CN220857622U - Protection circuit - Google Patents
Protection circuit Download PDFInfo
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- CN220857622U CN220857622U CN202322648045.7U CN202322648045U CN220857622U CN 220857622 U CN220857622 U CN 220857622U CN 202322648045 U CN202322648045 U CN 202322648045U CN 220857622 U CN220857622 U CN 220857622U
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Abstract
The utility model provides a protection circuit which comprises a first switch and a second switch, wherein the first switch and the second switch are connected with pins, the first switch is connected into a first voltage division branch, the second switch is connected into a second voltage division branch, the first voltage division branch comprises a variable resistor, a third switch is connected with the first switch, and the level output by a port of the third switch corresponds to the working state of the circuit. The protection circuit has simple structure, low cost and wide application.
Description
Technical Field
The utility model relates to the technical field of switching power supplies, in particular to a protection circuit.
Background
A switching power supply is a high-efficiency, small-sized, lightweight power supply that is widely used in various electronic devices. However, due to poor heat dissipation, overload work, power supply damage or aging and other reasons, the switching power supply can be overheated; the switching power supply overcurrent can be caused by the reasons of driving faults of the switching tube, load short circuit, output capacitance damage and the like. This requires the construction of an over-temperature or over-current protection circuit.
The common protection scheme at present adopts a comparator or an operational amplifier to build a protection circuit, and the cost is high.
Disclosure of utility model
In order to solve the problems, the protection circuit provided by the utility model adopts the following technical scheme:
A protection circuit comprises a first resistor, a first end of the first resistor is connected with a ground end,
A second resistor, a first end of the second resistor is connected with a second end of the first resistor,
A third resistor, the first end of the third resistor is connected with the second end of the second resistor,
A first switch, a first end of the first switch is connected with a first end of the third resistor, a second end of the first switch is connected with a second end of the third resistor, a third end of the first switch outputs a control signal,
A second switch, a first end of the second switch is connected with a second end of the first switch, a second end of the second switch is connected with a series midpoint of the second resistor and the first resistor, a third end of the second switch is connected with the first end of the first resistor,
A fourth resistor, the first end of the fourth resistor is connected with the third end of the second switch,
A fifth resistor, a first end of the fifth resistor is connected with a second end of the fourth resistor, a second end of the fifth resistor is connected with a first end of the first switch,
The first end of the third switch is connected with the second end of the fifth resistor, the second end of the third switch is connected with the series midpoint of the fifth resistor and the fourth resistor, and the third end of the third switch is connected with the first end of the fourth resistor;
The fifth resistor, the fourth resistor, and the second resistor and the first resistor have variable resistors.
Implementations may include any or all of the following features.
Further, the circuit further comprises a first diode, and the anode of the first diode is connected with the third end of the first switch.
Further, the circuit further comprises a sixth resistor, wherein a first end of the sixth resistor is connected with the cathode of the first diode, and a second end of the sixth resistor outputs the control signal.
Further, the circuit further comprises a seventh resistor, wherein the first end of the seventh resistor is connected with the third end of the second switch and the third end of the third switch, and the second end of the seventh resistor is connected with the ground end.
Further, the switch further comprises an eighth resistor, wherein the first end of the eighth resistor is connected with the first end of the third resistor, and the second end of the eighth resistor is connected with the first end of the third switch.
Further, the circuit further comprises a second diode, and the anode of the second diode is connected with the third end of the first switch.
Further, the circuit further comprises a ninth resistor, wherein a first end of the ninth resistor is connected with the cathode of the second diode, and a second end of the ninth resistor is connected with a series midpoint of the second resistor and the first resistor.
Further, the fifth resistor and the fourth resistor form a voltage division branch, and the second resistor and the first resistor form a voltage division branch.
Further, the resistance change of the variable resistor affects the switch of the second switch, thereby affecting the switch of the first switch, and causing the level of the control signal to change.
Further, the control signal is sent to an external circuit to realize open circuit or short circuit protection.
In the technical scheme, two switches connected with the same pin are respectively connected into respective voltage division networks, one of the voltage division branches comprises a variable resistor, the switch connected into the voltage division branch comprising the variable resistor is connected with a third switch, and the working state of the circuit corresponding to the level is output through a port of the third switch.
In summary, the protection circuit has the advantages of simple structure, low cost and wide application.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings that are needed in the embodiments of the present utility model will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present utility model, and other drawings may be obtained according to the drawings for those skilled in the art.
Fig. 1 shows an embodiment of a protection circuit according to the present utility model.
Fig. 2 shows an embodiment of the present utility model for over-temperature protection.
Fig. 3 shows an embodiment of the present utility model for overcurrent protection.
The attached drawings are used for identifying and describing:
11. 21, 31-protection circuits.
Detailed Description
The technical scheme of the present utility model will be clearly and completely described in the following with reference to the accompanying drawings of the embodiments of the present utility model. It will be apparent that the described embodiments are some, but not all, embodiments of the utility model. All other embodiments, which can be made by a person skilled in the art without creative efforts, based on the described embodiments of the present utility model fall within the protection scope of the present utility model.
As shown in fig. 1, the present utility model provides a protection circuit 11, which includes a resistor R1, a resistor R2, a resistor R3, a switch Q1, a switch Q2, a resistor R4, a resistor R5 and a switch Q3, wherein a first end of the resistor R1 is connected to a ground GND; the resistor R2 is a variable resistor, and a first end of the resistor R2 is connected with a second end of the resistor R1; the first end of the resistor R3 is connected with the second end of the resistor R2; an emitter of the switch Q1 is connected with a first end of the resistor R3, a base of the switch Q1 is connected with a second end of the resistor R3, and a collector of the switch Q1 outputs a control signal V prot; the collector of the switch Q2 is connected with the base of the switch Q1, the base of the switch Q2 is connected with the midpoint of the series connection of the resistor R2 and the resistor R1, and the emitter of the switch Q2 is connected with the first end of the resistor R1; the first end of the resistor R4 is connected with the emitter of the switch Q2; the first end of the resistor R5 is connected with the second end of the resistor R4, and the second end of the resistor R5 is connected with the emitter of the switch Q1; the collector of the switch Q3 is connected with the second end of the resistor R5, the base of the switch Q3 is connected with the midpoint of the series connection of the resistor R5 and the resistor R4, and the emitter of the switch Q3 is connected with the first end of the resistor R4. The resistor R5 and the resistor R4 form a partial pressure branch, and the resistor R2 and the resistor R1 form a partial pressure branch; the change of the resistance value of the resistor R2 affects the switching of the switch Q2, thereby affecting the switching of the switch Q1, and causing the level of the control signal V prot to change. Optionally, the switch Q3 and the switch Q2 are NPN transistors, and the switch Q1 is a PNP transistor.
The working principle of the embodiment is as follows: the resistance value of the resistor R2 is regulated, so that the base voltage of the switch Q2 is larger than the base voltage of the switch Q3, the base voltage of the switch Q2 is larger than the emitter voltage of the switch Q2, the switch Q2 is conducted, the base voltage of the switch Q1 is pulled down, the switch Q1 is conducted, and the control signal V prot is in a high level; the switch Q2 is turned off, the switch Q1 is turned off correspondingly, and the control signal V prot is at low level. The level of the control signal V prot corresponds to the running state of the circuit, the control signal V prot is sent to an external circuit, and the external circuit adopts open circuit or short circuit protection measures according to the running state.
As shown in fig. 2, the present utility model provides a protection circuit 21, which includes a resistor R1, a resistor RT1, a resistor R2, a switch Q1, a diode D1, a resistor R3, a diode D2, a resistor R4, a switch Q2, a resistor R5, a resistor R6, a resistor R7 and a switch Q3, wherein a first end of the resistor R1 is connected to a ground terminal PGND; the resistor RT1 is a thermistor, a first end of the resistor RT1 is connected with a second end of the resistor R1, and a second end of the resistor RT1 is connected with a power supply VCC; the first end of the resistor R2 is connected with the second end of the resistor RT 1; an emitter of the switch Q1 is connected with a first end of the resistor R2, and a base of the switch Q1 is connected with a second end of the resistor R2; the anode of the diode D1 is connected with the collector of the switch Q1 to prevent current backflow; the first end of the resistor R3 is connected with the cathode of the diode D1, and the second end of the resistor R3 is connected with the midpoint of the series connection of the resistor RT1 and the resistor R1 to play a role in current limiting; the anode of the diode D2 is connected with the collector of the switch Q1 to prevent current backflow; the first end of the resistor R4 is connected with the cathode of the diode D2, and the second end of the resistor R4 outputs a control signal V prot to play a role in current limiting; the collector of the switch Q2 is connected with the base of the switch Q1, and the base of the switch Q2 is connected with the second end of the resistor R3; the first end of the resistor R5 is connected with the emitter of the switch Q2, and the second end of the resistor R5 is connected with the first end of the resistor R1; the first end of the resistor R6 is connected with the second end of the resistor R5; the first end of the resistor R7 is connected with the second end of the resistor R6, and the second end of the resistor R7 is connected with the emitter of the switch Q1; the collector of the switch Q3 is connected with the second end of the resistor R7, the base of the switch Q3 is connected with the midpoint of the series connection of the resistor R7 and the resistor R6, and the emitter of the switch Q3 is connected with the first end of the resistor R5. The resistor R7 and the resistor R6 form a voltage division branch, and the resistor RT1 and the resistor R1 form a voltage division branch; the resistance change of the resistor RT1 affects the switch of the switch Q2, thereby affecting the switch of the switch Q1, and causing the level of the control signal V prot to change. Optionally, the switch Q3 and the switch Q2 are NPN transistors, and the switch Q1 is a PNP transistor.
The working principle of the embodiment is as follows: when the temperature is too high, the resistance of the resistor RT1 becomes smaller to a certain threshold value, so that the base voltage of the switch Q2 is larger than the base voltage of the switch Q3, the base voltage of the switch Q2 is larger than the emitter voltage of the switch Q2, the switch Q2 is turned on, the base voltage of the switch Q1 is pulled down, the switch Q1 is turned on, and the control signal V prot is at a high level; when the temperature is normal, the resistance of the resistor RT1 does not decrease to a certain threshold, so that the switch Q2 is turned off, the switch Q1 is turned off correspondingly, and the control signal V prot is low level. The level of the control signal V prot corresponds to the temperature, the control signal V prot is sent to an external circuit, and if the control signal V prot is at a high level, the external circuit realizes open circuit or short circuit protection. The resistor R2, the switch Q1, the diode D1 and the resistor R3 form an over-temperature return difference circuit, so that heating is stopped after the temperature rises to a certain degree, and the condition of overhigh temperature is avoided.
As shown in fig. 3, the present utility model provides a protection circuit 31, which includes a resistor R1, a resistor R2, a resistor R3, a switch Q1, a diode D1, a switch Q2, a resistor R4, a resistor R5, a resistor R6, a switch Q3 and a resistor R7, wherein a first end of the resistor R1 is connected to a ground terminal SGND; the resistor R2 is a variable resistor, a first end of the resistor R2 is connected with a second end of the resistor R1, and a second end of the resistor R2 inputs a feedback voltage VF; the first end of the resistor R3 is connected with the second end of the resistor R2; an emitter of the switch Q1 is connected with a first end of the resistor R3, and a base of the switch Q1 is connected with a second end of the resistor R3; the anode of the diode D1 is connected with the collector of the switch Q1, and the cathode of the diode D1 outputs a control signal V prot to prevent current backflow; the collector of the switch Q2 is connected with the base of the switch Q1, and the base of the switch Q2 is connected with the midpoint of the series connection of the resistor R2 and the resistor R1; the first end of the resistor R4 is connected with the emitter of the switch Q2, and the second end of the resistor R4 is connected with the first end of the resistor R1; the first end of the resistor R5 is connected with the second end of the resistor R4; the first end of the resistor R6 is connected with the second end of the resistor R5, and the second end of the resistor R6 is connected with a power supply VCC; the collector of the switch Q3 is connected with the second end of the resistor R6, the base of the switch Q3 is connected with the midpoint of the series connection of the resistor R6 and the resistor R5, and the emitter of the switch Q3 is connected with the first end of the resistor R4; the resistor R7 is a current sampling resistor, a first end of the resistor R7 is connected with the collector of the switch Q3, and a second end of the resistor R7 is connected with the emitter of the switch Q1. The resistor R6 and the resistor R5 form a partial pressure branch, and the resistor R2 and the resistor R1 form a partial pressure branch; the change of the resistance value of the resistor R2 affects the switching of the switch Q2, thereby affecting the switching of the switch Q1, and causing the level of the control signal V prot to change. Optionally, the switch Q3 and the switch Q2 are NPN transistors, and the switch Q1 is a PNP transistor.
The working principle of the embodiment is as follows: the resistor R7 samples current, and the feedback voltage VF is the voltage on the resistor R7; the resistor R2 may change a resistance value according to temperature. When the current value is too large, the feedback voltage VF becomes larger than a certain threshold value, so that the base voltage of the switch Q2 is larger than the base voltage of the switch Q3, the base voltage of the switch Q2 is larger than the emitter voltage of the switch Q2, the switch Q2 is turned on, the base voltage of the switch Q1 is pulled down, the switch Q1 is turned on, and the control signal V prot is at a high level; when the current value is normal, the feedback voltage VF does not become larger than a certain threshold, so that the switch Q2 is turned off, the switch Q1 is turned off correspondingly, and the control signal V prot is low. The resistor R3, the switch Q1 and the diode D1 form a current return difference circuit to control the stability of current.
When the temperature is too high, the resistance value of the resistor R2 becomes smaller to a certain threshold value, so that the base voltage of the switch Q2 is larger than the base voltage of the switch Q3, the base voltage of the switch Q2 is larger than the emitter voltage of the switch Q2, the switch Q2 is conducted, the base voltage of the switch Q1 is pulled down, the switch Q1 is conducted, and the control signal V prot is at a high level; when the temperature is normal, the resistance value of the resistor R2 does not decrease to a certain threshold value, so that the switch Q2 is turned off, the switch Q1 is turned off correspondingly, and the control signal V prot is at a low level.
The level of the control signal V prot corresponds to the temperature or the current value, the control signal V prot is sent to an external circuit, and if the control signal V prot is at a high level, the external circuit realizes open circuit or short circuit protection.
According to the utility model, the base voltage of the switch Q2 is different from the base voltage of the switch Q3 through the resistance change of the variable resistor, and the on-off of the switch Q2 is controlled, so that the on-off of the switch Q1 is controlled, and the level change of the control signal V prot is realized. The level change of the control signal V prot is sent to an external circuit, and whether the control circuit adopts open circuit or short circuit protection or not is judged.
It should be understood that the foregoing detailed description of the present utility model is provided for illustration only and is not limited to the technical solutions described in the embodiments of the present utility model, and those skilled in the art should understand that the present utility model may be modified or substituted for the same technical effects; as long as the use requirement is met, the utility model is within the protection scope of the utility model.
Claims (10)
1. A protection circuit, characterized in that: comprising the steps of (a) a step of,
A first resistor, a first end of which is connected with a ground end,
A second resistor, a first end of the second resistor is connected with a second end of the first resistor,
A third resistor, the first end of the third resistor is connected with the second end of the second resistor,
A first switch, a first end of the first switch is connected with a first end of the third resistor, a second end of the first switch is connected with a second end of the third resistor, a third end of the first switch outputs a control signal,
A second switch, a first end of the second switch is connected with a second end of the first switch, a second end of the second switch is connected with a series midpoint of the second resistor and the first resistor, a third end of the second switch is connected with the first end of the first resistor,
A fourth resistor, the first end of the fourth resistor is connected with the third end of the second switch,
A fifth resistor, a first end of the fifth resistor is connected with a second end of the fourth resistor, a second end of the fifth resistor is connected with a first end of the first switch,
The first end of the third switch is connected with the second end of the fifth resistor, the second end of the third switch is connected with the series midpoint of the fifth resistor and the fourth resistor, and the third end of the third switch is connected with the first end of the fourth resistor;
And the fifth resistor, the fourth resistor, the second resistor and the first resistor are provided with variable resistors.
2. A protection circuit according to claim 1, wherein: the circuit further comprises a first diode, and the anode of the first diode is connected with the third end of the first switch.
3. A protection circuit according to claim 2, characterized in that: the first end of the sixth resistor is connected with the cathode of the first diode, and the second end of the sixth resistor outputs the control signal.
4. A protection circuit according to claim 1, wherein: the circuit further comprises a seventh resistor, wherein the first end of the seventh resistor is connected with the third end of the second switch and the third end of the third switch, and the second end of the seventh resistor is connected with the ground end.
5. A protection circuit according to claim 1, wherein: the switch further comprises an eighth resistor, wherein the first end of the eighth resistor is connected with the first end of the third resistor, and the second end of the eighth resistor is connected with the first end of the third switch.
6. A protection circuit according to claim 1, wherein: the circuit further comprises a second diode, and the anode of the second diode is connected with the third end of the first switch.
7. A protection circuit according to claim 6, wherein: the circuit further comprises a ninth resistor, wherein the first end of the ninth resistor is connected with the cathode of the second diode, and the second end of the ninth resistor is connected with the midpoint of the series connection of the second resistor and the first resistor.
8. A protection circuit according to claim 1, wherein: the fifth resistor and the fourth resistor form a voltage division branch, and the second resistor and the first resistor form a voltage division branch.
9. A protection circuit according to claim 1, wherein: the resistance change of the variable resistor affects the switch of the second switch, thereby affecting the switch of the first switch, and causing the level of the control signal to change.
10. A protection circuit according to claim 1, wherein: the control signal is sent to an external circuit to realize open circuit or short circuit protection.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322648045.7U CN220857622U (en) | 2023-09-27 | 2023-09-27 | Protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322648045.7U CN220857622U (en) | 2023-09-27 | 2023-09-27 | Protection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN220857622U true CN220857622U (en) | 2024-04-26 |
Family
ID=90780887
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202322648045.7U Active CN220857622U (en) | 2023-09-27 | 2023-09-27 | Protection circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN220857622U (en) |
-
2023
- 2023-09-27 CN CN202322648045.7U patent/CN220857622U/en active Active
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