CN212063492U - RJ45 net mouth protection circuit - Google Patents
RJ45 net mouth protection circuit Download PDFInfo
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- CN212063492U CN212063492U CN202020367672.7U CN202020367672U CN212063492U CN 212063492 U CN212063492 U CN 212063492U CN 202020367672 U CN202020367672 U CN 202020367672U CN 212063492 U CN212063492 U CN 212063492U
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Abstract
The utility model relates to a RJ45 net gape protection circuit, include: the network transformer comprises an RJ45 net port, a network transformer, a chip and a self-recovery fuse, wherein the network transformer comprises a primary end and a secondary end, the self-recovery fuse is connected between the RJ45 net port and the primary end of the network transformer, the current limit of the self-recovery fuse is 50mA at most, and the withstand current of the network transformer is 600mA at least. The problem that the network transformer is easy to damage can be solved by reducing the current limiting of the self-recovery fuse and increasing the tolerant current of the network transformer, the stability of the circuit is improved, and the protection effect of the circuit is enhanced.
Description
Technical Field
The utility model relates to a RJ45 net gape, especially a prevent that RJ45 net gape from inserting by mistake and leading to RJ45 net gape protection circuit that power and device damaged.
Background
In a usage scenario of the RJ45 network port, the RJ45 network port may be used as a standard ethernet interface, and may also be used as an interface for other communication circuits and power supplies, where different communication interfaces correspond to different definitions of signals in the RJ 45. However, when different communication interfaces are plugged in wrong pairs, the situation that the power supply is short-circuited can occur, so that the power supply and devices are damaged.
In the prior art, several common protection devices are usually added to an RJ45 network interface circuit to protect the interface circuit. For example, only the self-recovery fuse and the gas discharge tube are adopted to limit the current in the circuit, and when short circuit or large current impact occurs, the self-recovery fuse carries out overcurrent protection, and simultaneously, large voltage difference is formed between two ends of the self-recovery fuse, so that the three-level ceramic gas discharge tube is broken down to form short circuit, and the transformer is protected to prevent the transformer from being broken down.
However, in this type of scheme, since a self-recovery fuse having a current limit value of 100mA or more is generally used, the current limit value is large, and therefore, the operation time of the self-recovery fuse is long. The current endurance value of the network transformer is small, and before the network transformer enters an overcurrent protection state, more current actually enters the network transformer, so that the network transformer is damaged.
Therefore, in order to solve the above problems, a better RJ45 net port protection circuit must be designed.
SUMMERY OF THE UTILITY MODEL
In order to solve one of the above problems, the utility model also provides a RJ45 net gape protection circuit, include: the network transformer comprises an RJ45 net port, a network transformer, a chip and a self-recovery fuse, wherein the network transformer comprises a primary end and a secondary end, the self-recovery fuse is connected between the RJ45 net port and the primary end of the network transformer, the current limit of the self-recovery fuse is 50mA at most, and the withstand current of the network transformer is 600mA at least.
As a further improvement of the present invention, the RJ45 net gape protection circuit further includes a first common mode inductor disposed between the primary terminal and the RJ45 net gape, the first common mode inductor includes a first coil and a second coil, the first coil one end is connected to the first current inlet of the primary terminal, the second coil one end is connected to the current outlet of the primary terminal.
As a further improvement of the present invention, the RJ45 net mouth includes first difference signal end and impedance matching end, the self-resuming fuse is including first self-resuming fuse and second self-resuming fuse, first self-resuming fuse establish ties in between first difference signal end and the first coil, the second self-resuming fuse establish ties in between impedance matching end and the second coil.
As a further improvement of the present invention, the current tolerance of the first common mode inductor is greater than 0.65A.
As a further improvement of the present invention, the instantaneous current carrying capacity of the network transformer is greater than 3A.
As a further improvement of the present invention, the RJ45 net mouth protection circuit includes a second common mode inductor disposed between the secondary terminal and the chip, and the second common mode inductor includes a third coil and a fourth coil; one end of the third coil is connected to the current inlet of the secondary end, and the other end of the third coil is connected to the differential signal interface of the chip; one end of the fourth coil is connected to the current outlet of the secondary end, and the other end of the fourth coil is connected to the other differential signal pair interface of the chip.
As a further improvement of the present invention, the RJ45 net mouth protection circuit includes a transient diode, the transient diode is connected in parallel between two differential signal pair interfaces of the chip.
As a further improvement of the present invention, the RJ45 net mouth includes the second differential signal end, the RJ45 net mouth protection circuit includes a resistor assembly, resistor assembly one end connect in the second differential signal end, the other end is connected in the second current inlet of primary.
As a further improvement of the present invention, the resistor assembly includes two pull-up matching resistors, and the resistance of the matching resistors is 50 Ω.
Compared with the prior art, the problem that the network transformer is easy to damage can be solved by reducing the current limit of the self-recovery fuse to 50mA and increasing the tolerant current of the network transformer to 600mA, the stability of the circuit is improved, and the protection effect of the circuit is enhanced.
Drawings
Fig. 1 is a circuit schematic diagram of the RJ45 network port protection circuit of the present invention.
Detailed Description
In order to make the technical solutions in the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts shall belong to the protection scope of the present invention.
As shown in fig. 1, the utility model provides a RJ45 net gape protection circuit, including RJ45 net gape 1, network transformer 2, chip 3, network transformer 2 includes primary 21 and secondary 22, and obviously, RJ45 net gape 1 is connected with primary 21, chip 3 is connected with secondary 22, network transformer 2 undertakes the effect of changing voltage. And, the primary side 21 of the network transformer 2 comprises a current inlet and a current outlet.
The RJ45 net mouth protection circuit further comprises a self-recovery fuse 5 arranged between the primary end 21 and the RJ45 net mouth 1, the current limit of the self-recovery fuse 5 is 50mA at most, and the withstand current of the network transformer 2 is 600mA at least.
Therefore, by reducing the current limit of the self-recovery fuse 5 and increasing the withstand current of the network transformer 2, the problem that the network transformer 2 is easy to damage can be solved, the stability of the circuit is improved, and the protection effect of the circuit is enhanced.
The RJ45 net mouth protection circuit further includes a first common mode inductor 4 disposed between the primary terminal 21 and the RJ45 net mouth 1, where the first common mode inductor 4 includes a first coil 41 and a second coil 42, one end of the first coil 41 is connected to the first current inlet of the primary terminal 21, and one end of the second coil 42 is connected to the current outlet of the primary terminal 21.
Therefore, in the invention, the first common mode inductor 4 is added between the transformer 2 and the RJ45 network port 1, so that after a short circuit occurs at the RJ45 network port 1, the common mode voltage at the RJ45 network port 1 can be suppressed, thereby further enhancing the protection effect of the circuit.
Specifically, the RJ45 network port 1 includes a first differential signal terminal J6 and an impedance matching terminal J3, and in the present embodiment, the self-healing fuse 5 includes a first self-healing fuse and a second self-healing fuse, the first self-healing fuse is connected in series between the first differential signal terminal J6 and the first coil 41, and the second self-healing fuse is connected in series between the impedance matching terminal J3 and the second coil 42.
That is, the first coil 41 and the first self-healing fuse are connected between the first differential signal terminal J6 of the RJ45 port 1 and the first current inlet of the primary side 21 of the network transformer 2, and the second coil 42 and the second self-healing fuse are connected between the impedance matching terminal J3 of the RJ45 port 1 and the current outlet of the primary side 21 of the network transformer 2. Thus, if a short circuit occurs between the first differential signal terminal J6 and the impedance matching terminal J3 of the RJ45 network port 1, a short-circuit current flows from the first differential signal terminal J6 of the RJ45 network port 1 to the first current inlet of the primary terminal 21 of the network transformer 2 through the first self-healing fuse and the first coil 41, and then flows from the current outlet to the impedance matching terminal J3 through the second coil 42 and the second self-healing fuse, as shown by the dashed line a in fig. 1. Therefore, the currents in the first coil 41 and the second coil 42 of the first common mode inductor 4 flow in opposite directions, and can play a role of suppressing the common mode voltage.
Moreover, the self-recovery fuse 5 can be fused under the condition of short circuit, and is equivalent to a resistor with a larger resistance value, so that the current in a circuit loop is reduced, the network transformer 2 is prevented from being damaged, and other devices are also protected.
Therefore, the self-recovery fuse 5 is matched with the first common-mode inductor 4, on one hand, when short circuit occurs and large current passes through, the self-recovery fuse 5 has not yet reacted, and the first common-mode inductor 4 can also reduce the common-mode inductor; on the other hand, the self-recovery fuse 5 immediately works to reduce the current in the circuit, thereby completing the protection of the power supply and the electronic device.
The self-recovery fuse 5 is a self-recovery fuse that is limited to a current of at most 50 mA. The self-restoring fuse is an overcurrent electronic protection element, and is made up by using high-molecular organic polymer, under the conditions of high pressure, high temp. and sulfurization reaction, and adding conductive particle material and adopting special technological process. The traditional self-recovery fuse 5 can only protect once and is blown to be replaced, and the self-recovery fuse has the dual functions of overcurrent and overheating protection and automatic recovery. Therefore, the self-recovery fuse 5 in the invention adopts the self-recovery fuse, and can still automatically recover after the current is normal after the self-recovery fuse 5 is fused, so that the trouble of replacement is avoided. In addition, the self-recovery fuse adopts 50mA current limiting, can meet the current of the RJ45 network port 1 in the short-circuit condition, and can prevent the transformer from being damaged.
The current endurance of the first common mode inductor 4 is greater than 0.65A. The larger the current tolerance of the first common mode inductor 4 is, the better the stability of the first common mode inductor 4 in the circuit is, and the more the common mode voltage at the RJ45 network port 1 can be suppressed.
The network transformer 2 has a withstand current of at least 600 mA. The higher withstand current may make the stability of the network transformer 2 stronger. The withstand current of the network transformer 2 is adapted to the current limit of the self-healing fuse. Because the network transformer 2 selected in the invention has large tolerance current and strong tolerance capability, and because of the cooperation of the first common mode inductor 4, the short circuit current in the circuit is not enough to damage the network transformer 2 before the self-recovery fuse 5 is fused. Then the self-recovery fuse 5 is blown out, the current in the circuit is reduced to be minimum, and the protection of the RJ45 network port 1, the network transformer 2 and other devices is completed. In addition, the instant current bearing capacity of the network transformer is larger than 3A, and the safety of the network transformer is further improved.
In addition, as shown in fig. 1, the RJ45 net port protection circuit further includes a second common mode inductor 6 disposed between the secondary side 22 of the network transformer 2 and the chip 3, where the second common mode inductor 6 includes a third coil 61 and a fourth coil 62; the third coil 61 has one end connected to the current inlet of the secondary terminal 22 and the other end connected to the differential signal interface of the chip 3; the fourth coil 62 is connected at one end to the current outlet of the secondary side 22 and at the other end to another differential signal pair interface of the chip 3.
The second common-mode inductor 6 arranged between the secondary end 22 of the network transformer 2 and the chip 3 can further suppress the common-mode voltage penetrating at the primary end 21 of the network transformer 2, protect the chip 3 and further enhance the anti-interference capability of the circuit.
In addition, as shown in fig. 1, the RJ45 net port protection circuit also includes a transient diode 7, and the transient diode 7 is connected in parallel between two differential signal pair interfaces of the chip 3. In the present invention, the transient diodes 7 are arranged in a plurality of combinations.
A Transient diode 7(Transient Voltage super) is abbreviated as TVS, and is a high-performance protection device in the form of a diode. When two poles of the TVS diode are impacted by reverse transient high energy, the TVS diode can change the high impedance between the two poles into low impedance at the speed of 10 to the order of minus 12 seconds, absorb surge power of thousands of watts and clamp the voltage between the two poles at a preset value, thereby effectively protecting precise components in an electronic circuit from being damaged by various surge pulses. Therefore, the transient diode 7 is adopted in the invention to prevent static electricity, further protect the chip 3 and improve the stability of signal transmission.
The RJ45 net port 1 further includes a second differential signal terminal J7, and the RJ45 net port protection circuit further includes a resistor component, one end of the resistor component is connected to the second differential signal terminal J7, and the other end of the resistor component is connected to the second current inlet of the primary terminal 21.
When a short circuit occurs between the second differential signal terminal J7 and the impedance matching terminal J3, as shown by the dashed line B in fig. 1, a short-circuit current in the circuit flows from the second differential signal terminal J7, through the resistor assembly, into the second current inlet of the primary terminal 21 of the network transformer 2, out of the current outlet, and back to the impedance matching terminal J3 of the RJ45 network port 1. Thus, as shown in fig. 1, the short circuit current flows through the second coil 42 of the first common mode inductor 4 and a self-recovery fuse 5.
When a short circuit occurs between the second differential signal terminal J7 and the impedance matching terminal J3, the current in the circuit is greatly reduced due to the resistance component, and the short-circuit current is smaller than the maximum current allowed by the network transformer 2, so that the protection effect can be achieved.
The RJ45 network port 1 of the present invention includes a first differential signal terminal J6 and a second differential signal terminal J7, and correspondingly, the primary terminal 21 of the network transformer 2 also includes the first current inlet and the second current inlet to form different current loops.
Specifically, in the present invention, the resistor assembly includes two pull-up matching resistors 8, and the resistance of the matching resistor 8 is 50 Ω. Since the voltage of the first differential signal terminal J6 and the second differential signal terminal J7 ranges from 5V to 15V, the second differential signal terminal J7 is at the highest voltage, and if a short circuit occurs, the current on the matching resistor 8 is about 150mA, while as mentioned above, the withstand current of the network transformer 2 is at least 600mA, which is higher than 150mA, so that the circuit device can be protected even if the second differential signal terminal J7 is short-circuited. Of course, if the resistor assembly has other resistor structures and the resistance of the resistor has other values, the invention is within the protection scope as long as the purpose of the invention can be satisfied.
Therefore, in summary, the RJ45 net port protection circuit of the present invention can overcome the problem that the network transformer 2 is easily damaged by reducing the current limit of the self-healing fuse 5 and increasing the withstand current of the network transformer 2, thereby improving the stability of the circuit and enhancing the protection effect of the circuit.
And the first common mode inductor 4 is added between the network transformer 2 and the RJ45 network port 1, so that the common mode voltage at the RJ45 network port 1 can be suppressed after the RJ45 network port 1 is short-circuited, and the protection effect of the circuit is further enhanced.
Furthermore, in the invention, a second common-mode inductor 6 and a transient diode 7 are arranged between the secondary end 22 of the network transformer 2 and the chip 3, so that common-mode voltage can be further inhibited, the rear-stage chip 3 can be protected, and the stability of signals can be improved.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should make the description as a whole, and the embodiments may be appropriately combined to form other embodiments understood by those skilled in the art.
The above list of details is only for the feasible embodiments of the present invention, and is not intended to limit the scope of the present invention, and all equivalent embodiments or modifications that do not depart from the technical spirit of the present invention are intended to be included within the scope of the present invention.
Claims (9)
1. An RJ45 net port protection circuit, comprising: RJ45 net mouth, network transformer, chip, self-recovery fuse, the network transformer includes primary side and secondary side, characterized in that, the self-recovery fuse is connected between RJ45 net mouth and the primary side of network transformer, the current limiting of self-recovery fuse is 50mA at most, and the withstand current of network transformer is 600mA at least.
2. The RJ45 net port protection circuit according to claim 1, wherein the RJ45 net port protection circuit further comprises a first common mode inductor disposed between the primary terminal and the RJ45 net port, the first common mode inductor comprises a first coil and a second coil, one end of the first coil is connected to the first current inlet of the primary terminal, and one end of the second coil is connected to the current outlet of the primary terminal.
3. The RJ45 net gape protection circuit of claim 2, wherein the RJ45 net gape comprises a first differential signal terminal and an impedance matching terminal, the self-restoring fuse comprises a first self-restoring fuse and a second self-restoring fuse, the first self-restoring fuse is connected in series between the first differential signal terminal and a first coil, and the second self-restoring fuse is connected in series between the impedance matching terminal and a second coil.
4. The RJ45 net port protection circuit of claim 2, wherein the current tolerance of the first common mode inductor is greater than 0.65A.
5. The RJ45 net gape protection circuit of claim 1, wherein the instantaneous current carrying capacity of the network transformer is greater than 3A.
6. The RJ45 net gape protection circuit of claim 1, wherein the RJ45 net gape protection circuit comprises a second common mode inductor disposed between a secondary and a chip, the second common mode inductor comprising a third coil and a fourth coil; one end of the third coil is connected to the current inlet of the secondary end, and the other end of the third coil is connected to the differential signal interface of the chip; one end of the fourth coil is connected to the current outlet of the secondary end, and the other end of the fourth coil is connected to the other differential signal pair interface of the chip.
7. The RJ45 portal protection circuit of claim 1, wherein the RJ45 portal protection circuit comprises a transient diode connected in parallel between two differential signal pair interfaces of the chip.
8. The RJ45 net gape protection circuit of claim 1, wherein the RJ45 net gape comprises a second differential signal terminal, and the RJ45 net gape protection circuit comprises a resistor component, one end of the resistor component is connected to the second differential signal terminal, and the other end of the resistor component is connected to the second current inlet of the primary terminal.
9. The RJ45 net gape protection circuit of claim 8, wherein the resistor assembly comprises two pull-up matching resistors, and the resistance of the matching resistors is 50 Ω.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020367672.7U CN212063492U (en) | 2020-03-20 | 2020-03-20 | RJ45 net mouth protection circuit |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202020367672.7U CN212063492U (en) | 2020-03-20 | 2020-03-20 | RJ45 net mouth protection circuit |
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| CN212063492U true CN212063492U (en) | 2020-12-01 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112637089A (en) * | 2020-12-09 | 2021-04-09 | 锐捷网络股份有限公司 | Switch |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112637089A (en) * | 2020-12-09 | 2021-04-09 | 锐捷网络股份有限公司 | Switch |
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