CN101882998B - Ethernet interface circuit - Google Patents
Ethernet interface circuit Download PDFInfo
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- CN101882998B CN101882998B CN2010102059285A CN201010205928A CN101882998B CN 101882998 B CN101882998 B CN 101882998B CN 2010102059285 A CN2010102059285 A CN 2010102059285A CN 201010205928 A CN201010205928 A CN 201010205928A CN 101882998 B CN101882998 B CN 101882998B
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Abstract
The invention relates to the field of Ethernet power supply, in particular to an Ethernet interface circuit capable of preventing high voltage produced by lightning stroke from affecting the resistance between power supply line pairs when the high voltage enters from non power supply line pairs. The Ethernet interface circuit comprises a first isolating transformer, a second isolating transformer, a third isolating transformer, a fourth isolating transformer, a second capacitor and a fifth capacitor, wherein the secondary coil output ends of the first isolating transformer and the second isolating transformer are the power supply line pairs respectively, and the secondary coil output ends of the third isolating transformer and the fourth isolating transformer are the non power supply line pairs respectively; one end of the second capacitor is connected with a center tap of a secondary coil of the second isolating transformer, while the other end is grounded through a sixth capacitor; center taps of secondary coils of the third isolating transformer and the fourth isolating transformer are grounded through the sixth capacitor; and one end of the fifth capacitor is connected with a center tap of a secondary coil of the first isolating transformer, while the other end is grounded.
Description
Technical field
The present invention relates to the POE field, especially a kind of ethernet interface circuit.
Background technology
POE (Power Over Ethernet, POE) technology is a kind ofly to carry galvanic mode in transmission in the data through the Ethernet cable.Wherein, the POE system comprises: power supply unit (Power Source Equipment, PSE) and power receiving equipment (Powered Device, PD).In the POE system, provide the equipment of power supply to be called power supply unit, the equipment of accepting the DC power supply that PSE equipment provides is called power receiving equipment.In the POE system, generally adopt ethernet interface circuit, connect PSE and PD, be illustrated in figure 1 as the structure chart of POE system, the CABLE SIDE (cable-side) of ethernet interface circuit is wiring cable one end, load is connected with far-end PD through cable; PCB SIDE (physical layer) end of ethernet interface circuit is connected with the coherent signal of Ethernet switch; Wherein CH1+/--CH4+/-be connected with the signal of the correspondence of the physical chip of Ethernet switch; Be used for transmission and receive data; Pin11, pin12 and PSE link to each other, and are used to realize the power supply of PSE to far-end PD load.
Be illustrated in figure 2 as the existing Ethernet interface circuit, CABLE end is wiring cable one end, and 8 twisted-pair feeders are arranged, and totally 4 pairs of differential lines are right, be divided into supply lines to (1,2 and 3,6) and non-supply lines to (4,5 and 7,8); Ethernet interface circuit comprises: isolating transformer T1/A, T2/A, T3/A, T4/A, the secondary coil output of T1/A and T2/A are respectively supply lines to (1,2) and (3,6), and it is right that the secondary coil output of T3/A and T4/A is respectively non-supply lines; Also comprise capacitor C 1, C2, C3, C4, capacitance is 0.022uF, and withstand voltage is 250V, resistance R 1, R2, R3, R4, and resistance is 75OHM.T5 is the common mode inhibition device, and pin11, pin12 link to each other with PSE, and the differential lines that is coupled to CABLE end through T5 then is the PD electric of far-end to last.
POE powered operation process is: testing process, PD hold device class, begin power supply, supply power, cut off the power supply.Wherein, Testing process is the detection voltage that PSE sends a 2.8V-10V; Be used to detect the PD that cable terminations connects and whether meet the IEEE802.3af standard, only meet the IEEE802.3af standard, could supply power for PD; A PD who meets the IEEE802.3af standard, its supply lines between resistance and electric capacity following requirement: 19K≤Rgood≤26.5K and Cgood≤150nF are arranged; A PD who does not meet IEEE802.3af, its supply lines between resistance and electric capacity be: Rbad＜15K or Rbad＞33K or Cbad＞10uF.
When ethernet interface circuit connects the PD load; Supply lines between the equivalent circuit diagram of resistance as shown in Figure 3; RJ45CABLE end supply lines to the resistance Rab between the AB and far-end PD electric line between resistance Rpd be that parallel connection concerns; After the parallel connection, PD electric line between equivalent resistance R=1/ (1/Rab+1/Rpd).Because the equivalent resistance of C1, C2 is infinitely great, so the resistance Rab between AB be infinity, according to R=1/ (1/Rab+1/Rpd), can obtain PD electric line between resistance R=Rpd.
When power supply units such as Ethernet switch are power receiving equipment such as IP phone machine, wireless local network connecting point AP, secure network video camera and some other IP-based terminal transmission data-signal; Kind equipment provides the ability of direct current supply for this reason; But for Ethernet switch; Its wiring system more is a portion outside the building, therefore is struck by lightning more easily.Thunderbolt is that the cable of portion discharges to laying outside the building, and lightning wave on the cable or overvoltage are almost invaded power supply unit, caused power supply unit to damage along cable line with the light velocity.
Therefore, when being struck by lightning, the supply lines of the CABLE end that the high pressure that thunderbolt produces can be through ethernet interface circuit to or non-supply lines to coming in, through the internal circuit of ethernet interface circuit, arrive the PCB end, the high pressure that thunderbolt produces is released.
The high pressure that produces when thunderbolt from the supply lines of the CABLE end of ethernet interface circuit when coming in; When supply lines is come in to 3,6; The path that electric current passes through is: hold to pin12 through the centre cap of the secondary coil of isolating transformer T2/A from supply lines 3 or 6, can the high pressure that thunderbolt produces be released; When supply lines is come in to 1,2, the path that electric current passes through is: arrive the pin11 end from supply lines 1 or 2 centre caps through the secondary coil of isolating transformer T1/A, the high pressure that thunderbolt produces is released.Like this, when coming in, not through C1, C2, therefore the high pressure that produces of thunderbolt can not puncture C1, C2 the high pressure that produces when thunderbolt from the supply lines of the CABLE end of ethernet interface circuit.Therefore can not influence the power supply of PSE to far-end PD load.
The high pressure that produces when thunderbolt from the non-supply lines of the CABLE end of ethernet interface circuit when coming in; When non-supply lines is come in to 7,8; The path that electric current passes through is: electric current is come in from non-supply lines 7 or 8; Arrive the pin11 of PCB end through capacitor C 4, resistance R 4, R1 and capacitor C 1, and, the high pressure that thunderbolt produces is released through the pin12 that C4, R4, R2, C2 arrive the PCB end.Have only capacitor C 4, C2, the C1 of 250V because passed through withstand voltage in this path, so the high pressure (such as 2KV) of working as the thunderbolt generation will cause C4, C2 and C1 to be in half conducting state when coming in to C4, C2 and C1 puncture.Like this, the equivalent resistance of C1, C2 just is not infinitely great, and might be tens K or tens K; Therefore in the PSE testing process that load is supplied power to far-end because the equivalent resistance of C1, C2 is not infinitely great, according to PD electric line between equivalent resistance R=1/ (1/Rab+1/Rpd); R ≠ Rpd, therefore, in the PSE testing process; Might make script meet the Rpd of IEEE802.3af standard; The result who detects becomes and does not meet the IEEE802.3af standard, thus PSE can erroneous judgement to occur to the PD load disconnected, influence the power supply of PSE to far-end PD load.For example: after C1, C2 were breakdown, the equivalent resistance of C1 and C2 was 25K, i.e. Rab=25K; And the Rpd=20K of standard P D; PD equivalent resistance R=1 (1/25+1/20)=11.1K between the supply lines of then parallelly connected back, and the resistance of a standard compliant PD is 19K≤Rgood≤26.5K, therefore can make the PD that meets the IEEE802.3af standard originally become the standard of not meeting; Just PSE is disconnected to PD load appearance erroneous judgement in testing process, has influenced the power supply of PSE to far-end PD load.
Summary of the invention
The present invention provides a kind of ethernet interface circuit; When the high pressure that produces of can avoiding being struck by lightning is come in from interface circuit; To supply lines between resistance impact, it is disconnected to make PSE erroneous judgement can not occur to the judgement of far-end PD load, has guaranteed the reliability and the correctness of POE function.
A kind of ethernet interface circuit; Comprise: first isolating transformer, second isolating transformer, the 3rd isolating transformer, the 4th isolating transformer, common mode inhibition device; In two coils of said common mode inhibition device one is connected between the centre cap of secondary coil of positive source and said first isolating transformer of power supply unit; Another is connected between the centre cap of secondary coil of power cathode and said second isolating transformer of said power supply unit; It is right that the secondary coil output of said first isolating transformer and second isolating transformer is respectively supply lines; It is right that the secondary coil output of said the 3rd isolating transformer and the 4th isolating transformer is respectively non-supply lines, also comprises:
Second electric capacity and the 6th electric capacity; One end of said second electric capacity connects the centre cap of the secondary coil of second isolating transformer; The other end is through the 6th capacity earth, and the centre cap of the secondary coil of said the 3rd isolating transformer, the 4th isolating transformer is through the 6th capacity earth;
The 5th electric capacity, an end connects the centre cap of the secondary coil of first isolating transformer, other end ground connection.
Further, said interface circuit also comprises one of following or its combination:
First resistance is connected between the centre cap and the 5th electric capacity of secondary coil of said first isolating transformer;
Second resistance is connected between second electric capacity and the 6th electric capacity;
The 3rd resistance is connected between the centre cap and the 6th electric capacity of secondary coil of the 3rd isolating transformer;
The 4th resistance is connected between the centre cap and the 6th electric capacity of secondary coil of said the 4th isolating transformer.
Further, said interface circuit also comprises:
First electric capacity is connected between the centre cap and the 5th electric capacity of secondary coil of first isolating transformer;
First resistance is connected between said first electric capacity and the 5th electric capacity.
Further, said interface circuit also comprises:
The 3rd electric capacity is connected between the centre cap and the 6th electric capacity of secondary coil of the 3rd isolating transformer;
The 3rd resistance is connected between said the 3rd electric capacity and the 6th electric capacity.
Further, said interface circuit also comprises:
The 4th electric capacity is connected between the centre cap and the 6th electric capacity of secondary coil of the 4th isolating transformer;
The 4th resistance is connected between said the 4th electric capacity and the 6th electric capacity.
A kind of ethernet interface circuit; Comprise: first isolating transformer, second isolating transformer, the 3rd isolating transformer, the 4th isolating transformer, common mode inhibition device; In two coils of said common mode inhibition device one is connected between the centre cap of secondary coil of positive source and said first isolating transformer of power supply unit; Another is connected between the centre cap of secondary coil of power cathode and said second isolating transformer of said power supply unit; It is right that the secondary coil output of said first isolating transformer and second isolating transformer is respectively supply lines; It is right that the secondary coil output of said the 3rd isolating transformer and the 4th isolating transformer is respectively non-supply lines, also comprises:
The 3rd electric capacity, the 4th electric capacity and the 6th electric capacity; One end of said the 3rd electric capacity connects the centre cap of the secondary coil of the 3rd isolating transformer; The other end is through the 6th capacity earth; One end of said the 4th electric capacity connects the centre cap of the secondary coil of the 4th isolating transformer, and the other end is through the 6th capacity earth, and the centre cap of the secondary coil of said second isolating transformer is through the 6th capacity earth;
The 5th electric capacity, an end connects the centre cap of the secondary coil of first isolating transformer, other end ground connection.
Further, said interface circuit also comprises one of following or its combination:
First resistance is connected between the centre cap and the 5th electric capacity of secondary coil of first isolating transformer;
Second resistance is connected between the centre cap and the 6th electric capacity of secondary coil of second isolating transformer;
The 3rd resistance is connected between the 3rd electric capacity and the 6th electric capacity;
The 4th resistance is connected between the 4th electric capacity and the 6th electric capacity.
Further, said interface circuit also comprises:
First electric capacity is connected between the centre cap and the 5th electric capacity of secondary coil of first isolating transformer;
First resistance is connected between first electric capacity and the 5th electric capacity.
Further, said interface circuit also comprises:
Second electric capacity is connected between the centre cap and the 6th electric capacity of secondary coil of second isolating transformer;
Second resistance is connected between second electric capacity and the 6th electric capacity.
Ethernet interface circuit provided by the invention; Can be in the cable-side of interface circuit, with non-supply lines a pair of common through high-voltage capacitance ground connection to two pairs of supply lines centerings, another of supply lines centering is to separately through high-voltage capacitance ground connection; When the high pressure that can make thunderbolt produce is come in from the cable-side of interface circuit; Even with supply lines between capacitance puncture, the two pairs of supply lines between can conducting yet, make in the POE power supply process; It is disconnected that PSE erroneous judgement can not occur to far-end PD load, can not influence the power supply of PSE meeting far-end PD load.
Description of drawings
Fig. 1 is the POE system construction drawing;
Fig. 2 is the structure chart of ethernet interface circuit in the prior art;
When Fig. 3 connects the PD load for ethernet interface circuit supply lines between the equivalent circuit diagram of resistance;
Fig. 4 is the structure chart of the ethernet interface circuit of the embodiment of the invention one;
When Fig. 5 connects the PD load for the ethernet interface circuit of the embodiment of the invention one supply lines between the equivalent circuit diagram of resistance;
Fig. 6 is the structure chart of the ethernet interface circuit of the embodiment of the invention two;
Fig. 7 is the structure chart of the ethernet interface circuit of the embodiment of the invention three.
Embodiment
Based on the existing Ethernet interface circuit, when adopting supply lines to (1,2 and 3,6) when supplying power, the high voltage that produces when thunderbolt from non-supply lines to (4,5 and 7,8) when coming in; Can cause supply lines breakdown to the electric capacity between (1,2 and 3,6); Cause supply lines between conducting, though can not produce short circuit, make in the POE power supply process; It is disconnected that PSE erroneous judgement occurs to far-end PD load, influenced the power supply of PSE to far-end PD load.The embodiment of the invention provides a kind of ethernet interface circuit; Make when network interface is impacted by lightning surge, though the electric capacity that supply lines is right puncture, the two pairs of supply lines between conducting can not appear; Avoid in the POE power supply process, PSE is disconnected to the erroneous judgement of far-end PD load.
Embodiment one
As shown in Figure 4; The structure chart of the ethernet interface circuit that provides for the embodiment of the invention one; The difference of ethernet interface circuit of the present invention and existing ethernet interface circuit (Fig. 2) is; In the existing Ethernet interface circuit; Supply lines to non-supply lines to be connected to high-voltage capacitance C5 and the ground connection of 1000pf/2KV respectively jointly through filter circuit, the non-supply lines of the ethernet interface circuit in the embodiment of the invention is connected to high-voltage capacitance and ground connection through filter circuit respectively jointly to a pair of (3,6) of (4,5 and 7,8) and supply lines centering, supply lines is connected to high-voltage capacitance and ground connection to (1,2) separately through filter circuit; Wherein, filter circuit is made up of the electric capacity of a 0.022uF/250V and the resistance of a 75OHM.
As shown in Figure 4; The PCB SIDE end of ethernet interface circuit is connected with switch; Wherein CH1+/--CH4+/-be connected with the signal of the correspondence of switch related chip; Be used for transmission and receive data, the DC power supply of pin11, pin12 and switch is that PSE links to each other, and is used to realize the power supply of PSE to far-end PD load.The CABLE SIDE end of ethernet interface circuit is connected with PD equipment through Ethernet cable.Wherein, Ethernet cable comprises 8 twisted-pair feeders, and promptly 4 pairs of differential lines are right.The POE process is to utilize 2 couple of 4 pairs of differential lines centerings that PD is supplied power.Ethernet interface circuit comprises:
Isolating transformer T1/A, T2/A, T3/A, T4/A; Wherein, The secondary coil output of T1/A and T2/A is respectively supply lines to (1,2) and (3,6), and the secondary coil output of T3/A and T4/A is respectively non-supply lines to (4,5) and (7,8), isolating transformer T1/A, T2/A, T3/A, T4/A; Signal to the ethernet interface circuit both sides can't harm transmission, the effect of playing filtering simultaneously and isolating the both sides signal;
Common mode inhibition device T5; In its two coils one is connected between the centre cap of secondary coil of positive source and isolating transformer T1/A of power supply unit PSE; Another is connected between the centre cap of secondary coil of power cathode and isolating transformer T2/A of power supply unit PSE; The both positive and negative polarity of PSE device power supply (DPS) just is coupled to the centre tap of isolating transformer T1/A, T2/A through common mode inhibition device T5 like this; Centre tap power supply through to isolating transformer T1/A, T2/A applies voltage between two pairs of supply lines are to (1,2) (3,6).Supply lines is connected to PD equipment to (1,2) and (3,6), is used for the power devices to PD, and common mode inhibition device T5, can play the effect of isolating both sides signal and filtering;
Branch road one end that capacitor C 1 forms after connecting with resistance R 1 is connected the centre cap of the secondary coil of isolating transformer T1/A, and the other end is through high-voltage capacitance C5 ground connection;
Branch road one end that capacitor C 2 forms after connecting with resistance R 2 is connected the centre cap of the secondary coil of isolating transformer T2/A, and the other end is through capacitor C 6 ground connection; Branch road one end that capacitor C 3 forms after connecting with resistance R 3 is connected the centre cap of the secondary coil of isolating transformer T3/A, and the other end is through capacitor C 6 ground connection; Branch road one end that capacitor C 4 forms after connecting with resistance R 4 is connected the centre cap of the secondary coil of isolating transformer T4/A, and the other end is through capacitor C 6 ground connection; Be the centre cap of the secondary coil of isolating transformer T2/A, the centre cap of the secondary coil of isolating transformer T3/A, the centre cap of the secondary coil of isolating transformer T4/A connects capacitance and resistance respectively, again through common high-voltage capacitance C6 ground connection; The effect when power supply of capacitor C 1, C2, C3, C4 be avoid supply lines on direct current arrive non-supply lines on, play the effect of isolated DC electricity;
Wherein, foregoing circuit also comprises capacitor C 7, is electrically connected between the centre cap of secondary coil of isolating transformer T1/A, T2/A, and the effect of capacitor C 7 is filtering.
Wherein, C1, C2, C3, C4 are generally 0.022uF/250V, and R1, R2, R3, R4 are generally 75OHM, all are empirical values, do not limit their value in the present invention; Capacitor C 5, C6 are generally high-voltage capacitance, can value 1000pF/2000V, and withstand voltage is high more good more certainly, but withstand voltage is high, and cost is just big more.
Adopt above-mentioned ethernet interface circuit circuit; When connecting the PD load, when adopting supply lines to (1,2) (3,6) when supplying power, supply lines between the equivalent circuit diagram of resistance; As shown in Figure 5; The CABLE of interface circuit end supply lines to the resistance Rab between the AB and far-end PD electric line between resistance Rpd be that parallel connection concerns, after the parallel connection, PD electric line between equivalent resistance R=1/ (1/Rab+1/Rpd).Wherein, Rab is that CABLE holds supply lines to the resistance between A, B, is Rab=R
C1+ R1+R
C5+ R
C6+ R2+R
C2, wherein, R
C1, R
C5, R
C6, R
C2Be respectively the equivalent resistance of capacitor C 1, C5, C6 and C2; Under the normal condition; When ethernet interface circuit was not struck by lightning, because the equivalent resistance of C1, C2, C5, C6 is infinitely great, so the resistance Rab between AB was infinitely great; According to R=1/ (1/Rab+1/Rpd), can obtain PD electric line between resistance R=Rpd.
The high pressure that produces when thunderbolt from the non-supply lines of ethernet interface circuit to (4,5) (7,8) when coming in, when high pressure from the non-supply lines of ethernet interface circuit to (7,8) when coming in, because the pin12 terminal voltage is lower; And capacitor C 6 is a high-voltage capacitance, can be not breakdown, so the path that electric current passes through is: electric current is come in from non-supply lines 7 or 8; Through capacitor C 4, resistance R 4, resistance R 2, capacitor C 2, arrive the pin12 of PCB end, through back-end circuit lightning current is released naturally; Like this, though can supply lines be punctured the capacitor C 2 of isolating the connection of transformer T2/A centre cap between (3,6), because supply lines passes through high-voltage capacitance C6, C5 ground connection to (3,6) and supply lines respectively to (1,2); And in when thunderbolt, high-voltage capacitance C5, C6 can not puncture, thus supply lines to (3,6) and supply lines to can conducting between (1,2); The equivalent resistance that is C5, C6 is still for infinitely great, and therefore, the resistance Rab between AB is infinitely great; According to R=1/ (1/Rab+1/Rpd), can obtain PD electric line between resistance R=Rpd, therefore; PSE can erroneous judgement not occur to the PD load in testing process disconnected, can not influence the power supply of PSE to far-end PD load.
Simultaneously, adopt above-mentioned ethernet interface circuit, when non-supply lines when being struck by lightning, the high electric current that thunderbolt produces can with non-supply lines between puncture, arrive supply lines to and back-end circuit, through back-end circuit lightning current is released naturally.Therefore; When thunderbolt; Non-supply lines to and supply lines between also can not to produce higher voltage poor; Avoided non-supply lines to and supply lines between puncture between and signal that hypotelorism takes place too high because of voltage difference, and avoided non-supply lines to and supply lines between the big differential mode composition that produces when puncturing be coupled to the PCB end, cause the damage of device and equipment room.
In the foregoing description one, the effect when power supply of capacitor C 1, C2, C3, C4 be avoid supply lines on direct current arrive non-supply lines on, play the effect of isolated DC electricity.
Embodiment two
As shown in Figure 6; The ethernet interface circuit that provides for the embodiment of the invention two; Be on the basis of embodiment one ethernet interface circuit, omit non-supply lines to the capacitor C 4 between (7,8) and non-supply lines to the capacitor C 3 between (4,5), it is same like this that can to avoid in the PSE testing process erroneous judgement being appearred in the PD load disconnected; Can not influence the power supply of PSE, and supply lines arrives non-supply lines to last to last direct current also can avoid supplying power the time to far-end PD load.
Certainly, also can omit among C3, the C4, perhaps omit C1.
Among the embodiment two as long as capacitor C 2 existence that the supply lines that is connected to high-voltage capacitance C6 jointly with the right centre cap of non-supply lines is connected the centre cap of (3,6); C1, C3, C4 can exist; Can not exist yet; In the time of can avoiding supplying power supply lines between direct current arrive non-supply lines to last, can not influence the power supply of PSE to the PD load.
Embodiment three
As shown in Figure 7; The ethernet interface circuit that provides for the embodiment of the invention three; Be on the basis of embodiment one ethernet interface circuit, when non-supply lines to the capacitor C 3 between (4,5 and 7,8), when C4 exists, supply lines to the capacitor C 2 between (3,6) and supply lines to the capacitor C 3 between (1,2); Can all omit; Same like this can to avoid in the PSE testing process that erroneous judgement is appearred in the PD load disconnected, can not influence the power supply of PSE to far-end PD load, and supply lines arrives non-supply lines to last to last direct current also can avoid supplying power the time.
Certainly; Supply lines to the capacitor C 2 between (3,6) and supply lines to the capacitor C 3 between (1,2); Also can only omit one; As long as non-supply lines all exists capacitor C 3, C4 between (4,5 and 7,8), in the time of can avoiding supplying power supply lines between direct current arrive non-supply lines to last.
Certainly, the ethernet interface circuit that the embodiment of the invention provides can also have other distortion, also can change such as: each line resistance to the resistance R 1 that connects through centre cap, R2, R3, R4, and also can omit.
Certainly; The ethernet interface circuit that the embodiment of the invention provides; Can also connect high-voltage capacitance C5 and ground connection separately to the centre cap between (3,6) by supply lines; Supply lines to (1,2) and non-supply lines to (4,5) (7,8) jointly through high-voltage capacitance C6 ground connection, same like this can so that the high electric current that thunderbolt produces release naturally, simultaneously the two pairs of supply lines between because there is high-voltage capacitance; Thereby can not make that erroneous judgement to be appearred in the PD load in the PSE testing process disconnected, can not influence the power supply of PSE to far-end PD load.Certainly, equally for fear of supply lines between direct current arrive non-supply lines to last, also must comprise supply lines in this ethernet interface circuit to the capacitor C 1 between (1,2), perhaps non-supply lines between capacitor C 3, C4; When comprising C1, C2, C4, C4 can omit arbitrarily, and when comprising C3, C4, C1, C2 can omit arbitrarily.
On the occupation mode that focuses on high-voltage capacitance C5, C6 of the present invention; As long as be that non-supply lines passes through high-voltage capacitance C6 ground connection jointly to a pair of centre cap with supply lines centering; Another right centre cap of supply lines centering is separately through high-voltage capacitance C5 ground connection; Just can be so that the high pressure that thunderbolt produces can be through supply lines to arriving back-end circuit, the high electric current that makes thunderbolt produce is released naturally, simultaneously the two pairs of supply lines between because there is high-voltage capacitance; Thereby can not make that erroneous judgement to be appearred in the PD load in the PSE testing process disconnected, can not influence the power supply of PSE to far-end PD load.
The foregoing description is that example explain of the present invention scheme through supply lines to (1,2 and 3,6) ethernet interface circuit circuit diagram that load is supplied power to PD with PSE just; When PSE through line to (4,5 and 7,8) when load is supplied power to PD; The design philosophy of foregoing circuit is suitable equally; It is right that (4,5 and 7,8) are supply lines at this moment, and it is right that (1,2 and 3,6) are non-supply lines.
Obviously, those skilled in the art can carry out various changes and modification to the present invention and not break away from the spirit and scope of the present invention.Like this, belong within the scope of claim of the present invention and equivalent technologies thereof if of the present invention these are revised with modification, then the present invention also is intended to comprise these changes and modification interior.
Claims (9)
1. ethernet interface circuit; Comprise: first isolating transformer, second isolating transformer, the 3rd isolating transformer, the 4th isolating transformer, common mode inhibition device; In two coils of said common mode inhibition device one is connected between the centre cap of secondary coil of positive source and said first isolating transformer of power supply unit; Another is connected between the centre cap of secondary coil of power cathode and said second isolating transformer of said power supply unit; It is right that the secondary coil output of said first isolating transformer and second isolating transformer is respectively supply lines; It is right that the secondary coil output of said the 3rd isolating transformer and the 4th isolating transformer is respectively non-supply lines, it is characterized in that, also comprises:
Second electric capacity and the 6th electric capacity; One end of said second electric capacity connects the centre cap of the secondary coil of second isolating transformer; The other end is through the 6th capacity earth, and the centre cap of the secondary coil of said the 3rd isolating transformer, the 4th isolating transformer is through the 6th capacity earth;
The 5th electric capacity, an end connects the centre cap of the secondary coil of first isolating transformer, other end ground connection.
2. interface circuit as claimed in claim 1 is characterized in that, also comprises one of following or its combination:
First resistance is connected between the centre cap and the 5th electric capacity of secondary coil of said first isolating transformer;
Second resistance is connected between second electric capacity and the 6th electric capacity;
The 3rd resistance is connected between the centre cap and the 6th electric capacity of secondary coil of the 3rd isolating transformer;
The 4th resistance is connected between the centre cap and the 6th electric capacity of secondary coil of said the 4th isolating transformer.
3. interface circuit as claimed in claim 1 is characterized in that, also comprises:
First electric capacity is connected between the centre cap and the 5th electric capacity of secondary coil of first isolating transformer;
First resistance is connected between said first electric capacity and the 5th electric capacity.
4. interface circuit as claimed in claim 1 is characterized in that, also comprises:
The 3rd electric capacity is connected between the centre cap and the 6th electric capacity of secondary coil of the 3rd isolating transformer;
The 3rd resistance is connected between said the 3rd electric capacity and the 6th electric capacity.
5. interface circuit as claimed in claim 1 is characterized in that, also comprises:
The 4th electric capacity is connected between the centre cap and the 6th electric capacity of secondary coil of the 4th isolating transformer;
The 4th resistance is connected between said the 4th electric capacity and the 6th electric capacity.
6. ethernet interface circuit; Comprise: first isolating transformer, second isolating transformer, the 3rd isolating transformer, the 4th isolating transformer, common mode inhibition device; In two coils of said common mode inhibition device one is connected between the centre cap of secondary coil of positive source and said first isolating transformer of power supply unit; Another is connected between the centre cap of secondary coil of power cathode and said second isolating transformer of said power supply unit; It is right that the secondary coil output of said first isolating transformer and second isolating transformer is respectively supply lines; It is right that the secondary coil output of said the 3rd isolating transformer and the 4th isolating transformer is respectively non-supply lines, it is characterized in that, also comprises:
The 3rd electric capacity, the 4th electric capacity and the 6th electric capacity; One end of said the 3rd electric capacity connects the centre cap of the secondary coil of the 3rd isolating transformer; The other end is through the 6th capacity earth; One end of said the 4th electric capacity connects the centre cap of the secondary coil of the 4th isolating transformer, and the other end is through the 6th capacity earth, and the centre cap of the secondary coil of said second isolating transformer is through the 6th capacity earth;
The 5th electric capacity, an end connects the centre cap of the secondary coil of first isolating transformer, other end ground connection.
7. interface circuit as claimed in claim 6 is characterized in that, also comprises one of following or its combination:
First resistance is connected between the centre cap and the 5th electric capacity of secondary coil of first isolating transformer;
Second resistance is connected between the centre cap and the 6th electric capacity of secondary coil of second isolating transformer;
The 3rd resistance is connected between the 3rd electric capacity and the 6th electric capacity;
The 4th resistance is connected between the 4th electric capacity and the 6th electric capacity.
8. interface circuit as claimed in claim 6 is characterized in that, also comprises:
First electric capacity is connected between the centre cap and the 5th electric capacity of secondary coil of first isolating transformer;
First resistance is connected between first electric capacity and the 5th electric capacity.
9. interface circuit as claimed in claim 6 is characterized in that, also comprises:
Second electric capacity is connected between the centre cap and the 6th electric capacity of secondary coil of second isolating transformer;
Second resistance is connected between second electric capacity and the 6th electric capacity.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010102059285A CN101882998B (en) | 2010-06-12 | 2010-06-12 | Ethernet interface circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010102059285A CN101882998B (en) | 2010-06-12 | 2010-06-12 | Ethernet interface circuit |
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| Publication Number | Publication Date |
|---|---|
| CN101882998A CN101882998A (en) | 2010-11-10 |
| CN101882998B true CN101882998B (en) | 2012-05-30 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN2010102059285A Expired - Fee Related CN101882998B (en) | 2010-06-12 | 2010-06-12 | Ethernet interface circuit |
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Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107995000B (en) * | 2017-12-08 | 2021-01-05 | 锐捷网络股份有限公司 | Power supply detection method and equipment |
| CN112600016B (en) * | 2020-11-25 | 2022-08-05 | Oppo广东移动通信有限公司 | Interface device, power supply apparatus, power receiving apparatus, and power consumption system |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2922307Y (en) * | 2006-07-12 | 2007-07-11 | 中兴通讯股份有限公司 | Ethernet interface isolating transformer central tap grounding circuit |
| CN201256393Y (en) * | 2008-07-29 | 2009-06-10 | 福建星网锐捷通讯股份有限公司 | Power supply circuit for communication equipment network port isolation transformer |
| CN101640409A (en) * | 2008-07-29 | 2010-02-03 | 福建星网锐捷通讯股份有限公司 | Power supply circuit for communication equipment network port isolation transformer |
| CN101640413A (en) * | 2008-07-29 | 2010-02-03 | 福建星网锐捷通讯股份有限公司 | Lightning protection circuit for user lines of communication equipment |
-
2010
- 2010-06-12 CN CN2010102059285A patent/CN101882998B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2922307Y (en) * | 2006-07-12 | 2007-07-11 | 中兴通讯股份有限公司 | Ethernet interface isolating transformer central tap grounding circuit |
| CN201256393Y (en) * | 2008-07-29 | 2009-06-10 | 福建星网锐捷通讯股份有限公司 | Power supply circuit for communication equipment network port isolation transformer |
| CN101640409A (en) * | 2008-07-29 | 2010-02-03 | 福建星网锐捷通讯股份有限公司 | Power supply circuit for communication equipment network port isolation transformer |
| CN101640413A (en) * | 2008-07-29 | 2010-02-03 | 福建星网锐捷通讯股份有限公司 | Lightning protection circuit for user lines of communication equipment |
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| CN101882998A (en) | 2010-11-10 |
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