CN220305706U - Overvoltage and undervoltage protection circuit of Darlington voltage stabilizer - Google Patents

Abstract

The utility model relates to the technical field of electronic circuits, and specifically discloses a Darlington regulator overvoltage and undervoltage protection circuit. The first end of the first capacitor is connected to the first end of the MOS tube, and the second end of the first capacitor is connected to the first end of the first capacitor. The second end of the first switch module is connected to the second end of the MOS tube and the first end of the first resistor; the second end of the first switch module is connected to the negative electrode of the battery pack, and the controlled end of the first switch module is connected to the second end of the first resistor. The output end of the undervoltage protection module and the output end of the overvoltage protection module; the first end of the first voltage regulator tube is connected to the second end of the first resistor and the controlled end of the Darlington voltage regulator, and the first voltage regulator tube The second end of the voltage tube is connected to the negative electrode of the battery pack; the second end of the Darlington regulator, the input end of the undervoltage protection module and the input end of the overvoltage protection module are all connected to the VCC output end; the utility model can Increase the noise immunity of the voltage regulator circuit, and have under-voltage protection and over-voltage protection functions to prevent the battery pack from running out of power and damaging the subsequent circuit in the event of a fault.

Description

A Darlington regulator overvoltage and undervoltage protection circuit

Technical field

The utility model relates to the technical field of electronic circuits, in particular to a Darlington regulator overvoltage and undervoltage protection circuit.

Background technique

Darlington regulator, also known as Darlington tube, or composite tube, properly connects two triodes together to form an equivalent new triode. This is equivalent to the amplification factor of the triode being two In the field of electronic circuit design, Darlington connection is often used in power amplifiers and regulated power supplies.

The existing Darlington voltage regulator circuit does not have any effective fault protection action under power supply, and cannot play the role of cutting off fault events. For example, in an under-voltage fault state, it is easy to drain the battery pack, causing the battery to fail. loss; in an overvoltage fault state, it is easy to cause the subsequent circuit to exceed the withstand voltage and be damaged, affecting the use of the product and posing certain safety hazards.

Utility model content

In view of the above-mentioned problem that the Darlington regulator circuit is easy to drain the battery pack or cause the subsequent circuit to exceed the withstand voltage and be damaged, the utility model provides a Darlington regulator overvoltage and undervoltage protection circuit. It can increase the noise immunity of the voltage regulator circuit, and has under-voltage protection and over-voltage protection functions to prevent the battery pack from running out of power and damaging the subsequent circuit in the event of a fault.

In order to solve the above technical problems, the specific solutions provided by this utility model are as follows:

A Darlington regulator overvoltage and undervoltage protection circuit, including a MOS tube, a first capacitor, a first resistor, a first switch module, a first voltage regulator tube, a Darlington regulator, an undervoltage protection module and Overvoltage protection module;

The first end of the MOS tube is connected to the positive electrode of the battery pack, the second end of the MOS tube is connected to the first end of the Darlington regulator, and the controlled end of the MOS tube is connected to the first end of the first switch module;

The first end of the first capacitor is connected to the first end of the MOS tube, and the second end of the first capacitor is connected to the second end of the MOS tube and the first end of the first resistor;

The second end of the first switch module is connected to the negative electrode of the battery pack, and the controlled end of the first switch module is connected to the second end of the first resistor, the output end of the undervoltage protection module and the output end of the overvoltage protection module;

The first end of the first voltage regulator tube is connected to the second end of the first resistor and the controlled end of the Darlington regulator, and the second end of the first voltage regulator tube is connected to the negative electrode of the battery pack;

The second terminal of the Darlington voltage regulator, the input terminal of the undervoltage protection module and the input terminal of the overvoltage protection module are all connected to the VCC output terminal.

In some embodiments, the first switch module includes a first transistor, a second resistor, and a third resistor;

The first end of the second resistor is connected to the second end of the first resistor, the output end of the undervoltage protection module and the output end of the overvoltage protection module, and the second end of the second resistor is connected to the base of the first transistor. ;

The first end of the third resistor is connected to the base of the first transistor, and the second end of the third resistor is connected to the negative electrode of the battery pack;

The collector of the first triode is connected to the controlled end of the MOS tube, and the emitter of the first triode is connected to the negative electrode of the battery pack, so that when the first triode is turned on, the MOS tube can be turned on. When the first transistor is turned off, the MOS transistor is turned off, and the battery pack stops supplying power.

In some embodiments, a fourth resistor is provided between the collector of the first triode and the controlled end of the MOS tube. The fourth resistor can cause the collector voltage of the first triode to change with the base current. The voltage on the collector resistor changes due to the change, which plays a role in current amplification and prompts the MOS tube to conduct.

In some embodiments, a fifth resistor is disposed between the first end of the MOS transistor and the controlled end, a first diode is disposed between the first end of the MOS transistor and the anode of the battery pack, and the fifth resistor It plays the role of providing bias voltage and discharge resistance, and protects the MOS tube.

In some embodiments, a second diode is provided between the first end of the first voltage regulator tube and the controlled end of the Darlington voltage regulator, which acts as a unidirectional conductor and improves the stability of the circuit. sex.

In some embodiments, the undervoltage protection module includes a third diode, a fourth diode and a fifth diode connected in series, and the first end of the third diode is connected to the VCC output end. , the second end of the fifth diode is connected to the first end of the second resistor to realize under-voltage protection for the Darlington regulator.

In some embodiments, the overvoltage protection module includes a second voltage regulator tube, a sixth resistor, and a second transistor;

The first end of the second voltage regulator tube is connected to the VCC output terminal, the second end of the second voltage regulator tube is connected to the base of the second transistor and the first end of the sixth resistor, and the sixth resistor is connected to the first end of the second voltage regulator tube. Connect the two terminals to the negative terminal of the battery pack;

The collector of the second transistor is connected to the first end of the second resistor, and the emitter of the second transistor is connected to the negative electrode of the battery pack to achieve overvoltage protection for the Darlington regulator.

In some embodiments, the overvoltage protection module further includes a second capacitor, the first end of the second capacitor is connected to the first end of the second voltage regulator tube, and the second end of the second capacitor is connected to the sixth resistor. The second terminal plays a filtering role and improves the stability of the circuit.

In some embodiments, the Darlington regulator includes a third triode and a fourth triode, the base of the third triode is connected to the emitter of the fourth triode, and the third triode The collector of the transistor and the collector of the fourth triode are connected to the positive electrode of the battery pack, the emitter of the third triode is connected to the VCC output terminal, and the base of the fourth triode is connected to the first terminal of the first voltage regulator tube. terminal, connect the third triode and the fourth triode to increase the amplification factor and meet the circuit usage requirements.

In some embodiments, the Darlington regulator further includes a seventh resistor. The first end of the seventh resistor is connected to the collector of the third transistor and the second end of the MOS transistor. The second end is connected to the collector of the fourth triode, and the seventh resistor can realize that the collector voltage of the third triode changes with the change of the base current and the voltage on the collector resistor changes, thereby playing a current amplification role.

The utility model provides a Darlington regulator overvoltage and undervoltage protection circuit. By setting an undervoltage protection module and an overvoltage protection module, when an undervoltage fault state or an overvoltage fault state occurs, the first switch can The module turns off the MOS tube, thereby stopping the Darlington voltage regulator from working, which can increase the immunity of the voltage regulator circuit. It has under-voltage protection and over-voltage protection functions to prevent the battery pack from running out of power and damaging the subsequent stage during a fault. circuit, effectively improving the stability and safety of the circuit.

Description of drawings

Figure 1 is a schematic diagram of a Darlington regulator overvoltage and undervoltage protection circuit provided in an embodiment of the present invention;

Figure 2 is a schematic diagram of the first switch module;

Figure 3 is a schematic diagram of the undervoltage protection module;

Figure 4 is a schematic diagram of the overvoltage protection module;

10-First switch module;

20-Darlington regulator;

30-Under voltage protection module;

40-Overvoltage protection module.

Detailed ways

The preferred embodiments of the present application will be described in detail below in conjunction with the accompanying drawings, so that the advantages and features of the present application can be more easily understood by those skilled in the art, and the protection scope of the present application can be more clearly defined.

Please refer to the drawings, in which the same component symbols represent the same components. The principles of the present application are exemplified by implementation in a suitable computing environment. The following description is based on the illustrated specific embodiments of the present application, and should not be regarded as limiting other specific embodiments of the present application that are not described in detail here.

For example, a Darlington regulator overvoltage and undervoltage protection circuit includes a MOS tube, a first capacitor, a first resistor, a first switch module, a first voltage regulator tube, a Darlington regulator, and undervoltage protection. module and overvoltage protection module; the first end of the MOS tube is connected to the positive electrode of the battery pack, the second end of the MOS tube is connected to the first end of the Darlington regulator, and the controlled end of the MOS tube is connected to the first switch module The first end of the first capacitor is connected to the first end of the MOS tube, and the second end of the first capacitor is connected to the second end of the MOS tube and the first end of the first resistor; the first switch The second end of the module is connected to the negative electrode of the battery pack, and the controlled end of the first switch module is connected to the second end of the first resistor, the output end of the undervoltage protection module and the output end of the overvoltage protection module; the first voltage regulator The first end of the tube is connected to the second end of the first resistor and the controlled end of the Darlington regulator, the second end of the first regulator tube is connected to the negative electrode of the battery pack; the third end of the Darlington regulator The two terminals, the input terminal of the undervoltage protection module and the input terminal of the overvoltage protection module are connected to the VCC output terminal.

This embodiment provides a Darlington voltage regulator overvoltage and undervoltage protection circuit, which can increase the immunity of the voltage regulator circuit, has undervoltage protection and overvoltage protection functions, and prevents the battery pack from being exhausted during a fault. Damage the downstream circuit.

Example 1:

As shown in Figure 1, a Darlington voltage regulator overvoltage and undervoltage protection circuit includes a MOS tube, a first capacitor, a first resistor, a first switch module 10, a first voltage regulator tube, and a Darlington voltage regulator. The device 20, the undervoltage protection module 30 and the overvoltage protection module 40, wherein the MOS tube is Q1, the first capacitor is C1, the first resistor is R5, and the first voltage regulator tube is ZD2.

The first terminal of the MOS tube Q1 is connected to the positive terminal BAT+ of the battery pack, the second terminal of the MOS tube Q1 is connected to the first terminal of the Darlington regulator 20 , and the controlled terminal of the MOS tube Q1 is connected to the first terminal of the first switch module 10 terminal; the first terminal of the first capacitor C1 is connected to the first terminal of the MOS tube Q1, and the second terminal of the first capacitor C1 is connected to the second terminal of the MOS tube Q1 and the first terminal of the first resistor R5; the first switch module 10 The second end is connected to the negative electrode GND of the battery pack, and the controlled end of the first switch module 10 is connected to the second end of the first resistor R5, the output end of the undervoltage protection module 30 and the output end of the overvoltage protection module 40; the first The first end of the voltage regulator tube ZD2 is connected to the second end of the first resistor R5 and the controlled end of the Darlington regulator 20, and the second end of the first voltage regulator tube ZD2 is connected to the negative electrode GND of the battery pack; Darlington The second terminal of the voltage regulator 20, the input terminal of the undervoltage protection module 30 and the input terminal of the overvoltage protection module 40 are all connected to the VCC output terminal.

The Darlington voltage regulator overvoltage and undervoltage protection circuit provided in this example is used to use the Darlington voltage regulator 20 to realize the battery pack to supply power to the subsequent circuit. When an undervoltage or overvoltage fault occurs, The first switch module 10 turns off the MOS transistor, thereby stopping the Darlington regulator 20 from working.

The specific working process of the protection circuit is as follows. Since the MOS transistor Q1 and the first capacitor C1 are in a parallel relationship, at startup, the first capacitor C1 is short-circuited instantaneously, and the first switch module 10 is turned on through the first resistor R5, thereby causing the MOS transistor Q1 to be connected in parallel. The tube Q1 is turned on, and the positive electrode BAT+ of the battery pack is powered normally, causing the first voltage regulator tube ZD2 to work in the breakdown zone, forming a stable voltage state. The VCC output terminal outputs normal voltage to supply power to the subsequent circuit, completing the Darlington regulator. 20 circuit start-up work.

When an undervoltage fault occurs in the Darlington regulator 20, the output terminal VCC is pulled down by the load of the subsequent circuit, and the first switch module 10 is turned off through the undervoltage protection module 30, and then the MOS transistor Q1 is turned off, and the Darlington stabilizer The voltage regulator 20 stops working; when an overvoltage fault occurs in the Darlington regulator 20, a voltage spike appears at the VCC output, and the first switch module 10 is cut off through the overvoltage protection module 40, and then the MOS tube Q1 is cut off, and the Darlington regulator 20 is cut off. The voltage stabilizer 20 stops working, thus functioning as under-voltage protection and over-voltage protection, preventing the battery pack from being depleted of power and damaging the downstream circuit during a fault, effectively improving the stability and safety of the circuit.

Example 2:

As shown in FIG. 2 , the first switch module 10 includes a first transistor, a second resistor, and a third resistor. The first transistor is Q4, the second resistor is R6, and the third resistor is R7.

The first end of the second resistor R6 is connected to the second end of the first resistor R5, the output end of the undervoltage protection module 30 and the output end of the overvoltage protection module 40. The second end of the second resistor R6 is connected to the first transistor. The base of Q4; the first end of the third resistor R7 is connected to the base of the first transistor Q4, and the second end of the third resistor R7 is connected to the negative electrode GND of the battery pack; the collector of the first transistor Q4 is connected to the MOS The controlled end of transistor Q1 and the emitter of the first transistor Q4 are connected to the negative electrode GND of the battery pack, so that when the first transistor Q4 is turned on, the MOS transistor Q1 can be turned on, so that the battery pack can supply power normally. ; When the first transistor Q4 is turned off, the MOS tube Q1 is turned off, and the battery pack stops supplying power.

Specifically, at startup, the first capacitor C1 is short-circuited instantaneously, and a loop is formed through the first resistor R5, the second resistor R6, and the third resistor R7. The value of the third resistor R7 satisfies the voltage formed by the third resistor R7. The voltage drop can meet the conduction requirement of the first transistor Q4, provide a short-term voltage to turn on the MOS tube Q1, and the battery pack provides normal power supply, so that the first voltage regulator ZD2 works in the breakdown zone, forming a stable voltage state, and the VCC output terminal Output normal voltage to supply power to the subsequent circuit to complete the startup work of the Darlington regulator 20 circuit.

When an undervoltage fault occurs in the Darlington regulator 20, the output terminal VCC is pulled low by the load of the subsequent circuit, and the base voltage of the first transistor Q4 is pulled low through the undervoltage protection module 30. The tube Q4 is cut off, and the MOS tube Q1 is cut off accordingly, and the Darlington voltage regulator 20 stops working; when the Darlington voltage regulator 20 has an overvoltage fault state, a voltage spike appears at the VCC output end, and the overvoltage protection module 40 The base voltage of the first transistor Q4 is pulled low, the first transistor Q4 is turned off, and the MOS transistor Q1 is cut off accordingly, and the Darlington voltage regulator 20 stops working, realizing undervoltage of the Darlington voltage regulator 20 protection and overvoltage protection.

In some application scenarios, a fourth resistor is provided between the collector of the first transistor Q4 and the controlled end of the MOS transistor Q1. The fourth resistor is R4. The fourth resistor R4 can make the first transistor Q4 The collector voltage changes as the base current changes, and the voltage on the collector resistor changes, which acts as a current amplifier and prompts the MOS tube Q1 to turn on.

A fifth resistor is provided between the first end of the MOS transistor Q1 and the controlled end, and the fifth resistor is R3. A first diode is provided between the first end of the MOS transistor Q1 and the positive electrode BAT+ of the battery pack. The diode is D2, the fifth resistor R3 serves to provide bias voltage and discharge resistance, and protects the MOS tube Q1. The first diode D2 serves to conduct electricity in one direction, improving the stability of the circuit. sex.

A second diode is provided between the first end of the first voltage regulator tube ZD2 and the controlled end of the Darlington regulator 20. The second diode is D3. The second diode D3 functions as a single It acts as a conductor to improve the stability of the circuit.

Embodiment three:

As shown in FIG. 3 , the undervoltage protection module 30 includes a third diode, a fourth diode and a fifth diode connected in series. The third diode is D4, the fourth diode is D5, The fifth diode is D6, the first end of the third diode D4 is connected to the VCC output end, and the second end of the fifth diode D6 is connected to the first end of the second resistor R6 to achieve Darlington voltage stabilization. The undervoltage protection function of device 20.

When an undervoltage fault occurs in the Darlington regulator 20, the output terminal VCC is pulled low by the load of the subsequent circuit, and the third diode D4, the fourth diode D5 and the fifth diode D6 are turned on, causing the The base voltage of the first transistor Q4 is pulled down, the first transistor Q4 is turned off, the MOS transistor Q1 is cut off accordingly, and the Darlington regulator 20 stops working.

The third diode D4, the fourth diode D5 and the fifth diode D6 are used here to ensure that under normal circumstances, when the Darlington regulator 20 is turned on, the third diode D4, the fourth diode D4 and the fifth diode D6 are used. The voltage drop of the fourth diode D5 and the fifth diode D6 is too small to conduct, so the second resistor R6 and the third resistor R7 divide the voltage. The voltage of the third resistor R7 needs to be approximately greater than 0.7V and less than 2V, so that The first transistor Q4 can be turned on under normal conditions and turned off when an undervoltage fault occurs.

Embodiment 4:

As shown in Figure 4, the overvoltage protection module 40 includes a second voltage regulator tube, a sixth resistor, and a second triode. The second voltage regulator tube is ZD1, the sixth resistor is R8, and the second triode is Q5. The first terminal of the second voltage stabilizing tube ZD1 is connected to the VCC output terminal, and the second terminal of the second voltage stabilizing tube ZD1 is connected to the base of the second transistor Q5 and the first terminal of the sixth resistor R8. The second end is connected to the negative electrode GND of the battery pack; the collector of the second transistor Q5 is connected to the first end of the second resistor R6, and the emitter of the second transistor Q5 is connected to the negative electrode GND of the battery pack to realize Darlington Overvoltage protection function of voltage regulator 20.

When the Darlington regulator 20 has an overvoltage fault state, a voltage spike appears at the VCC output terminal. When the voltage spike reaches the breakdown voltage of the second voltage regulator tube ZD1, the second voltage regulator tube ZD1 works in the breakdown state. The current flowing through the sixth resistor R8 causes a voltage drop across the sixth resistor R8, turning on the second transistor Q5, pulling down the base voltage of the first transistor Q4, and turning off the first transistor Q4. , the MOS transistor Q1 is cut off, and the Darlington voltage regulator 20 stops working, thereby realizing overvoltage protection for the Darlington voltage regulator 20 .

In one example, the overvoltage protection module 40 further includes a second capacitor, the second capacitor is C2, the first end of the second capacitor C2 is connected to the first end of the second voltage regulator tube ZD1, and the second end of the second capacitor C2 Connected to the second end of the sixth resistor R8, the second capacitor C2 plays a filtering role to improve the stability of the circuit.

Embodiment five:

The Darlington regulator 20 includes a third triode and a fourth triode. The third triode is Q2 and the fourth triode is Q3. The base of the third triode Q2 is connected to the fourth triode. The emitter of tube Q3, the collector of the third triode Q2 and the collector of the fourth triode Q3 are connected to the positive electrode BAT+ of the battery pack, the emitter of the third triode Q2 is connected to the VCC output, and the fourth triode The base of the tube Q3 is connected to the first end of the first voltage stabilizing tube ZD2, and the third transistor Q2 and the fourth transistor Q3 are connected to increase the amplification factor and meet the circuit usage requirements.

The Darlington regulator 20 also includes a seventh resistor, which is R2. The first end of the seventh resistor R2 is connected to the collector of the third transistor Q2 and the second end of the MOS tube Q1. The seventh resistor R2 The second end is connected to the collector of the fourth transistor Q3. The seventh resistor R2 can realize that the collector voltage of the third transistor Q2 changes with the change of the base current and the voltage on the collector resistor changes, thereby amplifying the current. effect.

To sum up, the utility model provides a Darlington regulator overvoltage and undervoltage protection circuit. By setting an undervoltage protection module and an overvoltage protection module, when an undervoltage fault state or an overvoltage fault state occurs, It can cut off the MOS tube through the first switch module, thereby stopping the Darlington voltage regulator from working. It can increase the immunity of the voltage regulator circuit and has under-voltage protection and over-voltage protection functions to prevent the battery pack from being exhausted in the event of a fault. power and damage to the subsequent circuit, effectively improving the stability and safety of the circuit.

The term "module" as used herein may be a software or hardware object executing on the computing system. The various components, modules, engines, and services described herein may be implemented on the computing system. The devices and methods described in this article can be implemented in the form of software, and of course can also be implemented in hardware, which are all within the scope of protection of this application.

Reference herein to "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The appearances of this phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those skilled in the art understand, both explicitly and implicitly, that the embodiments described herein may be combined with other embodiments.

In the description of this application, it should be noted that, unless otherwise clearly stated and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection. Connection, or integral connection; it can be mechanical connection, electrical connection or mutual communication; it can be direct connection, or indirect connection through an intermediary, it can be internal connection of two elements or interaction of two elements relation. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

Claims (10)

1. A Darlington voltage regulator overvoltage and undervoltage protection circuit, characterized in that it includes a MOS tube, a first capacitor, a first resistor, a first switch module, a first voltage regulator tube, and a Darlington voltage regulator , Undervoltage protection module and overvoltage protection module; The first end of the MOS tube is connected to the positive electrode of the battery pack, the second end of the MOS tube is connected to the first end of the Darlington regulator, and the controlled end of the MOS tube is connected to the first end of the first switch module; The first end of the first capacitor is connected to the first end of the MOS tube, and the second end of the first capacitor is connected to the second end of the MOS tube and the first end of the first resistor; The second end of the first switch module is connected to the negative electrode of the battery pack, and the controlled end of the first switch module is connected to the second end of the first resistor, the output end of the undervoltage protection module and the output end of the overvoltage protection module; The first end of the first voltage regulator tube is connected to the second end of the first resistor and the controlled end of the Darlington regulator, and the second end of the first voltage regulator tube is connected to the negative electrode of the battery pack; The second terminal of the Darlington voltage regulator, the input terminal of the undervoltage protection module and the input terminal of the overvoltage protection module are all connected to the VCC output terminal. 2. The Darlington regulator overvoltage and undervoltage protection circuit according to claim 1, characterized in that the first switch module includes a first transistor, a second resistor and a third resistor; The first end of the second resistor is connected to the second end of the first resistor, the output end of the undervoltage protection module and the output end of the overvoltage protection module, and the second end of the second resistor is connected to the base of the first transistor. ; The first end of the third resistor is connected to the base of the first transistor, and the second end of the third resistor is connected to the negative electrode of the battery pack; The collector of the first triode is connected to the controlled end of the MOS tube, and the emitter of the first triode is connected to the negative electrode of the battery pack. 3. The Darlington regulator overvoltage and undervoltage protection circuit according to claim 2, characterized in that a fourth transistor is further provided between the collector of the first transistor and the controlled end of the MOS tube. resistance. 4. The Darlington regulator overvoltage and undervoltage protection circuit according to claim 1, characterized in that a fifth resistor is provided between the first end of the MOS tube and the controlled end, and the third resistor of the MOS tube is A first diode is arranged between one end and the positive electrode of the battery pack. 5. The Darlington voltage regulator overvoltage and undervoltage protection circuit according to claim 1, characterized in that, between the first end of the first voltage regulator tube and the controlled end of the Darlington voltage regulator A second diode is provided. 6. The Darlington regulator overvoltage and undervoltage protection circuit according to claim 2, wherein the undervoltage protection module includes a third diode, a fourth diode and a third diode connected in series. Five diodes, the first end of the third diode is connected to the VCC output end, and the second end of the fifth diode is connected to the first end of the second resistor. 7. The Darlington regulator overvoltage and undervoltage protection circuit according to claim 2, characterized in that the overvoltage protection module includes a second voltage regulator tube, a sixth resistor and a second transistor; The first end of the second voltage regulator tube is connected to the VCC output terminal, the second end of the second voltage regulator tube is connected to the base of the second transistor and the first end of the sixth resistor, and the sixth resistor is connected to the first end of the second voltage regulator tube. Connect the two terminals to the negative terminal of the battery pack; The collector of the second transistor is connected to the first end of the second resistor, and the emitter of the second transistor is connected to the negative electrode of the battery pack. 8. The Darlington regulator overvoltage and undervoltage protection circuit according to claim 7, wherein the overvoltage protection module further includes a second capacitor, and the first end of the second capacitor is connected to the second capacitor. The first end of the voltage stabilizing tube and the second end of the second capacitor are connected to the second end of the sixth resistor. 9. The Darlington regulator overvoltage and undervoltage protection circuit according to claim 1, characterized in that the Darlington regulator includes a third triode and a fourth triode, and the third triode The base of the third triode is connected to the emitter of the fourth triode, the collector of the third triode and the fourth triode are connected to the positive terminal of the battery pack, and the emitter of the third triode is connected to VCC. At the output end, the base of the fourth transistor is connected to the first end of the first voltage regulator tube. 10. The Darlington voltage regulator overvoltage and undervoltage protection circuit according to claim 9, characterized in that the Darlington voltage regulator further includes a seventh resistor, the first end of the seventh resistor is connected to The collector of the third triode is connected to the second terminal of the MOS tube, and the second terminal of the seventh resistor is connected to the collector of the fourth triode.