TWI898479B - Docking device, electronic device and power supply managing method - Google Patents

Abstract

A docking device, an electronic device and a power supply managing method are provided. The docking device includes a power delivery (PD) controller and a switch unit. The PD controller conducts a power supplying to the electronic device. The switch unit is coupled to the PD controller. The switch unit receives a power supply voltage. When the electronic device is switched from a first mode to a second mode, the PD controller determines whether to disable the switch unit according to notice message, conducts a protocol communication with the electronic device again, and determines whether to modulate an output power value of the PD controller for conducting the power supplying to the electronic device, thereby a power of the power supplying being automatically modulated when the electronic device switches the modes.

Description

Expansion device, electronic device, and power management method

The present invention relates to an electronic device, and more particularly to an expansion device that supplies power through an expansion device, an electronic device, and a power management method.

Current computer devices can be charged via expansion devices. These devices can also be connected to one or more external electronic devices to expand their functionality. Generally, when a computer device is closed or powered off, the external electronic devices cease operation, thereby reducing power consumption on the expansion device's transmission interface.

However, because the expansion device cannot switch charging modes, it cannot improve the charging efficiency of the computer device in applications where power consumption is reduced. Therefore, even if the power consumption of the expansion device's transmission interface is reduced, the expansion device cannot charge the computer device at a higher output power value.

An embodiment of the present invention provides an expansion device that can automatically adjust the power supplied to the electronic device when the electronic device switches modes.

An expansion device according to an embodiment of the present invention includes a first power transmission controller and a switching element. The first power transmission controller is coupled to an electronic device. The first power transmission controller is configured to supply power to the electronic device. The switching element is coupled to the first power transmission controller. The switching element is configured to receive a power voltage. When the electronic device switches from a first mode to a second mode, the first power transmission controller determines, based on notification information, whether to disable the switching element, re-establish protocol communication with the electronic device, and determine whether to adjust the output power value of the first power transmission controller for supplying power to the electronic device.

Another embodiment of the present invention provides an electronic device. The electronic device includes a second power transmission controller and a switching element. The second power transmission controller is coupled to the first power transmission controller of the expansion device. The switching element is coupled to the second power transmission controller. The switching element is used to receive a power voltage. When the electronic device switches from a first mode to a second mode, the second power transmission controller determines whether to disable the switching element based on notification information, re-establishes protocol communication with the first power transmission controller, and determines whether to adjust the output power value of the first power transmission controller for powering the electronic device.

An embodiment of the present invention further provides a power management method. The power management method includes the following steps. Powering an electronic device through an expansion device. When the electronic device switches from a first mode to a second mode, the power management method further includes the following steps. Determining whether to disable a switching element based on notification information through a power transmission controller in the expansion device or the electronic device. The switching element is coupled to the power transmission controller and is used to receive a power voltage. Re-communication is performed through the expansion device and the electronic device. Determining whether to adjust the output power value of the expansion device for powering the electronic device through the power transmission controller.

Based on the above, in applications where an electronic device switches between different modes, the expansion device, electronic device, and power management method of the present invention, by determining whether a switching element is disabled, enable the expansion device and the electronic device to re-establish a protocol communication. This allows the expansion device and the electronic device to automatically adjust the output power level of the expansion device to power the electronic device.

In order to make the above features and advantages of the present invention more clearly understood, embodiments are given below and described in detail with reference to the accompanying drawings.

Some embodiments of the present invention are described in detail below with reference to the accompanying drawings. Reference symbols in the following description will identify identical or similar elements when the same symbols appear in different drawings. These embodiments are only a portion of the present invention and do not disclose all possible implementations of the present invention. Rather, these embodiments are merely examples within the scope of the present invention's patent application.

Figure 1 is a block diagram of an expansion device according to one embodiment of the present invention. Referring to Figure 1 , expansion device 100 can utilize Universal Serial Bus Type-C (USB Type-C) as a power delivery (PD) interface. Expansion device 100 can be plugged into electronic device 200 and can connect to one or more external electronic devices (not shown in Figure 1 ). Electronic device 200 can then use these external electronic devices through expansion device 100.

In this embodiment, the electronic device 200 may be, for example, a mobile phone, a computer, a tablet computer, a laptop computer, a desktop computer, etc. The external electronic device may be, for example, a power supply, a display, an external hard drive, and various communication interface devices.

In this embodiment, the expansion device 100 may include a first power transfer controller 110 and a switch element 120. The switch element 120 receives a power voltage VBUSP. The switch element 120 is also coupled to the first power transfer controller 110. The first power transfer controller 110 is coupled to the electronic device 200. The first power transfer controller 110 supplies power to the electronic device 200.

In this embodiment, the first power delivery controller 110 may be, for example, a power delivery (PD) controller. The first power delivery controller 110 may include a signal converter, a field programmable gate array (FPGA), or other programmable general-purpose or special-purpose microprocessor, digital signal processor (DSP), programmable controller, application-specific integrated circuit (ASIC), programmable logic device (PLD), or other similar devices or combinations thereof. The first power delivery controller 110 may be capable of loading and executing computer program-related firmware or software to implement computing, control, and execution functions.

FIG2 is a flow chart illustrating a power management method according to an embodiment of the present invention. Referring to FIG1 and FIG2 , the expansion device 100 may execute steps S210 to S240. The order of steps S210 to S240 is for illustrative purposes only and is not intended to be limiting.

In step S210 , the expansion device 100 supplies power to the electronic device 200 . Specifically, the expansion device 100 performs the power supply operation through the first power transmission controller 110 and the corresponding power supply (VBUS) pin of the expansion device 100 .

In step S220, when the electronic device 200 switches from the first mode to the second mode, the power transfer controller (i.e., the first power transfer controller 110) in the expansion device 100 determines whether to disable the switch element 120 based on the notification information S1. The notification information S1 may be information indicating that the electronic device 200 has switched to the second mode.

In this embodiment, the first mode of the electronic device 200 may be, for example, an operating mode. The second mode of the electronic device 200 may be, for example, a non-operating mode. In this embodiment, the second mode may include an off mode, a closed mode, and a sleep mode.

In step S230, when the electronic device 200 switches from the first mode to the second mode, based on the determination in step S220 (e.g., disabling the switch element 120), the expansion device 100 (e.g., the first power transmission controller 110) resumes protocol communication with the electronic device 200. This protocol communication may utilize USB Type-C protocol communication, for example. Through this protocol communication, the expansion device 100 and the electronic device 200 confirm various settings for power supply operation. These settings may include the output power value for power supply operation.

It should be noted that when the switch element 120 is disabled, it stops receiving the power voltage VBUSP, disconnecting the corresponding VBUS pin of the expansion device 100 (i.e., "VBUS Removed"). The expansion device 100 ceases to supply power to the electronic device 200. At this point, based on the USB Type-C transmission specification, the electronic device 200 switches from the power-drawing connected state (i.e., "Attached.SNK") to the power-drawing disconnected state (i.e., "Unattached.SNK"), allowing the expansion device 100 and the electronic device 200 to resume protocol communication.

In step S240, when the electronic device 200 switches from the first mode to the second mode, the first power transmission controller 110 determines whether to adjust the output power level of the expansion device 100 (e.g., the first power transmission controller 110) supplying power to the electronic device 200. Based on the determination in step S240 (e.g., the output power level is adjusted), the expansion device 100 and the electronic device 200 complete a protocol communication. The first power transmission controller 110 then supplies power to the electronic device 200 based on the result of this protocol communication (i.e., the adjusted output power level).

It's worth noting that when the electronic device 200 switches between different modes, the first power transmission controller 110 can disconnect the VBUS pin based on whether the switching element 110 is disabled, allowing the expansion device 100 and the electronic device 200 to re-establish protocol communication. This allows the expansion device 100 and the electronic device 200 to automatically adjust the power supplied by the expansion device 100 to the electronic device 200.

Figure 3 is a block diagram of an electronic device according to one embodiment of the present invention. Referring to Figure 3 , electronic device 400 can utilize USB Type-C power transmission via expansion device 300. Computer device 400 can also utilize one or more external electronic devices (not shown in Figure 3 ) through expansion device 300. The expansion device 300 and electronic device 400 can be used, for example, in another embodiment as shown in Figure 1 .

In this embodiment, electronic device 400 may include a second power transfer controller 410 and a switching element 420. Switching element 420 receives power voltage VBUSP. Switching element 420 is also coupled to second power transfer controller 410. Second power transfer controller 410 is coupled to first power transfer controller 310 in expansion device 300. First power transfer controller 310 supplies power to second power transfer controller 410. Second power transfer controller 410 may be, for example, a PD controller.

Compared to the embodiment of FIG1 , the switch element 420 is configured in the electronic device 400. In the embodiment of FIG3 , in response to the switching of the electronic device 400 between different modes, the protocol communication between the expansion device 300 and the electronic device 400 can be automatically restarted through the switch element 420 to adjust the power supply operation accordingly.

In detail, referring to FIG2 , the electronic device 400 may execute steps S210 to S240 to illustrate another embodiment of the power management method. The operation details of the electronic device 400 executing steps S210 to S240 may refer to the relevant descriptions of the embodiments shown in FIG1 and FIG2 and be deduced accordingly.

In step S210 , the expansion device 200 supplies power to the electronic device 400 .

In step S220, when the electronic device 400 switches from the first mode to the second mode, the power transmission controller (ie, the second power transmission controller 410) in the electronic device 400 determines whether to disable the switch element 420 according to the notification information S1.

In step S230, when the electronic device 400 switches from the first mode to the second mode, based on the determination result of step S220 (e.g., disabling the switch element 420), the electronic device 400 (e.g., the second power transmission controller 410) resumes protocol communication with the expansion device 300 (e.g., the first power transmission controller 310).

In step S240, when the electronic device 400 switches from the first mode to the second mode, the second power transmission controller 410 determines whether to adjust the output power level of the expansion device 100 (e.g., the first power transmission controller 110) supplying power to the electronic device 400 (e.g., the second power transmission controller 410). Based on the determination in step S240 (e.g., the output power level is adjusted), the expansion device 300 completes protocol communication with the electronic device 400. The first power transmission controller 310 then supplies power to the electronic device 400 based on the result of this protocol communication (i.e., the adjusted output power level).

Figure 4 is a block diagram of an expansion device and an electronic device according to another embodiment of the present invention. Referring to Figure 4 , expansion device 500 may include a first power transfer controller 510, a switching element 520, one or more first connection ports (e.g., first connection port P1), and a third connection port P3. The first power transfer controller 510 and switching element 520 can be described with reference to the description of expansion device 100, and similar applications may be applied.

In this embodiment, the first port P1 is coupled to the first power transfer controller 510. The expansion device 500 is connected to the external electronic device 540 via the first port P1. In this embodiment, the third port P3 is coupled to the first power transfer controller 510. The third port P3 is also coupled to the switching element 520 to receive the power voltage VBUSP. The expansion device 500 is connected to the electronic device 600 via the third port P3.

In the embodiment shown in FIG4 , electronic device 600 may include a second power transfer controller 610, a processor 630, and a second connection port P2. Second power transfer controller 610 is coupled to processor 630 and second connection port P2. Electronic device 600 is connected to third connection port P3 via second connection port P2, thereby coupling second power transfer controller 610 to first power transfer controller 510.

In this embodiment, the second port P2 and the third port P3 can each be a USB Type-C port. The expansion device 500 and the electronic device 600 communicate via a set of Configuration Channel (CC) pins on each of the ports P2 and P3.

Referring to FIG. 5 , FIG. 5 is a circuit diagram of a switch element according to the embodiment of FIG. 4 . In the embodiment of FIG. 5 , the switch element 520 can be implemented, for example, as a switch integrated circuit to perform a switching operation based on the control signal VBUSP_EN from the first power transfer controller 510 .

Specifically, the switching element 520 may include a voltage regulator circuit (e.g., including a resistor R and a capacitor C) to receive a reference voltage VLP and a power voltage VBUSP. The input pin IN of the switching element 520 is coupled to the voltage regulator circuit to receive the power voltage VBUSP. The output pin OUT of the switching element 520 is coupled to the VBUS pin of the third port P3 to transmit the output voltage VBUSP_OUT to the electronic device 600 via the VBUS pin. In other words, the switching element 520 is positioned in the path between the power voltage VBUSP and the VBUS pin.

Continuing with the above description, the reference pin GND of the switching element 520 is grounded. The enable pin EN of the switching element 520 is coupled to the control pin of the first power transfer controller 510 to receive the control signal VBUSP_EN. In other words, the switching element 520 performs a switching operation under the control of the control signal VBUSP_EN. When the switching element 520 is enabled (i.e., turned on), the output voltage VBUSP_OUT is the power voltage VBUSP. Conversely, when the switching element 520 is disabled (i.e., turned off), the output voltage VBUSP_OUT is 0, disconnecting the VBUS pin.

In this embodiment, the control pin of the first power transfer controller 510 may be, for example, a general-purpose input/output (GPIO) pin.

Figure 6 is a flow chart of the power management method according to the embodiment shown in Figure 4 of the present invention. Referring to Figures 4 and 6 , the expansion device 500 is connected to the second port P2 of the electronic device 600 via the third port P3. In this application, the electronic device 600 can be powered on and operated in a first mode (i.e., working mode). The expansion device 500 and the electronic device 600 can execute steps S610-640 and S651-S657. The order of these steps S610-640 and S651-S657 is for illustrative purposes only and is not intended to be limiting.

In step S610, the expansion device 500 (e.g., the first power transmission controller 510) obtains status information (not shown) from the electronic device 600. The first power transmission controller 510 also determines whether the electronic device 600 is operating in the first mode based on the status information.

In this embodiment, the status information may, for example, indicate the current operating mode of the electronic device 600. That is, when the electronic device 600 is connected to the expansion device 500, the first power transmission controller 510 determines whether the electronic device 600 is powered on and operating in the working mode based on the status information.

If the result of step S610 is yes, the electronic device 600 is operating in the first mode. The expansion device 500 proceeds to step S620. In step S620, the expansion device 500 (e.g., the first power transmission controller 510) supplies power to the electronic device 600 according to the preset second power transmission profile (PD Profile). In other words, the expansion device 500 supplies power using the preset power supply scheme.

In this embodiment, since the expansion device 500 is connected to the external electronic device 540 via the first port P1, the expansion device 500 needs to power not only the electronic device 600 but also the external electronic device 540. Therefore, while reserving power consumption for the first port P1, the default second power transmission profile instructs the expansion device 500 to power the electronic device 600 at a default output power value, as described below with respect to the embodiment of FIG. 7 .

On the other hand, if the determination result in step S610 is negative, it indicates that the electronic device 600 is not operating in the first mode. The expansion device 500 proceeds to step S630. In step S630, the expansion device 500 (e.g., the first power transmission controller 510) further determines, based on the status information, whether the electronic device 600 has switched from the first mode to the second mode (e.g., the closed mode).

If the result of the determination in step S630 is negative, it indicates that the electronic device 600 has not switched to the second mode. In other words, the electronic device 600 is not covered. The expansion device 500 proceeds to step S640. In step S640, the expansion device 500 (e.g., the first power transmission controller 510) continues to supply power to the electronic device 600 according to the preset second power transmission profile. The expansion device 500 then returns to step S620.

On the other hand, when the determination result in step S630 is yes, indicating that the electronic device 600 switches from the first mode to the second mode, the expansion device 500 and the electronic device 600 proceed to steps S651 to S657 to automatically adjust (e.g., increase) the output power value of the expansion device 500 when supplying power.

Specifically, since the electronic device 600 originally operates in the first mode, when the electronic device 600 is connected to the expansion device 500 , the electronic device 600 can be charged through the expansion device 500 and use the external electronic device 540 through the expansion device 500 .

In step S651 , the switch element 520 of the expansion device 500 is enabled by default, so that the VBUS pin of the third port P3 receives the power voltage VBUSP through the switch element 520 .

In step S652, when the electronic device 600 switches from the first mode to the second mode, the processor 630 generates a notification message S1 and transmits the notification message S1 to the second power transmission controller 610. In other words, when the electronic device 600 is closed, the processor 630 notifies the second power transmission controller 610 of the fact that the electronic device 600 is closed (i.e., the notification message S1).

In addition, when the electronic device 600 switches from the first mode to the second mode, the processor 630 disables the external electronic device 540. The electronic device 600 transmits the notification message S1 to the first power transmission controller 510 via the second power transmission controller 610.

Specifically, in step S653, when the electronic device 600 switches from the first mode to the second mode, the second power transmission controller 610 transmits notification information S1 to the first power transmission controller 510 via the CC pin of the second port P2 and the CC pin of the third port P3. In other words, the second power transmission controller 610 further notifies the first power transmission controller 510 of the information that the electronic device 600 is closed (i.e., notification information S1) via the CC pins.

In step S654, the first power transmission controller 510 outputs a control signal VBUSP_EN based on notification information S1 to disable the switch element 520. This means that the switch element 520 is turned off, severing the power path between the power voltage VBUSP and the VBUS pin of the third port P3. The VBUS pin of the second port P2 is correspondingly disconnected. Thus, the VBUS pin used for power transmission is disconnected. The expansion device 500 and the electronic device 600 will re-establish protocol communication to adjust the output power level of the expansion device 500 supplying power to the electronic device 600.

In step S655, when the first power transmission controller 510 determines that the output power value needs to be adjusted, it enables the switching element 520 to restore the power path between the power voltage VBUSP and the VBUS pin. Furthermore, the first power transmission controller 510 selects a first power transmission profile based on a preset table. In this embodiment, the output power value of the first power transmission profile is greater than the output power value of the preset second power transmission profile.

Referring also to FIG. 7 , FIG. 7 is a schematic diagram illustrating the operation of the expansion device according to the embodiment of FIG. 4 of the present invention. When the electronic device 600 is switched to the second mode (e.g., closed mode), the power supply function settings of the expansion device 500 can be displayed, for example, by the preset power consumption table shown in FIG. The power consumption required by the transmission interface of the expansion device 500 can be recorded in field F71. The output power of the expansion device 500 can be recorded in the preset table represented by field FOUT.

In field F71, since various external electronic devices (e.g., external electronic device 540) connected to expansion device 500 are disabled, the power consumption of various connection ports (e.g., the first connection port P1 using USB 3.2 Gen 1 Type A) of expansion device 500 is 0.

In the embodiment shown in FIG. 7 , the preset table may include a power transmission profile designated "PDO2" in field F72. This "PDO2" power transmission profile serves as the default second power transmission profile for use when the expansion device 500 is simultaneously powering the external electronic device 540 and the electronic device 600. Specifically, during power supply operation, the maximum output voltage of the expansion device 500 is approximately 12 volts (V). The maximum output current of the expansion device 500 is approximately 3 amperes (A). The maximum output power of the expansion device 500 is approximately 36W.

It should be noted that when the electronic device 600 is closed, the power consumption of the transmission interface of the expansion device 500 is reduced, allowing the expansion device 500 to be powered using a different power transmission profile with a higher output power value. At this time, by disconnecting and then reconnecting the power voltage VBUSP on the VBUS pin via the switch element 520, the first power transmission controller 510 can reselect a power transmission profile from the preset table based on the current application scenario (i.e., the scenario when the electronic device 600 is closed).

In this embodiment, the power transmission profile selected by the first power transmission controller 510 may be, for example, the first power transmission profile indicated by "PDO5" in field F73. This means that during subsequent power supply operations to the covered electronic device 600, the maximum output voltage of the expansion device 500 is approximately 20 volts (V). The maximum output current of the expansion device 500 is approximately 3 amperes (A). The maximum output power of the expansion device 500 is approximately 60 W. In some embodiments, the first power transmission profile may be, for example, the power transmission profile indicated by "PDO3" or "PDO4."

Returning to Figure 6 , in step S656, when the first power transmission controller 510 determines that the output power value needs to be adjusted, it switches from the second power transmission profile (e.g., the "PDO2" power transmission profile in Figure 7 ) to the first power transmission profile (e.g., the "PDO5" power transmission profile in Figure 7 ). In other words, the expansion device 500 changes its power supply scheme. Furthermore, the first power transmission controller 510 supplies power to the electronic device 600 according to the current first power transmission profile.

In step S657, the electronic device 600 can be switched from the second mode back to the first mode (eg, flip-up mode). The expansion device 500 and the electronic device 600 re-execute step S610.

In summary, when an electronic device switches to a second mode, such as a shutdown state or a closed state, the expansion device, electronic device, and power management method of the present invention automatically switch power transmission profiles by operating a switch element. Consequently, the expansion device can supply power to the electronic device at a higher output power level, thereby improving power transmission efficiency. In some embodiments, the switch element can be configured in at least one of the expansion device and the electronic device to enhance application flexibility.

Although the present invention has been disclosed above by way of embodiments, they are not intended to limit the present invention. Any person having ordinary skill in the art may make slight modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope of the attached patent application.

100, 300, 500: Expansion device 110, 310, 510: First power transfer controller 120, 420, 520: Switching device 200, 400, 600: Electronic device 410, 610: Second power transfer controller 540: External electronic device 630: Processor C: Capacitor F71-F73, FOUT: Fields P1: First port P2: Second port P3: Third port R: Resistor S1: Notification message S210-S240, S610-S640, S651-S657: Steps VBUSP: Power supply voltage VBUSP_EN: Control signal VBUSP_OUT: Output voltage VLP: Reference Voltage

Figure 1 is a block diagram of an expansion device according to an embodiment of the present invention. Figure 2 is a flow chart of a power management method according to an embodiment of the present invention. Figure 3 is a block diagram of an electronic device according to an embodiment of the present invention. Figure 4 is a block diagram of an expansion device and an electronic device according to another embodiment of the present invention. Figure 5 is a circuit diagram of a switch element according to the embodiment of Figure 4 of the present invention. Figure 6 is a flow chart of a power management method according to the embodiment of Figure 4 of the present invention. Figure 7 is a schematic diagram of the operation of the expansion device according to the embodiment of Figure 4 of the present invention.

S210~S240: Steps

Claims (10)

An expansion device includes: a first power transmission controller coupled to an electronic device for supplying power to the electronic device; and a switch element coupled to the first power transmission controller and coupled between a power voltage and a power channel pin between the expansion device and the electronic device. When the electronic device switches from a first mode to a second mode, the first power transmission controller determines, based on notification information, whether to disable the switch element to disconnect the power channel pin, re-establish protocol communication with the electronic device, and adjust an output power value of the first power transmission controller for supplying power to the electronic device. The expansion device of claim 1, wherein when the first power transfer controller determines to adjust the output power value, the first power transfer controller enables the switching element and selects a first power transfer profile according to a preset table. The expansion device as described in claim 2, wherein when the first power transmission controller determines to adjust the output power value, the first power transmission controller switches from a second power transmission profile to the first power transmission profile and supplies power to the electronic device according to the first power transmission profile. The expansion device of claim 3, wherein an output power value of the first power transmission profile is greater than an output power value of the second power transmission profile. The expansion device as described in claim 1 further includes: at least one first connection port, coupled to the first power transfer controller, for connecting to an external electronic device; and a third connection port, coupled to the first power transfer controller and the switching element, for connecting to the electronic device, wherein when the electronic device switches from the first mode to the second mode, the electronic device disables the external electronic device and transmits the notification information to the first power transfer controller. An expansion device as described in claim 1, wherein the electronic device includes: a second power transfer controller coupled to the first power transfer controller; and a processor coupled to the second power transfer controller, wherein when the electronic device switches from the first mode to the second mode, the processor generates the notification information and transmits the notification information to the second power transfer controller. The expansion device as described in claim 6, wherein the electronic device further includes: a second connection port coupled to the second power transfer controller for connecting to the expansion device, wherein when the electronic device switches from the first mode to the second mode, the second power transfer controller transmits the notification information to the first power transfer controller through a set of configuration channel pins of the second connection port. The expansion device as described in claim 1, wherein the second mode includes a power-off mode, a closed mode, and a sleep mode. An electronic device includes: a second power transmission controller coupled to a first power transmission controller of an expansion device; and a switch element coupled to the second power transmission controller and coupled between a power voltage and a power channel pin between the expansion device and the electronic device. When the electronic device switches from a first mode to a second mode, the second power transmission controller determines, based on notification information, whether to disable the switch element to disconnect the power channel pin, re-establish protocol communication with the first power transmission controller, and determine whether to adjust the output power value of the first power transmission controller for powering the electronic device. A power management method includes: supplying power to an electronic device via an expansion device. When the electronic device switches from a first mode to a second mode, the power management method further includes: determining, via a power transmission controller in the expansion device or the electronic device, based on notification information, whether to disable a switch element to disconnect a power channel pin, wherein the switch element is coupled to the power transmission controller and is coupled between a power voltage and the power channel pin between the expansion device and the electronic device; re-establishing a protocol communication between the expansion device and the electronic device; and determining, via the power transmission controller, whether to adjust an output power value of the expansion device used to power the electronic device.