Method for protecting high-voltage starting circuit

Abstract

The invention discloses a method for protecting a high-voltage starting circuit, which relates to the technical field of electrical engineering, and comprises the following steps: when high-voltage input is started, controlling a switching circuit by using a delay circuit, ensuring that a first-stage voltage stabilizing circuit works within a preset time, providing an initial voltage for a second-stage voltage stabilizing circuit, monitoring an output voltage by a sampling circuit, and reaching a set value; the first-stage voltage stabilizing circuit is switched into a low-power-consumption mode, if the output voltage is not established within the preset time, the switching circuit is closed and the power supply of the first-stage voltage stabilizing circuit is cut off after the delay circuit is charged, and the first-stage voltage stabilizing circuit is accurately controlled to work by optimizing the parameters of the delay circuit. The sampling circuit accurately detects the output voltage and generates an enable signal, so that the first-stage voltage stabilizing circuit enters a low-power-consumption mode after the output voltage is stabilized, and if the output voltage is not established in time, the switching circuit is turned off in time, power supply of the first-stage voltage stabilizing circuit is cut off, and overheating damage is prevented.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical engineering, and specifically to a method for protecting a high-voltage startup circuit. Background Art

[0002] In the field of high-voltage startup circuits, the development of technology has continuously promoted the innovation and improvement of circuit design. With the increasing requirements of electronic devices for power supply performance, high-voltage startup circuits play an increasingly important role in various electronic devices. These circuits not only need to provide a stable high-voltage output but also maintain high efficiency and high reliability under various working conditions.

[0003] Chinese Patent No. CN119298644A discloses a high-voltage auxiliary power supply startup circuit, which includes a startup logic processing unit, a power energy storage unit, and a charge release unit. The input end of the power supply startup circuit is connected to an external input voltage, a temperature detection signal, and a maintaining voltage after startup completion, and the output end is connected to an external power supply main control circuit to provide auxiliary power supply startup energy and a protection shutdown signal.

[0004] However, with the increase in the operating voltage of the circuit, the problem of thermal damage faced by circuit devices during startup is becoming increasingly prominent. Especially when the output voltage fails to be established in a timely manner, the high-voltage startup devices in the circuit may generate excessive losses due to continuously working under high voltage and large current conditions, thereby causing thermal damage. This not only affects the reliability of the circuit but may also cause cascading damage to other devices.

[0005] Therefore, a method for protecting a high-voltage startup circuit is proposed to solve the above problems. Summary of the Invention

[0006] The purpose of the present invention is to disclose a method for protecting a high-voltage startup circuit, which realizes preventing thermal damage to high-voltage startup circuit devices through a hardware self-protection mechanism when the output voltage fails to be established in a timely manner, and at the same time avoids further damage to other devices, so as to solve the problems raised in the above background art.

[0007] To achieve the above purpose, the present invention is realized through the following technical solutions: A method for protecting a high-voltage startup circuit includes the following steps: S1, when starting with high-voltage input, control the conduction state of the switch circuit through a delay circuit, so that the first-stage voltage stabilization circuit works within a preset time and provides an initial voltage for the second-stage voltage stabilization circuit; S2, detect whether the output voltage is established through a sampling circuit. When the output voltage reaches the set value, generate a high-level enable signal to maintain the conduction state of the switch circuit, and make the first-stage voltage stabilization circuit enter a low-power consumption mode; S3. When the output voltage is not established within the preset time, the charging of the delay circuit is completed, causing the switching circuit to turn off and cutting off the power supply to the first-stage voltage stabilization circuit.

[0008] As a preferred technical solution of the present invention, the charging time of the delay circuit is set to be greater than the expected time for the normal establishment of the output voltage, and the conduction threshold voltage of the switching circuit matches the voltage change of the delay circuit to ensure automatic triggering of the turn-off when the establishment of the output voltage fails.

[0009] As a preferred technical solution of the present invention, the switching circuit is a MOS transistor. The gate of the switching circuit is connected to the output terminal of the delay circuit, and the source is grounded. When the delay circuit is charged to a voltage lower than the conduction threshold voltage of the switching circuit, the switching circuit turns off, and the power supply to the first-stage voltage stabilization circuit is cut off through the drive circuit.

[0010] As a preferred technical solution of the present invention, the switching circuit is a triode. The base of the switching circuit is connected to the output terminal of the delay circuit, and the emitter is grounded. When the delay circuit is charged to a voltage lower than the conduction voltage of the switching circuit, the switching circuit turns off, and then the power supply to the first-stage voltage stabilization circuit is cut off through the drive circuit.

[0011] As a preferred technical solution of the present invention, the generation of the enable signal includes: sampling the output voltage through a voltage-dividing resistor. When the sampled voltage exceeds the breakdown voltage of the third zener diode, a high-level signal is generated, and the switching circuit is driven through a current-limiting resistor to maintain the conducting state.

[0012] As a preferred technical solution of the present invention, the sum of the breakdown voltage of the third zener diode and the conduction threshold voltage of the switching circuit is less than the set value of the output voltage to ensure that the enable signal can stably maintain the conduction of the switching circuit when the output voltage is normally established.

[0013] As a preferred technical solution of the present invention, overvoltage protection is also provided for the gate-source voltage of the switching circuit: a fourth zener diode is connected in parallel between the gate and the source of the switching circuit. When the gate-source voltage exceeds the breakdown voltage of the fourth zener diode, the current is forcibly discharged to protect the switching circuit.

[0014] As a preferred technical solution of the present invention, the shutdown process of the first-stage voltage stabilization circuit includes: when the switching circuit turns off, the base voltage of the drive circuit increases, causing the drive circuit to conduct and pulling the gate voltage of the first-stage voltage stabilization circuit to the cut-off state.

[0015] As a preferred technical solution of the present invention, the second-stage voltage stabilizing circuit is an NPN transistor. The base of the second-stage voltage stabilizing circuit is connected to the output terminal of the first-stage voltage stabilizing circuit through a first voltage stabilizing diode. After the output voltage is established, the collector voltage of the second-stage voltage stabilizing circuit is clamped by reverse biasing of the diode, so that the first-stage voltage stabilizing circuit only provides the conduction current of the voltage stabilizing diode.

[0016] As a preferred technical solution of the present invention, the input voltage of the high-voltage starting circuit exceeds 200V, and the total power loss of the first-stage voltage stabilizing circuit and the second-stage voltage stabilizing circuit is reduced to below the safety threshold by turning off the switching circuit when the output voltage is not established.

[0017] Compared with the prior art, the beneficial effects of the present invention are at least as follows: 1. By reasonably setting the parameters of the delay circuit, the present invention accurately controls the working time of the first-stage voltage stabilizing circuit, ensures that the high-voltage starting circuit operates according to the expected logic, avoids abnormal operation, the sampling circuit accurately detects the output voltage and generates an enabling signal, prompting the first-stage voltage stabilizing circuit to enter the low-power mode after the output voltage is stable, reducing power consumption and heat generation, improving energy efficiency and stability. When the output voltage is not established in time, the switching circuit is turned off in time to cut off the power supply of the first-stage voltage stabilizing circuit and prevent overheating damage, enhancing the safety and reliability of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is the basic type double-stage voltage stabilizing circuit diagram of the present invention; Figure 2 It is the improved type double-stage voltage stabilizing protection circuit diagram of the present invention; Figure 3 It is the flowchart of the start and initial voltage stabilization of the high-voltage starting circuit of the present invention; Figure 4 It is the flowchart of the low-power mode after the output voltage is established in the present invention; Figure 5 It is the flowchart of the protection mechanism when the output voltage is not established in the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present 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 only used to explain the present invention and are not used to limit the present invention.

[0020] It can be understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but unless otherwise specified, these elements are not limited by these terms. These terms are only used to distinguish the first element from another element. For example, without departing from the scope of this application, the first xx script may be referred to as the second xx script, and similarly, the second xx script may be referred to as the first xx script.

[0021] Please refer to Figures 1 to 5 , this embodiment discloses a method for protecting a high-voltage startup circuit, including the following steps: S1, when the high-voltage input Vin starts, control the conduction state of the switch circuit Q4 through the RC delay circuit, so that the first-stage voltage regulation circuit Q1 works within a preset time and provides an initial voltage for the second-stage voltage regulation circuit Q2.

[0022] As Figure 2 shown, the RC delay circuit is composed of a resistor R1 and a capacitor C1, and is used to control the conduction state of the switch circuit Q4. The charging time of the RC delay circuit is set to be greater than the expected time for the normal establishment of the output voltage Vout, ensuring that the switch circuit Q4 maintains the corresponding conduction state within an appropriate time period, realizing precise control of the working time of the first-stage voltage regulation circuit Q1, and ensuring that the entire high-voltage startup circuit operates according to the expected logic.

[0023] The switch circuit Q4 can be a MOS transistor or a triode. When it is a MOS transistor, the gate of the MOS transistor is connected to the output terminal of the RC delay circuit, and the source is grounded; when the switch circuit Q4 is a triode, the base of the triode is connected to the output terminal of the RC delay circuit, and the emitter is grounded.

[0024] The charging time of the RC delay circuit needs to be reasonably set to ensure that the conduction duration of the switch circuit Q4 can be precisely controlled, and to ensure the normal operation of the first-stage voltage regulation circuit Q1 and the second-stage voltage regulation circuit Q2.

[0025] Specifically, taking an industrial power supply device as an example, the input voltage Vin is 300V, the value of R1 in the RC delay circuit is 10kΩ, and the value of C1 is 10μF. According to the RC circuit charging time formula , where T represents time, R represents the resistance value, and C represents the capacitance value, the time of this RC delay circuit can be calculated as F = 100ms.

[0026] When the power supply starts, Vin is connected to the circuit (such as Figure 2 the connection point of Vin in the figure), the RC delay circuit starts to work, and the current charges the capacitor C1 through the resistor R1. As the voltage across the capacitor C1 gradually increases, when the voltage reaches the conduction threshold of the switch circuit Q4, the switch circuit Q4 conducts.

[0027] The first - stage voltage - stabilizing circuit Q1 selects an N - MOS transistor with a breakdown voltage of 400V (Q1 in the figure). It starts to work after the switch circuit Q4 is turned on, preliminarily stabilizes the high - voltage input Vin, and provides a relatively stable initial voltage for the second - stage voltage - stabilizing circuit Q2; the second - stage voltage - stabilizing circuit Q2 uses an NPN transistor with a breakdown voltage of 100V (such as Figure 2 Q2 in the figure).

[0028] It should be noted that it is crucial to reasonably set the parameters of the RC delay circuit. In the design based on analog circuits, the charging time can be adjusted by replacing resistors R1 with different resistance values and capacitors C1 with different capacitance values; in the circuit using digital control, the microcontroller can control the switching elements to dynamically adjust the equivalent resistance or capacitance value to precisely control the charging time.

[0029] Using the above steps, by reasonably setting the parameters of the RC delay circuit, ensure that the switch circuit Q4 is turned on in an appropriate time period, realize the precise control of the working time of the first - stage voltage - stabilizing circuit Q1, ensure that the entire high - voltage startup circuit can start and operate according to the expected logic, and avoid the abnormal operation of the first - stage voltage - stabilizing circuit caused by improper parameter setting, which affects the subsequent voltage - stabilizing output and circuit performance.

[0030] S2, detect whether the output voltage Vout is established through the sampling circuit. When the output voltage Vout reaches the set value, generate a high - level enable signal Enable to maintain the on - state of the switch circuit Q4, and make the first - stage voltage - stabilizing circuit Q1 enter the low - power mode; Among them, the sampling circuit consists of resistor R7 and resistor R8, and needs to be reasonably configured according to the set value of the output voltage Vout and the circuit characteristics to accurately detect whether the output voltage Vout reaches the set value and reliably generate the enable signal Enable.

[0031] Specifically, the set value of the output voltage Vout is 24V. The sampling circuit consists of R7 (20kΩ) and R8 (10kΩ). According to the voltage - division principle, the sampling voltage .

[0032] When the output voltage Vout reaches 24V, the sampling voltage is 8V. The third voltage - regulating diode ZD3 selects a model with a breakdown voltage of 5.1V. When the sampling voltage exceeds 5.1V, the third voltage - regulating diode ZD3 breaks down and conducts, generating a high - level signal. The high - level signal drives the switch circuit Q4 (such as Figure 2 Q4 in the figure) through the current - limiting resistor R6 (with a value of 1kΩ) to maintain the on - state of the switch circuit Q4.

[0033] After the first - stage voltage - regulating circuit Q1 enters the low - power mode after the switching circuit Q4 conducts continuously and the output voltage Vout is stably established, at this time, since the output voltage Vout takes over most of the power output, the first - stage voltage - regulating circuit Q1 only needs to provide the conduction current for the first voltage - stabilizing diode ZD1 in the second - stage voltage - regulating circuit Q2, thereby reducing its own power consumption and heat generation.

[0034] It should be noted that the resistance value selection of the sampling circuit should comprehensively consider factors such as the output voltage Vout range, detection accuracy, and the driving ability of the subsequent circuit. In practical applications, the resistance value can also be fine - tuned through experimental tests to ensure that the output voltage Vout can be accurately detected and a reliable enabling signal can be generated under different working conditions.

[0035] Using the above steps, the sampling circuit can accurately detect whether the output voltage Vout reaches the set value, and reliably generate an enabling signal to maintain the conduction of the switching circuit Q4, prompting the first - stage voltage - regulating circuit Q1 to enter the low - power mode after the output voltage Vout is stably established. It avoids the detection error and power - consumption problems caused by improper sampling - circuit parameters, and reduces the power consumption and heat generation of the first - stage voltage - regulating circuit Q1.

[0036] S3, when the output voltage Vout is not established within the preset time, the RC delay circuit is charged, resulting in the switching circuit Q4 being turned off, cutting off the power supply of the first - stage voltage - regulating circuit Q1 to prevent device thermal damage.

[0037] As Figure 2 shown, the drive circuit consists of Q3, R2, and R4, and is used to cut off the power supply of the first - stage voltage - regulating circuit Q1 when the switching circuit Q4 is turned off.

[0038] Furthermore, the conduction threshold voltage Vth of the switching circuit Q4 and the voltage change of the RC delay circuit need to be precisely matched to ensure that the switching circuit Q4 can be triggered to turn off timely and reliably when the establishment of the output voltage Vout fails.

[0039] Specifically, taking the IRF540N - type MOS tube as the switching circuit Q4 as an example, the conduction threshold voltage Vth of the switching circuit Q4 is 2 - 4V. Assuming that the conduction threshold voltage Vth of this tube is 2.5V, within the preset time (determined by the charging time of the RC delay circuit, here it is 100ms), if due to circuit failures (such as component damage, line breakage, etc.), the output voltage Vout does not reach the set value of 24V, the RC delay circuit (R1 = 10kΩ, C1 = 10μF) is charged. As the capacitor C1 is charged to the end, the voltage across it gradually decreases. When the voltage is lower than the conduction threshold voltage Vth (2.5V) of the switching circuit Q4, the switching circuit Q4 is turned off.

[0040] In the drive circuit, the transistor Q3 is selected as 2N3904. The resistance value of the resistor R2 in the drive circuit is 1 kΩ, and the resistance value of the resistor R4 in the drive circuit is 10 kΩ. When the switch circuit Q4 is turned off, the original current path flowing through the switch circuit Q4 changes, causing the base voltage of the transistor Q3 in the drive circuit to increase, and the transistor Q3 in the drive circuit conducts. After the transistor Q3 in the drive circuit conducts, the gate voltage of the first-stage voltage regulator circuit Q1 (an N-MOS transistor with a breakdown voltage of 400 V) is pulled down to the cut-off state, cutting off the power supply of the first-stage voltage regulator circuit Q1, and preventing the first-stage voltage regulator circuit Q1 from generating excessive heat due to long-term operation under high load and resulting in thermal damage.

[0041] It should be noted that the matching degree between the conduction threshold voltage Vth of the switch circuit Q4 and the voltage change of the RC delay circuit directly affects the protection effect of the circuit. During the actual circuit debugging process, the resistance and capacitance values of the RC delay circuit are adjusted, or different switch transistors with different conduction thresholds are replaced to achieve the best matching effect.

[0042] Using the above steps, when the output voltage Vout is not established within the preset time, by using the precise matching between the RC delay circuit and the conduction threshold voltage of the switch circuit Q4, Q4 is turned off in time and the power supply of the first-stage voltage regulator circuit Q1 is cut off through the drive circuit, preventing Q1 from being damaged due to excessive heat generated by long-term high-load operation, and ensuring the safety and reliability of the entire high-voltage startup circuit.

[0043] Taking the above industrial power supply device as an example, the charging time of the RC delay circuit is greater than the expected time for the normal establishment of the output voltage Vout. The expected time for the normal establishment of the output voltage Vout is 80 ms, and the charging time setting of the RC delay circuit (R1 = 10 kΩ, C1 = 10 μF) is 100 ms. The switch circuit Q4 selects a MOS transistor, and the conduction threshold voltage Vth of the MOS transistor is 2 V. During the charging process of the RC delay circuit, the change in the output voltage Vout of the RC delay circuit matches the conduction threshold voltage Vth of Q4. When the output voltage Vout is not established within 80 ms, it indicates that the establishment of Vout fails. When the charging of the RC delay circuit is completed at 100 ms, the output voltage Vout is lower than the conduction threshold voltage Vth (2 V) of the switch circuit Q4, and the switch circuit Q4 automatically turns off, triggering the protection of the circuit and avoiding circuit failures caused by the failure to establish the output voltage Vout.

[0044] Furthermore, in the industrial power supply circuit, the switch circuit Q4 selects an IRF540N type MOS transistor, and the gate of the MOS transistor is connected to the output terminal of the RC delay circuit composed of R1 (10 kΩ) and C1 (10 μF) (as shown in the appendix Figure 2The connection point shown), the source is grounded. In the drive circuit, transistor Q3 is a 2N3904 transistor, the value of R2 is 1 kΩ, and the value of R4 is 10 kΩ.

[0045] When the RC delay circuit charges to a voltage lower than the turn-on threshold voltage Vth of IRF540N (assuming the Vth of the MOS transistor is 2.5 V), the switch circuit Q4 turns off. At this time, the base voltage of transistor Q3 in the drive circuit increases, and transistor Q3 turns on, pulling down the gate voltage of the first-stage voltage regulator circuit Q1 (such as the N-MOS transistor with a breakdown voltage of 400 V mentioned above) to the cut-off state, realizing the cut-off of the power supply of the first-stage voltage regulator circuit Q1 through Q3, R2, and R4 in the drive circuit. By cutting off the power supply of the first-stage voltage regulator circuit Q1, the thermal effect and power consumption problems caused by the continuous operation of the first-stage voltage regulator circuit Q1 are avoided.

[0046] Further, assume that in the design of another version of the industrial power supply circuit, the switch circuit Q4 is a 2N2222 transistor. The base of the transistor is connected to the output terminal of the RC delay circuit (R1 = 10 kΩ, C1 = 10 μF), the emitter is grounded, and the drive circuit is also composed of Q3 (2N3904 transistor), R2 (1 kΩ), and R4 (10 kΩ). The turn-on voltage VBE of the 2N2222 transistor is 0.7 V. When the RC delay circuit charges to a voltage lower than 0.7 V, the switch circuit Q4 turns off, the base voltage of transistor Q3 in the drive circuit increases, and transistor Q3 turns on, pulling down the gate voltage of the first-stage voltage regulator circuit Q1 and cutting off the power supply of the first-stage voltage regulator circuit Q1, realizing the protection of the industrial power supply circuit.

[0047] The generation of the enable signal Enable includes: sampling the output voltage Vout through voltage-dividing resistors. Resistor R7 and resistor R8 form the voltage-dividing resistors. When the sampled voltage exceeds the breakdown voltage of the third zener diode ZD3, a high-level signal is generated, and the switch circuit Q4 is driven through the current-limiting resistor R6 to maintain the on state, ensuring that the entire high-voltage startup circuit can operate stably according to the expected logic.

[0048] In the above industrial power supply device, the value of the voltage-dividing resistor R7 is 20 kΩ, the value of R8 is 10 kΩ, sampling the output voltage Vout (set value 24 V), the third zener diode ZD3 is a 1N4733A, and the breakdown voltage is 5.1 V. When Vout reaches 24 V, the sampled voltage is 8 V, exceeding the breakdown voltage of the third zener diode ZD3, which is 5.1 V, generating a high-level signal. The switch circuit Q4 (such as Q4 in the attachment Figure 2 can be the IRF540N MOS transistor or 2N2222 transistor mentioned above) is driven through the current-limiting resistor R6 (with a value of 1 kΩ) to maintain the on state, ensuring that the first-stage voltage regulator circuit Q1 enters the low-power consumption mode.

[0049] Further, the sum of the breakdown voltage of the third voltage regulator ZD3 and the conduction threshold voltage (Vth) of the switching circuit Q4 is less than the set value of the output voltage Vout, ensuring that when the output voltage Vout is normally established, the enable signal (Enable) can stably maintain the conduction of the switching circuit Q4.

[0050] If the IRF540N MOS transistor is selected for the switching circuit Q4, the conduction threshold voltage Vth is 2.5V, the 1N4733A is selected for the third voltage regulator ZD3, the breakdown voltage is 5.1V, and the set value of the output voltage Vout is 24V. , meeting the conditions.

[0051] When the output voltage Vout reaches 24V, the high-level signal generated by sampling through the voltage-dividing resistor, after passing through the third voltage regulator ZD3, has sufficient remaining voltage to drive Q4 (IRF540N) to maintain the conduction state, ensuring that the first-stage voltage regulator circuit Q1 stably enters the low-power mode, effectively reducing the circuit power consumption.

[0052] A fourth voltage regulator ZD4 is connected in parallel between the gate and source of the switching circuit Q4. When the gate-source voltage GS exceeds the breakdown voltage of the fourth voltage regulator ZD4, current is forcibly discharged to protect Q4, realizing overvoltage protection for the gate-source voltage GS of the switching circuit Q4.

[0053] Specifically, for the switching circuit Q4 (such as the IRF540N MOS transistor), a fourth voltage regulator ZD4 is connected in parallel between the MOS transistor gate and source. The BZV55-C5V6 is selected, and the breakdown voltage is 5.6V. In the case of an abnormal circuit, if the gate-source voltage GS exceeds 5.6V, the fourth voltage regulator ZD4 breaks down, forcibly discharging current to protect the switching circuit Q4 from being damaged by the excessive gate-source voltage GS. For example, when the gate-source voltage GS instantaneously reaches 7V due to electromagnetic interference or other reasons, the fourth voltage regulator ZD4 quickly conducts and discharges current, clamping the gate-source voltage GS at about 5.6V, protecting the safety of the switching circuit Q4 and ensuring that the switching circuit Q4 is not damaged by the excessive gate-source voltage GS in abnormal situations.

[0054] The shutdown process of the first-stage voltage regulator circuit Q1 includes: when the switching circuit Q4 is turned off, the base voltage of Q3 in the drive circuit increases, Q3 in the drive circuit conducts, and the gate voltage of the first-stage voltage regulator circuit Q1 is pulled down to the cut-off state.

[0055] Specifically, taking the first-stage voltage regulator circuit Q1 in the industrial power supply circuit as an N-MOS transistor with a breakdown voltage of 400V, the switching circuit Q4 as an IRF540N MOS transistor, and Q3 in the drive circuit as a 2N3904 transistor as an example, when the switching circuit Q4 is turned off, the current path originally flowing through the switching circuit Q4 changes, causing the base voltage of the transistor Q3 to rise. After the transistor Q3 (2N3904) conducts, it pulls down the gate voltage of the first-stage voltage regulator circuit Q1. For example, the original gate voltage of the first-stage voltage regulator circuit Q1 is 10V to make the transistor Q3 conduct. After the transistor Q3 conducts, through the circuit connection, the gate voltage of the first-stage voltage regulator circuit Q1 is pulled down to below 1V, causing the first-stage voltage regulator circuit Q1 to enter the cut-off state, cutting off the power supply, and avoiding the possible risks brought by the continuous operation of the first-stage voltage regulator circuit Q1.

[0056] The second-stage voltage regulator circuit Q2 is an NPN transistor, and its base is connected to the output terminal of the first-stage voltage regulator circuit Q1 through the first voltage regulator ZD1. When the output voltage Vout is established, the collector voltage of the second-stage voltage regulator circuit Q2 is clamped in reverse bias through the diode D1, so that the first-stage voltage regulator circuit Q1 only provides the conduction current of the first voltage regulator ZD1.

[0057] Specifically, in the industrial power supply circuit, the second-stage voltage regulator circuit Q2 selects a 2N3906 NPN transistor. The base of the 2N3906 NPN transistor is connected to the output terminal of the first-stage voltage regulator circuit Q1 through the first voltage regulator ZD1 (such as 1N4735A, breakdown voltage 6.8V). When the output voltage Vout is established (such as reaching 24V), the diode D1 (such as 1N4007) clamps the collector voltage of the second-stage voltage regulator circuit Q2 in reverse bias. At this time, the first-stage voltage regulator circuit Q1 only provides the conduction current of the first voltage regulator ZD1. Assuming that the conduction current of the first voltage regulator ZD1 is 10mA, the excess current output by the first-stage voltage regulator circuit Q1 no longer flows through the second-stage voltage regulator circuit Q2, but is processed by other parts of the circuit, so as to ensure the stable and low-power operation of the circuit.

[0058] The input voltage of the high-voltage startup circuit exceeds 200V, and the total power loss of the first-stage voltage regulator circuit Q1 and the second-stage voltage regulator circuit Q2 is reduced to below the safety threshold through the turn-off of the switching circuit Q4 when the output voltage Vout is not established.

[0059] Specifically, in an industrial power supply device, the input voltage Vin of the high-voltage startup circuit is 300V. When the first-stage voltage regulation circuit Q1 (an N-MOS transistor with a breakdown voltage of 400V) and the second-stage voltage regulation circuit Q2 (a 2N3906 NPN transistor with a breakdown voltage of 100V) are operating normally, if the output voltage Vout is not established, the total power loss is relatively large. By setting appropriate circuit parameters and a turn-off protection mechanism for the switch circuit Q4, when the output voltage Vout is not established within a preset time (such as 100 ms), the switch circuit Q4 turns off, cutting off the power supply to Q1. After the switch circuit Q4 turns off, the total power loss of the first-stage voltage regulation circuit Q1 and the second-stage voltage regulation circuit Q2 is reduced from the original 5W to 0.5W (below the safety threshold, assuming the safety threshold is 1W), effectively preventing device thermal damage caused by excessive power loss.

[0060] It should be understood that although the steps in the flowcharts of the embodiments of the present invention are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear indication in this article, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least some of the steps in each embodiment may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed alternately or in turn with at least a part of other steps or sub-steps or stages of other steps.

[0061] Those of ordinary skill in the art can understand that all or part of the processes of implementing the methods in the above embodiments can be completed by instructing relevant hardware through a computer program. The above program can be stored in a non-volatile computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, storage, database, or other medium used in the various embodiments provided in the present application can include non-volatile and / or volatile memories. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and Rambus dynamic RAM (RDRAM), etc.

[0062] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, 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, it should be considered as the scope described in this specification.

[0063] The above embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

[0064] The above is only the preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for protecting a high-voltage starting circuit, characterized in that It includes the following steps: S1. When starting with high - voltage input, control the conduction state of the switching circuit through a delay circuit, so that the first - stage voltage - stabilizing circuit works within a preset time and provides an initial voltage for the second - stage voltage - stabilizing circuit; S2. Detect whether the output voltage is established through a sampling circuit. When the output voltage reaches the set value, generate a high - level enable signal to maintain the conduction state of the switching circuit, and make the first - stage voltage - stabilizing circuit enter the low - power mode; S3. When the output voltage is not established within the preset time, the charging of the delay circuit is completed, which causes the switching circuit to turn off and cuts off the power supply of the first - stage voltage - stabilizing circuit.

2. The method for protecting a high-voltage startup circuit according to claim 1, wherein: The charging time of the delay circuit is set to be greater than the expected time for the normal establishment of the output voltage, and the conduction threshold voltage of the switching circuit matches the voltage change of the delay circuit to ensure automatic triggering of the turn - off when the establishment of the output voltage fails.

3. The method for protecting a high-voltage startup circuit according to claim 1 or 2, characterized in that: The switching circuit is a MOS transistor. The gate of the switching circuit is connected to the output terminal of the delay circuit, and the source is grounded. When the delay circuit is charged to a voltage lower than the conduction threshold voltage of the switching circuit, the switching circuit turns off, and the power supply of the first - stage voltage - stabilizing circuit is cut off through a drive circuit.

4. The method for protecting a high-voltage startup circuit according to claim 1 or 2, characterized in that: The switching circuit is a triode. The base of the switching circuit is connected to the output terminal of the delay circuit, and the emitter is grounded. When the delay circuit is charged to a voltage lower than the conduction voltage of the switching circuit, the switching circuit turns off, and then the power supply of the first - stage voltage - stabilizing circuit is cut off through a drive circuit.

5. The method for protecting a high-voltage startup circuit according to claim 1, wherein: The generation of the enable signal includes: sampling the output voltage through a voltage - dividing resistor. When the sampled voltage exceeds the breakdown voltage of the third zener diode, a high - level signal is generated, and the switching circuit is driven through a current - limiting resistor to maintain the conduction state.

6. The method for protecting a high-voltage startup circuit according to claim 5, characterized in that: The sum of the breakdown voltage of the third zener diode and the conduction threshold voltage of the switching circuit is less than the set value of the output voltage to ensure that when the output voltage is normally established, the enable signal can stably maintain the conduction of the switching circuit.

7. The method for protecting a high-voltage startup circuit according to claim 1, wherein: It also includes over - voltage protection for the gate - source voltage of the switching circuit: a fourth zener diode is connected in parallel between the gate and source of the switching circuit. When the gate - source voltage exceeds the breakdown voltage of the fourth zener diode, current is forcibly discharged to protect the switching circuit.

8. The method for protecting a high-voltage starting circuit according to claim 1, wherein: The shutdown process of the first - stage voltage - stabilizing circuit includes: when the switching circuit turns off, the base voltage of the drive circuit increases, causing the drive circuit to conduct, and pulling down the gate voltage of the first - stage voltage - stabilizing circuit to the cut - off state.

9. The method for protecting a high-voltage startup circuit according to claim 1, wherein: The second - stage voltage - stabilizing circuit is an NPN triode. The base of the second - stage voltage - stabilizing circuit is connected to the output terminal of the first - stage voltage - stabilizing circuit through a first zener diode. After the output voltage is established, the collector voltage of the second - stage voltage - stabilizing circuit is clamped by reverse - bias of the diode, so that the first - stage voltage - stabilizing circuit only provides the conduction current of the zener diode.

10. The method for protecting a high-voltage startup circuit according to claim 1, wherein: The input voltage of the high - voltage startup circuit exceeds 200V, and the total power loss of the first - stage voltage - stabilizing circuit and the second - stage voltage - stabilizing circuit is reduced to below the safety threshold through the turn - off of the switching circuit when the output voltage is not established.

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