216 may be performed during a predetermined time period, during which an attached receiving device is verified. If no valid receiving device is attached (as determined at 220), the process loops back to 202 and the process may be repeated. However, if a valid receiving device is attached, the power supply 120 is configured (through the appropriate combination of the CTL1 and CTL2 signals to produce a predetermined output voltage (e.g., 5V), and the power switch 116 is turned on by the voltage auto-detection PD controller 120 to provide the predetermined voltage to the VBUS node 110. The power switch is turned on by a control signal from the voltage auto-detection PD controller 120, as explained above.

[0048] At 224, the voltage auto-detect PD controller 120 generates and transmits a packet to the receiving device to announce the various voltages determined to be producible by the power supply. As described above, the announcement may include the actual voltage measured or a rounded version of the measured voltage.

[0049] Specific terms are used throughout the following description and claims to refer to specific system components. As will be appreciated by those skilled in the art, different companies may use different names to refer to a component. This document is not intended to distinguish between components that differ in name but not function. In the following discussion and in the claims, the terms "include" and "comprise" are used in an open manner and should therefore be interpreted to mean "including but not limited to...". Moreover, the term "coupled" is intended to mean an indirect or direct wired or wireless (e.g., optical) connection. Therefore, if a first device is coupled to a second device, the connection may be through a direct connection, or through an indirect connection through other devices and connections. The above discussion is intended to illustrate the principles and embodiments of the present invention. For those skilled in the art, many changes and modifications will become apparent once the above disclosure is fully understood. It is hoped that the attached claims will be interpreted as encompassing all such changes and modifications.

Claims

1. A power transmission device, comprising: Voltage bus VBUS terminal; Control channel CC terminal; as well as a controller coupled to the VBUS terminal and the CC terminal, the controller having a voltage supply input and a control output, the controller being configured to: regulating a reference voltage via the control output to regulate a supply voltage received at the voltage supply input; measuring regulated supply voltage; as well as A packet including a voltage capability message is generated based on the measured supply voltage. 2 . The device of claim 1 , wherein the voltage capability message complies with a Universal Serial Bus (USB) Power Delivery (PD) standard. 3 . The apparatus of claim 1 , wherein the voltage capability message includes a voltage level of at least one of 5V, 9V, 15V, or 20V.

4. The apparatus of claim 1 , wherein the controller is configured to isolate the VBUS terminal from the voltage supply input before the regulated supply voltage is measured, and is configured to couple the VBUS terminal to the voltage supply input after the regulated supply voltage is measured. 5 . The apparatus of claim 1 , wherein the controller is configured to detect a power receiving device via the CC terminal, and is configured to transmit the packet to the power receiving device via the CC terminal. 6 . The apparatus of claim 1 , wherein the controller is configured to detect a power receiving device via the CC terminal and is configured to couple the VBUS terminal to the voltage supply input after the power receiving device is detected.

7. The apparatus of claim 1, further comprising: a voltage divider having a first terminal coupled to the voltage supply input, an intermediate terminal, and a second terminal coupled to a ground terminal, Wherein the controller is configured to generate a control signal via the control output, the control signal configured to adjust a resistance of the voltage divider to adjust the reference voltage at the intermediate terminal.

8. The apparatus of claim 1, further comprising: A voltage supply has a voltage output coupled to the voltage supply input of the controller and a reference voltage input coupled to receive the reference voltage.

9. The apparatus of claim 1, wherein: The reference voltage includes a plurality of reference voltages; The regulated supply voltage includes a plurality of regulated supply voltages, the plurality of regulated supply voltages corresponding one-to-one to the plurality of reference voltages; and The voltage capability message selectively includes the plurality of regulated supply voltages compliant with a Universal Serial Bus (USB) Power Delivery (PD) standard.

10. The apparatus of claim 1, wherein the controller is configured to apply 5V to the VBUS terminal after the regulated supply voltage is measured.

11. A power transmission device, comprising: Voltage bus VBUS terminal; Control channel CC terminal; as well as A controller having a voltage supply input and a control output, the controller being configured to: isolating the VBUS terminal from the voltage supply input; regulating a reference voltage via the control output to regulate a supply voltage received at the voltage supply input; measuring regulated supply voltage; as well as A packet including a voltage capability message is generated based on the measured supply voltage.

12. The apparatus of claim 11, wherein the controller is configured to couple the VBUS terminal to the voltage supply input after the regulated supply voltage is measured.

13. The apparatus of claim 11, wherein the controller is configured to detect a power receiving device via the CC terminal and is configured to couple the VBUS terminal to the voltage supply input after the power receiving device is detected.

14. The apparatus of claim 11, further comprising: a voltage divider having a first terminal coupled to the voltage supply input, an intermediate terminal, and a second terminal coupled to a ground terminal, Wherein the controller is configured to generate a control signal via the control output, the control signal being configured to adjust a resistance of the voltage divider to thereby adjust the reference voltage at the intermediate terminal.

15. The apparatus of claim 11, wherein: The reference voltage includes a plurality of reference voltages; The regulated supply voltage supply includes a plurality of regulated supply voltages, the plurality of regulated supply voltages corresponding one-to-one with the plurality of reference voltages; and The voltage capability message selectively includes the plurality of regulated supply voltages compliant with a Universal Serial Bus (USB) Power Delivery (PD) standard.

16. The apparatus of claim 11, wherein the voltage capability message includes a voltage level of at least one of 5V, 9V, 15V, or 20V.

17. A power supply device, comprising: A controller having a voltage bus VBUS terminal and a control channel CC terminal, a voltage supply input and a control output, the controller being configured to: detecting a power receiving device via the CC terminal; decoupling the VBUS terminal from the voltage supply input; generating, via the control output, a first reference voltage received by a voltage supply; measuring, at the voltage supply input, a first supply voltage received from the voltage supply; generating, via the control output, a second reference voltage received by the voltage supply; measuring, at the voltage supply input, a second supply voltage received from the voltage supply; as well as A packet including a voltage capability message is generated based on the measured first and second supply voltages.

18. The apparatus of claim 17, wherein the voltage capability message complies with the Universal Serial Bus (USB) Power Delivery (PD) standard.

19. The apparatus of claim 17, wherein the voltage capability message includes a voltage level of at least one of 5V, 9V, 15V, or 20V.

20. The apparatus of claim 17, further comprising: a voltage divider having a first terminal coupled to the voltage supply input, an intermediate terminal, and a second terminal coupled to a ground terminal, Wherein the controller is configured to generate first and second control signals via the control output, each of the first and second control signals being configured to adjust a resistance of the voltage divider to generate the first and second reference voltages, respectively, at the intermediate terminal.

21. A method of supplying power from a power supply device to a power receiving device, the method comprising: Operate in low power state; detecting connection of the power receiving device to the power supply device via a cable; measuring, by a controller included in the power supply device, a supply voltage that can be supplied by a voltage source included in the power supply device; verifying, by the controller, the power receiving device; as well as The supply voltage that can be supplied is notified to the power receiving device through the power supply device.

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