A self-locking circuit for doorbell drive and overcurrent protection

Abstract

The present application belongs to the field of doorbell system design, and is a kind of electric doorbell drive and overcurrent protection self-locking circuit, including an electronic doorbell, a doorbell switch circuit, a current acquisition circuit, a doorbell control circuit and a self-locking circuit; the electronic doorbell is connected to an AC power supply; the doorbell switch circuit is connected to the electronic doorbell, and the doorbell switch circuit is used to provide switch control for the electronic doorbell; the current acquisition circuit is connected to the doorbell switch circuit; the input end of the doorbell control circuit is connected to the MCU, and the output end is connected to the doorbell switch circuit, and the doorbell control circuit is used to control the opening and closing of the doorbell switch circuit; the input end of the self-locking circuit is connected to the current acquisition circuit, and the output end is connected to the doorbell control circuit; the overcurrent protection self-locking system monitors the current in real time through the sampling resistor, which greatly improves the safety protection level of the system. The doorbell is intelligentized through the application of a microcontroller unit. The self-locking and recovery design provides significant convenience and safety.

Description

Technical Field

[0001] The present application belongs to the field of doorbell system design, and in particular to an electric doorbell drive and overcurrent protection self-locking circuit. Background Art

[0002] In the security access control doorbell system, the traditional solution usually adopts a simple circuit design, including a power supply, a button and an electric bell. The user presses the doorbell button to directly connect the circuit between the power supply and the electric bell, making the electric bell sound. However, this traditional design has some disadvantages, as follows:

[0003] 1. Lack of intelligent control: Traditional doorbell systems cannot implement complex control logic, such as remote control, timed ringing, etc.

[0004] 2. Safety hazards: In the event of overcurrent or short circuit, the lack of an effective protection mechanism may cause circuit damage or safety accidents.

[0005] 3. Inconvenient maintenance: Once the fuse blows or the circuit is damaged, the user needs to manually replace the components, which is inconvenient and costly to maintain.

[0006] To solve these problems, some improvement solutions have appeared on the market, such as using electronic circuits and microcontrollers to achieve more intelligent control and protection functions.

[0007] However, these solutions still have some shortcomings, namely:

[0008] 1. Imperfect protection mechanism: Although some improvement schemes provide overcurrent protection, they are usually implemented through disposable fuses. Once the fuse blows, it needs to be replaced and cannot be automatically restored.

[0009] 2. Limited degree of intelligence: Although some solutions use microcontrollers, the control logic and user interaction are still relatively simple and cannot meet the needs of modern smart homes.

[0010] Therefore, how to improve the safety and convenience of the doorbell system is a problem that needs to be solved. Summary of the invention

[0011] The purpose of this application is to provide an electric doorbell drive and overcurrent protection self-locking circuit to solve the problems of potential safety hazards and inconvenient maintenance in the existing doorbell system.

[0012] The technical solution of the present application is: an electric doorbell drive and overcurrent protection self-locking circuit, comprising an electronic doorbell, a doorbell switch circuit, a current acquisition circuit, a doorbell control circuit and a self-locking circuit; the electronic doorbell is connected to an AC power supply; the doorbell switch circuit is connected to the electronic doorbell, and the doorbell switch circuit is used to provide switch control for the electronic doorbell; the current acquisition circuit is connected to the doorbell switch circuit, and the current acquisition circuit is used to collect current data of the electronic doorbell and send it to the self-locking circuit; the input end of the doorbell control circuit is connected to the MCU, and the output end is connected to the doorbell switch circuit, and the doorbell control circuit is used to control the opening and closing of the doorbell switch circuit; the input end of the self-locking circuit is connected to the current acquisition circuit, and the output end is connected to the doorbell control circuit, and the self-locking circuit is used to protect the doorbell switch circuit, the current acquisition circuit and the doorbell control circuit when an abnormality occurs in the electronic doorbell or the AC power supply; the doorbell switch circuit comprises an upper circulation circuit and a lower circulation circuit, the upper circulation circuit is connected to the power supply AC+, and the lower circulation circuit is connected to the power supply AC-, and the upper circulation circuit and the lower circulation circuit are combined to form a complete power supply circuit.

[0013] Preferably, the upper loop circuit includes a first diode, a second MOS tube, a fourth resistor and a fifth resistor; the positive electrode of the first diode is connected to the doorbell control circuit, the negative electrode is connected to the gate of the second MOS tube, the drain of the second MOS tube is connected to the first contact P1 of the electronic doorbell, the source is connected to one end of the fifth resistor, the other end of the fifth resistor is grounded, and the fourth resistor is connected between the first diode and the second MOS tube;

[0014] The lower circulation circuit includes a second diode, a third MOS tube, a sixth resistor and a seventh resistor; the anode of the second diode is connected to the doorbell control circuit, the cathode is connected to the gate of the third MOS tube, the drain of the third MOS tube is connected to the second contact P2 of the electronic doorbell, the source is connected to one end of the seventh resistor, the other end of the seventh resistor is grounded, and the sixth resistor is connected between the second diode and the third MOS tube;

[0015] The second MOS tube and the third MOS tube are both N-type MOS tubes.

[0016] Preferably, the doorbell control circuit includes a first resistor, a first transistor and a first MOS tube; one end of the first resistor is connected to pin 3 of the MCU, and the other end is connected to the base of the first transistor; the collector of the first transistor is connected to the gate of the first MOS tube, and the emitter is grounded, a second resistor is provided between the first resistor and the first transistor, and the other end of the second resistor is grounded; the source of the first MOS tube is connected to the power supply VDD, and the drain is connected to the doorbell switch circuit; a third resistor is provided between the gate of the first MOS tube and the power supply VDD; the first MOS tube is a P-type MOS tube; the first transistor is an NPN tube.

[0017] Preferably, the self-locking circuit includes a twelfth resistor, a second triode, a third triode and a fourth triode, one end of the twelfth resistor is provided with a connection interface SHORT_DET, and the other end is connected to the base of the second triode; the collector of the second triode is connected to the base of the third triode, and the emitter is grounded; the collector of the second triode is connected to the power supply VDD, and the emitter is connected to the interface AC_SHORT_DET; the second triode is an NPN tube, and the third triode is a PNP tube; the base of the second triode is connected to a thirteenth resistor, and the other end of the thirteenth resistor is connected to the interface AC_SHORT_DET; a fourteenth resistor is arranged between the thirteenth resistor and the base of the second triode, and the other end of the fourteenth resistor is grounded; a fifteenth resistor is arranged between the power supply VDD and the base of the third triode;

[0018] The base of the fourth transistor is connected to the emitter of the third transistor, the collector is provided with an interface SHORT_EN, and the emitter is grounded. The interface SHORT_EN is also provided at the base of the first transistor; the fourth transistor is an NPN transistor.

[0019] Preferably, the source of the first MOS transistor is connected to a first capacitor, the drain is connected to a second capacitor, the base of the second transistor is connected to a third capacitor, and the other ends of the first capacitor, the second capacitor and the third capacitor are all grounded.

[0020] Preferably, the current acquisition circuit includes an eighth resistor, a third diode, a ninth resistor and a fourth diode; one end of the eighth resistor is connected to the source of the second MOS tube, and the other end is connected to the anode of the third diode, one end of the ninth resistor is connected to the source of the third MOS tube, and the other end is connected to the anode of the fourth diode, and the cathodes of the third diode and the fourth diode are both connected to the interface SHORT_DET; the interface SHORT_DET is connected to the self-locking circuit.

[0021] Preferably, a tenth resistor is provided between the eighth resistor and the third diode, an eleventh resistor is provided between the ninth resistor and the fourth diode, and the other ends of the tenth resistor and the eleventh resistor are grounded.

[0022] The electric doorbell drive and overcurrent protection self-locking circuit of the present application has the following advantages:

[0023] 1. The overcurrent protection self-locking system monitors the current in real time through the sampling resistor. Once the current exceeds the preset threshold, the comparator will trigger the locking circuit and activate the MOS tube locking mechanism, thereby cutting off the power supply to prevent overcurrent damage. This design effectively and automatically blocks the flow of excessive current and maintains the locked state until the fault is eliminated, greatly improving the safety protection level of the system.

[0024] 2. Application of microcontroller unit (MCU): Using MCU to control the connection and disconnection of AC current not only replaces the traditional physical buttons or mechanical switches, but also allows for more intelligent control logic, such as remote operation, timing control, etc. The introduction of MCU is the key to realizing the intelligence of doorbells.

[0025] 3. Overcurrent protection self-locking and recovery function: After the fault is eliminated, the system can automatically return to normal working state without manual intervention by the user. This is of great significance to improving user experience and system reliability. Especially compared with traditional systems that require manual reset of fuses or circuit breakers, it provides significant convenience and safety.

[0026] 4. Safety protection in the off-power state: The self-locking mechanism ensures that even in the case of a power outage, the doorbell can be prevented from being accidentally triggered by sudden power-on, thereby improving the safety and stability of the device in uncertain environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solution provided by the present application, the following is a brief introduction to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present application.

[0028] Figure 1 This is the overall structural principle diagram of this application;

[0029] Figure 2 This is a schematic diagram of the electronic doorbell and doorbell switch circuit and current collection circuit structure of this application;

[0030] Figure 3 This is a schematic diagram of the doorbell control circuit structure of this application;

[0031] Figure 4 This is a schematic diagram of the self-locking circuit structure of this application.

[0032] 1. Electronic doorbell; 2. MCU; 3. First resistor; 4. First triode; 5. First MOS tube; 6. Second resistor; 7. Third resistor; 8. First diode; 9. Second MOS tube; 10. Fourth resistor; 11. Fifth resistor; 12. Second diode; 13. Third MOS tube; 14. Sixth resistor; 15. Seventh resistor; 16. Eighth resistor; 17. Third diode; 18. Ninth resistor; 19. Fourth diode; 20. Tenth resistor; 21. Eleventh resistor; 22. Twelfth resistor; 23. Second triode; 24. Third triode; 25. Fourth triode; 26. Thirteenth resistor; 27. Fourteenth resistor; 28. Fifteenth resistor; 29. ​​Sixteenth resistor; 30. Seventeenth resistor; 31. First capacitor; 32. Second capacitor; 33. Third capacitor. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] An electric doorbell drive and overcurrent protection self-locking circuit, such as Figure 1 As shown, it includes an electronic doorbell 1, a doorbell switch circuit, a current acquisition circuit, a doorbell control circuit and a self-locking circuit.

[0035] The electronic doorbell 1 is connected to an AC power supply; the doorbell switch circuit is connected to the electronic doorbell 1, and the doorbell switch circuit is used to provide switch control for the electronic doorbell 1; the current acquisition circuit is connected to the doorbell switch circuit, and the current acquisition circuit is used to acquire current data of the electronic doorbell 1 and send it to the self-locking circuit; the input end of the doorbell control circuit is connected to MCU2, and the output end is connected to the doorbell switch circuit, and the doorbell control circuit is used to control the opening and closing of the doorbell switch circuit; the input end of the self-locking circuit is connected to the current acquisition circuit, and the output end is connected to the doorbell control circuit, and the self-locking circuit is used to protect the doorbell switch circuit, the current acquisition circuit and the doorbell control circuit when an abnormality occurs in the electronic doorbell 1 or the AC power supply.

[0036] The doorbell switch circuit includes an upper circulation circuit and a lower circulation circuit. The upper circulation circuit is connected to the power supply AC+, and the lower circulation circuit is connected to the power supply AC-. The upper circulation circuit and the lower circulation circuit are combined to form a complete power supply circuit.

[0037] like Figure 2As shown, the upper circulation circuit includes a first diode 8, a second MOS tube 9, a fourth resistor 10 and a fifth resistor 11; the positive electrode of the first diode 8 is connected to the doorbell control circuit, the negative electrode is connected to the gate of the second MOS tube 9, the drain of the second MOS tube 9 is connected to the first contact P1 of the electronic doorbell 1, the source is connected to one end of the fifth resistor 11, the other end of the fifth resistor 11 is grounded, and the fourth resistor 10 is connected between the first diode 8 and the second MOS tube 9.

[0038] The lower loop circuit includes a second diode 12, a third MOS tube 13, a sixth resistor 14 and a seventh resistor 15. The anode of the second diode 12 is connected to the doorbell control circuit, the cathode is connected to the gate of the third MOS tube 13, the drain of the third MOS tube 13 is connected to the second contact P2 of the electronic doorbell 1, the source is connected to one end of the seventh resistor 15, the other end of the seventh resistor 15 is grounded, and the sixth resistor 14 is connected between the second diode 12 and the third MOS tube 13.

[0039] The second MOS transistor 9 and the third MOS transistor 13 are both N-type MOS transistors.

[0040] When the doorbell control circuit outputs a high level, the first diode 8 and the second diode 12 are turned on at the same time, the gate voltages of the second MOS transistor 9 and the third MOS transistor 13 are both greater than the source voltage, and the second MOS transistor 9 and the third MOS transistor 13 are turned on at the same time.

[0041] In the positive half cycle of the AC power supply, the electronic doorbell 1 is connected through the first contact P1, and the current is transmitted to the second MOS tube 9, so that the second MOS tube 9 is turned on, and then passes through the fifth resistor 11-GND-seventh resistor 15 and the parasitic diode inside the third MOS tube 13, and then returns to the AC power supply after passing through the second contact P2, forming a complete power supply circuit.

[0042] In the negative half cycle of the AC power supply, the third MOS tube 13 is connected through the second contact P2, and then passes through the seventh resistor 15-GND-the fifth resistor 11 and the parasitic diode inside the second MOS tube 9, and returns to the first contact P1, forming a complete loop passing through the doorbell, and the electronic doorbell 1 makes a sound.

[0043] like Figure 3Preferably, the doorbell control circuit includes a first resistor 3, a first transistor 4 and a first MOS transistor 5. One end of the first resistor 3 is connected to the 3rd pin of MCU2, and the other end is connected to the base of the first transistor 4; the collector of the first transistor 4 is connected to the gate of the first MOS transistor 5, and the emitter is grounded. A second resistor 6 is provided between the first resistor 3 and the first transistor 4, and the other end of the second resistor 6 is grounded; the source of the first MOS transistor 5 is connected to the power supply VDD, and the drain is connected to the doorbell switch circuit; a third resistor 7 is provided between the gate of the first MOS transistor 5 and the power supply VDD. The first MOS transistor 5 is a P-type MOS transistor. The first transistor 4 is an NPN transistor.

[0044] When the 3 pin of MCU2 outputs a low level, it is input to the base of the first transistor 4 through the first resistor 3, so that the first transistor 4 is not conducting. At this time, the gate of the first MOS transistor 5 is at a high level, the first MOS transistor 5 is not conducting, the drain of the first MOS transistor 5 outputs a low level, and the doorbell switch circuit does not work.

[0045] When the 3 pin of MCU2 outputs a high level, it is input to the base of the first transistor 4 through the first resistor 3, so that the first transistor 4 is turned on and grounded. At this time, the gate of the second MOS transistor 9 is at a low level, the first MOS transistor 5 is turned on, and the power supply VDD is input to the doorbell switch circuit through the drain of the first MOS transistor 5. The gates of the second MOS transistor 9 and the third MOS transistor 13 in the doorbell switch circuit receive the high level and are turned on, and the doorbell switch circuit starts to work.

[0046] Preferably, the current acquisition circuit includes an eighth resistor 16, a third diode 17, a ninth resistor 18 and a fourth diode 19. One end of the eighth resistor 16 is connected to the source of the second MOS tube 9, and the other end is connected to the positive electrode of the third diode 17. One end of the ninth resistor 18 is connected to the source of the third MOS tube 13, and the other end is connected to the positive electrode of the fourth diode 19. The cathodes of the third diode 17 and the fourth diode 19 are both connected to the interface SHORT_DET. The interface SHORT_DET is connected to the self-locking circuit.

[0047] When the voltage in the doorbell switch circuit changes, in the positive half cycle of the AC power supply, the eighth resistor 16 and the third diode 17 send the current and voltage signals to the self-locking circuit through the interface SHORT_DET; in the negative half cycle of the AC power supply, the ninth resistor 18 and the fourth diode 19 send the current and voltage signals to the self-locking circuit through the interface SHORT_DET to realize the collection of current and voltage.

[0048] Preferably, a tenth resistor 20 is provided between the eighth resistor 16 and the third diode 17, an eleventh resistor 21 is provided between the ninth resistor 18 and the fourth diode 19, and the other ends of the tenth resistor 20 and the eleventh resistor 21 are grounded for voltage division.

[0049] like Figure 4 Preferably, the self-locking circuit includes a twelfth resistor 22, a second triode 23, a third triode 24 and a fourth triode 25. One end of the twelfth resistor 22 is provided with a connection interface SHORT_DET, and the other end is connected to the base of the second triode 23; the collector of the second triode 23 is connected to the base of the third triode 24, and the emitter is grounded; the collector of the second triode 23 is connected to the power supply VDD, and the emitter is connected to the interface AC_SHORT_DET. The second triode 23 is an NPN tube, and the third triode 24 is a PNP tube.

[0050] A thirteenth resistor 26 is connected to the base of the second transistor 23, and the other end of the thirteenth resistor 26 is connected to the interface AC_SHORT_DET. A fourteenth resistor 27 is arranged between the thirteenth resistor 26 and the base of the second transistor 23, and the other end of the fourteenth resistor 27 is grounded for voltage division; a fifteenth resistor 28 is arranged between the power supply VDD and the base of the third transistor 24.

[0051] The base of the fourth transistor 25 is connected to the emitter of the third transistor 24, the collector is provided with an interface SHORT_EN, the emitter is grounded, and the interface SHORT_EN is also provided at the base of the first transistor 4. The fourth transistor 25 is an NPN transistor.

[0052] Preferably, a sixteenth resistor 29 is provided between the third transistor 24 and the fourth transistor 25 , and a seventeenth resistor 30 is further connected to the base of the third transistor 24 . Both the sixteenth resistor 29 and the seventeenth resistor 30 are used for voltage division.

[0053] Preferably, the source of the first MOS tube 5 is connected to the first capacitor 31, the drain is connected to the second capacitor 32, the base of the second transistor 23 is connected to the third capacitor 33, and the other ends of the first capacitor 31, the second capacitor 32 and the third capacitor 33 are all grounded, which can ensure voltage stability when the voltage fluctuates.

[0054] When the voltage of the AC power supply exceeds the standard, or the electronic doorbell 1 has internal leakage, short circuit or other abnormalities, causing the loop current to exceed the normal value of normal operation during operation, in the positive half cycle of the AC power supply, the greater the current flowing through the fifth resistor 11, the higher the voltage drop on the fifth resistor 11; when the current passes through the eighth resistor 16 and then passes through the third diode 17 and the twelfth resistor 22 to enter the second transistor 23, when the base voltage of the second transistor 23 is greater than its conduction threshold, the second transistor 23 is turned on, and the base voltage of the third transistor 24 is pulled down, so that the third transistor 24 is turned on. At this time, the voltage of the power supply VDD outputs a high level through the third transistor 24 and the interface AC_SHORT_DET, and the high level output by the interface AC_SHORT_DET is added to the thirteenth resistor 26, maintaining the second transistor 23 continuously turned on, and AC_SHORT_DET continuously outputs a high level. The same is true in the negative half cycle of the AC power supply, and the details are not repeated.

[0055] At the same time, the voltage of the power supply VDD applies a high level to the base of the fourth transistor 25 through the third transistor 24 and the sixteenth resistor 29, the fourth transistor 25 is turned on and grounded, the collector of the fourth transistor 25 outputs a low level, and then transmits the low level to the base of the first transistor 4 through the interface SHORT_EN, and the first transistor 4 is not turned on. At this time, the power supply VDD pulls up the tertiary voltage of the first MOS tube 5 through the third resistor 7, the first MOS tube 5 is not turned on, the drain of the first MOS tube 5 outputs a low level to the first diode 8 and the second diode 12, and the first diode 8 and the second diode 12 are not turned on. In the positive half cycle or the negative half cycle of the AC power supply, one of the first diode 8 and the second diode 12 is always not turned on, and a complete circuit cannot be formed. The electronic doorbell 1 does not make a sound, and over-current self-locking protection is achieved.

[0056] After the overcurrent self-locking protection, the interface SHORT_EN continuously outputs a low level, and the output end of MCU2 is pulled down through the first resistor 3. MCU2 recognizes the overcurrent protection self-locking state, and the WIFI doorbell camera control device emits a prompt sound or flashes a light, or pushes a prompt to the mobile phone APP. After the user resolves the overcurrent abnormality problem, the doorbell camera control device is restarted, and the entire system returns to normal.

[0057] In summary, this application has the following advantages:

[0058] 1. The overcurrent protection self-locking system monitors the current in real time through the sampling resistor. Once the current exceeds the preset threshold, the comparator will trigger the locking circuit and activate the MOS tube locking mechanism, thereby cutting off the power supply to prevent overcurrent damage. This design effectively and automatically blocks the flow of excessive current and maintains the locked state until the fault is eliminated, greatly improving the safety protection level of the system.

[0059] 2. Application of microcontroller unit (MCU): Using MCU to control the connection and disconnection of AC current not only replaces the traditional physical buttons or mechanical switches, but also allows for more intelligent control logic, such as remote operation, timing control, etc. The introduction of MCU is the key to realizing the intelligence of doorbells.

[0060] 3. Overcurrent protection self-locking and recovery function: After the fault is eliminated, the system can automatically return to normal working state without manual intervention by the user. This is of great significance to improving user experience and system reliability. Especially compared with traditional systems that require manual reset of fuses or circuit breakers, it provides significant convenience and safety.

[0061] 4. Safety protection in the off-power state: The self-locking mechanism ensures that even in the case of a power outage, the doorbell can be prevented from being accidentally triggered by sudden power-on, thereby improving the safety and stability of the device in uncertain environments.

[0062] Finally, it should be noted that: the drawings of the embodiments disclosed in the present invention only involve structures related to the embodiments disclosed in the present invention, and other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of the present invention can be combined with each other;

[0063] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A doorbell drive and overcurrent protection self-locking circuit, characterized in that: The electronic doorbell (1) comprises a doorbell switch circuit, a current collection circuit, a doorbell control circuit and a self-locking circuit; the electronic doorbell (1) is connected to an AC power supply; the doorbell switch circuit is connected to the electronic doorbell (1), and the doorbell switch circuit is used to provide switch control for the electronic doorbell (1); The current acquisition circuit is connected to the doorbell switch circuit, and the current acquisition circuit is used to collect current data of the electronic doorbell (1) and send it to the self-locking circuit; the input end of the doorbell control circuit is connected to the MCU (2), and the output end is connected to the doorbell switch circuit, and the doorbell control circuit is used to control the opening and closing of the doorbell switch circuit; the input end of the self-locking circuit is connected to the current acquisition circuit, and the output end is connected to the doorbell control circuit, and the self-locking circuit is used to protect the doorbell switch circuit, the current acquisition circuit and the doorbell control circuit when an abnormality occurs in the electronic doorbell (1) or the AC power supply; the doorbell switch circuit includes an upper circulation circuit and a lower circulation circuit, the upper circulation circuit is connected to the power supply AC+, and the lower circulation circuit is connected to the power supply AC-, and the upper circulation circuit and the lower circulation circuit are combined to form a complete power supply circuit; The upper circulation circuit comprises a first diode (8), a second MOS transistor (9), a fourth resistor (10) and a fifth resistor (11); the positive electrode of the first diode (8) is connected to the doorbell control circuit, the negative electrode is connected to the gate electrode of the second MOS transistor (9), the drain electrode of the second MOS transistor (9) is connected to the first contact point P1 of the electronic doorbell (1), the source electrode is connected to one end of the fifth resistor (11), the other end of the fifth resistor (11) is grounded, and one end of the fourth resistor (10) is connected to the negative electrode of the first diode (8), and the other end is grounded; The lower circulation circuit comprises a second diode (12), a third MOS tube (13), a sixth resistor (14) and a seventh resistor (15); the anode of the second diode (12) is connected to the doorbell control circuit, the cathode is connected to the gate of the third MOS tube (13), the drain of the third MOS tube (13) is connected to the second contact point P2 of the electronic doorbell (1), the source is connected to one end of the seventh resistor (15), the other end of the seventh resistor (15) is grounded, and one end of the sixth resistor (14) is connected to the cathode of the second diode (12), and the other end is grounded; The second MOS tube (9) and the third MOS tube (13) are both N-type MOS tubes; The doorbell control circuit comprises a first resistor (3), a first triode (4) and a first MOS tube (5); one end of the first resistor (3) is connected to pin 3 of the MCU (2), and the other end is connected to the base of the first triode (4); the collector of the first triode (4) is connected to the gate of the first MOS tube (5), and the emitter is grounded; a second resistor (6) is provided between the first resistor (3) and the first triode (4), and the other end of the second resistor (6) is grounded; the source of the first MOS tube (5) is connected to a power supply VDD, and the drain is connected to a doorbell switch circuit; a third resistor (7) is provided between the gate of the first MOS tube (5) and the power supply VDD; the first MOS tube (5) is a P-type MOS tube; and the first triode (4) is an NPN tube.

2. The doorbell driving and overcurrent protection self-locking circuit as claimed in claim 1, characterized in that: The self-locking circuit comprises a twelfth resistor (22), a second triode (23), a third triode (24) and a fourth triode (25); one end of the twelfth resistor (22) is provided with a connection interface SHORT_DET, and the other end is connected to the base of the second triode (23); the collector of the second triode (23) is connected to the base of the third triode (24), and the emitter is grounded; the emitter of the third triode (24) is connected to a power supply VDD, and the collector is connected to the interface AC_SHORT_DET; the second triode The first transistor (23) is an NPN transistor, and the third transistor (24) is a PNP transistor; the base of the second transistor (23) is connected to one end of the thirteenth resistor (26), and the other end of the thirteenth resistor (26) is connected to the interface AC_SHORT_DET; the base of the second transistor (23) is connected to one end of the fourteenth resistor (27), and the other end of the fourteenth resistor (27) is grounded; the power supply VDD is connected to one end of the fifteenth resistor (28), and the other end of the fifteenth resistor (28) is connected to the base of the third transistor (24); The base of the fourth triode (25) is connected to the collector of the third triode (24), the collector is provided with an interface SHORT_EN, and the emitter is grounded, and the interface SHORT_EN is also provided at the base of the first triode (4); the fourth triode (25) is an NPN tube.

3. The doorbell driving and overcurrent protection self-locking circuit as claimed in claim 2, characterized in that: The source of the first MOS transistor (5) is connected to a first capacitor (31), the drain is connected to a second capacitor (32), the base of the second triode (23) is connected to a third capacitor (33), and the other ends of the first capacitor (31), the second capacitor (32) and the third capacitor (33) are all grounded.

4. The doorbell driving and overcurrent protection self-locking circuit as claimed in claim 1, characterized in that: The current acquisition circuit comprises an eighth resistor (16), a third diode (17), a ninth resistor (18) and a fourth diode (19); one end of the eighth resistor (16) is connected to the source of the second MOS tube (9), and the other end is connected to the positive electrode of the third diode (17); one end of the ninth resistor (18) is connected to the source of the third MOS tube (13), and the other end is connected to the positive electrode of the fourth diode (19); the cathodes of the third diode (17) and the fourth diode (19) are both connected to an interface SHORT_DET; and the interface SHORT_DET is connected to a self-locking circuit.

5. The electric doorbell driving and overcurrent protection self-locking circuit as claimed in claim 4, characterized in that: The anode of the third diode (17) is connected to one end of the tenth resistor (20), and the other end of the tenth resistor (20) is grounded; the anode of the fourth diode (19) is connected to one end of the eleventh resistor (21), and the other end of the eleventh resistor (21) is grounded.

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