CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a national phase application under 35 U.S.C. § 371 of International Application No. PCT/CN2018/098538, filed Aug. 3, 2018, which claims the benefit of priority to Chinese patent application No. 201721677203.X filed with the China National Intellectual Property Administration on Dec. 6, 2017 and entitled “Power supply circuit, relay device and Power over Ethernet system”; and Chinese patent application No. 201721919828.2 filed with the China National Intellectual Property Administration on Dec. 29, 2017 and entitled “Network system and network extender”, each of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present application relates to the field of electronic technology, in particular to a power supply circuit, a relay device and a Power over Ethernet system.

BACKGROUND

Power over Ethernet (POE) technology refers to the technology of transmitting data signals and providing DC power supply for a network device (such as a network telephone, a WLAN access point or a network switch) through Ethernet twisted pair

In the related art, a POE system typically includes a power sourcing equipment (PSE) and a powered device (PD). Both the PSE and the PD can be provided with an RJ45 interface. The RJ45 interface in the PSE can be connected to the RJ45 interface in the PD through a network cable. The PSE can supply power to and exchange data signals with the PD through the network cable.

However, due to the limited transmission distance of data signals in Ethernet (typically, 100 meters), the distance between PSE and PD is limited by the transmission distance of data signals. This results in poor application flexibility of the Power over Ethernet technology.

SUMMARY

The present application provides a power supply circuit, a relay device, and a Power over Ethernet system, with which the problem of poor application flexibility of the Power over Ethernet technology in the related art can be addressed. The technical solutions are as follows.

In a first aspect, a power supply circuit is provided for powering a relay circuit in a relay device. The power supply circuit includes: at least one rectifier module and a switch control module.

Each rectifier module has an input end connected to an input interface of the relay device, a positive output end connected to a positive supply pin, and a negative output end connected to a first end of the switch control module, wherein, the positive supply pin is connected to a positive terminal of the relay circuit.

The switch control module has a second end connected to a negative supply pin, a control end connected to the positive supply pin, wherein, the negative supply pin is connected to a negative terminal of the relay circuit.

The switch control module allows conduction between the first end and the second end when the rectifier module outputs a voltage greater than a preset threshold.

Optionally, the switch control module comprises a switching transistor having a gate connected to the positive supply pin, a source connected to the negative output end, and a drain connected to the negative supply pin.

Optionally, the power supply circuit further includes: a first resistor and a first zener diode.

The first resistor has one end connected to the positive supply pin and the other end connected to a cathode of the first zener diode, and an anode of the first zener diode is connected to the gate of the switching transistor.

Optionally, the switch control module further includes: a second zener diode, a second resistor and a capacitor.

The second zener diode has a cathode connected to the gate of the switching transistor, and an anode connected to the source of the switching transistor.

The second resistor has one end connected to the gate of the switching transistor, and the other end connected to the source of the switching transistor.

The capacitor has one end connected to the gate of the switching transistor, and the other end connected to the source of the switching transistor.

Optionally, the switch control module includes: a powered device integrated chip.

The powered device integrated chip has an under voltage lock out pin connected to the positive supply pin, a return pin connected to the negative supply pin, a negative power pin connected to the negative output end, and a positive power pin connected to the positive supply pin.

The powered device integrated chip leaves a detection pin and a classification pin floating.

Optionally, the switch control module further includes: a third resistor, a fourth resistor and a fifth resistor.

The third resistor has one end connected to the positive supply pin, and the other end connected to the under voltage lock out pin.

The fourth resistor has one end connected to the under voltage lock out pin, and the other end connected to the negative output end.

The fifth resistor has one end connected to a current limiting pin of the powered device integrated chip, and the other end connected to the negative output end.

Optionally, the power supply circuit further includes: a first protection device, a second protection device, and a third protection device.

The first protection device has one end connected to the positive supply pin, and the other end connected to the negative supply pin.

The second protection device has one end connected to the negative output end, and the other end connected to the negative supply pin.

The third protection device has a negative terminal connected to the positive supply pin, and a positive terminal connected to the negative output end.

Optionally, the power supply circuit includes two rectifier modules, and the input interface of the relay device includes eight input pins.

One of the two rectifier modules has an input end connected to four input pins of the input interface, and the other rectifier module has an input end connected to the other four input pins of the input interface.

In a second aspect, a relay device is provided. The relay device includes a relay circuit for forwarding signals, and a power supply circuit as described in the first aspect.

The relay circuit has a positive terminal connected to a positive supply pin of the power supply circuit, and a negative terminal connected to a negative supply pin of the power supply circuit.

Optionally, the relay device further includes a first transformer and a second transformer.

The relay circuit is connected to the input interface of the relay device through the first transformer, and is connected to the output interface of the relay device through the second transformer.

In a third aspect, another relay device is provided. The relay device is used for connecting a first network cable with a second network cable. The relay device includes any of the foregoing power supply circuits, and further includes:

a first PHY chip connected to the first network cable and a second PHY chip connected to the second network cable, a data transmission interface of the first PHY chip is communicatively connected to a data reception interface of the second PHY chip, the data reception interface of the first PHY chip is communicatively connected to the data transmission interface of the second PHY chip, and the power supply circuit is connected to and powers the first PHY chip and the second PHY chip.

Optionally, the first PHY chip is connected to the first network cable through an RJ45 interface, and the second PHY chip is connected to the second network cable through an RJ45 interface.

Optionally, the first PHY chip comprises a first transceiving interface in which the data transmission interface and data reception interface of the first PHY chip are integrated; the second PHY chip comprises a second transceiving interface in which the data transmission interface and data reception interface of the second PHY chip are integrated; and the first transceiving interface is plugged and mated with the second transceiving interface.

Optionally, the first transceiving interface and the second transceiving interface are selected from a group consisting of an RMII interface, a GMII interface, an RGMII interface and a MII interface.

Optionally, the relay device further includes a housing in which the first PHY chip, the second PHY chip, and the power supply circuit are disposed.

Optionally, the relay device further includes an MCU control chip, which is disposed in the housing, connected to the first PHY chip and the second PHY chip, and configured for controlling initialization of the first PHY chip and the second PHY chip and matching a network rate of the first PHY chip with that of the second PHY chip.

Optionally, the first PHY chip is provided with a first MDIO interface connected to the MCU control chip, and the second PHY chip is provided with a second MDIO interface connected to the MCU control chip.

Optionally, the relay device further includes a clock circuit connected to both the first PHY chip and the second PHY chip, the clock circuit is provided in the housing, and is configured for synchronizing data transmission between the first PHY chip and the second PHY chip.

Optionally, the first PHY chip is provided with a first CLKIN interface connected to the clock circuit, and the second PHY chip is provided with a second CLKIN interface connected to the clock circuit.

In a fourth aspect, a Power over Ethernet system is provided. The system includes:

a power sourcing equipment, a powered device and the relay device as described in the second aspect.

The relay device has an input interface connected to the power sourcing equipment, and the output interface of the relay device is connected to the powered device.

Optionally, the system may further include: a first network cable and a second network cable. The first network cable and the second network cable are connected through the relay device as described above.

The beneficial effects of the technical solutions provided by the present application are as follows.

Embodiments of the present application provide a power supply circuit, a relay device, and a Power over Ethernet system. The power supply circuit can convert a received input voltage of uncertain polarity into an input voltage of determined polarity through a rectifier module, and can be controlled, by a switch control module, to stop the delay circuit from working if the input voltage is less than or equal to a preset threshold, without affecting the detection and classification process of the PSE. When the input voltage is greater than the preset threshold, that is, when the PSE is supplying power, the power supply circuit starts to power the relay circuit, so as to implement transmission of power signal and forwarding of data signal.

