CN112636314A - Current-limiting protection circuit - Google Patents
Current-limiting protection circuit Download PDFInfo
- Publication number
- CN112636314A CN112636314A CN202011422442.7A CN202011422442A CN112636314A CN 112636314 A CN112636314 A CN 112636314A CN 202011422442 A CN202011422442 A CN 202011422442A CN 112636314 A CN112636314 A CN 112636314A
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- Prior art keywords
- current
- circuit
- resistor
- limiting protection
- power supply
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
- H02H9/025—Current limitation using field effect transistors
Abstract
The application discloses a current-limiting protection circuit, which comprises a current sampling circuit connected with a power supply and used for collecting the output current of the power supply, and a switch circuit connected with the current sampling circuit and used for controlling the output current to be reduced when the output current exceeds a current-limiting value; wherein the reduced output current is not greater than the current limit value. By applying the technical scheme, the switching circuit can stabilize the output current of the power supply below the current limiting value, so that the condition that the current value supplied to the working circuit is overlarge is avoided, and the working circuit is protected.
Description
Technical Field
The application relates to the field of electronic circuits, in particular to a current-limiting protection circuit.
Background
In order to limit the amount of current that a particular operating circuit passes, and after the current returns to normal, the circuit can return to normal operation without additional operations, it is common practice to use a self-restoring fuse. However, if the fuse fails in a short circuit or a broken circuit, the fuse loses the current limiting function, which not only causes the whole circuit to fail to work normally, but also damages the circuit in a serious condition. Fig. 1 is a schematic diagram of a fuse working circuit provided in the prior art, as shown in fig. 1, after a short circuit occurs in a fuse 1, if an internal circuit of a working circuit 2 is broken, a power supply cannot be disconnected; after the fuse 1 is broken, the operating circuit 2 cannot operate normally because there is no power supply.
In view of the above-mentioned prior art, a current limiting protection circuit for fault safety is a problem to be solved by those skilled in the art.
Disclosure of Invention
The current-limiting protection circuit stabilizes the output current of a power supply below a current-limiting value, thereby avoiding the situation that the current value supplied to a working circuit is too large and protecting the working circuit.
In order to solve the technical problem, the present application provides a current-limiting protection circuit, which includes a current sampling circuit connected to a power supply for collecting an output current of the power supply, and a switch circuit connected to the current sampling circuit for controlling a decrease of the output current when the output current exceeds a current-limiting value; wherein the reduced output current is not greater than the current limit value.
Preferably, the switch circuit comprises a first switch tube, a voltage division circuit and a second switch tube;
the first end of the first switch tube is connected with the input end of the current sampling circuit, the control end of the first switch tube is connected with the output end of the current sampling circuit, the second end of the first switch tube is connected with the control end of the second switch tube, the first end of the second switch tube is connected with the output end of the current sampling circuit, and the second end of the second switch tube is connected with the working circuit;
the input end of the voltage division circuit is connected with the power supply, and the output end of the voltage division circuit is connected with the control end of the second switch tube.
Preferably, the current sampling circuit includes a first resistor and a second resistor, and the first resistor is connected in parallel with the second resistor.
Preferably, the voltage dividing circuit comprises a third resistor, a fourth resistor, a fifth resistor and a sixth resistor;
the first end of the third resistor is connected with the power supply, the fourth resistor is connected with the third resistor in series, the common end of the fourth resistor and the fifth resistor is connected with the control end of the second switch tube, the fifth resistor is connected with the sixth resistor in series, and the first end of the sixth resistor is grounded.
Preferably, the switch further comprises a filter circuit, and the filter circuit is respectively connected with the second end of the second switch tube and the working circuit.
Preferably, the filter circuit includes a first inductor and a first capacitor, a first end of the first inductor is connected to a second end of the second switching tube, a second end of the first inductor is connected to the working circuit, a first end of the first capacitor is connected to the working circuit, and a second end of the first capacitor is grounded.
Preferably, the current sampling circuit is a seventh resistor, a first end of the seventh resistor is connected to the power supply, and a second end of the seventh resistor is connected to the first end of the second switching tube.
Preferably, the first switching tube is a triode, and the second switching tube is a field effect tube.
Preferably, the triode is MMBT 3906.
Preferably, the model of the field effect transistor is SI2309 CDS.
The current-limiting protection circuit comprises a current sampling circuit connected with a power supply and used for collecting output current of the power supply, and a switch circuit connected with the current sampling circuit and used for controlling the output current to be reduced when the output current exceeds a current-limiting value; wherein the reduced output current is not greater than the current limit value. By applying the technical scheme, the switching circuit can stabilize the output current of the power supply below the current limiting value, so that the condition that the current value supplied to the working circuit is overlarge is avoided, and the working circuit is protected.
Drawings
In order to more clearly illustrate the embodiments of the present application, the drawings needed for the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings can be obtained by those skilled in the art without inventive effort.
FIG. 1 is a schematic diagram of a fuse circuit according to the prior art;
fig. 2 is a schematic structural diagram of a current limiting protection circuit according to an embodiment of the present disclosure;
fig. 3 is a schematic structural diagram of another current-limiting protection circuit according to an embodiment of the present disclosure.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without any creative effort belong to the protection scope of the present application.
The core of the application is to provide a current-limiting protection circuit, which stabilizes the output current of a power supply below a current-limiting value, thereby avoiding the condition that the current value supplied to a working circuit is overlarge and protecting the working circuit.
In order that those skilled in the art will better understand the disclosure, the following detailed description will be given with reference to the accompanying drawings.
Fig. 2 is a schematic structural diagram of a current-limiting protection circuit according to an embodiment of the present disclosure. As shown in fig. 2, the circuit includes a current sampling circuit 11 connected to the power supply 10 for collecting the output current of the power supply 10, and a switching circuit 12 connected to the current sampling circuit 11 for controlling the output current to decrease when the output current exceeds a current limit value; wherein the reduced output current is not greater than the current limit value.
When the current-limiting protection circuit is applied practically, the output voltage of the power supply 10 is unchanged, the output current changes according to the practical situation, and when the output current collected by the current sampling circuit 11 is greater than the current-limiting value, the switch circuit 12 controls the output current to be reduced to be below the current-limiting value.
It can be understood that the above embodiment does not limit the specific structure of the current sampling circuit 11, as long as the collection of the output current is achieved, and according to the actual situation, the current sampling circuit may be a current limiting resistor, an inductor, or another chip with a current collection function. The switch circuit 12 may be formed by a triode or a field effect transistor, the triode may be NPN type or PNP type, the field effect transistor may be PMOS or NMOS, and the switch circuit 12 may be controlled by the current sampling circuit 11 in this embodiment, or may be controlled by the controller, which is not limited herein.
The current-limiting protection circuit comprises a current sampling circuit connected with a power supply and used for collecting output current of the power supply, and a switch circuit connected with the current sampling circuit and used for controlling the output current to be reduced when the output current exceeds a current-limiting value; wherein the reduced output current is not greater than the current limit value. By applying the technical scheme, the switching circuit can stabilize the output current of the power supply below the current limiting value, so that the condition that the current value supplied to the working circuit is overlarge is avoided, and the working circuit is protected.
Fig. 3 is a schematic structural diagram of another current-limiting protection circuit according to an embodiment of the present disclosure. As shown in fig. 3, as a preferred embodiment, the switching circuit 12 includes a first switching tube Q1, a voltage dividing circuit and a second switching tube Q2;
a first end E of the first switch tube Q1 is connected with the input end of the current sampling circuit 11, a control end B of the first switch tube Q1 is connected with the output end of the current sampling circuit 11, a second end C of the first switch tube Q1 is connected with a control end G of the second switch tube Q2, a first end S of the second switch tube Q2 is connected with the output end of the current sampling circuit 11, and a second end D of the second switch tube Q2 is connected with the working circuit;
the input end of the voltage division circuit is connected with the power supply 10, and the output end of the voltage division circuit is connected with the control end G of the second switch tube Q2.
In a specific implementation, the power supply voltage of the operating circuit is set to 24V. The current sampling circuit 11 is used to detect the current supplied to the operating circuit by the field side, i.e. the output terminal +24V _ IN of the power supply. When the output current is smaller than the current limiting value, the first switching tube Q1 is cut off, so that the second switching tube Q2 is switched on, the +24V _ OUT is output to a working circuit, and the field instrument can work normally. When the output current exceeds the current limiting value, the first switch tube Q1 is switched on, so that the level of the control end of the second switch tube Q2 is increased, the voltage difference between the first end S and the second end G of the second switch tube Q2 is reduced, the on-resistance of the second switch tube Q2 is increased, the line current flowing through the current sampling circuit 11 is reduced, and finally, the balance is achieved, the current is maintained below the current limiting value, and the current value supplied to the working circuit is prevented from being too large.
As shown in fig. 3, the current sampling circuit 11 further includes a first resistor R1 and a second resistor R2, and the first resistor R1 is connected in parallel with the second resistor R2. A first end of the first resistor R1 is connected to the power supply 10, and a second end of the first resistor R1 is connected to the first end S of the second switch Q2.
It should be noted that the magnitude of the current limit value is determined by the current sampling circuit 11, and in this embodiment, the current limit value is:
wherein I is a restriction value, VEBR1 represents the resistance of the first resistor R1 and R2 represents the resistance of the second resistor R2 for the voltage between the first terminal E and the control terminal B of the first switching tube QI. In the present application, the first resistor R1 and the second resistor R2 both adopt a current limiting resistor with a resistance value of 27 Ω, and then I is 0.65/13.5 is 48mA, and the parallel first resistor R1 and the parallel second resistor R2 are adopted as the current sampling circuit 11, when the first resistor R1 or the second resistor R2 is disconnected, the current limiting value becomes 24mA, the normal operating current of the operating circuit is generally 4-20 mA, and the normal operating current is smaller than the current limiting value, so that the function of the current limiting protection circuit is still not affected.
It is understood that two resistors connected in parallel are used as the current sampling circuit 11 in fig. 3, and in other embodiments, the current sampling circuit 11 may also be implemented by a single resistor, that is, the current sampling circuit 11 is specifically a seventh resistor, a first end of the seventh resistor is connected to the power supply 10, and a second end of the seventh resistor is connected to the first end S of the second switching tube Q2. At this time, the seventh resistor adopts a current limiting resistor with a resistance value of 13.5 omega, and the current limiting value is still 48mA, so that the working circuit can be protected. It should be noted that, if the seventh resistor is short-circuited, the second switching tube Q2 is turned off, no current is output to the operating circuit from the +24V _ OUT terminal, and the operating circuit cannot operate normally.
Further, the voltage dividing circuit includes a third resistor R3, a fourth resistor R4, a fifth resistor R5 and a sixth resistor R6;
the first end of the third resistor R3 is connected with the power supply 10, the fourth resistor R4 is connected with the third resistor R3 in series, the common end of the fourth resistor R4 and the fifth resistor R5 is connected with the control end G of the second switch tube Q2, the fifth resistor R5 is connected with the sixth resistor R6 in series, and the first end of the sixth resistor R6 is grounded.
The current-limiting protection circuit provided by the embodiment utilizes four resistors as a voltage division circuit, and has the advantages of simple circuit structure, easiness in implementation and low cost.
The current-limiting protection circuit further comprises a filter circuit, and the filter circuit is connected with the second end D of the second switching tube Q2 and the working circuit respectively.
The filter circuit comprises a first inductor L1 and a first capacitor C1, wherein the first end of the first inductor L1 is connected with the second end D of the second switch tube Q2, the second end of the first inductor L1 is connected with the working circuit, the first end of the first capacitor C1 is connected with the working circuit, and the second end of the first capacitor is grounded.
The current-limiting protection circuit provided by the embodiment utilizes the first inductor and the first capacitor as the filter circuit, filters ripple components of voltage, and protects the working circuit.
Further, the first switching transistor Q1 is specifically a triode, and the second switching transistor Q2 is specifically a field effect transistor. The model of the triode is MMBT3906, and the model of the field effect transistor is SI2309 CDS.
When the general triode is used for a switching function, the action time is ns level, and compared with the action time of ms level of the self-recovery fuse, the rapidity is improved by about 1000 times. In the circuit, the adopted type of the triode is MMBT3906, the adopted type of the field effect transistor is SI2309CDS, the sum of the delay time and the rising/falling time is 110ns, and the speed of the current limiting protection circuit is further improved.
The current limiting protection circuit provided in the present application is described in detail above. The embodiments are described in a progressive manner in the specification, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. It should be noted that, for those skilled in the art, it is possible to make several improvements and modifications to the present application without departing from the principle of the present application, and such improvements and modifications also fall within the scope of the claims of the present application.
It is further noted that, in the present specification, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
Claims (10)
1. A current-limiting protection circuit is characterized by comprising a current sampling circuit connected with a power supply and used for collecting output current of the power supply, and a switch circuit connected with the current sampling circuit and used for controlling the output current to be reduced when the output current exceeds a current-limiting value; wherein the reduced output current is not greater than the current limit value.
2. The current-limiting protection circuit of claim 1, wherein the switching circuit comprises a first switching tube, a voltage divider circuit, and a second switching tube;
the first end of the first switch tube is connected with the input end of the current sampling circuit, the control end of the first switch tube is connected with the output end of the current sampling circuit, the second end of the first switch tube is connected with the control end of the second switch tube, the first end of the second switch tube is connected with the output end of the current sampling circuit, and the second end of the second switch tube is connected with the working circuit;
the input end of the voltage division circuit is connected with the power supply, and the output end of the voltage division circuit is connected with the control end of the second switch tube.
3. The current-limiting protection circuit of claim 2, wherein the current sampling circuit comprises a first resistor and a second resistor, the first resistor connected in parallel with the second resistor.
4. The current-limiting protection circuit of claim 3 wherein said voltage divider circuit comprises a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor;
the first end of the third resistor is connected with the power supply, the fourth resistor is connected with the third resistor in series, the common end of the fourth resistor and the fifth resistor is connected with the control end of the second switch tube, the fifth resistor is connected with the sixth resistor in series, and the first end of the sixth resistor is grounded.
5. The current-limiting protection circuit of claim 4, further comprising a filter circuit, wherein the filter circuit is respectively connected to the second terminal of the second switching tube and the operating circuit.
6. The current-limiting protection circuit of claim 5, wherein the filter circuit comprises a first inductor and a first capacitor, a first end of the first inductor is connected to the second end of the second switch tube, a second end of the first inductor is connected to the working circuit, a first end of the first capacitor is connected to the working circuit, and a second end of the first capacitor is grounded.
7. The current-limiting protection circuit of claim 2, wherein the current sampling circuit is a seventh resistor, a first end of the seventh resistor is connected to the power supply, and a second end of the seventh resistor is connected to the first end of the second switching tube.
8. The current-limiting protection circuit of claim 2, wherein the first switching transistor is a transistor, and the second switching transistor is a field effect transistor.
9. The current-limiting protection circuit of claim 8, wherein the triode is of the type MMBT 3906.
10. The current-limiting protection circuit of claim 8 wherein the fet is model SI2309 CDS.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011422442.7A CN112636314A (en) | 2020-12-08 | 2020-12-08 | Current-limiting protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011422442.7A CN112636314A (en) | 2020-12-08 | 2020-12-08 | Current-limiting protection circuit |
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| Publication Number | Publication Date |
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| CN112636314A true CN112636314A (en) | 2021-04-09 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202011422442.7A Pending CN112636314A (en) | 2020-12-08 | 2020-12-08 | Current-limiting protection circuit |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103595016A (en) * | 2013-11-22 | 2014-02-19 | 郑州光力科技股份有限公司 | Current-limiting protection circuit |
| CN105977921A (en) * | 2016-06-27 | 2016-09-28 | 中国兵器工业集团第二四研究所苏州研发中心 | Isolation power supply overcurrent turn-off delay protection circuit |
| CN205622209U (en) * | 2016-04-28 | 2016-10-05 | 深圳市智创电机有限公司 | Auto -lock of motor drive hardware and reset circuit |
| CN108964433A (en) * | 2018-06-28 | 2018-12-07 | 北京航天自动控制研究所 | A kind of overall process Inrush current restraining generalization device and control method based on PWM closed-loop control |
-
2020
- 2020-12-08 CN CN202011422442.7A patent/CN112636314A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103595016A (en) * | 2013-11-22 | 2014-02-19 | 郑州光力科技股份有限公司 | Current-limiting protection circuit |
| CN205622209U (en) * | 2016-04-28 | 2016-10-05 | 深圳市智创电机有限公司 | Auto -lock of motor drive hardware and reset circuit |
| CN105977921A (en) * | 2016-06-27 | 2016-09-28 | 中国兵器工业集团第二四研究所苏州研发中心 | Isolation power supply overcurrent turn-off delay protection circuit |
| CN108964433A (en) * | 2018-06-28 | 2018-12-07 | 北京航天自动控制研究所 | A kind of overall process Inrush current restraining generalization device and control method based on PWM closed-loop control |
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