Over-current and over-voltage detection settable, self-locking and unlocking protection circuit

Abstract

The utility model belongs to the technical field of protection circuits, and particularly relates to an overcurrent and overvoltage detection settable, self-locking and unlocking protection circuit, which comprises an input voltage, a protection circuit, an overcurrent detection circuit, an overvoltage response circuit, an overvoltage detection circuit, a self-locking circuit, an external unlocking circuit and an output voltage. The input voltage is accessed to the overcurrent detection circuit through the protection circuit, the overcurrent detection circuit is accessed to the overvoltage response circuit, the overvoltage response circuit is accessed to the overvoltage detection circuit, the overvoltage detection circuit is accessed to the output voltage, the overcurrent detection circuit and the overvoltage response circuit are connected with the self-locking circuit, and the self-locking circuit is connected with the protection circuit. The self-locking circuit is connected with the protection circuit, the self-locking circuit is connected to an external unlocking circuit, and the external unlocking circuit inputs an external unlocking signal. According to the utility model, when the load current and voltage exceed the set current and voltage, detection and self-locking can be carried out, the output is closed, the load is protected, and after a user searches a problem, the circuit is enabled to work normally through an unlocking signal.

Description

Technical Field

[0001] The utility model belongs to the technical field of protection circuits, and in particular relates to an over-current and over-voltage detection protection circuit which can be set to self-lock and unlock. Background Art

[0002] In product design, when power supply is required, when the power supply circuit has overcurrent and overvoltage, it will cause permanent damage to the load and affect the service life of the product. At present, most integrated ICs on the market have limited maximum current and voltage, and the IC only has very small current and voltage when used normally. When an abnormality occurs, the IC bears a large current, which causes IC damage. When the power supply voltage exceeds a certain value, it will also cause IC damage. When the product outputs power to the outside, due to improper operation by the customer, the power supply overcurrent or voltage abnormality will cause unstable product power supply and cause product failure. In severe cases, it may cause damage to the external power load and cause unnecessary losses.

[0003] In the prior art, most circuits only have overcurrent or voltage detection functions, which only upload the overcurrent or voltage fault signal to the controller, and then make logical judgments for protection, missing the best protection time. Some have protection functions, but no self-locking circuits. When overcurrent or overvoltage occurs, the circuit disconnects the power supply, and after the load is powered off, the fault is eliminated, and then the power supply is restarted, resulting in the failure to detect the real fault signal and burying hidden dangers, which ultimately leads to an increase in product defect rates. Utility Model Content

[0004] The purpose of the utility model is to provide an over-current and over-voltage detection protection circuit that can be set to self-lock and unlock. When the load current and voltage exceed the set current and voltage, it can detect and self-lock to shut down the output to protect the load. After finding the problem, the user can make the circuit work normally through the unlocking signal.

[0005] The technical solution adopted by the utility model is as follows:

[0006] An overcurrent and overvoltage detection protection circuit that can be set to self-lock and unlock, including input voltage, protection circuit, overcurrent detection circuit, overvoltage response circuit, overvoltage detection circuit, self-locking circuit, external unlocking circuit, and output voltage;

[0007] When overcurrent and overvoltage faults occur, the fault signal will open the self-locking circuit and cut off the output, thereby protecting the load. After the fault is eliminated according to the fault indicator light, the output can be restored by inputting an external unlocking signal without powering off the output.

[0008] The input voltage is connected to the overcurrent detection circuit through the protection circuit, the overcurrent detection circuit is connected to the overvoltage response circuit, the overvoltage response circuit is connected to the overvoltage detection circuit, the overvoltage detection circuit is connected to the output voltage, the overcurrent detection circuit and the overvoltage response circuit are connected to the self-locking circuit, the self-locking circuit is interconnected with the protection circuit, the self-locking circuit is connected to the external unlocking circuit, and the external unlocking circuit inputs an external unlocking signal input.

[0009] The protection circuit includes a transistor Q1, a resistor R2, and a resistor R8. The input voltage is connected to a first end of the resistor R2 and a collector of the transistor Q1. The second end of the resistor R2 is connected to a first end of the resistor R8. The base of the transistor Q1 is connected to a second end of the resistor R8.

[0010] The overcurrent detection circuit includes a resistor R1, a resistor R5, a capacitor C2, and a transistor Q2. The emitter of the transistor Q1 is connected to the first end of the resistor R1, the first end of the capacitor C2, and the emitter of the transistor Q2, respectively. The second end of the resistor R1 and the second end of the capacitor C2 are both connected to the first end of the resistor R5. The second end of the resistor R5 is connected to the base of the transistor Q2.

[0011] The self-locking circuit includes a capacitor C4, a thyristor Q5, a diode D1, a resistor R12, and a resistor R17. The second end of the resistor R8 is connected to the first end of the capacitor C4, the second end of the capacitor C4 is grounded, one end of the thyristor Q5 is connected to the base of the transistor Q1, the second end of the thyristor Q5 is grounded, the second end of the thyristor Q5 is connected to the first ends of the resistor R12 and the resistor R17, the second end of the resistor R17 is grounded, the second end of the resistor R12 is connected to the first end of the diode D1, and the second end of the diode D1 is connected to the collector of the transistor Q2.

[0012] The overvoltage response circuit includes a diode D2, a resistor R4, a transistor Q4, a resistor R10, and a resistor R16. The second end of the resistor R12 and the first end of the diode D1 are connected to the first end of the diode D2. The second end of the diode D2 is respectively connected to the first end of the resistor R4 and the collector of the transistor Q4. The emitter of the transistor Q4 is grounded. The base of the transistor Q4 is respectively connected to the first end of the resistor R10 and the second end of the resistor R16. The second end of the resistor R16 is connected to the emitter of the transistor Q4.

[0013] The overvoltage detection circuit includes a resistor R7, a reference chip U1, a capacitor C1, a resistor R6, a capacitor C3, a capacitor C5, a resistor R11, and a resistor R14. The second end of the resistor R4 is respectively connected to the input voltage and the first end of the resistor R7, the second end of the resistor R7 is respectively connected to the capacitor C3 and the first end of the reference chip U1, the second end of the capacitor C3 is respectively connected to the first ends of the capacitor C1, the resistor R6, and the resistor R14, the second end of the capacitor C1 is connected to the input voltage, the second end of the resistor R6 is connected to the output voltage, the second end of the resistor R14 is grounded, the second end of the reference chip U1 is grounded, the third end of the reference chip U1 is connected to the first end of the capacitor C5 and the first end of the resistor R11, the second end of the capacitor C5 is grounded, and the second end of the resistor R11 is connected to the first end of the resistor R14.

[0014] The external unlocking circuit includes a transistor Q3, a resistor R9, a resistor R13, and a capacitor C6. The collector of the transistor Q3 is connected to the second end of the resistor R2 and the first end of the resistor R8, the emitter of the transistor Q3 is grounded, the base of the transistor Q3 is respectively connected to the first end of the resistor R9 and the first end of the resistor R13, the second end of the resistor R9 is connected to the external unlocking signal input, the second end of the resistor R13 is grounded, and the capacitor C6 is connected in parallel to the resistor R13.

[0015] The technical effects achieved by the utility model are:

[0016] The utility model provides an over-current and over-voltage detection and self-locking and unlocking protection circuit which can automatically perform over-current self-locking protection according to the set current, will not be restarted repeatedly, and can work normally only after the fault is eliminated. It can effectively perform current protection, will not damage the load, and protect the product.

[0017] The utility model provides an over-current and over-voltage detection protection circuit which can be set to be self-locking and unlocking. The over-voltage self-locking protection can be automatically performed according to the set voltage, and will not be restarted repeatedly. It can work normally only after the fault is eliminated, and can effectively perform voltage protection without damaging the load.

[0018] The utility model discloses an over-current and over-voltage detection protection circuit which can be set to be self-locking and unlocking. The self-locking protection is adopted. When the user performs a wrong operation and causes the circuit protection, an unlocking signal can be given to make the circuit power supply normally. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a functional block diagram of an embodiment of the utility model;

[0020] Figure 2 It is a circuit diagram of an embodiment of the utility model. DETAILED DESCRIPTION

[0021] In order to make the purpose and advantages of the utility model more clear, the utility model is specifically described in combination with the following embodiments. It should be understood that the following text is only used to describe one or several specific implementations of the utility model, and does not strictly limit the protection scope of the specific request of the utility model.

[0022] Embodiment 1:

[0023] like Figure 1-2 As shown, an overcurrent and overvoltage detection protection circuit that can be set to self-lock and unlock includes an input voltage, a protection circuit, an overcurrent detection circuit, an overvoltage response circuit, an overvoltage detection circuit, a self-locking circuit, an external unlocking circuit, and an output voltage;

[0024] The input voltage is connected to the overcurrent detection circuit through the protection circuit, the overcurrent detection circuit is connected to the overvoltage response circuit, the overvoltage response circuit is connected to the overvoltage detection circuit, the overvoltage detection circuit is connected to the output voltage, the overcurrent detection circuit and the overvoltage response circuit are connected to the self-locking circuit, the self-locking circuit and the protection circuit are interconnected, the self-locking circuit is connected to the external unlocking circuit, and the external unlocking circuit inputs the external unlocking signal input.

[0025] The protection circuit includes a transistor Q1, a resistor R2, and a resistor R8. The input voltage is connected to the first end of the resistor R2 and the collector of the transistor Q1. The second end of the resistor R2 is connected to the first end of the resistor R8. The base of the transistor Q1 is connected to the second end of the resistor R8.

[0026] The overcurrent detection circuit includes a resistor R1, a resistor R5, a capacitor C2, and a transistor Q2. The emitter of the transistor Q1 is connected to the first end of the resistor R1, the first end of the capacitor C2, and the emitter of the transistor Q2, respectively. The second end of the resistor R1 and the second end of the capacitor C2 are both connected to the first end of the resistor R5. The second end of the resistor R5 is connected to the base of the transistor Q2.

[0027] The self-locking circuit includes a capacitor C4, a thyristor Q5, a diode D1, a resistor R12, and a resistor R17. The second end of the resistor R8 is connected to the first end of the capacitor C4, the second end of the capacitor C4 is grounded, one end of the thyristor Q5 is connected to the base of the transistor Q1, the second end of the thyristor Q5 is grounded, the second end of the thyristor Q5 is connected to the first ends of the resistor R12 and the resistor R17, the second end of the resistor R17 is grounded, the second end of the resistor R12 is connected to the first end of the diode D1, and the second end of the diode D1 is connected to the collector of the transistor Q2.

[0028] The overvoltage response circuit includes a diode D2, a resistor R4, a transistor Q4, a resistor R10, and a resistor R16. The second end of the resistor R12 and the first end of the diode D1 are connected to the first end of the diode D2. The second end of the diode D2 is respectively connected to the first end of the resistor R4 and the collector of the transistor Q4. The emitter of the transistor Q4 is grounded. The base of the transistor Q4 is respectively connected to the first end of the resistor R10 and the second end of the resistor R16. The second end of the resistor R16 is connected to the emitter of the transistor Q4.

[0029] The overvoltage detection circuit includes a resistor R7, a reference chip U1, a capacitor C1, a resistor R6, a capacitor C3, a capacitor C5, a resistor R11, and a resistor R14. The second end of the resistor R4 is respectively connected to the input voltage and the first end of the resistor R7, the second end of the resistor R7 is respectively connected to the first end of the capacitor C3 and the reference chip U1, the second end of the capacitor C3 is respectively connected to the first ends of the capacitor C1, the resistor R6, and the resistor R14, the second end of the capacitor C1 is connected to the input voltage, the second end of the resistor R6 is connected to the output voltage, the second end of the resistor R14 is grounded, the second end of the reference chip U1 is grounded, the third end of the reference chip U1 is connected to the first end of the capacitor C5 and the first end of the resistor R11, the second end of the capacitor C5 is grounded, and the second end of the resistor R11 is connected to the first end of the resistor R14.

[0030] The external unlocking circuit includes a transistor Q3, a resistor R9, a resistor R13, and a capacitor C6. The collector of the transistor Q3 is connected to the second end of the resistor R2 and the first end of the resistor R8, the emitter of the transistor Q3 is grounded, the base of the transistor Q3 is connected to the first end of the resistor R9 and the first end of the resistor R13 respectively, the second end of the resistor R9 is connected to the external unlocking signal input, the second end of the resistor R13 is grounded, and the capacitor C6 is connected in parallel to the resistor R13.

[0031] Embodiment 2:

[0032] like Figure 1-2 As shown, based on Example 1, the specific operating principle of the above embodiment is explained in detail:

[0033] The input voltage provides a conduction current for the base of the transistor Q1 through the protection circuit resistors R2 and R8. The capacitor C4 acts as a buffer, so that the transistor Q1 has a soft start when it is turned on and off, preventing it from being turned on and off too quickly and causing oscillation. When the collector and emitter of the transistor Q1 are turned on, the input voltage passes through the overcurrent detection circuit resistor R1 and provides a stable output voltage for the load.

[0034] When an overcurrent event occurs, the voltage drop of resistor R1 in the overcurrent detection circuit increases, causing the current of the emitter and base of transistor Q2 to increase, and finally causing the emitter and collector of transistor Q2 to be turned on. After transistor Q2 is turned on, the voltage passes through diode D2 and resistor R12 to provide a turn-on voltage for thyristor Q5. After thyristor Q5 is turned on, the base potential of transistor Q1 in the protection circuit is pulled down, so that the collector and emitter of transistor Q1 are closed, and the circuit has no output voltage. By modifying resistor R1, the overcurrent protection value can be changed, so that it can be widely used and save design costs.

[0035] When an overvoltage event occurs, the output voltage is divided by the overvoltage detection circuit resistors R6 and R14, and then enters the reference pin of the reference chip U1 after the RC filter composed of resistor R11 and capacitor C5, causing the cathode and anode of the reference chip U1 to be connected to the ground, and the potential at the connection between resistors R10, R16 and the base of transistor Q4 is zero, and the collector and emitter of transistor Q4 are closed. The output voltage provides a conduction voltage for the thyristor Q5 through resistor R4, diode D2, and resistor R12. After the thyristor Q5 is turned on, the base potential of the protection circuit transistor Q1 is pulled down, so that the collector and emitter of the transistor Q1 are closed, and the circuit has no output voltage. The capacitor C1 acts to provide an acceleration channel when the output voltage changes, so that the overvoltage protection can be performed faster. The overvoltage protection value can be changed by modifying the resistor R14.

[0036] After an overcurrent or overvoltage fault occurs, since there is no output voltage behind the protection circuit, the current and voltage detection returns to the initial state. However, due to the on-off characteristics of the thyristor Q5, the cathode and anode of the thyristor Q5 are always on, so the collector and emitter of the transistor Q1 are always off, and the entire circuit has no output voltage, which plays a self-locking protection role for the entire circuit. After the fault is checked and normal operation is required, only an external unlocking signal input is required, and the circuit can output normally only after the external unlocking signal is removed.

[0037] After the external unlocking signal is input, the base and emitter of the transistor Q3 are provided with a conduction current through the resistor R9, and the collector and emitter of the transistor Q3 are turned on, so that there is no voltage at the connection between the resistor R2 and the resistor R8, causing the thyristor Q5 to be closed, the external unlocking signal is removed, and the power output is normal.

[0038] The above is only a preferred embodiment of the present invention. It should be noted that, for ordinary technicians in the technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention. The structures, devices and operating methods not specifically described and explained in the present invention shall be implemented according to the conventional means in the field unless otherwise specified and limited.

Claims

1. A protection circuit for overcurrent and overvoltage detection that can be set to self-lock and unlock, characterized in that: Including input voltage, protection circuit, overcurrent detection circuit, overvoltage response circuit, overvoltage detection circuit, self-locking circuit, external unlocking circuit, output voltage; The input voltage is connected to the overcurrent detection circuit through the protection circuit, the overcurrent detection circuit is connected to the overvoltage response circuit, the overvoltage response circuit is connected to the overvoltage detection circuit, the overvoltage detection circuit is connected to the output voltage, the overcurrent detection circuit and the overvoltage response circuit are connected to the self-locking circuit, the self-locking circuit is interconnected with the protection circuit, the self-locking circuit is connected to the external unlocking circuit, and the external unlocking circuit inputs an external unlocking signal input.

2. The over-current and over-voltage detection protection circuit according to claim 1, characterized in that: The protection circuit includes a transistor Q1, a resistor R2, and a resistor R8. The input voltage is connected to a first end of the resistor R2 and a collector of the transistor Q1. The second end of the resistor R2 is connected to a first end of the resistor R8. The base of the transistor Q1 is connected to a second end of the resistor R8.

3. The over-current and over-voltage detection protection circuit according to claim 2, characterized in that: The overcurrent detection circuit includes a resistor R1, a resistor R5, a capacitor C2, and a transistor Q2. The emitter of the transistor Q1 is connected to the first end of the resistor R1, the first end of the capacitor C2, and the emitter of the transistor Q2, respectively. The second end of the resistor R1 and the second end of the capacitor C2 are both connected to the first end of the resistor R5. The second end of the resistor R5 is connected to the base of the transistor Q2.

4. The over-current and over-voltage detection protection circuit according to claim 3, characterized in that: The self-locking circuit includes a capacitor C4, a thyristor Q5, a diode D1, a resistor R12, and a resistor R17. The second end of the resistor R8 is connected to the first end of the capacitor C4, the second end of the capacitor C4 is grounded, one end of the thyristor Q5 is connected to the base of the transistor Q1, the second end of the thyristor Q5 is grounded, the second end of the thyristor Q5 is connected to the first ends of the resistor R12 and the resistor R17, the second end of the resistor R17 is grounded, the second end of the resistor R12 is connected to the first end of the diode D1, and the second end of the diode D1 is connected to the collector of the transistor Q2.

5. The over-current and over-voltage detection protection circuit according to claim 4, characterized in that: The overvoltage response circuit includes a diode D2, a resistor R4, a transistor Q4, a resistor R10, and a resistor R16. The second end of the resistor R12 and the first end of the diode D1 are connected to the first end of the diode D2. The second end of the diode D2 is respectively connected to the first end of the resistor R4 and the collector of the transistor Q4. The emitter of the transistor Q4 is grounded. The base of the transistor Q4 is respectively connected to the first end of the resistor R10 and the second end of the resistor R16. The second end of the resistor R16 is connected to the emitter of the transistor Q4.

6. The over-current and over-voltage detection protection circuit according to claim 5, characterized in that: The overvoltage detection circuit includes a resistor R7, a reference chip U1, a capacitor C1, a resistor R6, a capacitor C3, a capacitor C5, a resistor R11, and a resistor R14. The second end of the resistor R4 is respectively connected to the input voltage and the first end of the resistor R7, the second end of the resistor R7 is respectively connected to the capacitor C3 and the first end of the reference chip U1, the second end of the capacitor C3 is respectively connected to the first ends of the capacitor C1, the resistor R6, and the resistor R14, the second end of the capacitor C1 is connected to the input voltage, the second end of the resistor R6 is connected to the output voltage, the second end of the resistor R14 is grounded, the second end of the reference chip U1 is grounded, the third end of the reference chip U1 is connected to the first end of the capacitor C5 and the first end of the resistor R11, the second end of the capacitor C5 is grounded, and the second end of the resistor R11 is connected to the first end of the resistor R14.

7. The over-current and over-voltage detection protection circuit according to claim 2, characterized in that: The external unlocking circuit includes a transistor Q3, a resistor R9, a resistor R13, and a capacitor C6. The collector of the transistor Q3 is connected to the second end of the resistor R2 and the first end of the resistor R8, the emitter of the transistor Q3 is grounded, the base of the transistor Q3 is respectively connected to the first end of the resistor R9 and the first end of the resistor R13, the second end of the resistor R9 is connected to the external unlocking signal input, the second end of the resistor R13 is grounded, and the capacitor C6 is connected in parallel to the resistor R13.

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