Power supply switching circuit and Ethernet device using the same

Abstract

This text describes a power supply switching circuit and an Ethernet device using the same. This power supply switching circuit determines whether to use the power supplied by the Ethernet based on the change in the position of the pins inside the power supply socket used when an external power supply is inserted into the Ethernet device.

Description

Technical Field

[0001] The present invention relates to a power supply switching circuit, and particularly to a power supply switching circuit that realizes power supply switching according to the change of the pin position in a power supply socket and an Ethernet device using the same. Background Art

[0002] Power over Ethernet (POE) is a technology that can transmit both power and data to an electronic device in an Ethernet network using twisted pair wires. When the required power is not very large, an electronic device using the Power over Ethernet technology can operate normally without other external power supplies. Therefore, an electronic device using the Power over Ethernet technology can save the configuration cost of power cords and can also reduce the problems that may be encountered during wiring for users.

[0003] However, due to the limited power supply capacity of Power over Ethernet, some electronic devices using the Power over Ethernet technology still retain the function of connecting to other external power supplies to obtain the required power through other external power supplies when more power is required. However, because the load level of Ethernet electronic devices often changes, if the switching operation of the power supply is carried out manually, there may be a problem that the power supply switching operation cannot be immediately adapted to the load demand. The existence of this problem significantly limits the popularity of the Power over Ethernet technology. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, one of the objectives of the present invention is to provide a power supply switching circuit and an Ethernet device using the same, which can automatically perform the switching operation of the power supply according to the power source.

[0005] From one perspective, the present invention provides a power supply switching circuit for power over Ethernet (PoE) and external power supply in the following description and embodiments, including: an external power supply socket, a PoE pin, a detection circuit, and an Ethernet power output decision module. The external power supply socket includes a first pin, a second pin, and a third pin. The first pin is adapted to connect to an external power supply connector and transfer the first input power received from the external power supply connector to a working circuit. The second pin is electrically coupled to a first working potential source, and whether the external power supply connector is plugged into the external power supply socket determines whether the second pin is connected to the third pin. The PoE pin is electrically coupled to an Ethernet cable to transfer the second input power received from the Ethernet cable to the working circuit. The detection circuit includes a switching element, a first resistor, and an optocoupler. The switching element includes a control terminal, a first path terminal, and a second path terminal. The voltage applied to the control terminal determines whether electrical conduction exists between the first path terminal and the second path terminal, and the second path terminal is electrically coupled to the aforementioned first working potential source. The first end of the first resistor is electrically coupled to a second working potential source, and the second end of the first resistor is electrically coupled to the aforementioned control terminal and the third pin. The optocoupler includes a light-emitting diode and a photo-sensor. The first end of this light-emitting diode is electrically coupled to the aforementioned second working potential source, and the second end of this light-emitting diode is electrically coupled to the aforementioned first path terminal. Furthermore, whether the light-emitting diode emits light determines whether electrical conduction exists between the first end and the second end of the photo-sensor. The Ethernet power output decision module is electrically coupled to the aforementioned PoE pin and the first end and the second end of the photo-sensor. This Ethernet power output decision module stops providing the second input power received from the aforementioned PoE pin to the working circuit when electrical conduction exists between the first end and the second end of the photo-sensor.

[0006] In one embodiment, the aforementioned first input power is a direct current power supply.

[0007] In one embodiment, the potential of the aforementioned first working potential source is a ground potential, and the potential of the second working potential source is equal to the potential of the first input power.

[0008] In one embodiment, the aforementioned detection circuit further includes a second resistor. The first end of this second resistor is electrically coupled to the aforementioned second working potential source, and its second end is electrically coupled to the first end of the aforementioned light-emitting diode.

[0009] From another perspective, the present invention provides an Ethernet device in the following description and embodiments. This Ethernet device includes a working circuit and a power supply switching circuit. The working circuit operates between a first working potential and a second working potential; the power supply switching circuit includes an external power socket, an Ethernet power supply pin, a detection circuit, and an Ethernet power output determination module. The external power socket includes a first pin, a second pin, and a third pin. The first pin is adapted to be connected to an external power connector and transfer the first input power received from the external power connector to the working circuit. The second pin is electrically coupled to the first working potential source, and whether the external power connector is plugged into the external power socket determines whether the second pin is connected to the third pin. The Ethernet power supply pin is electrically coupled to the Ethernet cable to transfer the second input power received from the Ethernet cable to the working circuit. The detection circuit includes a switching element, a first resistor, and an optocoupler; the switching element includes a control terminal, a first path terminal, and a second path terminal. The voltage received by the control terminal determines whether there is electrical conduction between the first path terminal and the second path terminal, and the second path terminal is electrically coupled to the aforementioned first working potential source; the first end of the first resistor is electrically coupled to the second working potential source, and the second end of the first resistor is electrically coupled to the aforementioned control terminal and the third pin; the optocoupler includes a light-emitting diode and a light sensor. The first end of this light-emitting diode is electrically coupled to the aforementioned second working potential source and the second end of this light-emitting diode is electrically coupled to the aforementioned first path terminal. Furthermore, whether the light-emitting diode emits light determines whether there is electrical conduction between the first end and the second end of the light sensor. The Ethernet power output determination module is electrically coupled to the aforementioned Ethernet power supply pin and the first end and the second end of the light sensor. This Ethernet power output determination module stops providing the second input power received from the aforementioned Ethernet power supply pin to the working circuit when there is electrical conduction between the first end and the second end of the light sensor.

[0010] In one embodiment, the above-mentioned first input power is a direct current power supply.

[0011] In one embodiment, the potential of the above-mentioned first working potential source is the ground potential and the potential of the second working potential source is equal to the potential of the first input power.

[0012] In one embodiment, the above-mentioned detection circuit further includes a second resistor. The first end of this second resistor is electrically coupled to the above-mentioned second working potential source and its second end is electrically coupled to the first end of the above-mentioned light-emitting diode.

[0013] Through the above technology, the present invention enables the circuit characteristics of the detection circuit to change in response to the change in the pin position in the socket of the electronic device. Therefore, it is possible to automatically switch the power supply source when a powered external power connector is inserted into the socket without the need for manual power switching operation. Brief Description of the Drawings

[0014] Figure 1 It is a schematic diagram of the appearance of an Ethernet device according to an embodiment of the present invention.

[0015] Figure 2 It is suitable for use in Figure 1 The circuit diagram of the power supply switching circuit in the shown Ethernet device.

[0016] Figure 3 It is a circuit diagram of a power supply switching circuit that can be used in the Figure 1 shown Ethernet device according to an embodiment of the present invention.

[0017] Explanation of reference numerals:

[0018] 10: Ethernet device

[0019] 20, 30: Power supply switching circuit

[0020] 28: Working circuit

[0021] 100: External power socket

[0022] 110: Ethernet cable socket

[0023] 120: Power rectifier

[0024] 130: Ethernet cable

[0025] 200: Ethernet power supply pin

[0026] 210: Ethernet power output decision module

[0027] 212, 214: Control pins

[0028] 216: Output pin

[0029] 222: First pin

[0030] 224: Second pin

[0031] 226: Third pin

[0032] 230, 240: Diodes

[0033] 250: Optocoupler

[0034] 252: Light-emitting diode

[0035] 252a, 252b: One end of the light-emitting diode

[0036] 254: Light sensor

[0037] 254a, 254b: One end of the light sensor

[0038] 300: Switching element

[0039] 302: Control terminal

[0040] 304: First path terminal

[0041] 306: Second path terminal

[0042] R, R1: Resistors

[0043] VDD: High potential source Detailed implementation manners

[0044] In order to enable the content of the description to be clearly understood by those skilled in the art, it should be reminded here that the following phrase "electrically coupled" means enabling an electronic signal to be transmitted between two objects. Among them, the way of transmitting the electronic signal can be in a wired manner or a wireless manner, and the direction of transmitting the electronic signal can be unidirectional or bidirectional.

[0045] Please refer to Figure 1 , which is a schematic external view of an Ethernet device according to an embodiment of the present invention. As shown in the figure, the Ethernet device 10 provides an external power socket 100 and an Ethernet cable socket 110 on the outside. Among them, the external power socket 100 is adapted for a power adapter 120 to be inserted, and it can transfer the DC power provided by the power adapter 120 to the working circuit inside the Ethernet device 10; the Ethernet cable socket 110 is adapted for an Ethernet cable 130 to be inserted, and it can transfer the power provided by the Ethernet cable 130 to the working circuit inside the Ethernet device 10.

[0046] Please refer to together Figure 2 , which is suitable for use in Figure 1 the circuit diagram of the power supply switching circuit in the Ethernet device shown in Figure 2As shown, the power supply switching circuit 20 can selectively supply the power provided by the external power socket 100 or the power provided by the Ethernet cable socket 110 to the working circuit 28 of the Ethernet device 10 as the high potential source VDD of the working circuit 28. Specifically, after the connector of the power rectifier 120 (hereinafter also referred to as the external power connector) is inserted into the external power socket 100, the pin 222 (hereinafter also referred to as the first pin) in the external power socket 100 receives the power provided by the power rectifier 120 (hereinafter referred to as the first input power) due to being electrically coupled to the connector of the power rectifier 120. Then, this first input power will further pass through the diode 240 and be transmitted to the working circuit 28 to complete the operation of transferring the first input power to the working circuit 28. On the other hand, after the Ethernet cable 130 is inserted into the Ethernet cable socket 110, the Ethernet cable 130 can be electrically coupled to the Ethernet power supply pin 200 via the Ethernet cable socket 110. Thus, the power carried on the Ethernet cable 130 (hereinafter referred to as the second input power) can be transmitted to the Ethernet power output decision module 210, and the Ethernet power output decision module 210 determines the potential of the output pin 216 by detecting the current value flowing through the control pin 212 or 214. Finally, the power provided by the output pin 216 will pass through the diode 230 and be transmitted to the working circuit 28 to complete the operation of transferring the second input power to the working circuit 28.

[0047] To enable the Ethernet power output determination module 210 to determine the potential provided on its output pin 216 based on the presence of the first input power supply, the power supply switching circuit 20 utilizes the electrical characteristics of the optocoupler 250. Specifically, the optocoupler 250 includes a light-emitting diode 252 and a photoinductor 254. One end 252a of the light-emitting diode 252 is electrically coupled between the first pin 222 and the diode 240, the other end 252b of the light-emitting diode 252 is grounded (or electrically coupled to the ground power supply), one end 254a of the photoinductor 254 is electrically coupled to the control pin 214, and the other end 254b of the photoinductor 254 is electrically coupled to the control pin 212. Through the above circuit architecture, when the potential on the first pin 222 is insufficient to activate the light-emitting diode 252 (i.e., the power rectifier 120 does not provide sufficient power), the two ends 254a and 254b of the photoinductor 254 are not conducting. Thus, even if the Ethernet power output determination module 210 creates a preset potential difference between the control pins 212 and 214, current cannot flow through the path from the control pin 212 through the photoinductor 254 to the control pin 214. Therefore, the Ethernet power output determination module 210 detects that the current flowing through the control pin 212 or 214 is zero and accordingly outputs a preset potential on the output pin 216 for use by the working circuit 28. In contrast, when the potential on the first pin 222 is sufficient to activate the light-emitting diode 252, the two ends 254a and 254b of the photoinductor 254 can conduct. Thus, as long as the Ethernet power output determination module 210 creates a preset potential difference between the control pins 212 and 214, a flowing current can be generated through the path from the control pin 212 through the photoinductor 254 to the control pin 214. Therefore, the Ethernet power output determination module 210 can detect that the current flowing through the control pin 212 or 214 is not zero and accordingly stops providing the power received from the second input power supply to the output pin 216.

[0048] It should be noted that, to limit the current magnitude to prevent the light-emitting diode 252 from being damaged due to excessive current, the light-emitting diode 252 is generally connected in series with an electronic component having an appropriate resistance value. In Figure 2 the resistor R is the electronic component used to limit the current magnitude of the light-emitting diode 252.

[0049] From the above description, it can be known that Figure 2The circuit shown can indeed achieve the design purpose of automatically switching between two different input power supplies. However, in order to prevent the power supplied from output pin 216 from affecting the operation of light-emitting diode 252 and thus causing the Ethernet power output determination module 210 to misjudge the power supplied by output pin 216 as the power supplied by the first pin 222, a diode 240 must be provided between the light-emitting diode 252 and output pin 216 to block the current path from output pin 216 to the light-emitting diode 252. That is to say, in the Figure 2 circuit shown, the diode 240 is an absolutely necessary circuit component.

[0050] Next, please refer to Figure 3 , which is a circuit diagram of a power supply switching circuit that can be used in the Figure 1 Ethernet network device shown according to an embodiment of the present invention. In this embodiment, the power supply switching circuit 30 mainly includes an external power socket 100, an Ethernet power supply pin 200, a detection circuit, and an Ethernet power output determination module 210. Similar to Figure 2 that shown, after the Ethernet network cable 130 is inserted into the Ethernet network cable socket 110, the Ethernet network cable 130 can be electrically coupled to the Ethernet power supply pin 200 via the Ethernet network cable socket 110, so that the second input power carried on the Ethernet network cable 130 can be transmitted to the Ethernet power output determination module 210. The Ethernet power output determination module 210 determines the potential of the output pin 216 by detecting the current value flowing through the control pin 212 or 214. Finally, the power provided by the output pin 216 will pass through the diode 230 and be transmitted to the working circuit 28 to complete the operation of transferring the second input power to the working circuit 28.

[0051] Furthermore, in this embodiment, the external power socket 100 includes a first pin 222, a second pin 224, and a third pin 226. Among them, the first pin 222 is adapted to be connected to an external electrical connector (i.e., the connector of the power rectifier 120 as Figure 1 shown) and transfer the first input power received from the external electrical connector to the working circuit 28; the second pin 224 is electrically coupled to the ground power supply (i.e., the first working potential source hereinafter), and whether the external electrical connector is connected to the external power socket 100 can determine whether the second pin 224 is connected to the third pin 226. An external power socket 100 suitable for use here is a DC jack, but those skilled in the art should note that as long as the socket structure can meet the functional requirements of each pin in the above external power socket, it can be applied to this embodiment, so the present invention is not limited by the socket structure shown in the figure.

[0052] As Figure 3As shown, the detection circuit in this embodiment mainly includes a switching element 300, a resistor R1, and an optocoupler 250. Similar to Figure 2 that shown, the optocoupler 250 also includes a light-emitting diode 252 and a photoinductor 254. Among them, one end 252a of the light-emitting diode 252 is electrically coupled to one end of the resistor R, and the other end of the resistor R is electrically coupled to the first pin 222 and the high-potential source VDD (i.e., the second working potential source hereinafter); one end 254a of the photoinductor 254 is electrically coupled to the control pin 214 of the Ethernet power output determination module 210, and the other end 254b of the photoinductor 254 is electrically coupled to the control pin 212 of the Ethernet power output determination module 210. The switching element 300 in this embodiment includes a control terminal 302, a first path terminal 304, and a second path terminal 306. Among them, the voltage received by the control terminal 302 is used to determine whether electrical conduction can occur between the first path terminal 304 and the second path terminal 306. As shown in the figure, the control terminal 302 is simultaneously electrically coupled to the third pin 226 and one end of the resistor R1, and the other end of the resistor R1 is electrically coupled to the high-potential source VDD; the first path terminal 304 is electrically coupled to the other end 252b of the light-emitting diode 252; the second path terminal 306 is electrically coupled to the above-mentioned first working potential source (i.e., grounded).

[0053] With the above circuit architecture, when the power rectifier 120 has not been inserted into the external electrical socket 100, the potential of the third pin 226 will be equal to the ground potential because the third pin is in contact with the second pin 224. Thus, the potential of the control terminal 302 of the switching element 300 will also become the ground potential like the third pin 226. Since the potential of the control terminal 302 is the ground potential, the electrical path between the first path terminal 304 and the second path terminal 306 of the switching element 300 will not conduct, and further cause the light-emitting diode 252 not to emit light. In the situation where the light-emitting diode 252 does not emit light, conduction cannot occur between the two ends 254a and 254b of the photoinductor 254. Therefore, even if the Ethernet power output determination module 210 creates a preset potential difference between the control pins 212 and 214, current still cannot flow in the path from the control pin 212 through the photoinductor 254 to the control pin 214. That is to say, in this situation, the Ethernet power output determination module 210 detects that the current flowing through the control pin 212 or 214 will be zero, and thus can output a preset potential converted from the second input power supply at the output pin 216 for use by the working circuit 28 accordingly.

[0054] In contrast, when the power rectifier 120 is inserted into the external power socket 100, the second pin 224 will be pushed away by the external power connector, causing the second connector 224 to no longer contact the third pin 226. As a result, the third pin 226 will become in a floating state. At this time, the potentials of the third pin 226 and the control terminal 302 will both be equivalent to the potential of the high-potential source VDD. Therefore, the electrical path between the first path terminal 304 and the second path terminal 306 of the switching element 300 is turned on, and further causes the light-emitting diode 252 to also turn on. In the situation where the light-emitting diode 252 is on, conduction can occur between the two ends 254a and 254b of the light sensor 254. Thus, as long as the Ethernet power output determination module 210 creates a preset potential difference between the control pins 212 and 214, a flowing current can be generated on the path from the control pin 212 through the light sensor 254 to the control pin 214. Finally, the Ethernet power output determination module 210 can detect that the current flowing through the control pin 212 or 214 is not zero and accordingly stop supplying the power received from the second input power source to the output pin 216.

[0055] It should also be noted that the resistor R in this embodiment is used in the same way as the resistor R in Figure 2 to limit the magnitude of the current flowing through the light-emitting diode 252. As is known to those skilled in the art, on the premise of being able to perform the function of limiting the magnitude of the current flowing through the light-emitting diode 252, the resistor R can also be set at a place other than the position shown in Figure 3 . For example, the resistor R can be set between the resistor R1 and the high-potential source VDD, or the resistor R can also be set between the light-emitting diode 252 and the switching element 300.

[0056] From the above description, it can be known that because the switching element 300 is used in the embodiment shown in Figure 3 to control whether current can flow through the light sensor 254, there is no need to set a diode between the first pin 222 and the working circuit 28 to prevent the light sensor 254 from malfunctioning due to the Ethernet power. Therefore, Figure 3 the embodiment shown in Figure 2 can eliminate the energy loss caused by the voltage drop of the diode 240 in

[0057] In summary, through the power supply switching circuit provided by the above description of the present invention and the Ethernet device using the same, it is indeed possible to automatically perform the switching operation of the power supply according to the source of power; moreover, through a special circuit design method, the present invention can also reduce unnecessary energy loss to contribute to energy conservation and carbon reduction.

Claims

1. A power supply switching circuit for Ethernet power supply and external power supply, which is suitable for switching the power supply provided to a working circuit, and is characterized in that Comprising: An external power socket, including a first pin, a second pin and a third pin. Among them, the first pin is adapted to be connected to an external electrical connector and transfer a first input power received from the external electrical connector to the working circuit. The second pin is electrically coupled to a first working potential source, and whether the external electrical connector is plugged into the external power socket determines whether the second pin is connected to the third pin; An Ethernet power supply pin, electrically coupled to an Ethernet cable to transfer a second input power received from the Ethernet cable to the working circuit; A detection circuit, including: A switching element, which includes a control terminal, a first path terminal and a second path terminal. The voltage received by the control terminal determines whether there is electrical conduction between the first path terminal and the second path terminal. The second path terminal is electrically coupled to the first working potential source; A first resistor, the first end of which is electrically coupled to a second working potential source, and the second end of which is electrically coupled to the control terminal and the third pin; and An optocoupler, having a light-emitting diode and a light sensor. The first end of the light-emitting diode is electrically coupled to the second working potential source, and the second end of the light-emitting diode is electrically coupled to the first path terminal. Whether the light-emitting diode emits light determines whether there is electrical conduction between the first end and the second end of the light sensor; and An Ethernet power output determination module, electrically coupled to the Ethernet power supply pin and the first end and the second end of the light sensor. The Ethernet power output determination module stops providing the second input power received from the Ethernet power supply pin to the working circuit when there is electrical conduction between the first end and the second end of the light sensor.

2. The power supply switching circuit according to claim 1, wherein the first input power is a DC power supply.

3. The power supply switching circuit according to claim 2, wherein the potential of the first working potential source is the ground potential and the potential of the second working potential source is equal to the potential of the first input power.

4. The power supply switching circuit according to claim 1, wherein the detection circuit further includes a second resistor, the first end of which is electrically coupled to the second working potential source, and the second end of which is electrically coupled to the first end of the light-emitting diode.

5. An Ethernet network device, characterized in that Comprising: A working circuit, operating between a first working potential and a second working potential; And A power supply switching circuit, including: An external power socket, including a first pin, a second pin and a third pin. Among them, the first pin is adapted to be connected to an external electrical connector and transfer a first input power received from the external electrical connector to the working circuit. The second pin is electrically coupled to the first working potential source, and whether the external electrical connector is plugged into the external power socket determines whether the second pin is connected to the third pin; An Ethernet power supply pin, electrically coupled to an Ethernet cable to transfer a second input power received from the Ethernet cable to the working circuit; A detection circuit, including: A switching element, which includes a control terminal, a first path terminal, and a second path terminal. The voltage applied to the control terminal determines whether there is electrical conduction between the first path terminal and the second path terminal. The second path terminal is electrically coupled to the first working potential source; A first resistor, the first end of which is electrically coupled to the second working potential source, and the second end of which is electrically coupled to the control terminal and the third pin; and An optocoupler having a light-emitting diode and a photosensor. The first end of the light-emitting diode is electrically coupled to the second working potential source and the second end of the light-emitting diode is electrically coupled to the first path terminal. Whether the light-emitting diode emits light determines whether there is electrical conduction between the first end and the second end of the photosensor; and An Ethernet power output determination module, which is electrically coupled to the Ethernet power supply pin and the first end and the second end of the photosensor. The Ethernet power output determination module stops providing the second input power received from the Ethernet power supply pin to the working circuit when there is electrical conduction between the first end and the second end of the photosensor.

6. The Ethernet device according to claim 5, wherein the first input power is a DC power source.

7. The Ethernet device according to claim 6, wherein the potential of the first working potential source is the ground potential and the potential of the second working potential source is equal to the potential of the first input power.

8. The Ethernet device according to claim 5, wherein the detection circuit further includes a second resistor, the first end of which is electrically coupled to the second working potential source, and the second end of which is electrically coupled to the first end of the light-emitting diode.

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