VCC self-powered control circuit and method for switching power supply control chip

Abstract

The invention discloses a VCC self-powered control circuit for a switching power supply control chip, and the circuit comprises an input voltage processing module which is connected with an input voltage signal VIN, and is used for processing the input voltage signal VIN, and outputting a first voltage signal and a second voltage signal; the input end of the charging branch module is connected to the first output end of the input voltage processing module, the charging branch module is used for receiving the first voltage signal, the output end of the charging branch module is connected to the VCC end of the switching power supply control chip, and the charging branch module is used for charging the VCC end when the first voltage signal is lower than a preset threshold value and a charging control signal is received; the first input end of the logical judgment module is connected to the second output end of the input voltage processing module, the second input end of the logical judgment module is connected to the VCC voltage of the switching power supply control chip, and the output end of the logical judgment module is connected to the charging branch module; and the logic judgment module is set to generate a charging control signal based on the second voltage signal and the VCC voltage and output the charging control signal to the charging branch module so as to control connection and disconnection of the charging branch module.

Description

Technical Field

[0001] This invention relates to the field of circuit design, and more specifically to a VCC self-powered control circuit and method for a switching power supply control chip. Background Technology

[0002] As the structure of switching power supply systems has gradually simplified, auxiliary windings have been eliminated. Control chips typically now draw power directly from the high-voltage input to supply VCC via an internally integrated self-powered circuit. While this method allows the chip to operate normally without an auxiliary winding, it essentially provides a constant current to the high-voltage side. Regardless of whether the VCC capacitor needs additional power, energy flow is always present in the power supply path. This results in significant power consumption not only during chip operation but also in standby mode when current demand is extremely low, leading to substantial energy waste and a significant decrease in overall power supply efficiency. Therefore, existing self-powered solutions have low energy utilization under light load or standby conditions, necessitating a more flexible and efficient VCC power supply control scheme. Summary of the Invention

[0003] The purpose of this invention is to provide a VCC self-powered control circuit and method for switching power supply control chips, so as to flexibly control the conduction and disconnection of the power supply path according to the VCC voltage state and the input voltage, thereby reducing unnecessary energy consumption and improving the overall power supply efficiency.

[0004] To achieve the above objectives, the present invention discloses the following technical solution: A first aspect of the present invention provides a VCC self-powered control circuit for a switching power supply control chip, comprising: The input voltage processing module receives the input voltage signal VIN, processes the input voltage signal VIN, and outputs a first voltage signal and a second voltage signal. The charging branch module has its input terminal connected to the first output terminal of the input voltage processing module for receiving the first voltage signal. The output terminal of the charging branch module is connected to the VCC terminal of the switching power supply control chip for charging the VCC terminal when the first voltage signal is lower than a preset threshold VA_min and a charging control signal is received. The logic judgment module has a first input terminal connected to the second output terminal of the input voltage processing module for receiving the second voltage signal. The second input terminal of the logic judgment module is connected to the VCC voltage of the switching power supply control chip, and the output terminal of the logic judgment module is connected to the charging branch module. The logic judgment module is configured to generate a charging control signal based on the second voltage signal and the VCC voltage and output it to the charging branch module to control the conduction and disconnection of the charging branch module.

[0005] Optionally, the input voltage processing module includes a first diode D1, a second diode D2, a first resistor R1, a second resistor R2, a first node A, and a second node B; The anodes of the first diode D1 and the second diode D2 are both connected to the input voltage signal VIN, and the cathodes of the first diode D1 and the second diode D2 are both connected to the first node A; the first node A serves as the first output terminal of the input voltage processing module, and the voltage at the first node A is the first voltage signal. The first end of the first resistor R1 is connected to the first node A, and the second end is connected to the second node B. The first end of the second resistor R2 is connected to the second node B, and the second end of the second resistor R2 is grounded. The second node B serves as the second output terminal of the input voltage processing module, and the voltage at the second node B is the second voltage signal.

[0006] Optionally, the charging branch module includes a third resistor R3, a third diode D3, and a switch K; The first end of the third resistor R3 is connected to the first node A, the second end of the third resistor R3 is connected to the anode of the third diode D3, and the cathode of the third diode D3 is connected to the VCC terminal of the switching power supply control chip through the switch K.

[0007] Optionally, the logic judgment module includes: The first comparator CMP1 has a non-inverting input connected to a reference voltage Vref, and an inverting input connected to the second voltage signal as the first input of the logic judgment module. The second comparator CMP2 has its non-inverting input connected to a first preset voltage VCC_min, and its inverting input serving as the second input of the logic judgment module, connected to the VCC voltage of the switching power supply control chip. The third comparator CMP3 has its non-inverting input connected to the VCC voltage of the switching power supply control chip, and its inverting input connected to a second preset voltage VCC_max.

[0008] Optionally, the logic judgment module further includes an RS flip-flop and an AND gate A1; The set terminal S of the RS flip-flop is connected to the output terminal of the second comparator CMP2, the reset terminal R of the RS flip-flop is connected to the output terminal of the third comparator CMP3, the output terminal Q of the RS flip-flop is connected to the first input terminal of the AND gate A1; the second input terminal of the AND gate A1 is connected to the output terminal of the first comparator CMP1, and the output terminal of the AND gate A1 is connected to the control terminal of the switch K.

[0009] Optionally, it also includes: The first capacitor C1 has its first end connected to the VCC terminal of the switching power supply control chip, and its second end grounded.

[0010] Optionally, the first preset voltage VCC_min is the minimum value of VCC voltage when it is working normally, and the second preset voltage VCC_max is the maximum value of VCC voltage when it is working normally.

[0011] Optionally, when the VCC voltage of the switching power supply control chip is less than the first preset voltage VCC_min, and the voltage of the second node B is less than the reference voltage Vref, the AND gate A1 outputs a high-level signal, causing the switch K to close. When the VCC voltage of the switching power supply control chip is greater than the second preset voltage VCC_max, or the voltage of the second node B is greater than the reference voltage Vref, the AND gate A1 outputs a low-level signal, causing the switch K to open.

[0012] A second aspect of the present invention provides a switching power supply, including a rectifier and filter circuit, a switching power supply control chip, and a VCC self-powered control circuit as described above, wherein the VCC terminal of the switching power supply control chip is connected to the output terminal of the VCC self-powered control circuit.

[0013] A third aspect of the present invention provides a VCC self-powered control method for a VCC self-powered control circuit as described above, the method comprising: The input voltage signal VIN is received and processed to obtain a first voltage signal and a second voltage signal; The first voltage signal is output to the charging branch module as a charging power source; The second voltage signal is output to the logic judgment module, and the VCC voltage of the switching power supply control chip is input to the logic judgment module. Based on the second voltage signal and the VCC voltage, a charging control signal is generated by the logic judgment module, and the charging control signal is output to the charging branch module; When the first voltage signal is lower than the preset threshold VA_min and the charging control signal is received, the charging branch module is turned on to charge the VCC terminal of the switching power supply control chip.

[0014] The effects described in the invention are merely those of the embodiments, and not all the effects of the invention. One of the above technical solutions has the following advantages or beneficial effects: The VCC self-powered control circuit provided in this application process the input voltage signal into a first voltage signal and a second voltage signal. Combined with a logic judgment module that monitors the second voltage signal and the VCC voltage in real time, it can automatically generate a charging control signal to control the on / off state of the charging branch module, thereby achieving dynamic power supply management of the VCC terminal of the switching power supply control chip. Specifically, the charging branch module 120 only supplies power to the VCC terminal when the first voltage signal is below a preset threshold VA_min and the charging conditions are met. This avoids unnecessary charging when the input voltage is high, helping to reduce the surge risk on the VCC capacitor and the overall energy consumption of the system. The technical solution of this invention has a simple structure and good automatic adjustment capability, ensuring that the switching power supply control chip can stably obtain the required voltage under different operating states, improving the overall energy efficiency of the switching power supply system, reducing power waste, and adapting to energy-saving trends.

[0015] Furthermore, this invention introduces a rectifier-divider structure composed of diodes and resistors into the input voltage processing module, which can stabilize the input voltage signal and output different voltage signals for control and charging. Setting a current-limiting resistor and rectifier diodes in the charging branch can effectively suppress inrush current during charging, improving system safety. The logic judgment module constructs a clear voltage judgment and control path through multi-stage comparators, RS flip-flops, and AND gates, enabling the system to judge charging under different voltage conditions. When insufficient VCC voltage is detected and charging conditions are met, the charging branch automatically conducts, supplying power to the VCC terminal of the control chip; when the VCC voltage meets the operating requirements or charging conditions are no longer met, the charging branch promptly disconnects, achieving dynamic maintenance and precise control of the VCC voltage. Through the cooperation of the above functional modules, this invention can ensure a stable VCC voltage supply while achieving automatic control of the charging process and effective judgment of the voltage state, thereby improving the power supply reliability and control accuracy of the switching power supply system. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this application and, together with the specification, serve to explain the principles of this application.

[0017] Figure 1A structural block diagram of a VCC self-powered control circuit for a switching power supply control chip according to an embodiment of the present invention is shown. Figure 2 A VCC self-powered control circuit topology for a switching power supply control chip according to an embodiment of the present invention is shown. Figure 3 It shows Figure 2 Waveform diagrams of some signals in the VCC self-powered control circuit topology; Figure 4 A flowchart illustrating a VCC self-powered control method according to an embodiment of the present invention is shown. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] It should be noted that references to "an embodiment," "embodiment," "example embodiment," etc., in this specification refer to the described embodiment including specific features, structures, or characteristics; however, not every embodiment must include these specific features, structures, or characteristics. Furthermore, such expressions do not refer to the same embodiment. Moreover, when describing specific features, structures, or characteristics in conjunction with embodiments, whether or not explicitly described, it is indicated that incorporating such features, structures, or characteristics into other embodiments is within the knowledge of those skilled in the art.

[0020] Furthermore, certain terms are used in the specification and subsequent claims to refer to specific components or parts. Those skilled in the art will understand that manufacturers may use different names or terms to refer to the same component or part. This specification and subsequent claims do not distinguish components or parts by differences in name, but rather by differences in function. The terms "comprising" and "including" used throughout the specification and subsequent claims are open-ended and should be interpreted as "including but not limited to." Additionally, the term "connection" here includes any direct and indirect electrical connection means. Indirect electrical connection means include connections made through other means.

[0021] Figure 1 A structural block diagram of a VCC self-powered control circuit for a switching power supply control chip according to an embodiment of the present invention is shown. Figure 1As shown, the VCC self-powered control circuit includes an input voltage processing module 110, a charging branch module 120, and a logic judgment module 130. The input voltage processing module 110 receives the input voltage signal VIN, processes it, and outputs a first voltage signal and a second voltage signal. The input voltage signal VIN is an unrectified voltage signal. The input terminal of the charging branch module 120 is connected to the first output terminal of the input voltage processing module 110 to receive the first voltage signal. The output terminal of the charging branch module 120 is connected to the VCC terminal of the switching power supply control chip, and it charges the VCC terminal when the first voltage signal is lower than a preset threshold VA_min and a charging control signal is received. The first input terminal of the logic judgment module 130 is connected to the second output terminal of the input voltage processing module 110 to receive the second voltage signal. The second input terminal of the logic judgment module 130 is connected to the VCC voltage of the switching power supply control chip, and the output terminal of the logic judgment module 130 is connected to the charging branch module 120. The logic judgment module 130 is configured to generate a charging control signal based on the second voltage signal and the VCC voltage and output it to the charging branch module 120 to control the conduction and disconnection of the charging branch module 120.

[0022] According to an embodiment of the present invention, by processing the input voltage signal into a first voltage signal and a second voltage signal respectively, and combining the logic judgment module 130 to monitor the second voltage signal and the VCC voltage in real time, a charging control signal can be automatically generated to control the conduction and disconnection of the charging branch module 120, thereby realizing dynamic power supply management of the VCC terminal of the switching power supply control chip. Specifically, the charging branch module 120 only supplies power to the VCC terminal when the first voltage signal is below a preset threshold VA_min and the charging conditions are met, avoiding unnecessary charging when the input voltage is high, which helps reduce the surge risk on the VCC capacitor and the overall energy consumption of the system. The technical solution of the present invention has a simple structure and good automatic adjustment capability, ensuring that the switching power supply control chip can stably obtain the required voltage under different operating states, improving the overall energy efficiency of the switching power supply system, reducing power waste, and adapting to the energy-saving trend.

[0023] Figure 2 A VCC self-powered control circuit topology for a switching power supply control chip according to an embodiment of the present invention is shown. Figure 2As shown, the input voltage processing module 110 includes a first diode D1, a second diode D2, a first resistor R1, a second resistor R2, a first node A, and a second node B. The anodes of both the first diode D1 and the second diode D2 are connected to the input voltage signal VIN, and the cathodes of both diodes D1 and D2 are connected to the first node A. The first node A serves as the first output terminal of the input voltage processing module 110, and its voltage is the first voltage signal. The first end of the first resistor R1 is connected to the first node A, and its second end is connected to the second node B. The first end of the second resistor R2 is connected to the second node B, and its second end is grounded. The second node B serves as the second output terminal of the input voltage processing module 110, and its voltage is the second voltage signal.

[0024] In one embodiment, the charging branch module 120 includes a third resistor R3, a third diode D3, and a switch K. The first end of the third resistor R3 is connected to the first node A, the second end of the third resistor R3 is connected to the anode of the third diode D3, and the cathode of the third diode D3 is connected to the VCC terminal of the switching power supply control chip via the switch K. The third resistor R3 is a current-limiting resistor, and the third diode D3 is a unidirectional conducting diode. The current-limiting resistor R3 is used to adjust the charging current flowing to VCC; its resistance value can be configured according to actual needs to set the current amplitude during charging. The third diode D3 is used to block the reverse conduction path when the VB voltage is lower than the VCC voltage, effectively preventing VCC voltage from flowing back into the preceding circuit and ensuring system stability. Furthermore, by adjusting the resistance value of the current-limiting resistor R3 and the capacity of the energy storage capacitor C1, the charging speed and single charging duration of the VCC capacitor can be flexibly set to adapt to the power management needs of different application scenarios.

[0025] In one embodiment, the logic judgment module 130 includes a first comparator CMP1, a second comparator CMP2, and a third comparator CMP3. The non-inverting input of the first comparator CMP1 is connected to a reference voltage Vref, and its inverting input serves as the first input of the logic judgment module 130, connected to a second voltage signal. The non-inverting input of the second comparator CMP2 is connected to a first preset voltage VCC_min, and its inverting input serves as the second input of the logic judgment module 130, connected to the VCC voltage of the switching power supply control chip. The non-inverting input of the third comparator CMP3 is connected to the VCC voltage of the switching power supply control chip, and its inverting input is connected to a second preset voltage VCC_max. The first preset voltage VCC_min is the minimum value of the VCC voltage during normal operation, and the second preset voltage VCC_max is the maximum value of the VCC voltage during normal operation.

[0026] In one embodiment, the logic judgment module 130 further includes an RS flip-flop and an AND gate A1. The set terminal S of the RS flip-flop is connected to the output terminal of the second comparator CMP2, the reset terminal R of the RS flip-flop is connected to the output terminal of the third comparator CMP3, and the output terminal Q of the RS flip-flop is connected to the first input terminal of the AND gate A1. The second input terminal of the AND gate A1 is connected to the output terminal of the first comparator CMP1, and the output terminal of the AND gate A1 is connected to the control terminal of the switch K.

[0027] In one embodiment, when the VCC voltage of the switching power supply control chip is less than the first preset voltage VCC_min, and the voltage of the second node B is less than the reference voltage Vref, AND gate A1 outputs a high-level signal, causing switch K to close. When the VCC voltage of the switching power supply control chip is greater than the second preset voltage VCC_max, or the voltage of the second node B is greater than the reference voltage Vref, AND gate A1 outputs a low-level signal, causing switch K to open.

[0028] According to the above embodiments, the working principle of the VCC self-powered control circuit of the present invention is as follows: After the switching power supply is started, the second comparator CMP2 and the third comparator CMP3 continuously monitor the VCC voltage status. When the VCC voltage is lower than the first preset voltage VCC_min, it indicates that the control chip may face the risk of insufficient power supply and needs to be replenished in time. At this time, the second comparator CMP2 outputs a high level to the set terminal S of the RS flip-flop, and the third comparator CMP3 outputs a low level to the reset terminal R of the RS flip-flop, so that the output terminal Q of the RS flip-flop outputs a high level and transmits it to the first input terminal of the AND gate A1.

[0029] The first comparator CMP1 is used to detect whether the input voltage signal meets the charging condition. Its non-inverting input is connected to the reference voltage Vref, and its inverting input receives the second voltage signal VB. This second voltage signal VB is the first voltage signal VA formed by rectifying the input mains signal VIN through the first diode D1 and the second diode D2, and then divided by a voltage divider network composed of the first resistor R1 and the second resistor R2. According to the voltage divider principle, VB = (R2 / (R1 + R2)) × VA. When the second voltage signal VB is lower than the reference voltage Vref, the first comparator CMP1 outputs a high level to the second input of AND gate A1. At this time, both inputs of AND gate A1 are at a high level, and its output is high, controlling switch K to conduct, so that the first voltage signal VA charges the VCC capacitor C1 through the third resistor R3 and the third diode D3, thereby increasing the VCC voltage.

[0030] As the VCC voltage gradually increases, when it is between the first preset voltage VCC_min and the second preset voltage VCC_max, the outputs of the second comparator CMP2 and the third comparator CMP3 are both low. The set terminal S and the reset terminal R of the RS flip-flop are both in a low-level state, and its output terminal Q remains unchanged from the previous state, continuing to maintain the on state of switch K, thereby achieving continuous power supply to VCC.

[0031] When the VCC voltage rises above the second preset voltage VCC_max, the third comparator CMP3 outputs a high level to the reset terminal R of the RS flip-flop, causing its output Q to flip to a low level. Alternatively, when the second voltage signal VB rises above the reference voltage Vref, the first comparator CMP1 outputs a low level to the second input terminal of the AND gate A1. After either of the above conditions is triggered, at least one input terminal of the AND gate A1 is at a low level, its output turns low, the control switch K closes, and the charging process of VCC is terminated. When the control chip continues to operate, and the VCC voltage drops below VCC_min again, the VCC self-powered control circuit of this invention will repeat the above charging control process to ensure that the VCC voltage is always maintained within the normal operating range, thereby achieving dynamic adjustment and stable protection of the power supply state of the control chip.

[0032] In one embodiment, reference Figure 1 and Figure 2 The VCC self-powered control circuit of the present invention further includes a first capacitor C1. The first terminal of the first capacitor C1 is connected to the VCC terminal of the switching power supply control chip, and the second terminal of the first capacitor C1 is grounded. The first capacitor C1 is used to store energy in the VCC voltage, suppressing voltage fluctuations caused by the conduction or disconnection of the charging branch, and improving the continuity and stability of the power supply. Simultaneously, when the charging branch is in the off state, C1 can temporarily release the stored energy to provide the necessary operating current for the control chip, avoiding voltage drops or power interruptions.

[0033] In one embodiment, reference Figure 1 and Figure 2 The second capacitor C2 and the rectifier bridge D together form a rectifier and filter circuit 200, which is used to rectify and filter the input voltage signal to obtain a relatively stable DC voltage signal. Figure 1 The structure of the rectifier filter circuit 200 shown is consistent with that of a typical rectifier filter circuit in the prior art, and will not be described in detail here.

[0034] According to the above embodiments, by introducing a rectifier-divider structure composed of diodes and resistors into the input voltage processing module 110, the input voltage signal can be stabilized and output different voltage signals for control and charging. Setting a current-limiting resistor and rectifier diodes in the charging branch can effectively suppress inrush current during charging and improve system safety. The logic judgment module 130 constructs a clear voltage judgment and control path through multi-stage comparators, RS flip-flops, and AND gates, enabling the system to judge charging under different voltage conditions. When insufficient VCC voltage is detected and charging conditions are met, the charging branch automatically turns on to supply power to the VCC terminal of the control chip; when the VCC voltage meets the operating requirements or charging conditions are no longer met, the charging branch is disconnected in time, achieving dynamic maintenance and precise control of the VCC voltage. Through the cooperation of the above functional modules, this invention can ensure a stable VCC voltage supply while achieving automatic control of the charging process and effective judgment of the voltage state, thereby improving the power supply reliability and control accuracy of the switching power supply system.

[0035] Figure 3 It shows Figure 2 The waveform diagram of some signals in the VCC self-powered control circuit topology is shown. For example... Figure 3 As shown, this includes the processed voltage signal VA and its corresponding preset threshold VA_min, the VCC voltage and its corresponding thresholds VCC_min and VCC_max. After the switching power supply starts up, the processed voltage VA fluctuates significantly with the change of the input voltage VIN, while the VCC voltage is maintained within the normal operating range between VCC_min and VCC_max through the power compensation mechanism of this control circuit. When VA drops to VA_min and VCC drops below VCC_min, the charging branch is turned on, and VCC begins to rise; when VCC exceeds VCC_max, the charging branch is turned off, and the VCC voltage remains stable. This waveform intuitively reflects the dynamic monitoring and adjustment process of VCC by the control circuit, effectively ensuring the stability of the power supply to the control chip and the overall energy efficiency of the switching power supply system.

[0036] The technical solution of this application will be further described below with reference to specific embodiments.

[0037] To improve power supply efficiency during the low-voltage phase, the system is configured to initiate a VCC power-up process when the input voltage VIN is less than 50V. The circuit parameters are: a 9:1 ratio of R1 to R2, a reference voltage Vref of 5V, a normal operating range of VCC of 18V to 22V, and a current-limiting resistor R3 of 30kΩ. After the switching power supply starts up, the startup branch closes, and the VCC voltage gradually decreases as the internal modules of the control chip operate. When VCC is below 18V, the second comparator CMP2 outputs a high level to the RS flip-flop set terminal, the third comparator CMP3 outputs a low level to the reset terminal, and the RS flip-flop outputs a high level to the first input terminal of AND gate A1. Simultaneously, if the second voltage signal VB obtained by dividing the rectified first voltage signal VA by the first resistor R1 and the second resistor R2 satisfies VB = (1 / 10) × VA < Vref, meaning the input voltage is in the lower range, the first comparator CMP1 will also output a high level to the second input terminal of AND gate A1. At this time, the output of AND gate A1 is high, the control switch K is closed, the charging branch is turned on, and the first voltage signal VA charges the VCC capacitor C1 through the current-limiting resistor R3 and the third diode D3. The third resistor R3 limits the charging current to approximately (VA - 0.7) / R3 ≈ 1mA, and the third diode D3 prevents voltage backflow when the second voltage signal VB is lower than VCC. The VCC voltage gradually rises. When the voltage is between 18V and 22V, the RS flip-flop remains in its state, and the charging process continues. When VCC exceeds 22V, the third comparator CMP3 outputs a high level to trigger a reset, the RS flip-flop output goes low, causing the AND gate A1 to output a low level, the control switch K to open, and the charging stops.

[0038] In this embodiment, the power consumption on capacitor C1 of VCC remains at 0.02W. However, due to the voltage limiting mechanism, the maximum power supply voltage is limited to within 50V, thus increasing the energy utilization rate to 40%. Compared to the prior art where the power supply current is 1mA, the VCC voltage is 20V, and the voltage after rectification and filtering reaches 300V, resulting in a power consumption of 0.3W, of which only 0.02W is effectively utilized by VCC, the power supply utilization rate is only 6.667%. This application effectively limits the power supply to occur during the low-voltage stage of VCC, significantly reducing ineffective energy loss while maintaining the same effective power supply power consumption, resulting in an efficiency improvement of 33.333%. Furthermore, when the system enters standby mode and the VCC power supply current further decreases, the energy-saving advantage of this solution becomes more obvious, helping to improve the overall efficiency of the power supply strategy.

[0039] This invention also provides a switching power supply, including a rectifier and filter circuit 200, a switching power supply control chip, and a VCC self-powered control circuit according to the above embodiments of this application. The VCC terminal of the switching power supply control chip is directly connected to the output terminal of the VCC self-powered control circuit, achieving stable power supply to the control chip. This structure effectively improves the power supply reliability and overall energy efficiency of the switching power supply, further perfecting the self-powered control scheme of this application.

[0040] Figure 4 A flowchart illustrating a VCC self-powered control method according to an embodiment of the present invention is shown. Figure 4 As shown, the method includes the following steps: Step S100: Input voltage signal VIN is received and processed to obtain first voltage signal and second voltage signal.

[0041] In step S200, the first voltage signal is output to the charging branch module 120 as a charging power source.

[0042] In step S300, the second voltage signal is output to the logic judgment module 130, and the VCC voltage of the switching power supply control chip is input to the logic judgment module 130.

[0043] In step S400, based on the second voltage signal and the VCC voltage, a charging control signal is generated by the logic judgment module 130 and output to the charging branch module 120.

[0044] In step S500, when the first voltage signal is lower than the preset threshold VA_min and a charging control signal is received, the charging branch module 120 is turned on to charge the VCC terminal of the switching power supply control chip.

[0045] The specific implementation methods of each step in the above VCC self-powered control method refer to the relevant content of the embodiment in the above VCC self-powered control circuit, and will not be repeated here.

[0046] Through the aforementioned control logic, the VCC self-powered control circuit and method of this invention can operate stably in various switching power supply systems, including different topologies such as forward, flyback, buck, and boost converters. The VCC voltage is maintained within a set range during system operation, ensuring stable chip operation and avoiding energy waste caused by ineffective power supply under high-voltage conditions. The VCC power supply is directly taken from the input voltage VIN, unaffected by system environment factors, and only replenishes energy to the VCC capacitor during low-voltage periods, effectively improving the overall energy efficiency of the switching power supply system and reducing power waste. Compared with traditional self-powered methods, efficiency is significantly improved under the same power consumption conditions, especially with lower energy consumption in standby mode, making it suitable for switching power supply applications with high energy efficiency requirements.

[0047] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0048] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A VCC self-powered control circuit for a switching power supply control chip, characterized in that, include: The input voltage processing module receives the input voltage signal VIN, processes the input voltage signal VIN, and outputs a first voltage signal and a second voltage signal. The charging branch module has its input terminal connected to the first output terminal of the input voltage processing module for receiving the first voltage signal. The output terminal of the charging branch module is connected to the VCC terminal of the switching power supply control chip for charging the VCC terminal when the first voltage signal is lower than a preset threshold VA_min and a charging control signal is received. The logic judgment module has a first input terminal connected to the second output terminal of the input voltage processing module for receiving the second voltage signal. The second input terminal of the logic judgment module is connected to the VCC voltage of the switching power supply control chip, and the output terminal of the logic judgment module is connected to the charging branch module. The logic judgment module is configured to generate a charging control signal based on the second voltage signal and the VCC voltage and output it to the charging branch module to control the conduction and disconnection of the charging branch module.

2. The VCC self-powered control circuit according to claim 1, characterized in that, The input voltage processing module includes a first diode D1, a second diode D2, a first resistor R1, a second resistor R2, a first node A, and a second node B; The anodes of the first diode D1 and the second diode D2 are both connected to the input voltage signal VIN, and the cathodes of the first diode D1 and the second diode D2 are both connected to the first node A; The first node A serves as the first output terminal of the input voltage processing module, and the voltage of the first node A is the first voltage signal. The first end of the first resistor R1 is connected to the first node A, and the second end is connected to the second node B. The first end of the second resistor R2 is connected to the second node B, and the second end of the second resistor R2 is grounded. The second node B serves as the second output terminal of the input voltage processing module, and the voltage at the second node B is the second voltage signal.

3. The VCC self-powered control circuit according to claim 2, characterized in that, The charging branch module includes a third resistor R3, a third diode D3, and a switch K; The first end of the third resistor R3 is connected to the first node A, the second end of the third resistor R3 is connected to the anode of the third diode D3, and the cathode of the third diode D3 is connected to the VCC terminal of the switching power supply control chip through the switch K.

4. The VCC self-powered control circuit according to claim 3, characterized in that, The logic judgment module includes: The first comparator CMP1 has a non-inverting input connected to a reference voltage Vref, and an inverting input connected to the second voltage signal as the first input of the logic judgment module. The second comparator CMP2 has its non-inverting input connected to a first preset voltage VCC_min, and its inverting input serving as the second input of the logic judgment module, connected to the VCC voltage of the switching power supply control chip. The third comparator CMP3 has its non-inverting input connected to the VCC voltage of the switching power supply control chip, and its inverting input connected to a second preset voltage VCC_max.

5. The VCC self-powered control circuit according to claim 4, characterized in that, The logic judgment module also includes an RS flip-flop and an AND gate A1; The set terminal S of the RS flip-flop is connected to the output terminal of the second comparator CMP2, the reset terminal R of the RS flip-flop is connected to the output terminal of the third comparator CMP3, the output terminal Q of the RS flip-flop is connected to the first input terminal of the AND gate A1; the second input terminal of the AND gate A1 is connected to the output terminal of the first comparator CMP1, and the output terminal of the AND gate A1 is connected to the control terminal of the switch K.

6. The VCC self-powered control circuit according to claim 5, characterized in that, Also includes: The first capacitor C1 has its first end connected to the VCC terminal of the switching power supply control chip, and its second end grounded.

7. The VCC self-powered control circuit according to claim 6, characterized in that, The first preset voltage VCC_min is the minimum value of VCC voltage when it is working normally, and the second preset voltage VCC_max is the maximum value of VCC voltage when it is working normally.

8. The VCC self-powered control circuit according to claim 7, characterized in that, When the VCC voltage of the switching power supply control chip is less than the first preset voltage VCC_min, and the voltage of the second node B is less than the reference voltage Vref, the AND gate A1 outputs a high-level signal, causing the switch K to close. When the VCC voltage of the switching power supply control chip is greater than the second preset voltage VCC_max, or the voltage of the second node B is greater than the reference voltage Vref, the AND gate A1 outputs a low-level signal, causing the switch K to open.

9. A switching power supply, characterized in that, It includes a rectifier and filter circuit, a switching power supply control chip, and a VCC self-powered control circuit as described in any one of claims 1 to 8, wherein the VCC terminal of the switching power supply control chip is connected to the output terminal of the VCC self-powered control circuit.

10. A VCC self-powered control method for a VCC self-powered control circuit as described in any one of claims 1-8, characterized in that, The method includes: The input voltage signal VIN is received and processed to obtain a first voltage signal and a second voltage signal; The first voltage signal is output to the charging branch module as a charging power source; The second voltage signal is output to the logic judgment module, and the VCC voltage of the switching power supply control chip is input to the logic judgment module. Based on the second voltage signal and the VCC voltage, a charging control signal is generated by the logic judgment module, and the charging control signal is output to the charging branch module; When the first voltage signal is lower than the preset threshold VA_min and the charging control signal is received, the charging branch module is turned on to charge the VCC terminal of the switching power supply control chip.

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