CN210294916U - Circuit for converting voltage into 4-20mA current - Google Patents
Circuit for converting voltage into 4-20mA current Download PDFInfo
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- CN210294916U CN210294916U CN201921562356.9U CN201921562356U CN210294916U CN 210294916 U CN210294916 U CN 210294916U CN 201921562356 U CN201921562356 U CN 201921562356U CN 210294916 U CN210294916 U CN 210294916U
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Abstract
The utility model provides a voltage changes 4-20mA electric current circuit, including output circuit and output protection circuit, its characterized in that, output protection circuit includes diode D1, fuse F1, output terminal CN1 and high-power TVS pipe D2; a first end of the diode D1 is connected with an output end of the output circuit; a first terminal of the fuse F1 is connected to the second terminal of the diode D1, and a second terminal of the fuse F1 is connected to the output terminal CN 1; a first end of the high-power TVS tube D2 is connected to the H point between the diode D2 and the fuse F1, and a second end of the high-power TVS tube D2 is grounded and connected to the output terminal CN 1. The utility model discloses an output protection circuit who comprises diode, high-power TVS pipe and self-resuming fuse is connected with output circuit, has effectively prevented that the electrostatic breakdown and misconnection forceful electric power lead to the output circuit receive the high energy to strike and damage.
Description
Technical Field
The utility model relates to an electricity technical field, concretely relates to voltage changes 4-20mA electric current circuit.
Background
Due to rapid development of the electronic industry, components are developed in a direction of small size and high integration level, so that the distance between wires is reduced, and an insulating film is thinner and thinner, so that breakdown-resistant voltage is reduced, and static electricity generated by an electronic product during transportation, installation and storage far exceeds the voltage-resistant threshold value of the electronic product, so that breakdown or failure in the period can be caused, the performance index of the product is influenced, and the reliability is reduced.
In the prior art, a back-flow prevention diode is usually added at an output end, and if static electricity is generated or alternating current strong electricity is wrongly connected, the diode is directly broken down, so that a back-end circuit element is damaged by impact of transient high energy.
SUMMERY OF THE UTILITY MODEL
The problem that in the prior art, only one anti-backflow diode is added at an output end, and when static electricity is generated in a circuit or alternating current strong electricity is misconnected, the diode is directly broken down, so that circuit elements at the rear end are damaged due to impact of transient high energy is solved. The utility model discloses an output protection circuit who comprises diode, high-power TVS pipe and self-resuming fuse is connected with output circuit, effectively prevents that the electrostatic breakdown and wrong output circuit who connects the forceful electric power to lead to from receiving the high energy impact and damaging.
In order to achieve the above purpose, the utility model adopts the following technical scheme:
a circuit for converting voltage into 4-20mA current comprises an output circuit and an output protection circuit, wherein the output protection circuit comprises a diode D1, a fuse F1, an output terminal CN1 and a high-power TVS tube D2;
a first end of the diode D1 is connected with an output end of the output circuit;
a first terminal of the fuse F1 is connected to the second terminal of the diode D1, and a second terminal of the fuse F1 is connected to the output terminal CN 1;
a first end of the high-power TVS tube D2 is connected to the H point between the diode D2 and the fuse F1, and a second end of the high-power TVS tube D2 is grounded and connected to the output terminal CN 1.
Preferably, the fuse F1 is a self-restoring fuse.
According to the above technical scheme, the utility model discloses fine solution under the prior art, only add one at the output and prevent flowing backward the diode, when the circuit produced static or wrong grafting alternating current forceful electric power, the diode was directly punctured, leads to the circuit element of rear end to receive the impact of transient state high energy and the problem of damage. The utility model discloses an output protection circuit who comprises diode, TVS pipe and self-resuming fuse is connected with output circuit, and the effectual output circuit who has prevented electrostatic breakdown and misconnection forceful electric power and lead to receives the high energy to strike and damages.
Drawings
Fig. 1 is a schematic diagram of a circuit connection according to the present invention;
Detailed Description
A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.
The circuit for converting voltage into 4-20mA current as shown in FIG. 1 comprises an output circuit and an output protection circuit, wherein the output protection circuit comprises a diode D1, a fuse F1, an output terminal CN1 and a high-power TVS tube D2; a first end of the diode D1 is connected with an output end of the output circuit; a first terminal of the fuse F1 is connected to the second terminal of the diode D1, and a second terminal of the fuse F1 is connected to the output terminal CN 1; a first end of the high-power TVS tube D2 is connected to the H point between the diode D2 and the fuse F1, and a second end of the high-power TVS tube D2 is grounded and connected to the output terminal CN 1.
As shown in fig. 1, the fuse F1 is a self-healing fuse, which is composed of specially processed polymer resin and conductive particles distributed therein, and under normal voltage, the polymer resin tightly binds the conductive particles outside the crystalline structure to form a chain-like conductive path, and the self-healing fuse is in a low-resistance state at this time, and the heat energy generated by the current flowing through the self-healing fuse on the circuit is small, and the crystal structure is not changed; when a circuit is short-circuited or overloaded, a large current flows through the self-recovery fuse, the generated heat melts the polymer resin, the volume is rapidly increased to form a high-resistance state, and the working current is rapidly reduced, so that the circuit is limited and protected; after the fault is eliminated, the self-recovery fuse is cooled and crystallized again, the volume shrinks, the conductive particles form a conductive path again, and the self-recovery fuse is recovered to be in a low-resistance state, so that the circuit is protected without manual replacement.
The working principle of the preferred embodiment is illustrated by three cases as follows:
the output terminal can be contacted to the inevitable meeting of specific product when production installation, has very probably produced static, and when static got into circuit through the incoming end and arrived TVS pipe D2, TVS pipe D2 switched on in the twinkling of an eye and directly led into the underground with the high voltage that static produced, played the effect of releasing high pressure, protection port.
When the output terminal CN1 is misconnected with strong current, the strong current instantly passes through the fuse F1 to reach the space between the TVS tube and the diode D1, when the TVS tube D2 is impacted by the instant high energy, its impedance is suddenly reduced, and at the same time, it absorbs the large current, and clamps the voltage between its two ends at a predetermined value, thereby ensuring that the following circuit elements are not damaged by the impact of the transient high energy; the part of the current exceeding the current absorbed by the TVS tube D2 is blocked by the diode D1 to prevent the current from flowing backwards, at the moment, the circuit is in an overload state, the high current flowing through the fuse F1 forms a high-resistance state, and the working current is rapidly reduced, so that the circuit is limited and protected; when the fault is eliminated, the fuse F1 reforms the conductive path, and the self-recovery fuse recovers to a low-resistance state, so that the circuit is protected without manual replacement.
When the external connection is short-circuited, the instantaneous current is increased, the fuse F1 is in a high-resistance state, the connection with the outside is broken, the circuit is protected, and when the external fault is eliminated, the fuse F1 forms a conductive path again and the normal operation is recovered.
The above-mentioned embodiments are only to describe the preferred embodiments of the present invention, but not to limit the scope of the present invention, and various modifications and improvements made by those skilled in the art without departing from the design spirit of the present invention should fall into the protection scope defined by the claims of the present invention.
Claims (2)
1. A circuit converting voltage into 4-20mA current comprises an output circuit and an output protection circuit, and is characterized in that the output protection circuit comprises a diode D1, a fuse F1, an output terminal CN1 and a high-power TVS tube D2;
a first end of the diode D1 is connected with an output end of the output circuit;
a first terminal of the fuse F1 is connected to the second terminal of the diode D1, and a second terminal of the fuse F1 is connected to the output terminal CN 1;
a first end of the high-power TVS tube D2 is connected to the H point between the diode D2 and the fuse F1, and a second end of the high-power TVS tube D2 is grounded and connected to the output terminal CN 1.
2. The circuit of claim 1, wherein the fuse F1 is a self-healing fuse.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921562356.9U CN210294916U (en) | 2019-09-19 | 2019-09-19 | Circuit for converting voltage into 4-20mA current |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921562356.9U CN210294916U (en) | 2019-09-19 | 2019-09-19 | Circuit for converting voltage into 4-20mA current |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN210294916U true CN210294916U (en) | 2020-04-10 |
Family
ID=70063431
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201921562356.9U Active CN210294916U (en) | 2019-09-19 | 2019-09-19 | Circuit for converting voltage into 4-20mA current |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN210294916U (en) |
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2019
- 2019-09-19 CN CN201921562356.9U patent/CN210294916U/en active Active
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