MCU low current start-up system

Abstract

This utility model provides a low-current startup system for an MCU, relating to the field of electrical equipment technology. It includes: a constant-current buck converter circuit, an LDO startup circuit, and an MCU load. The constant-current buck converter circuit includes an input power supply, a first resistor, a second resistor, a third resistor, an eighth resistor, a ninth resistor, a tenth resistor, a first Zener diode, a second Zener diode, a first NPN transistor, a third NPN transistor, a PNP transistor, a second capacitor, and a fourth capacitor. The LDO startup circuit includes a third Zener diode and a low-dropout linear regulator. The negative terminals of the second and third Zener diodes are connected. The low-dropout linear regulator is connected to the MCU load, providing an output voltage to the MCU load. By precisely controlling the current and voltage, reliable startup and stable operation of the MCU under low-current conditions are achieved.

Description

Technical Field

[0001] This utility model relates to the field of electrical equipment technology, and in particular to a low-current startup system for an MCU. Background Technology

[0002] An MCU (Microcontroller Unit) is a single-chip computer system that integrates a microprocessor (CPU), memory (RAM and ROM), input / output interfaces, and other functions. It is the core of embedded systems and is commonly used to control and automate various devices, such as home appliances, automobiles, industrial equipment, and smart homes.

[0003] Microcontrollers (MCUs) play a crucial role in modern electronic devices, greatly simplifying device design and manufacturing by integrating computing, storage, and communication functions. MCUs not only control device operation, such as sensor reading, signal processing, and data transmission, but also ensure efficient and stable system operation. Their low power consumption and small size make them ideal for embedded applications, widely used in consumer electronics, automotive electronics, and industrial control. With the rise of the Internet of Things (IoT) and smart devices, the importance of MCUs is becoming increasingly prominent; they are a core driving force behind intelligent development.

[0004] However, when faced with low startup currents below the MCU's normal operating current, especially under conditions of power supply current fluctuations or load current changes, traditional circuits cannot effectively support the MCU's normal startup and stable operation, and may even damage the MCU hardware in severe cases. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this utility model embodiment is to provide an MCU low current startup system, which can solve the technical problem that existing MCUs cannot effectively support normal startup and stable operation of the MCU when faced with a low startup current lower than the normal operating current of the MCU, especially under the condition of power supply current fluctuation or load current change, and may even damage the MCU hardware.

[0006] This utility model proposes a low-current startup system for an MCU, comprising: a constant current buck circuit, an LDO startup circuit, and an MCU load;

[0007] The constant current step-down circuit includes an input power supply, a first resistor, a second resistor, a third resistor, an eighth resistor, a ninth resistor, a tenth resistor, a first Zener diode, a second Zener diode, a first NPN transistor, a third NPN transistor, a PNP transistor, a second capacitor, and a fourth capacitor. The input power supply is connected to the first resistor, the second resistor, the third resistor, and the collector of the first NPN transistor. The first resistor is connected to the emitter of the PNP transistor. The base of the PNP transistor is connected to the emitter of the first NPN transistor and the eighth resistor. The base of the first NPN transistor is connected to the second resistor and the collector of the third NPN transistor. The base of the transistor is connected to the third resistor and the negative terminal of the first Zener diode, respectively; the positive terminal of the first Zener diode is connected to the tenth resistor; the emitter of the third NPN transistor is connected to the ninth resistor; the collector of the NPN transistor is connected to the negative terminal of the second Zener diode, the positive terminal of the second capacitor, and the negative terminal of the fourth capacitor, respectively; the eighth, ninth, and tenth resistors are all connected to the positive terminals of the second Zener diode, the negative terminals of the second and fourth capacitors, respectively; the eighth resistor is connected to the ninth and tenth resistors, respectively; the positive terminals of the second and fourth capacitors are both connected to the negative terminals of the second Zener diode; the negative terminals of the second and fourth capacitors are both connected to the positive terminals of the second Zener diode;

[0008] The LDO startup circuit includes a third Zener diode and a low-dropout linear regulator; the third Zener diode is connected to the low-dropout linear regulator.

[0009] The negative terminal of the second Zener diode is connected to the negative terminal of the third Zener diode;

[0010] The low-dropout linear regulator is connected to the MCU load and provides the output voltage to the MCU load.

[0011] The beneficial effects of the technical solution provided by this utility model embodiment include at least the following:

[0012] In this embodiment of the invention, by setting multiple transistors in the constant current buck circuit, when the load current on the side of the second Zener diode is less than the output current on the side of the PNP transistor, the voltage on the side of the second Zener diode continuously rises to the stable voltage value of the second Zener diode. At this time, excess current flows back through the second Zener diode, ensuring the stability of the input current of the input power supply and maintaining the stability of the power supply system. When the load current on the side of the second Zener diode is greater than the output current on the side of the PNP transistor, the voltage on the side of the second Zener diode drops, and the current no longer passes through the second Zener diode, but is entirely supplied to the load, namely the LDO startup circuit and the MCU load. If the voltage on the side of the second Zener diode is detected to be too low, the circuit can increase the current required by the load by controlling the first NPN transistor, the third NPN transistor, and the PNP transistor at multiple points, thereby achieving dynamic current compensation and ensuring the normal and stable operation of the load. Based on this, as the voltage on one side of the second Zener diode rises to the Zener value of the third Zener diode, the low-dropout linear regulator is triggered to operate. After starting, the low-dropout linear regulator supplies power to the MCU load. The energy pre-stored in the second and fourth capacitors can meet the MCU's demand for a large current at the moment of power-on, thus satisfying the startup conditions and achieving reliable startup. This MCU low-current startup system can support low-current startup and stable operation of the MCU. Attached Figure Description

[0013] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this invention. Throughout the drawings, the same reference numerals denote the same components. Obviously, the drawings described below are merely some embodiments of this invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0014] Figure 1 This is a schematic diagram of the structure of an MCU low-current startup system provided in an embodiment of the present invention;

[0015] Figure 2 This is a schematic diagram of another MCU low-current startup system provided in this embodiment of the present invention;

[0016] Figure 3 This is a schematic diagram illustrating an example application of a low-current startup system for an MCU provided in this embodiment of the present invention.

[0017] Input power supply VEE; First resistor R1; Second resistor R2; Third resistor R3; Fourth resistor R4; Eighth resistor R8; Ninth resistor R9; Tenth resistor R10; First Zener diode D1; Second Zener diode D2; Third Zener diode D3; First NPN transistor Q1; Third NPN transistor Q3; PNP transistor Q2; First capacitor C1; Second capacitor C2; Third capacitor C3; Fourth capacitor C4; Low dropout linear regulator LDO; Feedback pin VSE / FB, Enable pin EN, Ground pin GND, Output voltage pin Vout, Input voltage pin Vin, Output voltage VCC. Detailed Implementation

[0018] To enable those skilled in the art to better understand the technical solutions in the embodiments of this utility model, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. It should be understood that these descriptions are exemplary only and are not intended to limit the scope of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this utility model.

[0019] Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts disclosed in this utility model.

[0020] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this invention.

[0021] Reference manual attached Figure 1 The diagram shows a structural schematic of a low-current startup system for an MCU provided by an embodiment of the present invention.

[0022] Figure 1 This demonstrates a low-current startup system for MCUs. Figure 1In this circuit, the constant current buck converter's input power supply VEE is the system's input power, providing the initial current to the circuit. Resistors R1, R2, R3, R8, R9, and R10 are used for current shunting and voltage regulation, ensuring the current is appropriate for effective voltage conversion and regulation at each stage. Transistors Q1, Q2, and Q3 are responsible for current amplification and voltage regulation, ensuring the current follows the correct path and providing support for LDO startup. Specifically, Q1 is the start-up control transistor, controlling the operating state of Q2 and Q3 through its base current. Zener diodes D1 and D2 are used for current and voltage regulation, ensuring the overall power supply voltage is stable. Capacitors C2 and C4 work with Zener diode D2 to help smooth the current and ensure power system stability.

[0023] In the LDO startup circuit, the LDO ensures that the input power supply voltage (VEE) is converted to a stable output voltage (VDD) to power the MCU. The LDO controls the voltage through a Zener diode D3; when VDD rises to the Zener value of D3, the LDO is triggered. Capacitor C1 provides energy support during LDO startup. It charges and helps provide the necessary stable power to the MCU. Capacitors C4 and C2 pre-store energy during circuit startup, enabling them to provide a larger current at the moment of MCU startup, meeting the MCU's higher current requirements and ensuring smooth startup and stable operation.

[0024] Reference manual attached Figure 2 This diagram illustrates a structural schematic of another MCU low-current startup system provided in an embodiment of the present invention.

[0025] Figure 2 A block diagram of a low-current startup system for an MCU is shown. Starting from the power input, the system regulates the voltage through a constant-current buck converter and an LDO startup circuit, ultimately providing a stable power supply to the MCU. The constant-current buck converter provides a stable input current, while the LDO startup circuit ensures that the MCU can start smoothly and operate stably under low-current conditions. This system effectively solves the problems of low-current startup and load current fluctuations.

[0026] Reference manual attached Figure 3 The diagram illustrates an example application of a low-current startup system for an MCU provided by an embodiment of the present invention.

[0027] Figure 3This diagram illustrates an example application of an MCU low-current startup system. The system supplies power to multiple devices using low-current startup circuits via a two-stage linear control unit. Each device connects to the power supply and operates stably using its own low-current startup circuit. The diagram shows the connections between the devices and the power and communication lines, ensuring that each device can start up and operate smoothly under low-current conditions. This configuration is suitable for multi-device environments requiring low power consumption and a stable power supply.

[0028] This utility model provides a structure for a low-current startup system for an MCU, comprising: a constant current buck circuit, an LDO startup circuit, and an MCU load; the constant current buck circuit includes an input power supply, a first resistor, a second resistor, a third resistor, an eighth resistor, a ninth resistor, a tenth resistor, a first Zener diode, a second Zener diode, a first NPN transistor, a third NPN transistor, a PNP transistor, a second capacitor, and a fourth capacitor; the input power supply is connected to the first resistor, the second resistor, the third resistor, and the collector of the first NPN transistor; the first resistor is connected to the emitter of the PNP transistor; the base of the PNP transistor is connected to the emitter of the first NPN transistor and the eighth resistor; the base of the first NPN transistor is connected to the second resistor and the collector of the third NPN transistor; the base of the third NPN transistor is connected to the third resistor and the negative terminal of the first Zener diode; The anode of the first Zener diode is connected to the tenth resistor; the emitter of the third NPN transistor is connected to the ninth resistor; the collector of the NPN transistor is connected to the cathode of the second Zener diode, the anode of the second capacitor, and the cathode of the fourth capacitor, respectively; the eighth, ninth, and tenth resistors are all connected to the anode of the second Zener diode, the cathode of the second capacitor, and the cathode of the fourth capacitor, respectively; the eighth resistor is connected to the ninth and tenth resistors, respectively; the anodes of the second and fourth capacitors are both connected to the cathode of the second Zener diode; the cathodes of the second and fourth capacitors are both connected to the anode of the second Zener diode; the LDO startup circuit includes a third Zener diode and a low-dropout linear regulator; the third Zener diode is connected to the low-dropout linear regulator; the cathode of the second Zener diode is connected to the cathode of the third Zener diode; the low-dropout linear regulator is connected to the MCU load to power the MCU.

[0029] The constant current buck converter converts the input power supply voltage into a constant current output, ensuring a stable current supply to the system even with varying load current. It uses resistors, transistors, and Zener diodes to regulate and control the current. The LDO startup circuit is a voltage regulator circuit that stably supplies the voltage required by the MCU even with a very small voltage difference between the input and output voltages. It is responsible for starting the LDO under very low startup current conditions, ensuring successful startup and power supply to the MCU even with a VEE input voltage (very low current). The Zener diode is a diode with unique characteristics; it maintains a stable voltage when the reverse voltage exceeds a certain value. Its main purpose is to provide a stable voltage in the circuit. Transistors (NPN and PNP types) are used to regulate current flow; they control the collector current by controlling the base current. Capacitors store and release energy in the circuit. In this circuit, capacitors C2 and C4 store electrical energy, providing the large current required by the MCU during startup to ensure smooth startup. Resistors are used to control the current flow. The MCU load refers to the microcontroller unit (MCU) and the devices it drives. It is the ultimate goal of the circuit; the function of the power supply circuit is to provide stable voltage and current to the MCU and its associated loads.

[0030] In practical applications, when the input power supply VEE is connected, although the provided current is lower than the current required for normal MCU operation, the constant current buck circuit, through the cooperation of resistors, transistors, and Zener diodes, ensures current stability and provides necessary current and voltage support to the LDO circuit. When the VEE voltage rises and reaches the Zener diode D3's regulation value, it provides a stable output voltage VDD to the MCU load. The energy stored in capacitors C2 and C4 can provide additional current during MCU startup, ensuring the MCU can start under low current conditions. The constant current buck circuit is responsible for stabilizing the input power supply VEE by using the Zener diode and transistor to return excess current when the load current is small, thus ensuring the stability of the power supply system. When the load current is large, the current is directly supplied to the load, and the system ensures stable operation by adjusting the current compensation.

[0031] It should be noted that the MCU low-current startup system, through the collaboration of a constant current buck circuit and an LDO startup circuit, ensures stable startup and operation of the MCU load even when the input power supply provides only a low current. The constant current buck circuit regulates the current through resistors, transistors, and Zener diodes, while the LDO provides a stable output voltage. Capacitors C2 and C4 ensure that the MCU can start up smoothly and maintain power supply stability under load fluctuations.

[0032] The beneficial effects of the technical solution provided by this utility model embodiment include at least the following:

[0033] In this embodiment of the invention, by setting multiple transistors in the constant current buck circuit, when the load current on the side of the second Zener diode is less than the output current on the side of the PNP transistor, the voltage on the side of the second Zener diode continuously rises to the stable voltage value of the second Zener diode. At this time, excess current flows back through the second Zener diode, ensuring the stability of the input current of the input power supply and maintaining the stability of the power supply system. When the load current on the side of the second Zener diode is greater than the output current on the side of the PNP transistor, the voltage on the side of the second Zener diode drops, and the current no longer passes through the second Zener diode, but is entirely supplied to the load, namely the LDO startup circuit and the MCU load. If the voltage on the side of the second Zener diode is detected to be too low, the circuit can increase the current required by the load by controlling the first NPN transistor, the third NPN transistor, and the PNP transistor at multiple points, thereby achieving dynamic current compensation and ensuring the normal and stable operation of the load. Based on this, as the voltage on one side of the second Zener diode rises to the Zener value of the third Zener diode, the low-dropout linear regulator is triggered to operate. After starting, the low-dropout linear regulator supplies power to the MCU load. The energy pre-stored in the second and fourth capacitors can meet the MCU's demand for a large current at the moment of power-on, thus satisfying the startup conditions and achieving reliable startup. This MCU low-current startup system can support low-current startup and stable operation of the MCU.

[0034] In one possible implementation, the fourth capacitor is specifically a capacitor with a capacitance of 22 microfarads and a rated voltage of 16V.

[0035] It should be noted that the fourth capacitor has a capacitance of 22 microfarads (μF) and a rated voltage of 16V. This means that the capacitor can hold 22μF of charge when storing energy, and its maximum withstand voltage is 16V. The capacitor's function is to smooth the current, stabilize the voltage, and provide instantaneous current support for MCU startup, ensuring that the circuit can still operate stably when there are current fluctuations or voltage changes.

[0036] In one possible implementation, the low-dropout linear regulator includes a feedback pin, an enable pin, a ground pin, an output voltage pin, and an input voltage pin; the ground pin is grounded; the positive and negative terminals of a third Zener diode are connected to the enable pin and the input voltage pin, respectively; the output voltage pin is connected to the MCU load; and the feedback pin is connected to an external resistor divider network to adjust the output voltage from the output voltage pin to the MCU load.

[0037] It should be noted that the low-dropout linear regulator (LDO) provides a stable voltage output through multiple pins. The ground pin connects the LDO's ground to the circuit ground, ensuring proper current return; the enable pin controls whether the LDO is enabled or disabled; the input voltage pin connects to the input power supply voltage; the output voltage pin connects to the MCU load, providing a stable voltage; and the feedback pin adjusts the output voltage through an external resistor divider network, ensuring a stable power supply to the MCU. With this design, the LDO can adjust the voltage according to the load's needs, ensuring stable system operation.

[0038] In one possible implementation, the LDO startup circuit further includes: a first capacitor; the positive terminal of the first capacitor is connected to the output voltage pin; and the negative terminal of the first capacitor is grounded.

[0039] It should be noted that the first capacitor is used to provide power support for the LDO startup circuit. The positive terminal of the first capacitor is connected to the output voltage pin to store the electrical energy from the LDO output, while the negative terminal is grounded to ensure that the capacitor can effectively store and release energy. The function of this capacitor is to help provide a large instantaneous current during LDO startup, ensuring that the MCU can operate smoothly during low-current startup and maintain a stable voltage output during power supply fluctuations.

[0040] In one possible implementation, the LDO startup circuit further includes: a third capacitor and a fourth resistor; the enable pin is grounded through the fourth resistor; the third capacitor and the fourth resistor are connected in parallel; and both the third capacitor and the fourth resistor are connected to the positive terminal of a third Zener diode.

[0041] It should be noted that the third capacitor and the fourth resistor work together to help the LDO startup circuit operate stably. The enable pin is grounded through the fourth resistor to control the activation of the LDO; the third capacitor and the fourth resistor are connected in parallel to adjust the circuit's time constant, ensuring that the capacitor can provide instantaneous current to the circuit during startup. Both the third capacitor and the fourth resistor are connected to the positive terminal of the third Zener diode, utilizing the characteristics of the Zener diode to ensure voltage stability and assist in current regulation and voltage stabilization during startup.

[0042] In one possible implementation, the eighth resistor, the ninth resistor, the tenth resistor, the negative terminal of the second capacitor, the negative terminal of the fourth capacitor, and the positive terminal of the second Zener diode are all grounded.

[0043] It should be noted that the eighth, ninth, and tenth resistors, the negative terminals of the second and fourth capacitors, and the positive terminal of the second Zener diode are all grounded, forming the circuit's ground potential. Grounding these components ensures a smooth current return path and provides a stable reference voltage. Through grounding, the various parts of the circuit can work together to maintain current and voltage stability, preventing system instability or malfunctions due to voltage instability or current fluctuations, thereby ensuring the MCU can start up smoothly and operate normally.

[0044] For example, the startup mechanism of this MCU low-current startup system is as follows: when the product is powered on, even if the input power supply VEE can only provide a current as low as 200uA (while the normal operation of the product requires a power-on current greater than 5mA), this circuit can still ensure that the MCU starts normally. Specifically, as the VDD voltage rises to the regulated value of the Zener diode D3, the low-dropout linear regulator (LDO) is triggered. After the LDO starts, it charges capacitor C1 on one hand and supplies power to the MCU on the other. The pre-stored energy in capacitors C4 and C2 can meet the MCU's demand for a large current at the moment of power-on, thus meeting the startup conditions and achieving reliable startup.

[0045] The specific current path and voltage relationship of the MCU low-current startup system are as follows: Current path: The input voltage VEE passes sequentially through resistor R3, diode D1, and resistor R10, finally reaching the BE terminal of transistor Q1, forming a specific current path. Combined with... Figure 1 Voltage relationships: The voltage at point K1 is determined by the Zener diode D1. Due to the conduction characteristics of the transistor's BE junction, the voltage at this point is approximately 0.7V. The circuit exhibits the following precise voltage-current relationships: the voltage at point (VEE-K3) satisfies (VEE-K3) voltage = I9 * R2; the voltage at point (VEE-K4) satisfies (VEE-K4) voltage = I1 * R1, and based on the transistor's characteristics, the current I1 is approximately equal to the current at point Q2C.

[0046] Combination Figure 1 Describe in detail the adaptive load current adjustment and voltage regulation mechanism:

[0047] When the load current is small: When the load current at the VDD voltage terminal is less than the current at point Q2C, the VDD voltage continues to rise to the stable voltage value of the D2 Zener diode. At this time, the excess current flows back through D2, ensuring the stability of the VEE input current and maintaining the stability of the power supply system.

[0048] When the load current is large: When the load current at the VDD voltage terminal is greater than the current at point Q2C, the VDD voltage drops, and the current no longer passes through D2, but is entirely supplied to the load.

[0049] This utility model encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of this utility model. To provide the public with a thorough understanding of this utility model, specific details are described in detail in the preferred embodiments; however, those skilled in the art can fully understand this utility model without these details. Furthermore, to avoid unnecessary confusion regarding the essence of this utility model, well-known methods, processes, procedures, components, and circuits are not described in detail.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present utility model, and not to limit it. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present utility model. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present utility model should be included within the protection scope of the present utility model.

Claims

1. A low-current startup system for an MCU, characterized in that, include: Constant current step-down circuit, LDO startup circuit and MCU load; The constant current step-down circuit includes an input power supply, a first resistor, a second resistor, a third resistor, an eighth resistor, a ninth resistor, a tenth resistor, a first Zener diode, a second Zener diode, a first NPN transistor, a third NPN transistor, a PNP transistor, a second capacitor, and a fourth capacitor. The input power supply is connected to the first resistor, the second resistor, the third resistor, and the collector of the first NPN transistor. The first resistor is connected to the emitter of the PNP transistor. The base of the PNP transistor is connected to the emitter of the first NPN transistor and the eighth resistor. The base of the first NPN transistor is connected to the second resistor and the collector of the third NPN transistor. The base of the transistor is connected to the third resistor and the negative terminal of the first Zener diode, respectively; the positive terminal of the first Zener diode is connected to the tenth resistor; the emitter of the third NPN transistor is connected to the ninth resistor; the collector of the NPN transistor is connected to the negative terminal of the second Zener diode, the positive terminal of the second capacitor, and the negative terminal of the fourth capacitor, respectively; the eighth, ninth, and tenth resistors are all connected to the positive terminal of the second Zener diode, the negative terminal of the second capacitor, and the negative terminal of the fourth capacitor, respectively; the eighth resistor is connected to the ninth and tenth resistors, respectively; the positive terminals of the second and fourth capacitors are both connected to the negative terminal of the second Zener diode; the negative terminals of the second and fourth capacitors are both connected to the positive terminal of the second Zener diode; The LDO startup circuit includes a third Zener diode and a low-dropout linear regulator; the third Zener diode is connected to the low-dropout linear regulator. The negative terminal of the second Zener diode is connected to the negative terminal of the third Zener diode; The low-dropout linear regulator is connected to the MCU load and provides the output voltage to the MCU load.

2. The MCU low current start-up system of claim 1, wherein, The fourth capacitor is specifically a capacitor with a capacitance of 22 microfarads and a rated voltage of 16V.

3. The MCU low current start-up system of claim 1, wherein, The low-dropout linear regulator includes a feedback pin, an enable pin, a ground pin, an output voltage pin, and an input voltage pin. The grounding pin is grounded; The positive and negative terminals of the third Zener diode are connected to the enable pin and the input voltage pin, respectively. The output voltage pin is connected to the MCU load; The feedback pin is connected to an external resistor divider network to adjust the output voltage from the output voltage pin to the MCU load.

4. The MCU low current start-up system of claim 1, wherein, The LDO startup circuit also includes: a first capacitor; The positive terminal of the first capacitor is connected to the output voltage pin; The negative terminal of the first capacitor is grounded.

5. The MCU low current start-up system of claim 4, wherein, The LDO startup circuit also includes: a third capacitor and a fourth resistor; The enable pin is grounded through the fourth resistor; The third capacitor is connected in parallel with the fourth resistor; Both the third capacitor and the fourth resistor are connected to the positive terminal of the third Zener diode.

6. The MCU low-current startup system according to claim 1, characterized in that, The eighth resistor, the ninth resistor, the tenth resistor, the negative terminal of the second capacitor, the negative terminal of the fourth capacitor, and the positive terminal of the second Zener diode are all grounded.

Images