CN216598962U - Gas table DC alarm input interface protection circuit - Google Patents
Gas table DC alarm input interface protection circuit Download PDFInfo
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- CN216598962U CN216598962U CN202122957959.2U CN202122957959U CN216598962U CN 216598962 U CN216598962 U CN 216598962U CN 202122957959 U CN202122957959 U CN 202122957959U CN 216598962 U CN216598962 U CN 216598962U
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Abstract
The utility model discloses a protection circuit for an input interface of a DC alarm of a gas meter, which comprises a surge absorption circuit, an overvoltage protection circuit and an isolation and low-power consumption processing circuit. The utility model utilizes the high-voltage rectifier diode to weaken high voltage, when the voltage exceeds 24V, the overvoltage protection circuit can start and shut off the triode so as to prevent the high voltage from entering the isolation circuit, if the front-section overvoltage protection circuit fails, the high voltage enters the isolation circuit, and the isolation circuit physically isolates the high voltage, thereby realizing the safety and reliability of the circuit.
Description
Technical Field
The utility model belongs to the field of gas instruments, relates to a circuit, in particular to a DC interface protection circuit which is suitable for protecting an input interface of a gas alarm of a gas instrument and improving the reliability of the gas instrument.
Background
The alarm signal output modes of the combustible gas alarm are various, and the alarm signal output of the household gas alarm is generally acousto-optic alarm and pulse signal output. The pulse output is mostly used for directly controlling the electromagnetic valve and closing the fuel gas, and because combustible gas alarming manufacturers are more, the voltage values of the pulse signals of the matched electromagnetic valves are different, so that the output pulse signals of the alarm are different. The intelligent gas meter is compatible with pulse signals of different voltage values if the intelligent gas meter wants to acquire the pulse signals of the gas alarm, and the intelligent gas meter is not damaged. The input interface protection circuit of the DC alarm of the gas meter can ensure the correct input of signals and cannot influence the meter.
Disclosure of Invention
The utility model aims to provide a pulse interface compatible with different gas alarms and a method for mistakenly accessing high-voltage signals such as alternating current 220V and the like without causing damage to an intelligent gas meter. The protection circuit is designed according to the requirements of the two points and the requirement of low power consumption of the intelligent gas meter.
The input interface protection circuit of the gas meter DC alarm comprises a surge absorption circuit, an overvoltage protection circuit and an isolation and low power consumption processing circuit.
The surge absorption circuit comprises a PTC thermistor PT1 and a high-voltage rectifier diode D1, wherein the anode of the high-voltage rectifier diode D1 is connected with the anode of an external alarm input interface power supply J1; the cathode of the high-voltage rectifier diode D1 is connected with one end of the PTC thermistor PT 1.
The overvoltage protection circuit comprises a second current-limiting resistor R4, a second triode Q2, a third resistor R7, a first voltage-stabilizing diode D4, a second voltage-stabilizing diode D3, a third current-limiting resistor R8, a fourth resistor R5, a fifth resistor R6, a first triode Q1, a third voltage-stabilizing diode D2, a first resistor R2 and a second capacitor C2;
one end of a third resistor R7 is connected with one end of a second current-limiting resistor R4 and the cathode of a first voltage-stabilizing diode D4, the other end of the third resistor R7 is connected with the base of a second triode Q2 and the anode of a second voltage-stabilizing diode D3, and the anode of the first voltage-stabilizing diode D4 is connected with the cathode of an external alarm input interface power supply J1; one end of a third current-limiting resistor R8 is connected with the collector of the second triode Q2 and one end of a fourth resistor R5, and the other end of the third current-limiting resistor R8 is connected with the negative electrode of an external alarm input interface power supply J1; the cathode of the second voltage-stabilizing diode D3, the other end of the second current-limiting resistor R4, the other end of the fourth resistor R5, the emitter of the second triode Q2, the cathode of the third voltage-stabilizing diode D2 and the emitter of the first triode Q1 are connected with the other end of the PTC thermistor PT 1; the anode of the third voltage-stabilizing diode D2 is connected with the base of the first triode Q1 and one end of a fifth resistor R6, and the other end of the fifth resistor R6 is connected with the cathode of an external alarm input interface of a power supply J1; the collector of the first triode Q1 is connected with one end of the first resistor R2 and one end of the second capacitor C2;
the isolation and low-power consumption processing circuit comprises an isolation optocoupler U1, a first current-limiting resistor R1, a second resistor R3 and a first capacitor C1.
An input 1 pin of the isolation optocoupler U1 is connected with the other end of the first resistor R2, an input 2 pin is connected with the negative electrode of an input interface of the external alarm, an output 3 pin of the isolation optocoupler U1 is connected with the negative electrode of an internal system power supply, an output 4 pin of the isolation optocoupler U1 is connected with one end of the first current-limiting resistor R1, one end of the second resistor R3 and one end of the first capacitor C1, the other end of the first capacitor C1 is connected with the negative electrode of the internal system power supply, the other end of the first current-limiting resistor R1 is connected with a control pin BT _ POW of the internal protection object MCU, and the other end of the second R3 is connected with a signal input pin BT IN of the internal protection object MCU;
the utility model has the following beneficial effects:
according to the utility model, the high-voltage rectifier diode is used for weakening high-voltage electricity such as 220V alternating current, when the voltage exceeds 24V, the overvoltage protection circuit can start and shut off the triode, so that the high-voltage electricity is prevented from entering the isolation circuit, if the front-section overvoltage protection circuit fails, the high-voltage electricity enters the isolation circuit, the isolation circuit physically isolates the high-voltage electricity, and the safety and reliability of the circuit are realized.
Drawings
FIG. 1 is a circuit diagram according to an embodiment of the present invention.
Detailed Description
The utility model will be further explained with reference to the drawings.
As shown in fig. 1, the input interface protection circuit of the DC alarm of the gas meter includes a surge absorption circuit, an overvoltage protection circuit, and an isolation and low power consumption processing circuit.
The surge absorption circuit comprises a PTC thermistor PT1 and a high-voltage rectifier diode D1, wherein the anode of the high-voltage rectifier diode D1 is connected with the anode of an external alarm input interface power supply J1; the cathode of the high-voltage rectifier diode D1 is connected with one end of the PTC thermistor PT 1. The high-voltage rectifier diode D1 is used for eliminating negative voltage and reducing surge, and the PTC is used for restraining surge impact.
The overvoltage protection circuit comprises a second current-limiting resistor R4, a second triode Q2, a third resistor R7, a first voltage-stabilizing diode D4, a second voltage-stabilizing diode D3, a third current-limiting resistor R8, a fourth resistor R5, a fifth resistor R6, a first triode Q1, a third voltage-stabilizing diode D2, a first resistor R2 and a second capacitor C2;
one end of a third resistor R7 is connected with one end of a second current-limiting resistor R4 and the cathode of a first voltage-stabilizing diode D4, the other end of the third resistor R7 is connected with the base of a second triode Q2 and the anode of a second voltage-stabilizing diode D3, and the anode of the first voltage-stabilizing diode D4 is connected with the cathode of an external alarm input interface power supply J1; one end of a third current-limiting resistor R8 is connected with the collector of the second triode Q2 and one end of a fourth resistor R5, and the other end of the third current-limiting resistor R8 is connected with the negative electrode of an external alarm input interface power supply J1; the cathode of the second voltage-stabilizing diode D3, the other end of the second current-limiting resistor R4, the other end of the fourth resistor R5, the emitter of the second triode Q2, the cathode of the third voltage-stabilizing diode D2 and the emitter of the first triode Q1 are connected with the other end of the PTC thermistor PT 1; the anode of the third voltage-stabilizing diode D2 is connected with the base of the first triode Q1 and one end of a fifth resistor R8, and the other end of the fifth resistor R8 is connected with the cathode of an external alarm input interface of a power supply J1; the collector of the first triode Q1 is connected with one end of the first resistor R2 and one end of the second capacitor C2;
the isolation and low-power consumption processing circuit comprises an isolation optocoupler U1, a first current-limiting resistor R1, a second resistor R3 and a first capacitor C1.
An input 1 pin of the isolation optocoupler U1 is connected with the other end of the first resistor R2, an input 2 pin is connected with the negative electrode of an input interface of the external alarm, an output 3 pin of the isolation optocoupler U1 is connected with the negative electrode of an internal system power supply, an output 4 pin of the isolation optocoupler U1 is connected with one end of the first current-limiting resistor R1, one end of the second resistor R3 and one end of the first capacitor C1, the other end of the first capacitor C1 is connected with the negative electrode of the internal system power supply, the other end of the first current-limiting resistor R1 is connected with a control pin BT _ POW of the internal protection object MCU, and the other end of the second R3 is connected with a signal input pin BT IN of the internal protection object MCU;
the main devices used by the utility model, including the rectifier diode D1, the overvoltage control triode Q1, the Q2, the 24V voltage stabilizing diode, the 5V voltage stabilizing diode, the PTC, the isolation optocoupler and the like, are all the existing mature products and can be obtained through the market.
The main circuit parameters in the utility model are matched as follows:
setting: rated current of light emitting side of isolation optocoupler U1 is IFThe voltage of the light emitting tube is reduced to VFThe input signal voltage is u. Then:
IF＝(u-VF)/R112
the working process of the utility model is as follows:
1. when the input pulse signal V1 is not higher than 24V, the signal V1 is rectified by a high-voltage rectifier diode D1 to filter out negative voltage, and then enters a PTC thermistor PT1, and then enters an overvoltage protection circuit, since the signal V1 is not higher than 24V, the 24V voltage regulator is turned off, the signal V1 enters the base and the emitter of the second triode Q2 through the second current-limiting resistor R4 and the third resistor R7, since the emitter and the base of the second triode Q2 are the same potential, the second triode Q2 enters the off state, the fourth resistor R5 and the third current-limiting resistor R8 form a voltage divider circuit, since the fourth resistor R5 and the third current-limiting resistor R8 are the same resistance value, the signal V1 becomes 1/2V1, the signal 1/2V1 enters the base of the first triode Q1 through the fifth resistor R6, the signal V1 enters the emitter of the first triode Q1, since the emitter of the first resistor R1 and the positive bias of the first transistor Q base are the same, first triode Q1 saturation switches on, and the signal gets into first resistance R2, gets into isolation opto-coupler U1 through first resistance R2, and isolation opto-coupler U1's emitting diode switches on luminous, makes isolation opto-coupler U1's photosensitive end 3, 4 feet switch on, draws low resistance R1's one end, and resistance R3 becomes the low level from the high level this moment, and the signal successfully gathers.
2. When an input pulse signal V1 is higher than 24V, the signal enters the cathode of a voltage stabilizing diode D4 through a second current limiting resistor R4, the positive end of the voltage stabilizing diode is connected with the cathode of an input interface of an external alarm, the voltage stabilizing diode is in reverse breakdown due to the fact that the cathode of the voltage stabilizing diode is higher than the anode of the voltage stabilizing diode 24V, the time signal is kept at 24V, the 24V signal enters the base of a second triode Q2, a signal V1 enters the emitter of a second triode Q2, the second triode Q2 is conducted in a forward bias mode, the voltage at the connection position of a third current limiting resistor R8 and a fourth resistor R5 is V1 and enters the base of a first triode Q1 through a fifth resistor R6, the signal V1 enters the emitter of the first triode Q1, the first triode Q1 is conducted in a zero bias mode, the emitter of the triode is conducted with the collector, and the signal is blocked, so that the high-voltage signal is prevented from entering an isolation U1.
3. Because 4 feet of the photosensitive output end of the isolation optocoupler U1 are powered by the resistor R1, and the power supply is controlled by the single chip microcomputer, the power consumption caused by the leakage current of the isolation optocoupler U1 is reduced by periodically turning on and off the control power supply.
Claims (1)
1. The input interface protection circuit of the gas meter DC alarm is characterized by comprising a surge absorption circuit, an overvoltage protection circuit and an isolation and low-power consumption processing circuit;
the surge absorption circuit comprises a PTC thermistor PT1 and a high-voltage rectifier diode D1, wherein the anode of the high-voltage rectifier diode D1 is connected with the anode of an external alarm input interface power supply J1; the cathode of the high-voltage rectifier diode D1 is connected with one end of the PTC thermistor PT 1;
the overvoltage protection circuit comprises a second current-limiting resistor R4, a second triode Q2, a third resistor R7, a first voltage-stabilizing diode D4, a second voltage-stabilizing diode D3, a third current-limiting resistor R8, a fourth resistor R5, a fifth resistor R6, a first triode Q1, a third voltage-stabilizing diode D2, a first resistor R2 and a second capacitor C2;
one end of a third resistor R7 is connected with one end of a second current-limiting resistor R4 and the cathode of a first voltage-stabilizing diode D4, the other end of the third resistor R7 is connected with the base of a second triode Q2 and the anode of a second voltage-stabilizing diode D3, and the anode of the first voltage-stabilizing diode D4 is connected with the cathode of an external alarm input interface power supply J1; one end of a third current-limiting resistor R8 is connected with the collector of the second triode Q2 and one end of a fourth resistor R5, and the other end of the third current-limiting resistor R8 is connected with the negative electrode of an external alarm input interface power supply J1; the cathode of the second voltage-stabilizing diode D3, the other end of the second current-limiting resistor R4, the other end of the fourth resistor R5, the emitter of the second triode Q2, the cathode of the third voltage-stabilizing diode D2 and the emitter of the first triode Q1 are connected with the other end of the PTC thermistor PT 1; the anode of the third voltage-stabilizing diode D2 is connected with the base of the first triode Q1 and one end of a fifth resistor R6, and the other end of the fifth resistor R6 is connected with the cathode of an external alarm input interface of a power supply J1; the collector of the first triode Q1 is connected with one end of the first resistor R2 and one end of the second capacitor C2;
the isolation and low-power consumption processing circuit comprises an isolation optocoupler U1, a first current-limiting resistor R1, a second resistor R3 and a first capacitor C1;
an input 1 pin of the isolation optocoupler U1 is connected with the other end of the first resistor R2, an input 2 pin is connected with the negative electrode of an input interface of the external alarm, an output 3 pin of the isolation optocoupler U1 is connected with the negative electrode of an internal system power supply, an output 4 pin of the isolation optocoupler U1 is connected with one end of the first current-limiting resistor R1, one end of the second resistor R3 and one end of the first capacitor C1, the other end of the first capacitor C1 is connected with the negative electrode of the internal system power supply, the other end of the first current-limiting resistor R1 is connected with a control pin BT _ POW of the internal protection object MCU, and the other end of the second R3 is connected with a signal input pin BT IN of the internal protection object MCU.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122957959.2U CN216598962U (en) | 2021-11-29 | 2021-11-29 | Gas table DC alarm input interface protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122957959.2U CN216598962U (en) | 2021-11-29 | 2021-11-29 | Gas table DC alarm input interface protection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN216598962U true CN216598962U (en) | 2022-05-24 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202122957959.2U Active CN216598962U (en) | 2021-11-29 | 2021-11-29 | Gas table DC alarm input interface protection circuit |
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| Country | Link |
|---|---|
| CN (1) | CN216598962U (en) |
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2021
- 2021-11-29 CN CN202122957959.2U patent/CN216598962U/en active Active
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