CN220342028U - 485 communication interface circuit with overvoltage protection - Google Patents
485 communication interface circuit with overvoltage protection Download PDFInfo
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- CN220342028U CN220342028U CN202321867289.8U CN202321867289U CN220342028U CN 220342028 U CN220342028 U CN 220342028U CN 202321867289 U CN202321867289 U CN 202321867289U CN 220342028 U CN220342028 U CN 220342028U
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Abstract
The application relates to a 485 communication interface circuit with overvoltage protection, which relates to the technical field of communication interface circuits; the device comprises a 485 communication interface unit, a control unit, a voltage sampling unit, a 485 interface protection unit and a user access terminal P1; the input end of the voltage sampling unit is electrically connected to the output end of the user access terminal P1, and the output end of the voltage sampling unit is electrically connected to the input end of the control unit; the user access terminal P1 is electrically connected to the input end of the 485 communication interface unit through the 485 interface protection unit; the control end of the 485 interface protection unit is electrically connected to the output end of the control unit, and the 485 interface protection unit is used for controlling whether the user access terminal P1 is electrically connected with the input end of the 485 communication interface unit. The method has the effect of realizing overvoltage protection on the 485 communication interface circuit.
Description
Technical Field
The application relates to the technical field of communication interface circuits, in particular to a 485 communication interface circuit with overvoltage protection.
Background
Referring to fig. 1, the conventional 485 communication interface circuit includes a communication chip U1, two input terminals of the 485 communication interface circuit are used for user access, and two output terminals of the 485 communication interface circuit are used for being electrically connected to related pins of a controller, thereby realizing a communication function. The connection end used for access by the user is directly and electrically connected to the pin of the communication chip U1.
However, the current communication chip U1 pin can receive limited voltage range, when the user is mistakenly connected with the mains supply 220V or 380V, the voltage value connected by the user is far more than the voltage range which can be born by the pin, and the 485 communication interface circuit is burnt.
Disclosure of Invention
In order to realize overvoltage protection for the 485 communication interface circuit, the application provides the 485 communication interface circuit with overvoltage protection.
The 485 communication interface circuit with overvoltage protection provided by the application adopts the following technical scheme:
the 485 communication interface circuit with the overvoltage protection comprises a 485 communication interface unit, a control unit, a voltage sampling unit, a 485 interface protection unit and a user access terminal P1;
the input end of the voltage sampling unit is electrically connected to the output end of the user access terminal P1, and the output end of the voltage sampling unit is electrically connected to the input end of the control unit;
the output end of the user access terminal P1 is electrically connected to the input end of the 485 communication interface unit through the 485 interface protection unit;
the control end of the 485 interface protection unit is electrically connected to the output end of the control unit, and the 485 interface protection unit is used for controlling whether the output end of the user access terminal P1 is electrically connected with the input end of the 485 communication interface unit.
By adopting the technical scheme, the control unit is used for setting the output voltage range of the user access terminal P1, and then the voltage sampling unit is used for sampling the output voltage of the user access terminal P1; when the sampling voltage is within the set voltage range, the 485 interface protection unit controls the user access terminal P1 to be electrically connected with the input end of the 485 communication interface unit, so that the communication function can be normally realized; when the user is in a state of being connected with 220V or 380V of the mains supply by mistake and the sampled voltage exceeds the set voltage range, the 485 interface protection unit controls the user access terminal P1 to be disconnected with the 485 communication interface unit, so that overvoltage protection is realized.
Preferably, the 485 interface protection unit comprises a relay K1 and a triode Q1, wherein the output end of the control unit is electrically connected to the base electrode of the triode Q1, the emitter electrode of the triode Q1 is grounded, the collector electrode of the triode Q1 is electrically connected to the grounding end of the relay K1, and the power supply end of the relay K1 is electrically connected with a power supply V2; the first public end and the second public end of relay K1 are respectively electrically connected to the output end of user access terminal P1, the first normally closed contact and the second normally closed contact of relay K1 are all unsettled, the first normally open contact and the second normally open contact of relay K1 are respectively electrically connected to 485 communication interface unit input.
By adopting the technical scheme, when the output end of the user access terminal P1 does not output voltage or the sampling voltage exceeds the set voltage range or the user access terminal P1 does not output voltage, the control unit outputs a low-level signal to the base electrode of the triode Q1, the triode Q1 is cut off, the relay K1 does not work after power is not applied, the first public end and the second public end are respectively and electrically connected to the first normally-closed contact and the second normally-closed contact, namely, the user access terminal P1 is disconnected with the 485 communication interface unit at the moment, and overvoltage protection is realized; when the sampling voltage is within the set voltage range, the control unit outputs a high-level signal to the base electrode of the triode Q1 at this moment, the triode Q1 is conducted, the relay K1 is electrified to work at this moment, the first public end and the second public end are respectively electrically connected to the first normally open contact and the second normally open contact, namely, the output end of the user access terminal P1 is electrically connected with the input end of the 485 communication interface unit at this moment, and therefore the communication function can be normally realized.
Preferably, the 485 interface protection unit further comprises a freewheel diode D1, wherein an anode of the freewheel diode D1 is electrically connected to a ground terminal of the relay K1, and a cathode of the freewheel diode D1 is electrically connected to a power supply terminal of the relay K1.
By adopting the technical scheme, the freewheeling diode D1 is utilized to play a freewheeling role and is used for releasing reverse current generated by sudden power failure of the relay K1 and protecting the circuit.
Preferably, the voltage sampling unit includes a rectifier bridge DB, a first input terminal and a second input terminal of the rectifier bridge DB are respectively electrically connected to the output terminal of the user access terminal P1, the first output terminal and the second output terminal of the rectifier bridge DB are both electrically connected to the input terminal of the control unit, and the second output terminal of the rectifier bridge DB is grounded.
By adopting the technical scheme, the alternating current can be converted into direct current by the rectifier bridge DB so as to be conveniently output to the control unit.
Preferably, the voltage sampling unit further includes a low-pass filter capacitor C6 and a high-pass filter capacitor C7, wherein an anode of the low-pass filter capacitor C6 is electrically connected to a connection part between the first output end and the second output end of the rectifier bridge DB, and a cathode of the low-pass filter capacitor C6 is grounded; the positive electrode of the high-pass filter capacitor C7 is electrically connected to the positive electrode of the low-pass filter capacitor C6, and the negative electrode of the high-pass filter capacitor C7 is grounded.
By adopting the technical scheme, the stability of sampling voltage output can be improved by utilizing the low-pass filter capacitor C6 and the high-pass filter capacitor C7.
Preferably, the voltage sampling unit further includes a zener diode D2, an anode of the zener diode D2 is grounded, and a cathode of the zener diode D2 is electrically connected to a connection between the first output terminal and the second output terminal of the rectifier bridge DB.
By adopting the technical scheme, the stability of the output of the sampling voltage can be further improved by utilizing the zener diode D2.
Preferably, the control device further comprises an alarm unit, wherein the input end of the alarm unit is electrically connected to the output end of the control unit.
By adopting the technical scheme, when the sampling voltage is within the set voltage range, the control unit controls the alarm unit to not work; when the sampling voltage exceeds the set voltage range, the control unit controls the alarm unit to start working, and the alarm unit gives an alarm to remind a user of abnormal access voltage, so that the user can solve the problem in time.
Preferably, the alarm unit comprises a triode Q2 and a buzzer H1, the output end of the control unit is electrically connected to the base electrode of the triode Q2, the emitter electrode of the triode Q2 is grounded, the collector electrode of the triode Q2 is electrically connected to the grounding end of the buzzer H1, and the power supply end of the buzzer H1 is electrically connected with a power supply V3.
By adopting the technical scheme, when the sampling voltage is within the set voltage range, the control unit outputs a low-level signal to the base electrode of the triode Q2 at the moment, so that the triode Q2 is cut off, and the buzzer H1 is powered off; when the sampling voltage exceeds the set voltage range, the control unit outputs a high-level signal to the base electrode of the triode Q2 at the moment, so that the triode Q2 is conducted, the buzzer H1 works in a power-on mode, and an audible alarm is sent out.
In summary, the present application includes at least one of the following beneficial technical effects: setting an output voltage range of a user connecting terminal P1 through a control unit, sampling through a voltage sampling unit when the output end of the user connecting terminal P1 has voltage output, and outputting the sampled voltage to the control unit; when the sampling voltage exceeds the set voltage range, the control unit controls the 485 interface protection unit to be not operated, and at the moment, the user wiring terminal P1 is disconnected with the 485 communication interface unit, so that the function of protecting the 485 communication interface circuit is realized, and the alarm function can be realized through the alarm unit; when the sampling voltage is within the set voltage range, the control unit controls the 485 interface protection unit to work, and at the moment, the output end of the user wiring terminal P1 is electrically connected with the input end of the 485 communication interface unit, so that the 485 communication interface unit can work normally, and a communication function is realized.
1. Setting an output voltage range of the user connecting terminal P1 by using a control unit, and sampling the output voltage of the user connecting terminal P1 by using a voltage sampling unit; when the sampling voltage is within the set voltage range, the relay K1 works, at the moment, the output end of the user wiring terminal P1 is electrically connected with the input end of the 485 communication interface unit normally, and the communication function is normally realized; when the sampling voltage exceeds the set voltage range, the relay K1 does not work, so that the user wiring terminal P1 is disconnected with the 485 communication interface unit, and overvoltage protection is realized;
2. the alarm unit is utilized to give an alarm when the sampling voltage exceeds the set voltage range, so that a user can be reminded of timely solving the problem of abnormal access voltage.
Drawings
FIG. 1 is a circuit diagram of a conventional 485 communication interface circuit;
FIG. 2 is a schematic diagram of an embodiment of the present application;
fig. 3 is a circuit diagram of a control unit;
fig. 4 is a circuit diagram of a voltage sampling unit;
fig. 5 is a circuit diagram of a 485 interface protection unit;
fig. 6 is a circuit diagram of an alarm unit.
Reference numerals: 1. 485 communication interface unit; 2. a control unit; 3. a voltage sampling unit; 4. 485 interface protection unit; 5. and an alarm unit.
Detailed Description
The present application is described in further detail below in conjunction with figures 1-6.
Referring to fig. 1, the conventional 485 communication interface circuit includes a communication chip U1, and the 485 communication interface circuit includes a first input terminal RS485+, a second input terminal RS485-, a first output terminal 485-RX, and a second output terminal 485-TX. The first input end RS485+ and the second input end RS 485-are used for being accessed by a user, and the first output end 485-RX and the second output end 485-TX are used for being electrically connected to a controller, so that communication work can be realized. The first input end RS485+ and the second input end RS 485-are respectively electrically connected to the pin 6 and the pin 7 of the communication chip U1, and if the user outputs excessive voltage through the first input end RS485+ and the second input end RS485-, the pin 6 and the pin 7 are easy to burn out, so that the 485 communication interface circuit cannot work normally.
The embodiment of the application discloses a 485 communication interface circuit with overvoltage protection.
Referring to fig. 2, a 485 communication interface circuit with overvoltage protection includes a 485 communication interface unit 1, a control unit 2, a voltage sampling unit 3, a 485 interface protection unit 4, and a user access terminal P1, wherein the 485 communication interface unit 1 is configured to have the same structure as the existing 485 communication interface circuit. The output end of the user access terminal P1 is electrically connected to the input end of the voltage sampling unit 3, and the output end of the voltage sampling unit 3 is electrically connected to the access end of the control unit 2. The output end of the user access terminal P1 is also electrically connected to the input end of the 485 communication interface unit 1 through the 485 interface protection unit 4. The control end of the 485 interface protection unit 4 is electrically connected to the output end of the control unit 2, and the 485 interface protection unit 4 is used for controlling whether the user access terminal P1 can be electrically connected with the 485 communication interface unit 1. The control unit 2 can set the output voltage range of the user access terminal P1, and the voltage sampling unit 3 is configured to sample the output voltage of the user access terminal P1. If the sampled voltage is within the set voltage range, the control unit 2 enables the user access terminal P1 to be electrically connected with the 485 communication interface circuit through the 485 interface protection unit 4; otherwise, the control unit 2 can not realize the electric connection between the user access terminal P1 and the 485 communication interface circuit through the 485 interface protection unit 4, so that the overvoltage protection of the 485 communication interface unit 1 is realized. In addition, the embodiment further includes an alarm unit 5, wherein an input end of the alarm unit 5 is electrically connected to an output end of the control unit 2, and when the voltage sampled by the voltage sampling unit 3 exceeds the set voltage range, the control unit 2 outputs an alarm signal to the alarm unit 5 to make the alarm unit 5 alarm.
Referring to fig. 3, the control unit 2 includes a single-chip microcomputer U4 and its peripheral circuit elements, wherein a pin 42 is electrically connected to a second output 485-TX, and a pin 43 is electrically connected to a first output 485-RX. The pin 10 is electrically connected to an input terminal of the 485 interface protection unit 4 for outputting a closing signal CONTROL. The pin 11 is electrically connected to an output of the voltage sampling unit 3 for receiving a sampled voltage output signal SAMPLE for receiving a sampled voltage. The pin 12 is electrically connected to an input terminal of the ALARM unit 5 for outputting an ALARM signal ALARM.
Referring to fig. 4, the USER access terminal P1 includes a first output terminal user_ina and a second output terminal user_inb. The voltage sampling unit 3 includes a resistor R10, a resistor R11, a rectifier bridge DB, a resistor R12, a resistor R13, a high-frequency filter capacitor C6, a resistor R14, a low-frequency filter capacitor C7, and a zener diode D2, wherein the resistor R10 and the resistor R11 are provided as PTC resistors. The first output terminal user_ina is electrically connected to the input pin 2 of the rectifier bridge DB through a resistor R11, and the second output terminal user_inb is electrically connected to the input pin 1 of the rectifier bridge DB through a resistor R10. The output pin 3 of the rectifier bridge DB is electrically connected to one end of the resistor R12, the other end of the resistor R12 is electrically connected to one end of the resistor R13, the other end of the resistor R13 is electrically connected to the output pin 4 of the rectifier bridge DB, and the output pin 4 of the rectifier bridge DB is grounded. The alternating current can be converted into direct current by means of the rectifier bridge DB for reception by the control unit 2.
The negative electrode of the high-frequency filter capacitor C6 is grounded, and the positive electrode of the high-frequency filter capacitor C6 is electrically connected to the connection between the resistor R12 and the resistor R13. One end of the resistor R14 is electrically connected to the positive electrode of the high-frequency filter capacitor C6, the other end of the resistor R14 is electrically connected to the positive electrode of the low-frequency filter capacitor C7, and the negative electrode of the low-frequency filter capacitor C7 is grounded. The stability of the sampling voltage can be improved by providing the high-frequency filter capacitor C6 and the low-frequency filter capacitor C7.
The positive electrode of the zener diode D2 is grounded, and the negative electrode of the zener diode D2 is electrically connected to the positive electrode of the low-frequency filter capacitor C7. The stability of the sampled voltage output can be further improved by using the zener diode D2. The negative pole of the zener diode D2 is an output terminal of the voltage sampling unit 3, and is configured to output a sampling voltage output signal SAMPLE, thereby outputting a sampling voltage.
Referring to fig. 5, the 485 interface protection unit 4 includes a resistor R3, a resistor R5, a flywheel diode D1, a triode Q1, a relay K1, and a power supply V2, and the output voltage value of the power supply V2 in this embodiment is 12V. A pin for outputting a closing signal CONTROL in the CONTROL unit 2 is electrically connected to one end of a resistor R3, and the other end of the resistor R3 is electrically connected to the base of the transistor Q1. One end of the resistor R5 is grounded, and the other end of the resistor R5 is electrically connected to the base of the transistor Q1. The emitter of the triode Q1 is grounded, the collector of the triode is electrically connected to the grounding end of the relay K1, and the power supply end of the relay K1 is electrically connected to the output end of the power supply V2. The positive electrode of the freewheel diode D1 is electrically connected to the collector of the transistor Q1, and the negative electrode of the freewheel diode D1 is electrically connected to the output terminal of the power supply V2. The freewheeling diode D1 is used for playing a freewheeling role and is used for releasing reverse current generated by sudden power failure of the relay K1 to protect a circuit. The relay K1 further includes a first common terminal 1, a second common terminal 2, a first normally closed contact 3, a second normally closed contact 4, a first normally open contact 5, and a second normally open contact 6. The first public terminal 1 and the second public terminal 2 are respectively and electrically connected to a second output terminal USER_INB and a first output terminal USER_INA, the first normally closed contact 3 and the second normally closed contact 4 are suspended, and the first normally open contact 5 and the second normally open contact 6 are respectively and electrically connected to a first input terminal RS485+ and a second input terminal RS485-.
When the sampling voltage exceeds the set voltage range or the USER access terminal P1 does not output voltage, the control unit 2 outputs a low-level signal to the base electrode of the triode Q1, the triode Q1 is cut off, the relay K1 does not work, the first public terminal 1 and the second public terminal 2 are respectively and electrically connected to the first normally-closed contact and the second normally-closed contact 4, namely, at the moment, the first output end USER_INA is disconnected with the first input end RS485+, and the second output end USER_INB is disconnected with the second input end RS485-, so that the excessive output voltage cannot be directly output to the first input end RS485+ and the second input end RS485-, and an overvoltage protection effect is achieved; when the sampling voltage is within the set voltage range, the CONTROL unit 2 outputs a high-level closing signal CONTROL to the base electrode of the triode Q1, the triode Q1 is conducted, the relay K1 is powered on to work, the first public end 1 and the second public end 2 are respectively electrically connected to the first normally open contact 5 and the second normally open contact 6, the first output end USER_INA is electrically connected to the first input end RS485+, and the second output end USER_INB is electrically connected to the second input end RS485-, so that normal communication functions can be realized.
Referring to fig. 6, the alarm unit 5 includes a resistor R16, a resistor R15, a filter capacitor C8, a transistor Q2, a diode D3, a buzzer H1, and a power source V3, and the output voltage value of the power source V3 in this embodiment is 12V. A pin for outputting an ALARM signal ALARM in the control unit 2 is electrically connected to one end of a resistor R16, the other end of the resistor R16 is electrically connected to one end of a resistor R15, and the other end of the resistor R15 is grounded. The negative electrode of the filter capacitor C8 is grounded, and the positive electrode of the filter capacitor C8 is electrically connected to the connection between the resistor R16 and the resistor R15. The base electrode of the triode Q2 is electrically connected to the positive electrode of the filter capacitor C8, the emitter electrode of the triode Q2 is grounded, and the collector electrode of the triode Q2 is electrically connected to the output end of the power supply V3 through the buzzer H1. The diode D3 is connected in parallel to two ends of the buzzer H1, the positive electrode of the diode D3 is electrically connected to the collector electrode of the triode Q2, and the negative electrode of the diode D3 is electrically connected to the output end of the power supply V3.
The buzzer H1 belongs to an inductive component, and when the buzzer H1 is suddenly powered off, the current in the buzzer H1 cannot suddenly drop to 0. Therefore, when the buzzer H1 is suddenly powered off, reverse current can be generated, and the diode D3 can be used for discharging the reverse current, so that a protection effect is achieved. The filter capacitor C8 can further stably operate the alarm unit 5.
When the control unit 2 outputs a low level to the base electrode of the triode Q2, the triode Q2 is cut off, and the buzzer H1 does not work at the moment; when the control unit 2 outputs a high-level ALARM signal ALARM to the base electrode of the triode Q2, the triode Q2 is turned on, and the buzzer H1 starts to work at the moment to remind a user of misconnection.
The implementation principle of the 485 communication interface circuit with overvoltage protection in the embodiment of the application is as follows: setting an output voltage range of a user connecting terminal P1 through a control unit 2, when the output end of the user connecting terminal P1 has voltage output, firstly sampling the output voltage of the user connecting terminal P1 through a voltage sampling unit 3, and outputting the sampled voltage to the control unit 2; when the sampling voltage exceeds the set voltage range, the control unit 2 controls the relay K1 to be not operated, at the moment, the user wiring terminal P1 is disconnected with the 485 communication interface unit 1, so that an overvoltage protection function is realized, and an alarm function can be realized through the alarm unit 5; when the sampling voltage is within the set voltage range, the control unit 2 controls the relay K1 to work, and at the moment, the output end of the user wiring terminal P1 is electrically connected with the input end of the 485 communication interface unit 1, so that the 485 communication interface unit 1 can work normally, and a communication function is realized.
The foregoing are all preferred embodiments of the present application, and are not intended to limit the scope of the present application in any way, therefore: all equivalent changes in structure, shape and principle of this application should be covered in the protection scope of this application.
Claims (8)
1. The 485 communication interface circuit with the overvoltage protection comprises a 485 communication interface unit (1), and is characterized in that: the system also comprises a control unit (2), a voltage sampling unit (3), a 485 interface protection unit (4) and a user access terminal P1;
the input end of the voltage sampling unit (3) is electrically connected to the output end of the user access terminal P1, and the output end of the voltage sampling unit (3) is electrically connected to the input end of the control unit (2);
the output end of the user access terminal P1 is electrically connected to the input end of the 485 communication interface unit (1) through the 485 interface protection unit (4);
the control end of the 485 interface protection unit (4) is electrically connected to the output end of the control unit (2), and the 485 interface protection unit (4) is used for controlling whether the output end of the user access terminal P1 is electrically connected with the input end of the 485 communication interface unit (1).
2. A 485 communication interface circuit with overvoltage protection according to claim 1, characterized in that: the 485 interface protection unit (4) comprises a relay K1 and a triode Q1, wherein the output end of the control unit (2) is electrically connected to the base electrode of the triode Q1, the emitting electrode of the triode Q1 is grounded, the collecting electrode of the triode Q1 is electrically connected to the grounding end of the relay K1, and the power supply end of the relay K1 is electrically connected with a power supply V2; the first public end and the second public end of relay K1 are respectively electrically connected to the output of user access terminal P1, the first normally closed contact and the second normally closed contact of relay K1 are all unsettled, the first normally open contact and the second normally open contact of relay K1 are respectively electrically connected to the input of 485 communication interface unit (1).
3. A 485 communication interface circuit with overvoltage protection according to claim 2, characterized in that: the 485 interface protection unit (4) further comprises a freewheel diode D1, wherein the positive electrode of the freewheel diode D1 is electrically connected to the grounding end of the relay K1, and the negative electrode of the freewheel diode D1 is electrically connected to the power supply end of the relay K1.
4. A 485 communication interface circuit with overvoltage protection according to claim 1, characterized in that: the voltage sampling unit (3) comprises a rectifier bridge DB, a first input end and a second input end of the rectifier bridge DB are respectively and electrically connected to the output end of the user access terminal P1, the first output end and the second output end of the rectifier bridge DB are both electrically connected to the input end of the control unit (2), and the second output end of the rectifier bridge DB is grounded.
5. A 485 communication interface circuit with overvoltage protection according to claim 4, characterized in that: the voltage sampling unit (3) further comprises a low-pass filter capacitor C6 and a high-pass filter capacitor C7, wherein the positive electrode of the low-pass filter capacitor C6 is electrically connected to the joint between the first output end and the second output end of the rectifier bridge DB, and the negative electrode of the low-pass filter capacitor C6 is grounded; the positive electrode of the high-pass filter capacitor C7 is electrically connected to the positive electrode of the low-pass filter capacitor C6, and the negative electrode of the high-pass filter capacitor C7 is grounded.
6. A 485 communication interface circuit with overvoltage protection according to claim 4, characterized in that: the voltage sampling unit (3) further comprises a zener diode D2, the positive electrode of the zener diode D2 is grounded, and the negative electrode of the zener diode D2 is electrically connected to the connection part between the first output end and the second output end of the rectifier bridge DB.
7. A 485 communication interface circuit with overvoltage protection according to claim 1, characterized in that: the intelligent control system further comprises an alarm unit (5), wherein the input end of the alarm unit (5) is electrically connected to the output end of the control unit (2).
8. A 485 communication interface circuit with overvoltage protection according to claim 7, characterized in that: the alarm unit (5) comprises a triode Q2 and a buzzer H1, wherein the output end of the control unit (2) is electrically connected to the base electrode of the triode Q2, the emitting electrode of the triode Q2 is grounded, the collecting electrode of the triode Q2 is electrically connected to the grounding end of the buzzer H1, and the power supply end of the buzzer H1 is electrically connected with a power supply V3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321867289.8U CN220342028U (en) | 2023-07-17 | 2023-07-17 | 485 communication interface circuit with overvoltage protection |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321867289.8U CN220342028U (en) | 2023-07-17 | 2023-07-17 | 485 communication interface circuit with overvoltage protection |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN220342028U true CN220342028U (en) | 2024-01-12 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202321867289.8U Active CN220342028U (en) | 2023-07-17 | 2023-07-17 | 485 communication interface circuit with overvoltage protection |
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| Country | Link |
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| CN (1) | CN220342028U (en) |
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- 2023-07-17 CN CN202321867289.8U patent/CN220342028U/en active Active
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