CN2241356Y

CN2241356Y - Computer communication port overvoltage protection device

Info

Publication number: CN2241356Y
Application number: CN 95246243
Authority: CN
Inventors: 买云; 马培勇
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-11-24
Filing date: 1995-11-24
Publication date: 1996-11-27
Anticipated expiration: 2005-11-24

Abstract

The utility model relates to an overvoltage protection device for a computer communication interface, composed of a communication interface circuit, a communication signal wire, a communication working ground wire, a protection ground wire, a transient semiconductor protection circuit, an energy bleeder circuit for ground, a casing, etc., wherein, the transient semiconductor protection circuit is connected in parallel between the communication signal wire and the communication working ground wire; the potential difference between the signal wire and the working ground wire is limited within the range that the communication interface circuit can bear; the energy bleeder circuit for ground is connected between the communication working ground wire and the protection ground wire, and has the function of providing a bleed-off circuit for ground for the transient impact energy in the communication system. The utility model has fast response speed, overall protection, and favorable lightning protection effect.

Description

Computing machine communication interface anti-overvoltage protective device

The utility model relates to a kind of protective device, particularly a kind of Computer Communications Interface anti-overvoltage protective device.

According to researching and analysing discovery, owing to lightning induction, factors such as power induction, the transient overvoltage that produces on communication line is the one of the main reasons that causes compunication interruption and device damage.For computer serial communication interface RS232C, its communication distance relatively short (do not add and amplify circuit only about 100 meters); And, adopting the good concentric cable transmission signals of shielding for BNC cablet network or the thick cable network of N, the energy of the transient overvoltage of actual sensed is less relatively on these communication lines.Therefore in the holding circuit design of this class communication network, the response time is the factor of overriding concern in the design.In addition, since the signal transmission frequencies of coaxial communications cable in 10MHZ～100MHZ scope.Therefore,, guarantee communication quality, should make circuit simple and practical as far as possible, avoid adopting unnecessary circuit or device although insert attenuation for reducing circuit.

" lightning-arrest tester " disclosed in the Chinese patent (patent No. 93233960.3).But its protection effect is not ideal enough; there is following shortcoming: 1, in the design of holding circuit; owing to all might suffering induced voltage, any communication line cause equipment, interface to damage; therefore tackling all has the signal transmssion line that electrically connects (to comprise that postal is according to signal wire and control signal wire; protect down together), and can not only protect its part circuit.2, the delay circuit value may cause certain influence to communication more greatly, is example with the 10MHZ transfer rate, and its signal period is 0.1 microsecond, and the holding circuit delay time just reaches several microseconds.On the contrary, the delay circuit value is less, to lightning-arrest no positive effect.3, owing to voltage working value between high tension protection circuit, middle voltage protection circuit, the low-voltage protection circuit three differs greatly; less when the delay circuit value, in fact the transient overvoltage that is added on the circuit will cause at first merit work of the lower low-voltage protection circuit of operation voltage value.Because its amplitude limiting characteristic, external transient impact energy is added in low-voltage protection circuit with the overwhelming majority.Because the delay circuit value is little, so high tension protection circuit, middle voltage protection circuit will not have practical function.

The purpose of this utility model is to avoid above-mentioned the deficiencies in the prior art part and provides a kind of response speed fast, and protection is comprehensive, the Computer Communications Interface anti-overvoltage protective device that actual lightning protection effect is good.

The purpose of this utility model can reach by following measure: the utility model comprises communication interface circuit, signal of communication line, communication work ground wire, protection ground wire, housing; it is characterized in that: also have transient state semiconductor protection circuit, energy leadage circuit over the ground; transient state semiconductor protection circuit is connected between signal of communication line and the communication work ground wire, and the energy leadage circuit is connected between communication work ground wire and the protection ground wire over the ground.

The purpose of this utility model can also reach by following measure: electronic circuit board is loaded in the housing, and socket is loaded on the housing.Transient state semiconductor protection circuit can adopt 2～8 pin of transient state SIC (semiconductor integrated circuit) IC1, IC1 to join with 2～8 pin, 20 pin of IC2 in the communication interface circuit; 1,9,10 pin of 1C1 and 7 pin of IC2 join; and join with the end of discharge tube F1,1 pin of the other end of F1 and IC2 joins.Transient state semiconductor protection circuit also can adopt two-way transient state semiconductor diode S1, and the end of S1 and the heart yearn a of concentric cable join, and the end of the other end and coaxial outer shielding line b and discharge tube F1 joins, and the other end of F1 joins with protection ground.

Fig. 1 is a functional-block diagram of the present utility model;

Fig. 2 is a contour structures synoptic diagram of the present utility model;

Fig. 3 and Fig. 4 are two kinds of typical holding circuit figure of the utility model.

With reference to Fig. 1, Fig. 2, the utility model is by communication interface circuit 1, signal of communication line 2, communication work ground wire 3, protection ground wire 4, transient state semiconductor protection circuit 5, energy leadage circuit 6, housing 7 etc. are formed over the ground.Transient state semiconductor protection circuit 5 is connected in parallel between signal of communication line 2 and the communication work ground wire 3, and potential difference (PD) between signal wire and the working grounding cable is limited in the scope that communication interface circuit can bear.Energy leadage circuit 6 is connected between communication work ground wire 3 and the protection ground wire 4 over the ground, and its fundamental purpose is for the transient impact energy that is added in the communication system provides bleed-off circuit over the ground, and can not exert an influence to proper communication.In the housing 7 electronic circuit board is housed, socket 8 is loaded on the housing 7.

Fig. 3 is a RS232C serial communication interface holding circuit.A is the RS232C port among the figure; signal of communication line (2,3,4,5,6,8,20) is respectively guard signal line and control signal wire, and (this circuit is applicable to I8M9 line system RS232C standard; can design with reference to this circuit theory for IEEE25 line system RS232C standard); 7 lines are the signal working grounding cable, and 1 line is the protection ground wire.IC1 is transient state SIC (semiconductor integrated circuit) (model 1883); this chip principal feature is that it(?) at most can be simultaneously carry out meticulous protection to 9 road signal wires (this chip functions also can be substituted by 8 two-way transient state semiconductor diodes; function is close; but relative price is higher); 1883 die response times are 1ps only, can bear the above simulation of 10/700 μ S1000V impulse test.Impact residual voltage with respect to working grounding cable and be lower than 30V.F1 is discharge tube (can select the lower discharge tube of voltage nominal value, as 70V, 90V etc.), the magnitude of voltage height that is characterized in being failure to actuate, and after the action, through-flow energy is big, and the action residual voltage is low, do not have electric path between normal condition protection ground and place of working, and relative price is cheap.

When adding on the communication line, transient impact voltage (comprises forward and reverse impact); be positioned at two-way transient state semiconductor protection integrated circuit (IC) 1 (1883) transient response between signal of communication line and place of working; but by the circuit self-resistance with voltage limit between circuit and place of working in tolerance range; and absorb main impact energy; simultaneously; be connected in parallel on place of working and protection discharge tube F1 (also can adopt voltage dependent resistor (VDR) or the high-power transient state semiconductor devices) action between the ground, energy is released to greatly.

Fig. 4 for LAN (Local Area Network) with the coaxial thick cable of the coaxial cablet net of bnc connector or N connector Netcom letter interface lightning protection circuit.9,10 is respectively coaxial cable core wire and outer shielding among the figure, and S13 is two-way transient state semiconductor diode, and F2 is discharge tube (if when coaxial outer shields reliable ground, discharge tube F1 can omit need not).

RS232C serial communication interface holding circuit is similar among its principle of work and Fig. 3.Two-way transient state semiconductor diode is when having surge voltage to add to communication line, and transient response (response time is 1PS only) is carried out amplitude limit with the surge voltage between signal of communication line (cable core) and the working grounding cable (cable outer layer shielding) rapidly.Discharge tube F1 can release impact energy to greatly.

The utility model has following advantage compared to existing technology:

1, short to communication line or adopt coaxial cable do the communication system of telecommunication media (or Computer network) can satisfy the protection needs fully, and protect satisfactory for result.

2, adopt the transient state semiconductor devices, make holding circuit respond (1ps in the short time at the utmost point～1ns), and have automatic recovery ability.

3, because circuit is simple and direct, minimum to the insertion attenuation of communication line, dependable performance, cost is lower.

4, the lightning protection device by the utility model production can directly be inserted in the computer serial communication interface, and is transparent to the computer user under normal condition on the interfaces such as adapter, thus install and use very convenient.

Claims

1, a kind of computing machine communication interface anti-overvoltage protective device; comprise communication interface circuit 1, signal of communication line 2, communication work ground wire 3, protection ground wire 4, housing 7; it is characterized in that: also have transient state semiconductor protection circuit 5, energy leadage circuit 6 over the ground; transient state semiconductor protection circuit 5 is connected between signal of communication line 2 and the communication work ground wire 3, and energy leadage circuit 6 is connected between communication work ground wire 3 and the protection ground wire 4 over the ground.

2, protective device according to claim 1 is characterized in that: electronic circuit board is loaded in the housing 7, and socket 8 is loaded on the housing 7.

3, protective device according to claim 1; it is characterized in that: transient state semiconductor protection circuit 5 can adopt 2～8 pin of transient state SIC (semiconductor integrated circuit) IC1, IC1 to join with 2～8 pin, 20 pin of IC2 in the communication interface circuit 1; 1,9,10 pin of IC1 and 7 pin of IC2 join; and join with the end of discharge tube F1,1 pin of the other end of F1 and IC2 joins.

4, protective device according to claim 1; it is characterized in that: transient state semiconductor protection circuit 5 also can adopt two-way transient state semiconductor diode S1; the end of S1 and the heart yearn a of concentric cable join; the end of the other end and coaxial outer shielding line b and discharge tube F1 joins, and the other end of F1 joins with protection ground.