CN103560502A - 485 port hot plug protecting circuit - Google Patents
485 port hot plug protecting circuit Download PDFInfo
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- CN103560502A CN103560502A CN201310490429.9A CN201310490429A CN103560502A CN 103560502 A CN103560502 A CN 103560502A CN 201310490429 A CN201310490429 A CN 201310490429A CN 103560502 A CN103560502 A CN 103560502A
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- 230000001681 protective effect Effects 0.000 claims description 41
- 230000005669 field effect Effects 0.000 claims description 14
- 230000000087 stabilizing effect Effects 0.000 claims description 6
- 239000003990 capacitor Substances 0.000 claims description 4
- 230000005611 electricity Effects 0.000 description 7
- 230000005540 biological transmission Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000035611 feeding Effects 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 2
- 238000007689 inspection Methods 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
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Abstract
The invention relates to a 485 port hot plug protecting circuit, in particular to a 485 bus hot plug protecting circuit, and provides a protecting circuit capable of achieving hot plug of a 486 bus. According to the technical scheme, the hot plug protecting circuit comprises a plug, a power supply and port protecting circuit, an electronic switch circuit, a power supply ground detecting circuit and a port chip and control circuit, wherein the plug is connected with the power supply and port protecting circuit, the positive electrode output end of the power supply and port protecting circuit is connected with the positive electrode input end a1 of the electronic switch circuit, the negative electrode output end of the power supply and port protecting circuit is connected with the negative electrode input end of the port chip and control circuit, and a signal pin 485A and a signal pin 485B of the power supply and port protecting circuit are connected with a signal pin 485A and a signal pin 485B of the port chip and control circuit respectively. The 485 port hot plug protecting circuit is suitable for the communication field.
Description
Technical field
The present invention's heat 485 interface hot plug protective circuits, are specifically related to a kind of 485 bus hot plug protective circuits.
Background technology
485 buses are a kind of common serial bus standards, adopt the mode of balance transmission and differential received, there is long transmission distance, the advantages such as antijamming capability is strong, therefore be widely used in the data transmission link of different field, hot-swappable but 485 interfaces are not supported, because the voltage range that its level can bear is narrower, maximum differential mode ± 6V(TIA/EIA-485-A. standard), therefore surpassing this scope may cause interface circuit and chip to damage.
Support the interface of hot plug generally all to adopt special connector to protect in the mode of physical structure, power supply stitch is longer, and when plug inserts, the both positive and negative polarity of power supply or the ground of power supply are first connected stablely, then allow signal connect, as USB interface, and OBD interface etc.
485 bus direct current supply voltages are higher, industrial conventional 24V, as shown in Figure 1, if 24V power supply and 485 signal A first touch in plug insertion process, ground wire does not touch, from equipment end, be just equivalent to a resistance (R1), under the unsettled condition in ground, the voltage that A is ordered just equals supply voltage 24V, supply voltage can leak electricity to holding wire by interface chip, surpass the arrive+12V of common-mode voltage range-7V that interface chip can bear, the loop forming will cause interface chip to damage, even further damage control chip, and conventional TVS protection of pipe can cause the impact of power supply larger, can not stop the damage that interface circuit and chip cause because of hot plug.
Summary of the invention
The present invention overcomes the deficiency that prior art exists, and technical problem to be solved is: a kind of protective circuit that can hot plug 485 buses is provided.
For solving the problems of the technologies described above, the technical solution adopted in the present invention is: 485 interface hot plug protective circuits, comprising: plug, power supply and interface protective circuit, electronic switching circuit, power supply ground testing circuit and interface chip and control circuit;
Described plug is connected with power supply and interface protective circuit, the cathode output end of described power supply and interface protective circuit is connected with the electrode input end a1 of electronic switching circuit, the cathode output end of power supply and interface protective circuit is connected with the negative input of interface chip and control circuit, and the 485A signal pins of power supply and interface protective circuit is connected with 485B signal pins with the 485A signal pins of interface chip and control circuit respectively with 485B signal pins;
Described power supply ground testing circuit is attempted by the power output end of power supply and interface protective circuit; the power supply ground signal output part of testing circuit and the negative input a2 of electronic switching circuit are connected, and the cathode output end b1 of described electronic switching circuit is connected with the electrode input end of interface chip and control circuit.
The circuit structure of described electronic switching circuit is: the positive pole of diode D1 is connected with the electrode input end a1 of electronic switching circuit, one end of described diode D1 negative pole shunt-wound capacitance C1, behind one end of the negative pole of voltage stabilizing didoe DW1 and resistance R 1, be connected with the source electrode of P channel-type field effect transistor Q1, the other end of described capacitor C 1 also connects the positive pole of voltage stabilizing didoe DW1, behind one end of the other end of resistance R 1 and resistance R 2, be connected with the grid of P channel-type field effect transistor Q1, the other end of described resistance R 2 and connect the negative pole of diode D2 after be connected with the negative input a2 of electronic switching circuit, the cathode output end b1 that the drain electrode of described P channel-type field effect transistor Q1 is electronic switching circuit, the cathode output end b2 of the just very electronic switching circuit of described diode D2.
The beneficial effect that the present invention compared with prior art has is: the present invention substitutes original mode of protecting by connector mechanical type by the mode of electric circuit inspection power supply ground and electronic switch, efficiently solve the surge voltage or the electric current that in the hot-swappable open circuit process that easily causes power supply of 485 bus remote power feedings, produce and equipment is caused to the problem of damage, reduced the cost of failure rate and equipment maintenance; Whole circuit structure is succinct, and cost is lower, practical.
Accompanying drawing explanation
Below in conjunction with accompanying drawing, the present invention will be further described in detail:
Fig. 1 is the unearthed equivalent circuit diagram of existing 485 bus;
Fig. 2 is electrical block diagram of the present invention;
Fig. 3 is the circuit diagram of electronic switching circuit in the present invention;
In figure: 1 is that plug, 2 is that power supply and interface protective circuit, 3 are that electronic switching circuit, 4 is that power supply ground testing circuit, 5 is interface chip and control circuit.
Embodiment
As shown in Figure 2, the present invention's 485 interface hot plug protective circuits, comprising: plug 1, power supply and interface protective circuit 2, electronic switching circuit 3, power supply ground testing circuit 4 and interface chip and control circuit 5; Described plug 1 is connected with power supply and interface protective circuit 2; the cathode output end of described power supply and interface protective circuit 2 is connected with the electrode input end a1 of electronic switching circuit 3; the cathode output end of power supply and interface protective circuit 2 is connected with the negative input of interface chip and control circuit 5, and the 485A signal pins of power supply and interface protective circuit 2 is connected with 485B signal pins with the 485A signal pins of interface chip and control circuit 5 respectively with 485B signal pins.
Described power supply ground testing circuit 4 is attempted by the power output end of power supply and interface protective circuit 2; the power supply ground signal output part of testing circuit 4 and the negative input a2 of electronic switching circuit 3 are connected, and the cathode output end b1 of described electronic switching circuit 3 is connected with the electrode input end of interface chip and control circuit 5.
When the present invention is mainly used in solving current 485 bus interface hot plug, supply voltage can leak electricity to holding wire by interface chip, surpass the arrive+12V of common-mode voltage range-7V that interface chip can bear, the problem that the loop of formation causes interface chip and control chip to damage.
In the present invention, when described plug 1 is connected with power supply and interface protective circuit 2, and the feeder ear of the positive pole of plug 1 power supply contact power supply and interface protective circuit 2 is anodal, and plug 1 ground wire is not when contact with the earth terminal of power supply and interface protective circuit 2, the electrode input end a1 of electronic switching circuit 3 has electricity, power supply ground testing circuit 4 can't detect earth signal, testing circuit 4 output invalid signals in power supply ground are to the negative input a2 of electronic switching circuit 3, electronic switching circuit 3 is closed, the cathode output end b1 no-output of electronic switching circuit 3; When described plug 1 is connected with power supply and interface protective circuit 2; the positive pole contact power supply of plug 1 power supply and the feeder ear of interface protective circuit 2; and when plug 1 ground wire contacts with the earth terminal of power supply and interface protective circuit 2; the electrode input end a1 of electronic switching circuit 3 has electricity; power supply ground testing circuit 4 detects earth signal; testing circuit 4 output effective control signal in power supply ground is to the negative input a2 of electronic switching circuit 3; electronic switching circuit 3 is opened, and the cathode output end b1 of sub-switching circuit 3 is passed to interface chip and control circuit 5.
Described power supply and interface protective circuit 2 adopts the protective circuit of 485 bus routines, by rectifier diode, TVS pipe, certainly recover insurance etc. and form, can be to surge, and reversal connections etc. shield, and hot plug is played to auxiliary protection function.
As shown in Figure 3, the circuit structure of described electronic switching circuit 3 is: the positive pole of diode D1 is connected with the electrode input end a1 of electronic switching circuit 3, one end of described diode D1 negative pole shunt-wound capacitance C1, behind one end of the negative pole of voltage stabilizing didoe DW1 and resistance R 1, be connected with the source electrode of P channel-type field effect transistor Q1, the other end of described capacitor C 1 also connects the positive pole of voltage stabilizing didoe DW1, behind one end of the other end of resistance R 1 and resistance R 2, be connected with the grid of P channel-type field effect transistor Q1, the other end of described resistance R 2 and connect the negative pole of diode D2 after be connected with the negative input a2 of electronic switching circuit 3, the drain electrode of described P channel-type field effect transistor Q1 is the cathode output end b1 of electronic switching circuit 3, the cathode output end b2 of the just very electronic switching circuit 3 of described diode D2.
When plug 1 inserts main frame, the electrode input end a1 of electronic switching circuit 3 is linked into 24V power supply, when the negative input a2 of electronic switching circuit 3 does not touch negative pole (), the Vgs voltage 0V of P channel-type field effect transistor Q1, P channel-type field effect transistor Q1 cut-off, the cathode output end b1 of electronic switching circuit 3 can not form loop by chip and holding wire by output voltage, diode D2 now major function is that while preventing that plug is not plugged (contact), P channel-type field effect transistor Q1 forms loop by device signal end, causes abnormal; When plug 1 inserts main frame, the electrode input end a1 of electronic switching circuit 3 is linked into 24V power supply, the negative input a2 of electronic switching circuit 3 be also linked into power cathode () time, first capacitor C 1 is charged by R2, when voltage is charged to the threshold voltage Vgs(th that P channel-type field effect transistor Q1 opens) time, P channel-type field effect transistor Q1 starts conducting output, plays the effect of time delay output, now holding wire level can not produce high pressure electric leakage, contact that can be safe.
When described plug 1 is connected with power supply and interface protective circuit 2, and the feeder ear of the positive pole of plug 1 power supply contact power supply and interface protective circuit 2 is anodal, and plug 1 ground wire is not when contact with the earth terminal of power supply and interface protective circuit 2, the electrode input end a1 of electronic switching circuit 3 has electricity, power supply ground testing circuit 4 can't detect earth signal, testing circuit 4 output invalid signals in power supply ground are to the negative input a2 of electronic switching circuit 3, electronic switching circuit 3 is closed, the cathode output end b1 no-output of electronic switching circuit 3, the interface chip that now can not carry by plate forms loop and leaks electricity to 485A or 485B signal pins.
When described plug 1 is connected with power supply and interface protective circuit 2, and the feeder ear of the positive pole of plug 1 power supply contact power supply and interface protective circuit 2 is anodal, when plug 1 ground wire contacts with the earth terminal of power supply and interface protective circuit 2, the electrode input end a1 of electronic switching circuit 3 has electricity, power supply ground testing circuit 4 detects earth signal, testing circuit 4 output effective control signal in power supply ground is to the negative input a2 of electronic switching circuit 3, electronic switching circuit 3 is opened, the cathode output end b1 of electronic switching circuit 3 powers on, output to interface chip and control circuit 5, because interface chip and control circuit 5 have had common reference ground, therefore can not form loop of electric leakage yet.
Hence one can see that; the present invention by electric circuit inspection power supply add electronic switch mode substitute tradition by the mechanical protected mode of connector; efficiently solve 485 bus remote power feeding hot plugs; the surge voltage (electric current) producing in the open circuit process that causes power supply causes the problem of damage to equipment; reduced failure rate and equipment maintenance cost, this circuit also extends in the hot-plug equipment of other remote power feedings equally.
By reference to the accompanying drawings embodiments of the invention are explained in detail above, but the present invention is not limited to above-described embodiment, in the ken possessing those of ordinary skills, can also under the prerequisite that does not depart from aim of the present invention, makes a variety of changes.
Claims (2)
1.485 interface hot plug protective circuits, is characterized in that: comprising: plug (1), power supply and interface protective circuit (2), electronic switching circuit (3), power supply ground testing circuit (4) and interface chip and control circuit (5);
Described plug (1) is connected with power supply and interface protective circuit (2), the cathode output end of described power supply and interface protective circuit (2) is connected with the electrode input end a1 of electronic switching circuit (3), the cathode output end of power supply and interface protective circuit (2) is connected with the negative input of interface chip and control circuit (5), and the 485A signal pins of power supply and interface protective circuit (2) is connected with 485B signal pins with the 485A signal pins of interface chip and control circuit (5) respectively with 485B signal pins;
Described power supply ground testing circuit (4) is attempted by the power output end of power supply and interface protective circuit (2); the signal output part of power supply ground testing circuit (4) is connected with the negative input a2 of electronic switching circuit (3), and the cathode output end b1 of described electronic switching circuit (3) is connected with the electrode input end of interface chip and control circuit (5).
2. 485 interface hot plug protective circuits according to claim 1, it is characterized in that: the circuit structure of described electronic switching circuit (3) is: the positive pole of diode D1 is connected with the electrode input end a1 of electronic switching circuit (3), one end of described diode D1 negative pole shunt-wound capacitance C1, behind one end of the negative pole of voltage stabilizing didoe DW1 and resistance R 1, be connected with the source electrode of P channel-type field effect transistor Q1, the other end of described capacitor C 1 also connects the positive pole of voltage stabilizing didoe DW1, behind one end of the other end of resistance R 1 and resistance R 2, be connected with the grid of P channel-type field effect transistor Q1, the other end of described resistance R 2 and connect the negative pole of diode D2 after be connected with the negative input a2 of electronic switching circuit (3), the drain electrode of described P channel-type field effect transistor Q1 is the cathode output end b1 of electronic switching circuit (3), the cathode output end b2 of the just very electronic switching circuit (3) of described diode D2.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310490429.9A CN103560502A (en) | 2013-10-19 | 2013-10-19 | 485 port hot plug protecting circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310490429.9A CN103560502A (en) | 2013-10-19 | 2013-10-19 | 485 port hot plug protecting circuit |
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| Publication Number | Publication Date |
|---|---|
| CN103560502A true CN103560502A (en) | 2014-02-05 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201310490429.9A Pending CN103560502A (en) | 2013-10-19 | 2013-10-19 | 485 port hot plug protecting circuit |
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| Country | Link |
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| CN (1) | CN103560502A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110109792A (en) * | 2019-05-24 | 2019-08-09 | 珠海多士科技有限公司 | USB device plug-pull detecting circuit under a kind of operating system off-line state |
| CN110289607A (en) * | 2019-06-20 | 2019-09-27 | 深圳市中创工业互联网有限公司 | A kind of hot plug protection circuit and method |
| CN111949592A (en) * | 2020-08-13 | 2020-11-17 | 国家电网有限公司 | Hot plug circuit device suitable for LVDS |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000083181A (en) * | 1998-09-03 | 2000-03-21 | Matsushita Electric Ind Co Ltd | Monitoring camera device |
| CN101162840A (en) * | 2006-10-11 | 2008-04-16 | 大唐移动通信设备有限公司 | Interface protective circuit |
| CN103022966A (en) * | 2012-12-26 | 2013-04-03 | 深圳市伊爱高新技术开发有限公司 | Hot plug protection circuit for remote direct-current supply of RS485 bus |
| CN203553934U (en) * | 2013-10-19 | 2014-04-16 | 国家电网公司 | 485 interface hot-swap protection circuit |
-
2013
- 2013-10-19 CN CN201310490429.9A patent/CN103560502A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000083181A (en) * | 1998-09-03 | 2000-03-21 | Matsushita Electric Ind Co Ltd | Monitoring camera device |
| CN101162840A (en) * | 2006-10-11 | 2008-04-16 | 大唐移动通信设备有限公司 | Interface protective circuit |
| CN103022966A (en) * | 2012-12-26 | 2013-04-03 | 深圳市伊爱高新技术开发有限公司 | Hot plug protection circuit for remote direct-current supply of RS485 bus |
| CN203553934U (en) * | 2013-10-19 | 2014-04-16 | 国家电网公司 | 485 interface hot-swap protection circuit |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110109792A (en) * | 2019-05-24 | 2019-08-09 | 珠海多士科技有限公司 | USB device plug-pull detecting circuit under a kind of operating system off-line state |
| CN110289607A (en) * | 2019-06-20 | 2019-09-27 | 深圳市中创工业互联网有限公司 | A kind of hot plug protection circuit and method |
| CN111949592A (en) * | 2020-08-13 | 2020-11-17 | 国家电网有限公司 | Hot plug circuit device suitable for LVDS |
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Application publication date: 20140205 |