CN202904571U - Controller area network (CAN) bus interface circuit with electric isolation function - Google Patents
Controller area network (CAN) bus interface circuit with electric isolation function Download PDFInfo
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- CN202904571U CN202904571U CN 201220611132 CN201220611132U CN202904571U CN 202904571 U CN202904571 U CN 202904571U CN 201220611132 CN201220611132 CN 201220611132 CN 201220611132 U CN201220611132 U CN 201220611132U CN 202904571 U CN202904571 U CN 202904571U
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Abstract
The utility model discloses a controller area network (CAN) bus interface circuit with the electric isolation function. The CAN bus interface circuit comprises a bus controller, a bus transit-receive device, a first work power supply, a second work power supply and a digital signal isolating device, wherein the first work power supply and the second work power supply are mutually isolated in an electric mode. A power supply input end and a grounding end of the CAN bus transit-receive device are respectively connected with a corresponding end of the second work power supply. The digital signal isolating device comprises a group A of a signal input/output end, a power supply input end and a grounding end, and a group B of a signal input/output end, a power supply input end and a grounding end, wherein the group A of the signal input/output end, the power supply input end and the grounding end, and the group B of the signal input/output end, the power supply input end and the grounding end are mutually isolated in an electrical mode. The signal input/output end of the group A is connected with the CAN bus controller. The power supply input end and the grounding end of the group A are respectively connected with the corresponding end of the first work power supply. The signal input/output end of the group B is connected with the CAN transit-receive device. The power supply input end and the grounding end of the group B are respectively connected with the corresponding end of the second work power supply. The CAN bus interface circuit is faster in data transmission speed, and higher in timing sequence precision and transient common-mode rejection capacity compared with a photoelectric coupler.
Description
Technical field
The utility model relates to bus interface circuit, particularly a kind of CAN bus interface circuit with electrical isolation function.
Background technology
CAN(Controller Area Network) bus claims again the control area net（CAN） network, released by German BOSCH company the earliest, be used for that automotive interior is measured and execution unit between data communication, the CAN bus has been acknowledged as one of several the most promising fieldbus.Its bus specification has been worked out by ISO International Standards Organization and has been international standard.The major advantage of CAN bus: be the multi host control working method, can consist of easily the multi-computer back-up system; Can be point-to-point, point-to-multipoint and broadcast mode transceiving data, traffic rate can reach that 1Mb/s(communication data this moment is the longest to be 40m), the actual node number can reach 110, it is following that the direct communication distance can reach 10km(speed 5kB/s farthest); Node on the CAN network can be divided into different priority, to satisfy different requirement of real times; Adopt the non-destructive arbitration technique, can effectively avoid bus prominent in a state of excitement; Use short frame structure, the effective word joint number of each frame is 8, and the short frame transmission time is short, be disturbed that probability is little, the repeating transmission time is short, and every frame information has CRC check and other error checking measures, can guarantee the low error rate of data; Communication media can be twisted-pair feeder, concentric cable or optical fiber, selects flexibly; Bus node has the autoshutdown output function in the situation that mistake is serious, so that the operation of other nodes is unaffected on the bus.
At present, the CAN bus becomes one of fieldbus relatively more commonly used, but because some field conditions are very complicated, there is very high common mode voltage between each node, although what the CAN interface adopted is the differential transfer mode, ability with certain anti-common mode interference, but when common mode voltage surpasses the limit receiver voltage of CAN driver, the CAN driver just can't work, when serious even can burn chip and instrument and equipment, therefore, in order to adapt to strong interference environment or high performance requirement, must carry out electrical isolation to each communication node of CAN bus.CAN Bus isolation method commonly used is to adopt the photoelectrical coupler technology; come the isolation and protection testing circuit with light beam; and a safe interface is provided between high pressure and low-voltage electrical environment, but photoelectric coupling circuit is complicated, is unsuitable for the bus transfer of the instrument and equipment of the occasions such as down-hole.
The utility model content
The utility model provides a kind of simple and reliable CAN bus interface circuit with electrical isolation function for solving the technical matters that exists in the known technology.
The technical scheme that the utility model is taked for the technical matters that exists in the solution known technology is: a kind of CAN bus interface circuit with electrical isolation function, comprise the CAN bus controller, CAN bus transceiver and the first working power, described the first working power reaches the power devices that is connected with described CAN bus controller to described CAN bus controller, also comprise the second working power and digital signal isolator with the mutual electrical isolation of described the first working power, the power input of described CAN bus transceiver links to each other with the corresponding end of described the second working power respectively with earth terminal, described digital signal isolator comprises A, the signal I/O end of two groups of mutual electrical isolation of B, power input and earth terminal, wherein: the signal I/O end of A group links to each other with described CAN bus controller, and the power input of A group links to each other with the corresponding end of described the first working power respectively with earth terminal; The signal I/O end of B group links to each other with described CAN bus transceiver, and the power input of B group links to each other with the corresponding end of described the second working power respectively with earth terminal.
Be connected to the first capacitor C 1 between the power input of described CAN bus transceiver and the earth terminal.
Described digital signal isolator is the two-channel digital signal isolator.
Described two-channel digital signal isolator is ISO7221C type digital signal isolator.
Described the second working power comprises the linear power supply chip.
Described linear power supply chip is NCV1117ST33T3 Linear power supply chip.
Advantage and the good effect that the utlity model has are: the utility model adopts the digital signal isolators such as ISO7221C, simple in structure, the PCB layout is more convenient, make the logic input and output impact damper that the isolation barrier separates at chip, electric current isolation up to 4000V is provided. unite use with insulating power supply, can stop high voltage, isolate ground connection, and prevent that at data bus noise current or other circuit from entering local ground connection and interference or damaging sensitive circuit.Owing to not having to affect in the photoelectrical coupler opto-electronic conversion link of efficient, so have the message transmission rate higher than photoelectrical coupler, time sequence precision and transient state common mode inhibition capacity.And the digital signal isolator such as ISO7221C can provide forward and reverse link communication passage in same chip, so just can so that the transmission direction of signal is more flexible, simplify the hardware connection line of chip chamber.
Description of drawings
Fig. 1 is electrical schematic diagram of the present utility model;
Fig. 2 is the electrical schematic diagram of second source in the utility model.
Among the figure: C1, the first electric capacity.
Embodiment
For further understanding summary of the invention of the present utility model, Characteristic, hereby exemplify following examples, and cooperate accompanying drawing to be described in detail as follows:
See also Fig. 1 and Fig. 2, a kind of CAN bus interface circuit with electrical isolation function, comprise the CAN bus controller, CAN bus transceiver and the first working power, described the first working power reaches the power devices that is connected with described CAN bus controller to described CAN bus controller, also comprise the second working power and digital signal isolator with the mutual electrical isolation of described the first working power, the power input of described CAN bus transceiver links to each other with the corresponding end of described the second working power respectively with earth terminal, and namely the power input of described CAN bus transceiver links to each other with the output terminal of described the second working power; The earth terminal of described CAN bus transceiver links to each other with the earth terminal of described the second working power, described digital signal isolator comprises signal I/O end, power input and the earth terminal of A, two groups of mutual electrical isolation of B, wherein: the signal I/O end of A group links to each other with described CAN bus controller, the power input of A group links to each other with the corresponding end of described the first working power respectively with earth terminal, and namely the power input of A group links to each other with the output terminal of described the first working power; The earth terminal of described A group links to each other with the earth terminal of described the first working power; The signal I/O end of B group links to each other with described CAN bus transceiver, and the power input of B group links to each other with the corresponding end of described the second working power respectively with earth terminal, and namely the power input of B group links to each other with the output terminal of described the second working power; The earth terminal of described B group links to each other with the earth terminal of described the second working power.As described in Figure 1, the output terminal of the power input of A group+3.3 and described the first working power+3.3 link to each other; The earth terminal of described A group links to each other with the earth terminal of described the first working power; The power input Vb of B group links to each other with the output terminal Vb of described the second working power; The earth terminal Gb of described B group links to each other with the earth terminal Gb of described the second working power.
Can be connected to the first capacitor C 1 between the power input of described CAN bus transceiver and the earth terminal.
Described digital signal isolator can be the two-channel digital signal isolator; The optional ISO7221C type of described two-channel digital signal isolator digital signal isolator.
Described the second working power can comprise the linear power supply chip; The optional NCV1117ST33T3 Linear of described linear power supply chip power supply chip.
ISO7221 is a two-channel digital isolator.In order to make the PCB layout more convenient, passage all be face in the opposite direction, it has the logic input and output impact damper that is separated by the silicon dioxide of TI (SiO2) isolation barrier, and the electric current isolation up to 4000V is provided.Unite use with insulating power supply, this equipment can stop high voltage, isolates ground connection, and prevents that at data bus noise current or other circuit from entering local ground connection and interference or damaging sensitive circuit.
A binary input signal is translated into balanced signal through regulating, and is then distinguished by the Capacitor apart barrier.Behind the isolation barrier, a differential comparator receives logical message, then correspondingly set or reset a trigger and output circuit.Periodically update pulse and also can send by barrier, to guarantee to arrange correct DC rank.If do not receive this DC refresh pulse in per 4 μ s, then this input just is assumed that and is not powered or not by driven, and this fail-safe circuit is urged to a logic upper state with output.This little electric capacity and as a result time remaining provide signal rate at 0Mbps (dc) to the quick operation between 150Mbps.Article one, the signal transmission rate of circuit is that voltage transitions number of times with p.s. represents, unit is the bps(bits per second) A-, B-and C-option device has TTL input threshold values and an input end noise filter, and this can prevent that transient pulse is by the output terminal of equipment.The M option device has CMOS VCC/2 input threshold values and does not input noise filtering and extra propagation delay.
This equipment requirement 3.3V, two supply voltages of 5V, perhaps arbitrary combination.Power the equal tolerable 5V of all inputs voltage and all output when all being 4-mA CMOS when adopting a 3.3V power supply.ISO7221 is for the operation between 55 ° of C to 175 ° of C of environment temperature Zai –.
The utility model is for adopting ISO7221C as the downhole toolbus interface circuit with electrical isolation function of isolating chip design.In the circuit, the two paths of signals of CAN bus is by entering the CAN transponder chip behind the ISO7221C isolating chip.The power supply of ISO7221C chip one side (1,4 pin) is consistent with the power supply of connected single-chip microcomputer, and the power supply of its opposite side (8,5 pin) then is power supply independently, and the effect of isolation so just can be arranged.The power supply of the power supply of CAN transponder chip and ISO7221C chip opposite side (8,5 pin) is consistent.Like this, the input of the CAN bus of output and output just are isolated and have come.As the power supply of buffer circuit, NCV1117ST33T3 obtains by the linear power supply chip.Its input selection be the 5V power supply, this power supply should also be mutual isolation with the power supply that offers single-chip microcomputer.
Although the above is described preferred embodiment of the present utility model by reference to the accompanying drawings; but the utility model is not limited to above-mentioned embodiment; above-mentioned embodiment only is schematic; be not restrictive; those of ordinary skill in the art is under enlightenment of the present utility model; not breaking away from the scope situation that the utility model aim and claim protect, can also make a lot of forms, these all belong within the protection domain of the present utility model.
Claims (6)
1. CAN bus interface circuit with electrical isolation function, comprise the CAN bus controller, CAN bus transceiver and the first working power, described the first working power reaches the power devices that is connected with described CAN bus controller to described CAN bus controller, it is characterized in that, also comprise the second working power and digital signal isolator with the mutual electrical isolation of described the first working power, the power input of described CAN bus transceiver links to each other with the corresponding end of described the second working power respectively with earth terminal, described digital signal isolator comprises A, the signal I/O end of two groups of mutual electrical isolation of B, power input and earth terminal, wherein: the signal I/O end of A group links to each other with described CAN bus controller, and the power input of A group links to each other with the corresponding end of described the first working power respectively with earth terminal; The signal I/O end of B group links to each other with described CAN bus transceiver, and the power input of B group links to each other with the corresponding end of described the second working power respectively with earth terminal.
2. the CAN bus interface circuit with electrical isolation function according to claim 1 is characterized in that, is connected to the first electric capacity (C1) between the power input of described CAN bus transceiver and the earth terminal.
3. the CAN bus interface circuit with electrical isolation function according to claim 1 and 2 is characterized in that, described digital signal isolator is the two-channel digital signal isolator.
4. the CAN bus interface circuit with electrical isolation function according to claim 3 is characterized in that, described two-channel digital signal isolator is ISO7221C type digital signal isolator.
5. the CAN bus interface circuit with electrical isolation function according to claim 1 and 2 is characterized in that, described the second working power comprises the linear power supply chip.
6. the CAN bus interface circuit with electrical isolation function according to claim 5 is characterized in that, described linear power supply chip is NCV1117ST33T3 Linear power supply chip.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220611132 CN202904571U (en) | 2012-11-16 | 2012-11-16 | Controller area network (CAN) bus interface circuit with electric isolation function |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220611132 CN202904571U (en) | 2012-11-16 | 2012-11-16 | Controller area network (CAN) bus interface circuit with electric isolation function |
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| Publication Number | Publication Date |
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| CN202904571U true CN202904571U (en) | 2013-04-24 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN 201220611132 Expired - Fee Related CN202904571U (en) | 2012-11-16 | 2012-11-16 | Controller area network (CAN) bus interface circuit with electric isolation function |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104199365A (en) * | 2014-09-16 | 2014-12-10 | 衡阳泰豪通信车辆有限公司 | CAN (control area network) bus isolated communication protective circuit |
| CN109050444A (en) * | 2018-09-28 | 2018-12-21 | 深圳市道通科技股份有限公司 | CAN circuit structure and its vehicle diagnostic equipment |
| JP2019135830A (en) * | 2018-02-01 | 2019-08-15 | リニアー テクノロジー ホールディング エルエルシー | Transceiver utilizing isolated signaling and concealed isolated power to attain high common mode working voltage and tolerance |
-
2012
- 2012-11-16 CN CN 201220611132 patent/CN202904571U/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104199365A (en) * | 2014-09-16 | 2014-12-10 | 衡阳泰豪通信车辆有限公司 | CAN (control area network) bus isolated communication protective circuit |
| JP2019135830A (en) * | 2018-02-01 | 2019-08-15 | リニアー テクノロジー ホールディング エルエルシー | Transceiver utilizing isolated signaling and concealed isolated power to attain high common mode working voltage and tolerance |
| JP7302979B2 (en) | 2018-02-01 | 2023-07-04 | アナログ・ディヴァイシス・インターナショナル・アンリミテッド・カンパニー | Transceiver with Isolated Signaling and Hidden Isolated Power Addressing High Common-Mode Working Voltages and Tolerances |
| CN109050444A (en) * | 2018-09-28 | 2018-12-21 | 深圳市道通科技股份有限公司 | CAN circuit structure and its vehicle diagnostic equipment |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20130424 Termination date: 20151116 |