CN212412751U - PSE port common mode lightning stroke protection circuit - Google Patents

Abstract

The utility model discloses a PSE port common mode thunderbolt protection circuit, PSE port include power, PSE chip, TVS, diode D3-D4, net gape isolation transformer and diode D1-D2, net gape isolation transformer 4&5 central taking a percentage and 7&8 central taking a percentage of line pair connect the back diode D1 negative pole and diode D2 anodal, and diode D1 anodal connection power negative terminal, diode D2 negative pole connection power positive terminal. The utility model discloses a two fast recovery diodes D1, D2 have 1&2 line pairs and 3&6 line pairs of protection to the common mode thunderbolt direction, successfully solve to float ground AP butt joint ground connection PSE ethernet switch, PD mouth or PSE port common mode thunderbolt test damage's problem on the AP, PIN stitch problem of striking sparks when avoiding PSE port common mode thunderbolt test to also there is not harmful effects when floating ground AP to floating ground PSE, do not influence the common mode and keep apart.

Description

PSE port common mode lightning stroke protection circuit

Technical Field

The utility model belongs to the technical field of communication, concretely relates to PSE port common mode thunderbolt protection circuit.

Background

Wireless ap (access point): i.e., a wireless access point, which is used for a wireless switch of a wireless network, and is also the core of the wireless network. The wireless AP is an access point for a mobile computer user to enter a wired network, is mainly used in broadband families, buildings and parks, and can cover dozens of meters to hundreds of meters. The environment where the wireless AP is usually located is inconvenient to acquire an AC Power source, and generally, Power is obtained through a POE (Power Over Ethernet) function, for example, the AP obtains Power from a PSE (Power Sourcing Equipment) Ethernet switch, and simultaneously supports PSE output for AP cascade. The AP is usually floating equipment and is not connected with the ground, the lightning surge of the port is relative to the ground, active common-mode lightning surge protection measures cannot be carried out on the floating AP, and common-mode protection is realized by only depending on isolation. In the actual use scene, when floating AP when to the PSE ethernet switch of ground connection, often take place the trouble of AP differential mode protection damage, promote the protection level back to AP's differential mode, take place again that PSE interface common mode surge leads to the phenomenon of discharging between pin (stitch) on the AP.

A PD port lightning surge protection circuit on an AP device which is usually floating is shown in figure 1, and because the AP is not grounded, a common mode discharge path is not formed when the AP is tested independently. When the isolated AC-DC power adapter supplies power to the floating-ground AP, the common-mode protection in an isolation mode has no problem. However, when the floating AP is connected to a grounded PSE ethernet switch, since the ethernet switch is grounded, the PD and PSE common path between the PSE switch and the AP is the POE negative terminal. In POE applications, the PSE is powered by a 48V power supply. Typically, the PSE will have some common mode capacitance connected to earth ground on an ethernet switch connected to ground. These capacitors may be discrete capacitors, or may be interlayer capacitors of the PCB, or a combination of both types of capacitors. It is not excluded that some non-isolated PSE switches on the network do not consider the isolation between the POE negative terminal and ground at all. Because the ethernet switch PSE is not actually truly floating, when the floating AP is connected to the grounded PSE ethernet switch, the common path between the PSE switch and the PD of the AP and the PSE is the POE negative terminal, and the network has a coupling capacitance with the ground on the ethernet switch, so that the common mode test of the PD port or the PSE port on the AP becomes the differential mode of other networks on the network port to the POE negative terminal, but part of the energy is mainly low frequency and direct current components blocked by the common mode capacitance.

According to the customer's test specification, the common mode lightning stroke is 4000V, the equivalent impedance 2+200/8 is 27 ohms, the current is 148A (8/20 waveform), and the TVS diode SMA J58A originally reserved for the differential mode is only 53A (8/20 waveform), so the damage is caused. The TVS diode needs to be replaced by a 1500W SMC J58A (250A 8/20) and then the TVS diode can pass the verification. When the AP is connected with the grounded PSE Ethernet switch, after the differential mode protection of the PSE port on the AP is also replaced by a high-power TVS, although the TVS is not damaged in the common-mode lightning stroke test, the phenomenon of discharging among RJ45 pins exists, the reason is considered because the PSE port is POE + (enhanced POE), 1&2, 3&6 power supply, 4&5 and 7&8 power supply are omitted, so that when the 8-line-to-ground test of the network port is carried out, 1&2, 3&6 overvoltage is discharged, 4&5 and 7&8 overvoltage cannot be discharged, and the voltage difference among the pins is caused to discharge.

SUMMERY OF THE UTILITY MODEL

The utility model discloses the technical problem that needs solve is that the common mode lightning stroke protection circuit who avoids the common mode damage and avoid discharging between PSE port stitch when providing the AP butt joint grounding's PSE ethernet switch that floats ground.

In order to solve the above problems, the utility model adopts the following technical proposal:

a PSE port common mode lightning strike protection circuit comprises a power supply, a PSE chip, a TVS, diodes D3-D4 and a net mouth isolation transformer, wherein the TVS is a power supply differential mode surge protection device and is connected in parallel with a positive end and a negative end of the power supply, the positive end and the negative end of the power supply are connected with a power supply input end of the PSE chip to provide power supply input for the PSE chip, the output of the PSE chip is connected with a central tap of a net mouth isolation transformer 1&2 pair through a resistor R4 and is connected with a central tap of a net mouth isolation transformer 3&6 pair and a positive end of the power supply through a diode D3, the negative end of the power supply is connected with a central tap of a net mouth isolation transformer 1&2 pair and a central tap of a net mouth isolation transformer 3&6 pair through a diode D4 to provide electric energy for the net mouth isolation transformer 1&2 pair and the 3&6 pair, the circuit also comprises diodes D1-D2, the central taps of, the anode of the diode D1 is connected with the negative end of the power supply, and the cathode of the diode D2 is connected with the positive end of the power supply.

Preferably, the diodes D1-D4 are fast recovery diodes.

Further, the rated voltage of the diodes D1-D4 is 200V, and the rated current is 1A.

Preferably, the diodes D1-D2 are schottky diodes.

Preferably, the TVS employs 1500W transient voltage suppression diode SMCJ 58A.

Adopt the produced beneficial effect of above-mentioned technical scheme to lie in:

the utility model discloses a two fast recovery diodes D1, D2 have 1&2 line pairs and 3&6 line pairs of protection to the common mode thunderbolt direction, successfully solve to float ground AP butt joint ground connection PSE ethernet switch, PD mouth or PSE port common mode thunderbolt test damage problem on the AP, PIN stitch problem of striking sparks when avoiding PSE port common mode thunderbolt test to also there is not harmful effects when floating ground AP butt joint floats ground PSE, do not influence the common mode and keep apart.

Drawings

FIG. 1 is a lightning surge protection circuit of a PD port on a common floating ground AP device;

FIG. 2 is a schematic circuit diagram of the present invention;

Detailed Description

The utility model is described in further detail below with reference to the attached drawings:

the utility model relates to a be used for floating ground AP equipment butt joint ground connection PSE ethernet switch, avoid the common mode damage and avoid the common mode thunderbolt protection circuit that discharges between PSE port stitch. As shown in fig. 2, the utility model discloses the circuit includes the power, the PSE chip, TVS (transient voltage restraines the diode), diode D3-D4 and net gape isolation transformer, wherein TVS is power differential mode surge protection device, it is just parallelly connected at the power, the negative terminal, the power is just, PSE chip power input end is connected to the negative terminal, provide power input for the PSE chip, PSE chip output connects net gape isolation transformer 1&2 line pair center tap and connects net gape isolation transformer 3&6 line pair center tap and power positive terminal through diode D3 through resistance R4, the power negative terminal connects net gape isolation transformer 1&2 line pair center tap through diode D4, for net gape isolation transformer 1&2 line pair, 3&6 line pair provide the electric energy.

In order to meet the test specification of 4000V customer common mode lightning stroke, the TVS adopts 1500W SMCJ58A (250A8/20us), and the test can be passed. In the test that follows, when floating ground AP to the PSE ethernet switch of ground connection to after the differential mode protection of the PSE port on floating ground AP is changed for high-power (1500W) TVS equally, the phenomenon of discharging between RJ45 stitch appears, for solving this problem, the utility model discloses with two fast recovery diodes D1, D2 to the 1&2 line pair and 3&6 line pair that have the protection of common mode thunderbolt direction, connect diode D1 negative pole and diode D2 positive pole after the centre tap of net gape isolation transformer 4&5 line pair is connected with the centre tap of 7&8 line pair, diode D1 positive pole connection power negative terminal, diode D2 negative pole connection power positive terminal. That is, after the center taps of the 4&5 line pair and the 7&8 line pair are combined, a forward diode D2 is added to the center tap of the 3&6 line pair (power supply positive terminal), a backward diode D1 is added to the center tap of the 1&2 line pair (power supply negative terminal), the diodes D1-D2 adopt fast recovery diodes, the rated voltage of the fast recovery diodes is 200V, the rated current is 1A, the forward recovery time is about 30ns, and schottky diodes can be adopted.

In order to further reduce the common mode protection cost of the power supply pins, the diodes D3 and D4 also adopt fast recovery diodes, the rated voltage of the fast recovery diodes is 200V, and the rated current of the fast recovery diodes is 1A. I.e., diodes D1-D4 are of a uniform type.

Claims (5)

1. The utility model provides a PSE port common mode lightning strike protection circuit, the PSE port includes the power, the PSE chip, TVS, diode D3-D4 and net gape isolation transformer, wherein TVS is power differential mode surge protection device, connect in parallel at the power just, the negative terminal, the power is just, the negative terminal is connected PSE chip power input end, provide power input for the PSE chip, PSE chip output connects net gape isolation transformer 1&2 line pair center tap and connects net gape isolation transformer 3&6 line pair center tap and power positive terminal through diode D3 through resistance R4, the power negative terminal connects net gape isolation transformer 1&2 line pair center tap through diode D4, provide the electric energy for net gape isolation transformer 1&2 line pair, 3&6 line pair, its characterized in that: the power supply further comprises diodes D1-D2, the center tap of the network port isolation transformer 4&5 line pair is connected with the center tap of the 7&8 line pair and then connected with the cathode of the diode D1 and the anode of the diode D2, the anode of the diode D1 is connected with the negative end of the power supply, and the cathode of the diode D2 is connected with the positive end of the power supply.

2. The PSE port common mode lightning strike protection circuit of claim 1, characterized in that: the diodes D1-D4 are fast recovery diodes.

3. The PSE port common mode lightning strike protection circuit of claim 2, characterized in that: the rated voltage of the diodes D1-D4 is 200V, and the rated current is 1A.

4. The PSE port common mode lightning strike protection circuit of claim 1, characterized in that: the diodes D1-D2 are Schottky diodes.

5. The PSE port common mode lightning strike protection circuit of claim 1, characterized in that: the TVS employs 1500W transient voltage suppression diode SMCJ 58A.

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