Complete isolation transmission protection circuit for RS232 bus

Abstract

The utility model discloses an RS232 bus complete isolation transmission protection circuit, which is provided with a DC / DC isolation conversion power supply module to carry out power supply isolation on an RS232 power supply, and adopts a high-speed isolation chip-ADUM1201 chip to carry out isolation transmission on signals of an RX data line and a TX data line of the RS232, thereby realizing isolation on the RS232 power supply and simultaneously realizing the complete isolation transmission of the RS232 bus. According to the RS232 bus transmission circuit, the defect that the isolation effect is not ideal during high-speed communication when an optocoupler is adopted to carry out signal isolation on the TX data line and the RX data line of the RS232 is overcome, and the technical problems that an existing RS232 bus transmission circuit does not carry out isolation on the RS232 power supply, and the isolation effect is not reliable when the optocoupler is adopted to carry out signal isolation on the TX data line and the RX data line of the RS232 are solved.

Description

Technical Field

[0001] The utility model relates to the technical field of protection circuits, in particular to a fully isolated transmission protection circuit for an RS232 bus. Background Art

[0002] The RS232 interface is a serial communication interface on a computer. In the existing RS232 bus transmission circuit, only the TX (Transceive Data) data line and the RX (Receive Data) data line of the RS232 are signal-isolated, and the RS232 power supply is not isolated. At the same time, the signal isolation of the TX (Transceive Data) data line and the RX (Receive Data) data line of the RS232 is achieved by optocoupler isolation, and the speed of the optocoupler is limited, resulting in an unsatisfactory isolation effect during high-speed communication. Summary of the Utility Model

[0003] The utility model provides a fully isolated transmission protection circuit for an RS232 bus, which is used to solve the technical problems that the existing RS232 bus transmission circuit does not isolate the RS232 power supply, and the isolation effect of using an optocoupler to isolate the TX data line and the RX data line of the RS232 is unreliable.

[0004] In view of this, the utility model provides a fully isolated transmission protection circuit for an RS232 bus, which includes an MCU processor, an RS232 chip, a TVS tube protection circuit, a DC / DC isolation conversion power module, and an ADUM1201 chip;

[0005] The data receiving interface of the MCU processor is connected to the first logic output interface of the ADUM1201 chip, the data sending interface of the MCU processor is connected to the second logic input interface of the ADUM1201 chip, the first logic input interface of the ADUM1201 chip is connected to the first serial data output interface of the RS232 chip, the second logic output interface of the ADUM1201 chip is connected to the second serial data input interface of the RS232 chip, the first serial data input interface of the RS232 chip is connected to one end of the TVS tube protection circuit, the second serial data output interface of the RS232 chip is connected to the other end of the TVS tube protection circuit, and the TVS tube protection circuit is connected to an external interface;

[0006] The positive input terminal of the DC / DC isolated conversion power module is respectively connected to the DC power supply and the power supply voltage isolation side interface of the ADUM1201 chip. The negative input interface of the DC / DC isolated conversion power module is grounded. The positive output interface of the DC / DC isolated conversion power module is respectively connected to the isolator side power supply interface of the ADUM1201 chip and the power supply of the RS232 chip. The negative output interface of the DC / DC isolated conversion power module is grounded.

[0007] Optionally, the negative input interface of the DC / DC isolated conversion power module and the first grounding interface of the ADUM1201 chip are jointly connected to the system ground wire. The negative output interface of the DC / DC isolated conversion power module and the second grounding interface of the ADUM1201 chip are jointly connected to the RS232 bus ground wire. The grounding end of the TVS tube protection circuit is connected to the equipment housing ground wire.

[0008] Optionally, a resistor is connected in series between the RS232 bus ground wire and the equipment housing ground wire, and a capacitor is connected in parallel with the resistor.

[0009] Optionally, the TVS tube protection circuit includes a first through-hole bead, a second through-hole bead, a first self-resetting fuse, a second self-resetting fuse, a TVS tube, a first ceramic gas discharge tube, a second ceramic gas discharge tube, and a third ceramic gas discharge tube;

[0010] One end of the first self-resetting fuse is connected to the first serial data input interface of the RS232 chip. The other end of the first self-resetting fuse is connected to one end of the first through-hole bead. The other end of the first through-hole bead is connected to the external interface;

[0011] One end of the second self-resetting fuse is connected to the second serial data output interface of the RS232 chip. The other end of the second self-resetting fuse is connected to one end of the second through-hole bead. The other end of the second through-hole bead is connected to the external interface;

[0012] The TVS tube is a TVS tube of the PESD1CAN model with 24V. The first cathode of the TVS tube is connected to one end of the first self-resetting fuse. The second cathode of the TVS tube is connected to one end of the second self-resetting fuse. The common anode of the TVS tube is connected to the RS232 bus ground wire;

[0013] One end of the first ceramic gas discharge tube is connected to the other end of the second self-resetting fuse. The other end of the first ceramic gas discharge tube is connected to the equipment housing ground wire. One end of the second ceramic gas discharge tube is connected to the other end of the first self-resetting fuse. The other end of the second ceramic gas discharge tube is connected to the equipment housing ground wire. One end of the third ceramic gas discharge tube is connected to the common anode of the TVS tube. The other end of the third ceramic gas discharge tube is connected to the equipment housing ground wire.

[0014] Optionally, one end of the power pin of the RS232 chip is connected to one end of the fourth ceramic gas discharge tube, and the other end of the fourth ceramic gas discharge tube is connected to the ground wire of the device housing.

[0015] Optionally, the positive output interface of the DC / DC isolation conversion power module is connected to the negative output interface of the DC / DC isolation conversion power module through a first isolation capacitor. The power supply interface on the isolator side of the ADUM1201 chip is connected to the positive power management interface of the RS232 chip through a second capacitor. The connection point between the second capacitor and the positive power management interface of the RS232 chip is connected to the RS232 bus ground wire. The negative power management interface of the RS232 chip is connected to the RS232 bus ground wire.

[0016] Optionally, the RS232 chip is a MAX3232 chip.

[0017] Optionally, the DC / DC isolation conversion power module is an isolation module of model B0505S-1WR3.

[0018] Optionally, the first self-recovery fuse and the second self-recovery fuse are self-recovery fuses of model SMD0805-010 -15V.

[0019] Optionally, the first ceramic gas discharge tube, the second ceramic gas discharge tube, and the third ceramic gas discharge tube are ceramic gas discharge tubes of model SMD4532-350NF.

[0020] As can be seen from the above technical solutions, the RS232 bus fully isolated transmission protection circuit provided by the present utility model has the following advantages:

[0021] The RS232 bus fully isolated transmission protection circuit provided by the present utility model sets a DC / DC isolation conversion power module to isolate the RS232 power supply, and uses a high-speed isolation chip - ADUM1201 chip to isolate the transmission of the signals of the RX data line and the TX data line of the RS232. While achieving the isolation of the RS232 power supply, it avoids the defect that the isolation effect is not ideal during high-speed communication when using an optocoupler to isolate the signals of the TX data line and the RX data line of the RS232, and solves the technical problems that the existing RS232 bus transmission circuit does not isolate the RS232 power supply and the isolation effect of using an optocoupler to isolate the signals of the TX data line and the RX data line of the RS232 is unreliable. Description of the Drawings

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other related accompanying drawings can also be obtained based on these drawings.

[0023] Figure 1 It is a schematic structural diagram of a completely isolated transmission protection circuit for an RS232 bus provided in an embodiment of the present invention;

[0024] Figure 2 It is a schematic circuit diagram of a completely isolated transmission protection circuit for an RS232 bus provided in an embodiment of the present invention;

[0025] Figure 3 is Figure 2 a partial enlarged view in

[0026] Figure 4 is Figure 2 another partial enlarged view in Detailed implementation manners

[0027] In order to enable those skilled in the art to better understand the solution of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0028] For ease of understanding, please refer to Figure 1, an embodiment of a fully isolated transmission protection circuit for an RS232 bus is provided by the present utility model, which includes an MCU processor, an RS232 chip, a TVS tube protection circuit, a DC / DC isolation conversion power module, and an ADUM1201 chip. The data receiving interface RX of the MCU processor is connected to the first logic output interface VOA of the ADUM1201 chip U4, the data sending interface TX of the MCU processor is connected to the second logic input interface VIB of the ADUM1201 chip U4, the first logic input interface VIA of the ADUM1201 chip U4 is connected to the first serial data output interface ROUT1 of the RS232 chip U3, the second logic output interface VOB of the ADUM1201 chip U4 is connected to the second serial data input interface DINT1 of the RS232 chip U3, the first serial data input interface RIN1 of the RS232 chip U3 is connected to one end of the TVS tube protection circuit, the second serial data output interface DOUT1 of the RS232 chip U3 is connected to the other end of the TVS tube protection circuit, and the TVS tube protection circuit is connected to the external interface J1. The positive input terminal INV+ of the DC / DC isolation conversion power module U13 is respectively connected to the DC power supply P1 and the power supply voltage isolation side interface VDD1 of the ADUM1201 chip U4, the negative input interface INV- of the DC / DC isolation conversion power module U13 is grounded, the positive output interface OUTV+ of the DC / DC isolation conversion power module U13 is respectively connected to the isolator side power supply interface VDD2 of the ADUM1201 chip U4 and the RS232 chip power supply VCC, and the negative output interface OUTV- of the DC / DC isolation conversion power module U13 is grounded.

[0029] It should be noted that the positive input terminal INV+ of the DC / DC isolation conversion power module U13 is connected to the positive electrode (VCC_5V+) of the DC power supply P1, and the negative electrode of the DC power supply P1 is grounded. The DC / DC isolation conversion power module U13 is used as the level power supply of the RS232 chip U3, and can completely isolate the system power supply from the RS232 power supply. The ADUM1201 chip U4 is a high-speed isolation chip, which can isolate and transmit the signals of the RX data line and TX data line of the RS232 chip U3. The RS232 chip U3 can adopt the MAX3232 chip. The DC / DC isolation conversion power module can adopt the isolation module of the B0505S-1WR3 model.

[0030] The RS232 bus fully isolated transmission protection circuit provided by the present utility model sets a DC / DC isolation conversion power module to isolate the power supply of the RS232 power supply, and uses a high-speed isolation chip - ADUM1201 chip to isolate the transmission of the signals of the RX data line and the TX data line of the RS232. While achieving the isolation of the RS232 power supply, it avoids the defect that the isolation effect is not ideal during high-speed communication when using an optocoupler to isolate the signals of the TX data line and the RX data line of the RS232, and solves the technical problems that the existing RS232 bus transmission circuit does not isolate the RS232 power supply and the isolation effect of using an optocoupler to isolate the signals of the TX data line and the RX data line of the RS232 is unreliable.

[0031] In one embodiment, as Figure 2 、 Figure 3 and Figure 4 shown, the negative input interface INV- of the DC / DC isolation conversion power module U13 and the first ground interface GND1 of the ADUM1201 chip U4 are commonly connected to the system ground wire GND. The negative output interface OUTV- of the DC / DC isolation conversion power module U13 and the second ground interface GND2 of the ADUM1201 chip U4 are commonly connected to the RS232 bus ground wire RS232 - GND. The ground terminal of the TVS tube protection circuit is connected to the device housing ground wire PE - GND. The negative pole of the DC power supply P1 is connected to the system ground wire GND. The complete isolation of the ground wires of the system control part, the RS232 power supply part and the TVS tube protection part is achieved. A resistor R10 is connected in series between the RS232 bus ground wire RS232 - GND and the device housing ground wire PE - GND, and a capacitor CY4 is connected in parallel with the resistor R10, which can release the voltage on the RS232 bus ground wire RS232 - GND to the device housing ground wire PE - GND, achieving the effect of stabilizing the RS232 bus ground wire RS232 - GND.

[0032] In one embodiment, as Figures 2 to 4As shown in the figure, the TVS tube protection circuit includes a first through-hole bead F2, a second through-hole bead F3, a first self-resetting fuse PT1, a second self-resetting fuse PT2, a TVS tube TVS1, a first ceramic gas discharge tube E5, a second ceramic gas discharge tube E6, and a third ceramic gas discharge tube E7. One end of the first self-resetting fuse PT1 is connected to the first serial data input interface RIN1 of the RS232 chip U3, the other end of the first self-resetting fuse PT1 is connected to one end of the first through-hole bead F2, and the other end of the first through-hole bead F2 is connected to the external interface J1. One end of the second self-resetting fuse PT2 is connected to the second serial data output interface DOUT1 of the RS232 chip U3, the other end of the second self-resetting fuse PT2 is connected to one end of the second through-hole bead F3, and the other end of the second through-hole bead F3 is connected to the external interface J1. The TVS tube TVS1 is a TVS tube of the PESD1CAN model with 24V, which plays a role in protecting the TX data line and RX data line of the RS232 chip U3. The first cathode of the TVS tube TVS1 is connected to one end of the first self-resetting fuse PT1, the second cathode of the TVS tube is connected to one end of the second self-resetting fuse PT2, and the common anode of the TVS tube is connected to the RS232 bus ground wire RS232-GND. One end of the first ceramic gas discharge tube E5 is connected to the other end of the second self-resetting fuse PT2, the other end of the first ceramic gas discharge tube E5 is connected to the equipment shell ground wire PE-GND, one end of the second ceramic gas discharge tube E6 is connected to the other end of the first self-resetting fuse PT1, the other end of the second ceramic gas discharge tube E6 is connected to the equipment shell ground wire PE-GND, one end of the third ceramic gas discharge tube E7 is connected to the common anode of the TVS tube TVS1, and the other end of the third ceramic gas discharge tube E7 is connected to the equipment shell ground wire PE-GND.

[0033] The first self-resetting fuse PT1 and the second self-resetting fuse PT2 are self-resetting fuses of the SMD0805-010 -15V model, which play a current protection role when the voltage is greater than 15V and the current is 0.1A.

[0034] The first through-hole bead F2 and the second through-hole bead F3 are devices with magnetic beads outside the wire, which mainly play the role of anti-interference and anti-radiation.

[0035] The first ceramic gas discharge tube E5, the second ceramic gas discharge tube E6, and the third ceramic gas discharge tube E7 are the most widely used switching devices in lightning protection equipment, with the advantages of large surge current, up to 1KA - 150KA, extremely high insulation resistance, no leakage current, no aging failure, non-polar bidirectional protection, extremely small static capacitance, and relatively large dispersion of breakdown voltage. The first ceramic gas discharge tube E5, the second ceramic gas discharge tube E6, and the third ceramic gas discharge tube E7 can play a role in protecting the TVS tube protection circuit from lightning surges. The first ceramic gas discharge tube E5, the second ceramic gas discharge tube E6, and the third ceramic gas discharge tube E7 are ceramic gas discharge tubes of the SMD4532 - 350NF model.

[0036] In one embodiment, as Figures 2 to 4 shown, the power supply pin VCC of the RS232 chip U3 is connected to one end of the fourth ceramic gas discharge tube E8, and the other end of the fourth ceramic gas discharge tube E8 is connected to the equipment housing ground wire PE - GND. The fourth ceramic gas discharge tube E8 can play a role in protecting the DC / DC isolation conversion power module U13 from lightning surges.

[0037] In one embodiment, as Figures 2 to 4 shown, the positive output interface OUTV+ of the DC / DC isolation conversion power module U13 is connected to the negative output interface OUTV- of the DC / DC isolation conversion power module U13 through the first isolation capacitor C15. The isolator side power supply interface VDD2 of the ADUM1201 chip U4 is connected to the positive power management interface V+ of the RS232 chip U3 through the second capacitor C18. The connection point between the second capacitor and the positive power management interface V+ of the RS232 chip U3 is connected to the RS232 bus ground wire RS232 - GND. The negative power management interface V- of the RS232 chip U3 is connected to the RS232 bus ground wire RS232 - GND. A resistor R29 is connected in series between the power supply voltage isolation side interface VDD1 of the ADUM1201 chip U4 and the first logic output interface VOA of the ADUM1201 chip U4. A resistor R28 is connected in series between the power supply voltage isolation side interface VDD1 of the ADUM1201 chip U4 and the second logic input interface VIB of the ADUM1201 chip U4. A capacitor C65 is connected in series between the positive input terminal INV+ and the negative input terminal INV- of the DC / DC isolation conversion power module U13, and a capacitor C17 is connected in parallel with the capacitor C65.

[0038] The terms "first", "second", "third", etc. in the description of the present utility model are used to distinguish similar objects and do not necessarily describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances so that the embodiments of the present utility model described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units need not be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0039] As mentioned above, the above embodiments are only used to illustrate the technical solutions of the present utility model and are not intended to limit them; although the present utility model has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present utility model.

Claims

1. A RS232 bus complete isolation transmission protection circuit, characterized in that: Including MCU processor, RS232 chip, TVS tube protection circuit, DC / DC isolation conversion power supply module and ADUM1201 chip; The data receiving interface of the MCU processor is connected to the first logic output interface of the ADUM1201 chip, the data sending interface of the MCU processor is connected to the second logic input interface of the ADUM1201 chip, the first logic input interface of the ADUM1201 chip is connected to the first serial data output interface of the RS232 chip, the second logic output interface of the ADUM1201 chip is connected to the second serial data input interface of the RS232 chip, the first serial data input interface of the RS232 chip is connected to one end of the TVS tube protection circuit, the second serial data output interface of the RS232 chip is connected to the other end of the TVS tube protection circuit, and the TVS tube protection circuit is connected to the external interface; The positive input terminal of the DC / DC isolation conversion power module is respectively connected to the DC power supply and the power supply voltage isolation side interface of the ADUM1201 chip, the negative input interface of the DC / DC isolation conversion power module is grounded, the positive output interface of the DC / DC isolation conversion power module is respectively connected to the isolator side power supply interface of the ADUM1201 chip and the RS232 chip power supply, and the negative output interface of the DC / DC isolation conversion power module is grounded.

2. The RS232 bus complete isolation transmission protection circuit according to claim 1 is characterized in that: The negative input interface of the DC / DC isolation conversion power module and the first grounding interface of the ADUM1201 chip are connected to the system ground wire together, the negative output interface of the DC / DC isolation conversion power module and the second grounding interface of the ADUM1201 chip are connected to the RS232 bus ground wire together, and the grounding end of the TVS tube protection circuit is connected to the equipment casing ground wire.

3. The RS232 bus complete isolation transmission protection circuit according to claim 2 is characterized in that: A resistor is connected in series between the RS232 bus ground wire and the device housing ground wire, and a capacitor is connected in parallel to the resistor.

4. The RS232 bus complete isolation transmission protection circuit according to claim 2 or 3, characterized in that: The TVS tube protection circuit includes a first through-hole magnetic bead, a second through-hole magnetic bead, a first resettable fuse, a second resettable fuse, a TVS tube, a first ceramic gas discharge tube, a second ceramic gas discharge tube and a third ceramic gas discharge tube; One end of the first resettable fuse is connected to the first serial data input interface of the RS232 chip, the other end of the first resettable fuse is connected to one end of the first through-core magnetic bead, and the other end of the first through-core magnetic bead is connected to the external interface; One end of the second self-resetting fuse is connected to the second serial data output interface of the RS232 chip, the other end of the second self-resetting fuse is connected to one end of the second through-core magnetic bead, and the other end of the second through-core magnetic bead is connected to the external interface; The TVS tube is a 24V PESD1CAN model TVS tube, the first cathode of the TVS tube is connected to one end of the first resettable fuse tube, the second cathode of the TVS tube is connected to one end of the second resettable fuse tube, and the common anode of the TVS tube is connected to the ground wire of the RS232 bus; One end of the first ceramic gas discharge tube is connected to the other end of the second self-resettable fuse, the other end of the first ceramic gas discharge tube is connected to the ground wire of the equipment casing, one end of the second ceramic gas discharge tube is connected to the other end of the first self-resettable fuse, the other end of the second ceramic gas discharge tube is connected to the ground wire of the equipment casing, one end of the third ceramic gas discharge tube is connected to the common anode of the TVS tube, and the other end of the third ceramic gas discharge tube is connected to the ground wire of the equipment casing.

5. The RS232 bus complete isolation transmission protection circuit according to claim 1 is characterized in that: The power pin of the RS232 chip is connected to one end of the fourth ceramic gas discharge tube, and the other end of the fourth ceramic gas discharge tube is connected to the ground wire of the device shell.

6. The RS232 bus complete isolation transmission protection circuit according to claim 2 is characterized in that: The positive output interface of the DC / DC isolation conversion power supply module is connected to the negative output interface of the DC / DC isolation conversion power supply module through the first isolation capacitor, the isolator side power supply interface of the ADUM1201 chip is connected to the positive power management interface of the RS232 chip through the second capacitor, the connection point between the second capacitor and the positive power management interface of the RS232 chip is connected to the RS232 bus ground wire, and the negative power management interface of the RS232 chip is connected to the RS232 bus ground wire.

7. The RS232 bus complete isolation transmission protection circuit according to claim 1 is characterized in that: The RS232 chip is MAX3232 chip.

8. The RS232 bus complete isolation transmission protection circuit according to claim 1 is characterized in that: The DC / DC isolation conversion power module is a B0505S-1WR3 isolation module.

9. The RS232 bus complete isolation transmission protection circuit according to claim 4, characterized in that: The first resettable fuse and the second resettable fuse are SMD0805-010 -15V resettable fuses.

10. The RS232 bus complete isolation transmission protection circuit according to claim 4, characterized in that: The first ceramic gas discharge tube, the second ceramic gas discharge tube and the third ceramic gas discharge tube are SMD4532-350NF ceramic gas discharge tubes.

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