Serial port circuit design satisfying power on Ethernet (POE) non-isolated power system

Abstract

The present invention discloses a serial port circuit design satisfying a power on Ethernet (POE) non-isolated power system. The serial port circuit design includes a POE voltage stabilizing circuit, a main voltage generation module, a controllable switch array, an interface circuit and a system circuit. The POE voltage stabilizing circuit is used for rectifying a direct current with unknown polarities from an Ethernet power supply device so as to generate a high voltage with known polarities to output, converting the high voltage into a stable voltage to output, and transmitting data from the Ethernet to the system circuit. The main voltage generation module is used for converting the output of the POE voltage stabilizing circuit into a voltage required by the system, and delaying outputting of the voltage relatively to the output of the POE voltage stabilizing circuit. The controllable switch array is used for isolating the interface circuit from the system circuit and the main voltage generation module in an early establishment stage of the output of the POE voltage stabilizing circuit, and connecting the interface circuit with the main voltage generation module and the system circuit after the output establishment or starting of the system circuit. According to the serial port circuit design, a serial port path is prevented from bringing interference of a power system power frequency 50Hz of a user terminal into a chip detection terminal, so as not to cause detection failure to result in printed circuit board (PCB) powering starting failure.

Description

technical field [0001] The invention relates to a circuit, in particular to a serial port design circuit satisfying a POE non-isolated power supply system. Background technique [0002] Now more and more home terminals, monitoring equipment and enterprise network communication products are successively choosing to obtain system power supply through network cables, thus getting rid of the trouble caused by using AC adapters, and will further expand the application field of Ethernet technology. Products for such power supply and receiving power are called POE equipment, namely poweronEthernet. There are also two types of power receiving through POE: isolated and non-isolated. There is no direct electrical connection between the input circuit and the output circuit of the isolated power supply, and the input and output are in an isolated high-impedance state without a current circuit. It has strong anti-interference ability and high safety, but its structure is complex and bul...

AI Technical Summary

Problems solved by technology

[0008] figure 2 It is a schematic diagram of the voltage start signal of the PD chip detection terminal that is not connected to the serial port interface of the system to the PC. image 3 It is a schematic diagram of the voltage start signal of the PD chip detection terminal connected to the serial port interface of the system terminal to the PC. From the above two figures, it can be seen that when the system terminal is connected to the serial port, the 50Hz power frequency signal in the AC grid of the user debugging terminal will be interfered. Bringing in, this will affect the PSE's detection and judgment of whether the PD device exists

Sometimes it will enter the repeated detection process, which will cause the system to fail to power on normally

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