A power supply starting circuit and a power module

Abstract

The present application discloses a power supply startup circuit and a power module, including: a first current limiting module, a second current limiting module, a first voltage stabilizing module, an energy storage module and a second voltage stabilizing module, wherein the first end of the first voltage stabilizing module is connected to the ground end, and the second end is connected to the first node, and the first voltage stabilizing module is used to maintain the voltage of the first node at the first preset voltage when the voltage of the signal input end is greater than or equal to the preset value; the first end of the second voltage stabilizing module is connected to the ground end, and the second end is connected to the second node; the second voltage stabilizing module is used to output the second preset voltage when the voltage of the second node is less than or equal to the first preset voltage. The above dual voltage stabilizing module circuit can control the charging speed of the switch chip power supply when the second current limiting module is short-circuited, and the overall loss of the switch tube of the high-voltage short circuit is reduced, the thermal stress is reduced, and the reliability is improved.

Description

Technical Field

[0001] The present application relates to the field of switching power supplies, and in particular to a power supply starting circuit and a power module. Background Art

[0002] Conventional flyback auxiliary power soft power startup circuits generally use high voltage power supply through resistor current limiting and voltage division to provide current to the chip. Soft power startup circuits generally include startup resistors, capacitors, and voltage regulators. Considering that the input signal ranges from low voltage to high voltage, in order to ensure normal low-voltage startup, the startup resistors and other currents are calculated according to the low-voltage input, the capacitors are connected to the power pins of the chip, and the voltage regulators are generally greater than the normal voltage to prevent the voltage from exceeding the range and damaging the chip. After the startup is completed, the power energy of the chip is provided by the feedback winding of the transformer.

[0003] The current startup resistor designed for low voltage provides a large current when a high voltage is input over a wide range, which is several times larger than the low voltage. When the voltage regulator is short-circuited, the voltage at the power pin of the chip drops slowly and rises quickly due to the large current provided by the high voltage to the power pin of the chip. It is not easy to short-circuit and the short-circuit is long-term. Due to the large short-circuit switch loss, long short-circuit duration and short reset time, the switch has thermal risks. Summary of the invention

[0004] The main purpose of the present application is to provide a power supply starting circuit and a power module, aiming to solve the technical problem that the existing soft power supply starting circuit has large switching losses when short-circuited.

[0005] To achieve the above-mentioned objectives, the present application provides a power supply starting circuit, including: a first current limiting module, connected to a signal input terminal and a first node; a second current limiting module, connected to the first node and a second node; a first voltage stabilizing module, a first end of which is connected to a ground terminal, and a second end of which is connected to the first node, the first voltage stabilizing module being used to maintain the voltage of the first node at a first preset voltage when the voltage of the signal input terminal is greater than or equal to a preset value; a second voltage stabilizing module, a first end of which is connected to a ground terminal, and a second end of which is connected to a second node; the second voltage stabilizing module being used to output a second preset voltage when the voltage of the second node is less than or equal to the first preset voltage.

[0006] Optionally, a voltage stabilization value of the first voltage stabilization module is greater than a voltage stabilization value of the second voltage stabilization module.

[0007] Optionally, the first current limiting module includes: a first resistor connected to the signal input terminal and the first node; the second current limiting module includes: a second resistor connected to the first node and the second node.

[0008] Optionally, the first voltage stabilizing module includes: a first voltage stabilizing diode, an anode of which is connected to the ground terminal, and a cathode of which is connected to the first node; the second voltage stabilizing module includes: a second voltage stabilizing diode, an anode of which is connected to the ground terminal, and a cathode of which is connected to the second node.

[0009] Optionally, the power supply startup circuit further includes: an energy storage module connected to the second node and the ground terminal, and the energy storage module is used to store the voltage signal written into the second node.

[0010] In addition, to achieve the above-mentioned purpose, the present application also provides a power module, including a power supply module, a control module and the above-mentioned power supply start-up circuit; the power supply start-up circuit is used to power the control module during the startup stage of the power module; the power supply end of the control module is connected to the second node, and the output end is connected to the start-up control end of the power supply module, and the control module is used to output a start-up control signal to the start-up control end through the output end to start the power supply module; the first voltage output end of the power supply module is connected to the feedback input end of the control module, and the second voltage output end is connected to the power supply end of the control module, and the power supply module is used to power the control module after the power module startup is completed.

[0011] Optionally, the power supply module includes a second capacitor, a first switch, a third resistor, a transformer, a first diode, a second diode, a third capacitor, a fourth resistor and a fourth capacitor; wherein one end of the second capacitor is connected to the signal input end, and the other end is connected to the ground end; the positive and negative poles of the primary coil of the transformer are correspondingly connected to the signal input end and the fourth node, the positive and negative poles of the secondary coil are correspondingly connected to the fifth node and one end of the third capacitor, the other end of the third capacitor is connected to the first voltage output end, and the positive and negative poles of the feedback winding of the transformer are correspondingly connected to the third node and the ground end; the anode of the first diode is connected to the fifth node, and the cathode is connected to the first voltage output end; the anode of the second diode is connected to the third node, and the cathode is connected to the second voltage output end through the fourth resistor, and the fourth capacitor is connected to the second voltage output end and the ground end; the control end of the first switch serves as the start control end of the power supply module, the first end is connected to the fourth node, the second end is respectively connected to one end of the third resistor and the sampling end of the control module, and the other end of the third resistor is connected to the ground end.

[0012] Optionally, the control module includes a chip; a power pin of the chip serves as a power end of the control module, a feedback pin of the chip serves as a feedback input end of the control module, an output pin of the chip is connected to a sixth resistor and serves as an output end of the control module, a sampling pin of the chip is respectively connected to one end of a fifth resistor and one end of a fifth capacitor, the other end of the fifth capacitor is connected to a ground end, and the other end of the fifth resistor serves as a sampling end of the control module.

[0013] Optionally, the power module further includes: a sampling circuit connected in series between the first voltage output terminal and the feedback pin of the chip.

[0014] Optionally, the current limiting value of the second current limiting module is greater than the minimum starting current; the voltage stabilization values ​​of the first voltage stabilization module and the second voltage stabilization module are greater than or equal to the operating voltage of the control module.

[0015] The embodiment of the present application proposes a power supply startup circuit and a power module. The power supply startup circuit is used to provide power to the power module chip. A first current limiting module is set to limit the current and divide the voltage of the input signal at the signal input end, and a first voltage stabilizing module stabilizes the voltage divided signal to avoid the voltage of the second node being too high. Furthermore, the second current limiting module and the second voltage stabilizing module further limit the current and divide the voltage and stabilize the voltage signal of the second node. The above-mentioned dual voltage stabilizing module circuit can ensure that when the input signal is a high-voltage signal, the current is limited, thereby controlling the chip power charging speed when a short circuit occurs in the second voltage stabilizing module, thereby reducing the overall loss of the switch tube caused by the high-voltage short circuit, reducing thermal stress, and improving reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a structural schematic diagram of an embodiment of a power supply startup circuit of the present application;

[0017] Figure 2 A schematic diagram of the structure of a power module for this application;

[0018] Figure 3 It is a structural schematic diagram of a power supply module in a power module of the present application;

[0019] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0020] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0021] The first embodiment of the present application provides a power supply startup circuit. Figure 1 This is a structural diagram of a power supply startup circuit according to an embodiment of the present application. Figure 1 As shown, the power supply startup circuit 10 may include a first current limiting module 110, a first voltage stabilizing module 120, a second current limiting module 130 and a second voltage stabilizing module 150, wherein the first current limiting module 110 is connected to the signal input terminal Vin and the first node N1; the second current limiting module 130 is connected to the first node N1 and the second node N2; the first end of the first voltage stabilizing module 120 is connected to the ground end, and the second end is connected to the first node, and the first voltage stabilizing module 120 can be used to maintain the voltage of the first node N1 at a first preset voltage when the voltage of the signal input terminal Vin is greater than or equal to the preset value; the first end of the second voltage stabilizing module 150 is connected to the ground end, and the second end is connected to the second node N2, and the second voltage stabilizing module 150 can be used to output a second preset voltage when the voltage of the second node N2 is less than or equal to the first preset voltage.

[0022] In an exemplary embodiment, the voltage stabilization value of the first voltage stabilization module 120 is greater than the voltage stabilization value of the second voltage stabilization module 150 .

[0023] In this embodiment, the power supply startup circuit 10 is used to provide power for the power module in the startup stage. The first current limiting module 110 is set to limit the current and divide the input signal of the signal input terminal Vin. When the voltage division signal is greater than or equal to the preset value, the first voltage stabilizing module 120 limits the voltage of the first node N1 to maintain it at the first preset voltage to prevent the voltage of the second node N1 from being too high; then the second current limiting module 130 and the second voltage stabilizing module 150 further limit the current and divide the voltage and limit the voltage of the voltage signal of the second node N2 to maintain it at the second preset voltage, and the voltage stabilization value of the first voltage stabilizing module 120 is greater than the voltage stabilization value of the second voltage stabilizing module. The above-mentioned dual voltage stabilizing module circuit can ensure that when the input signal is a high-voltage signal, the current is limited, thereby controlling the charging speed of the power supply when a short circuit occurs in the second voltage stabilizing module 150, reducing the switch tube loss of the high-voltage short circuit as a whole, reducing thermal stress, and improving reliability.

[0024] In an exemplary embodiment, the power startup circuit 10 may further include an energy storage module 140 . The energy storage module 140 is connected to the second node N2 and the ground terminal. The energy storage module 140 may be used to store a voltage signal written into the second node N2 .

[0025] In this embodiment, by providing the energy storage module 140, voltage fluctuations can be reduced during the startup phase, providing a stable voltage for the power module; and within a short period of time after the startup is completed, the stored energy is released to provide auxiliary power for the power module.

[0026] The working principle of the power supply startup circuit of this embodiment is described in detail below.

[0027] The input signal of the signal input terminal Vin is limited and divided by the current through the first current limiting module 110. If the divided voltage signal is greater than the regulated voltage value of the first voltage stabilizing module 120, the first voltage stabilizing module 120 limits the voltage so that the divided voltage signal reaches the regulated voltage value output; if the divided voltage signal is less than or equal to the regulated voltage value of the first voltage stabilizing module 120, the first voltage stabilizing module 120 does not act; the signal after the voltage limit passes through the second current limiting module 130, and enters the energy storage module 140 to charge it. When the energy storage module 140 is fully charged, it discharges and transmits the voltage signal to the second node N2. If the voltage of the second node N2 is higher than the regulated voltage value of the second voltage stabilizing module 150, after the voltage is limited by the second voltage stabilizing module 150, the power supply pin of the input power module provides power for it. If the voltage of the second node N2 is less than the regulated voltage value of the second voltage stabilizing module 150, the second voltage stabilizing module 150 does not act, and the voltage of the second node N2 is input to the power supply pin of the power module to provide power for it. Through the above-mentioned power supply startup circuit, the voltage output by the energy storage module 140 can be controlled, thereby limiting the current, so that when the second voltage stabilizing module 150 is short-circuited and the chip voltage of the power module is lower than the undervoltage value and shuts down, the time for the power supply to rise from below the undervoltage point to the startup voltage is increased, thereby reducing the overall loss of the switch tube due to high-voltage short circuit, reducing thermal stress, and improving reliability. On the contrary, if the first voltage stabilizing module 120 is not set, assuming that the signal input terminal Vin is much larger than the power supply, the startup current at low voltage is Vin_min / (R1+R2), and the startup current at high voltage is Vin_max / (R1+R2). Assuming that the maximum voltage is 5 times the minimum voltage, the high-voltage startup current is 5 times the low voltage. In this case, the time for the high-voltage short circuit to occur will be relatively long, resulting in a large loss of the switch tube.

[0028] In an exemplary embodiment, the first current limiting module 110 may include a first resistor R1, the first resistor R1 is connected to the signal input terminal and the first node N1. The second current limiting module 130 may include a second resistor R2, the second resistor R2 is connected to the first node N1 and the second node N2. The first voltage stabilizing module 120 may include a first voltage stabilizing diode D1, the anode of the first voltage stabilizing diode D1 is connected to the ground terminal, and the cathode is connected to the first node N1. The second voltage stabilizing module 150 may include a second voltage stabilizing diode D2, the anode of the second voltage stabilizing diode D2 is connected to the ground terminal, and the cathode is connected to the second node N2.

[0029] Exemplarily, the energy storage module 140 may include a first capacitor C1 , and the first capacitor C1 is connected to the second node N2 and the ground terminal.

[0030] In this embodiment, the input signal of the signal input terminal Vin is output after being limited and divided by the first resistor R1. If the input DC voltage is greater than the voltage stabilization value of the first voltage stabilizing diode D1, the voltage stabilization value is output through the first voltage stabilizing diode D1; after the voltage stabilization signal is limited and divided by the second resistor R2, the voltage division signal is input to the first capacitor C1 to charge it. When the first capacitor C1 is fully charged, the voltage signal is transmitted to the second node N2. After the voltage signal of the second node N2 is limited by the second voltage stabilizing diode D2, the limited voltage is transmitted to the power module chip to supply power. In this process, the input signal is limited by the first voltage stabilizing diode D1 and the second voltage stabilizing diode D2, thereby limiting the input current. When the second voltage stabilizing diode D2 is short-circuited and the voltage of the power module chip is lower than the undervoltage value and shuts down, the speed of charging the power supply by the first capacitor C1 is controlled, and the switch loss of the high-voltage short circuit is reduced as a whole, the thermal stress is reduced, and the reliability is improved.

[0031] A second embodiment of the present application provides a power module, Figure 2 is a schematic diagram of the structure of a power module of the present application, such as Figure 2 As shown, the power module may include a control module 20, a power supply module 30 and a power supply start-up circuit 10 of the above-mentioned embodiment, and the power supply start-up circuit 10 may be used to supply power to the control module 20 during the start-up phase of the power module; the output end of the control module 20 is connected to the start-up control end of the power supply module 30; the power supply end Vcc of the control module 20 is connected to the second node N2; the control module 20 may be used to output a start-up control signal to the start-up control end of the power supply module 30 through the output end to start the power supply module 30; the first voltage output end Vo1 of the power supply module 30 is connected to the feedback input end of the control module 20, and the second voltage output end Vo2 of the power supply module 30 is connected to the power supply end Vcc of the control module 20; the power supply module may be used to supply power to the control module 20 after the start-up of the power module is completed.

[0032] In this embodiment, during the startup phase, the power supply startup circuit 10 inputs a voltage signal to the power supply terminal Vcc of the control module 20 through the energy storage module 140, thereby supplying power to the control module 20, and then driving the control module 20 to start; after the control module 20 completes startup, the control module 20 outputs a startup control signal through its output terminal to turn on the startup control terminal of the power supply module 30, thereby enabling the power supply module 30 to provide a stable power supply to the control module 20 to enter a stable working state. The power supply startup circuit 10 can reduce the short-circuit time of the second voltage regulator diode D2 at high voltage, increase the time for the power supply voltage of the control module 20 to rise from below the undervoltage point to the startup voltage, and thereby reduce the loss of the power supply module 30.

[0033] In an exemplary embodiment, the power module may be an ACDC power conversion module.

[0034] The power supply module 30 in the power module is introduced in detail below.

[0035] Figure 3 is a schematic diagram of the structure of a power supply module in a power module of the present application, such as Figure 3 As shown, the power supply module 30 may include a second capacitor C2, a first switch Q1, a third resistor R3, a transformer T, a first diode D3, and a third capacitor C3, wherein one end of the second capacitor C2 is connected to the signal input end, and the other end is connected to the ground end; the positive and negative poles of the primary coil of the transformer T are correspondingly connected to the signal input end and the fourth node N4, the positive and negative poles of the secondary coil of the transformer T are correspondingly connected to the fifth node N5 and one end of the third capacitor C3, the other end of the third capacitor C3 is connected to the first voltage output end Vo1, and the feedback winding of the primary coil of the transformer T is connected to the first voltage output end Vo1. The positive pole and the negative pole are connected to the third node N3 and the ground terminal respectively; the anode of the first diode D3 is connected to the fifth node N5, and the cathode is connected to the first voltage output terminal Vo1; the anode of the second diode D4 is connected to the third node N3, and the cathode of the second diode D4 is connected to the second voltage output terminal Vo2 through the fourth resistor R4, and the fourth capacitor C4 is connected to the second voltage output terminal Vo2 and the ground terminal; the control end of the first switch Q1 serves as the start control end of the power supply module, the first end is connected to the fourth node N4, the second end is respectively connected to one end of the third resistor R3 and the sampling end I p of the control module 20, and the other end of the third resistor R3 is connected to the ground terminal.

[0036] In this embodiment, the first switch Q1 may be a transistor, for example, an N-type transistor.

[0037] In the initial startup stage, the charge stored in the first capacitor C1 can be used to power the control module 20, and the startup control module 20 starts to work. The output end of the control module 20 outputs a startup control signal to control the first switch Q1 to be turned on; after the first switch Q1 is turned on, the voltage of the signal input end Vin is filtered by the second capacitor C2 and sent to the primary coil of the transformer T, and then the feedback winding of the primary coil induces a voltage. The induced voltage is rectified by the second diode D4, limited by the fourth resistor R4, and filtered by the fourth capacitor C4, and then outputs a direct current to the second voltage output end Vo2. The second voltage output end Vo2 powers the control module 20 through the second node N2, and the control module 20 enters a stable working state.

[0038] Exemplarily, when a fault occurs in the control module 20, such as the control module 20 consumes all the power, the voltage of the second voltage output terminal Vo2 continues to rise. At this time, the second voltage output terminal Vo2 is connected to the second node N2, and the second voltage output terminal Vo2 is limited by the second voltage regulator diode D2 to avoid excessive voltage.

[0039] In an exemplary embodiment, the control module 20 may include a chip, and the power pin of the chip serves as the power supply terminal Vcc of the control module 20, that is, the power pin of the chip is respectively connected to the second node N2 and the second voltage output terminal Vo2. The feedback pin of the chip serves as the feedback input terminal of the control module 20, that is, the feedback pin of the chip is connected to the first voltage output terminal Vo1. The output pin of the chip is connected to the sixth resistor R6 and serves as the output terminal of the control module 20, that is, the output pin of the chip is connected to the control terminal of the first switch Q1 through the sixth resistor R6. The sampling pins of the chip are respectively connected to one end of the fifth resistor R5 and one end of the fifth capacitor C5, the other end of the fifth capacitor C5 is connected to the ground terminal, and the other end of the fifth resistor R5 serves as the sampling terminal Ip of the control module 20.

[0040] In addition, the power module may further include a sampling circuit, which is connected in series between the first voltage output terminal Vo1 and the feedback pin of the chip. The sampling circuit of this embodiment may be any circuit capable of realizing the current collection function, for example, it may be a TL431+ optocoupler sampling control circuit, and the structure of the TL431+ optocoupler sampling control circuit may refer to an existing circuit, and the above-mentioned sampling circuit is not specifically limited here.

[0041] In this embodiment, the output voltage of the startup circuit 10 provides a startup power supply for the chip. After the chip is started, the power supply module 30 is turned on. The power supply module 30 provides power to the chip to enable it to enter a stable working state. During this process, the sampling pin of the chip obtains the voltage of the signal input terminal Vin after filtering by the fifth resistor R5 and the fifth capacitor C5.

[0042] In an exemplary embodiment, the chip may be a UCC2844 chip, and specifically, the UCC2844 chip may include a power supply pin Vcc, an output pin OUT, a feedback pin FB, and a sampling pin CS. The working principle of the power module is described below using the UCC2844 chip as an example.

[0043] The power supply pin Vcc of the UCC2844 chip is connected to the second node N2. At the beginning, the second node N2 is connected to the power supply pin Vcc through the second node N2. When the UCC2844 chip is started, the output pin OUT of the UCC2844 chip turns on the first switch Q1. The voltage of the signal input terminal Vin is filtered by the second capacitor C2 and sent to the primary coil of the transformer T. Then the feedback winding of the primary coil of the transformer T induces a voltage. The induced voltage is rectified by the second diode D4 and filtered by the fourth capacitor C4 to output direct current to the second node N2, and is transmitted to the power supply pin Vcc of the UCC2844 chip. At the same time, the secondary coil of the transformer T induces a voltage. The voltage is rectified by the first diode D3 and filtered by the third capacitor C3 and enters the first voltage output terminal Vo1. The voltage signal of the first voltage output terminal Vo1 of the power supply module 30 is connected to the feedback pin FB of the UCC2844 chip through the sampling circuit to form a feedback loop. In this loop, the output signal of the power supply module 30 enters the sampling circuit to adjust the input current. The output pin OUT of the UCC2844 chip is connected to the control end of the first switch Q1. The output PWM duty cycle is adjusted according to the voltage of the feedback pin FB to control the on and off time of the first switch Q1. Then, through the transformer T and the feedback loop, the changing voltage across the third capacitor C3 can be converted into a regulated output.

[0044] In an exemplary embodiment, the current limiting value of the second current limiting module 130 is greater than the minimum starting current; the voltage stabilization values ​​of the first voltage stabilization module 120 and the second voltage stabilization module 150 are greater than or equal to the operating voltage of the control module 20 .

[0045] It is worth noting that the operating voltage in this embodiment refers to the voltage when the control module 20 enters normal operation.

[0046] It can be known that the voltage inputted by the signal input terminal Vin is a DC voltage, and the voltage range of the signal input terminal Vin is relatively wide, so in this embodiment, when the signal input terminal Vin is a low voltage signal, the sum of the current limiting values ​​of the first resistor R1 and the second resistor R2 is greater than the minimum starting current of the control module 20, and a margin is left, which can meet the low voltage starting requirement; when the signal input terminal Vin is a high voltage signal, the current limiting value of the second resistor R2 is greater than the minimum starting current, ensuring the normal starting of the control module 20. Furthermore, the voltage stabilization values ​​of the first voltage stabilizing diode D1 and the second voltage stabilizing diode D2 are greater than the starting voltage of the control module 20, further ensuring the normal starting of the control module 20.

[0047] The following example illustrates the selection ranges of the first resistor R1 , the second resistor R2 , the first Zener diode D1 , and the second Zener diode D2 .

[0048] For the first resistor R1 and the second resistor R2, the signal input terminal Vin is 300V-1000V, and the minimum startup current of the control module 20 is 100uA. In order to meet the low-voltage startup, the sum of the first resistor R1 and the second resistor R2 needs to be greater than 100uA, and a margin is left. In addition, when the voltage of the signal input terminal Vin increases, the first voltage regulator diode D1 clamps and breaks down, and the current of the second resistor R2 is equal to the voltage difference between the voltage regulator value of the first voltage regulator diode D1 and the power supply terminal Vcc divided by the second resistor R2. The current (the current of the second resistor R2) should also be selected as greater than 100uA.

[0049] For the first Zener diode D1 and the second Zener diode D2, for example, if the working voltage of the power supply terminal Vcc is about 13V, the voltage regulation value of the first Zener diode D1 should be greater than 13V, and a Zener diode with a voltage regulation value greater than 26V can be selected.

[0050] Furthermore, the control module 20 may include a UCC2844 chip. The UCC2844 chip is taken as an example below to further illustrate the selection ranges of the first resistor R1, the second resistor R2, the first Zener diode D1, and the second Zener diode D2.

[0051] For example, if the starting voltage of UCC2844 is greater than 14V, then at this time, the second Zener diode D2 should select a Zener diode greater than 14V, such as an 18V Zener diode, and the first Zener diode D1 can select a 36V Zener diode; when the signal input terminal Vin is a high-voltage signal and the first Zener diode D1 is clamped, the voltage difference of the second resistor R2 is at least 36V-18V=18V. At this time, select the second resistor R2 with a suitable resistance value according to the current limiting value greater than 100uA; after the second resistor R2 is selected, the resistance value of the first resistor R1 can be determined according to the current limiting value of R1+R2 being greater than 100uA.

[0052] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A power supply starting circuit, characterized in that: include: A first current limiting module, connected to the signal input terminal and the first node; A second current limiting module, connected to the first node and the second node; a first voltage stabilizing module, a first end of which is connected to the ground end, and a second end of which is connected to the first node, the first voltage stabilizing module being used to maintain the voltage of the first node at a first preset voltage when the voltage of the signal input end is greater than or equal to a preset value; A second voltage stabilizing module, a first end of which is connected to the ground end, and a second end of which is connected to the second node; The second voltage stabilization module is used for outputting a second preset voltage when the voltage of the second node is less than or equal to the first preset voltage.

2. The power supply startup circuit according to claim 1, characterized in that: The voltage stabilization value of the first voltage stabilization module is greater than the voltage stabilization value of the second voltage stabilization module.

3. The power supply startup circuit according to claim 1, characterized in that: The first current limiting module comprises: A first resistor, connected to the signal input terminal and the first node; The second current limiting module includes: The second resistor connects the first node and the second node.

4. The power supply startup circuit according to claim 1, characterized in that: The first voltage stabilizing module comprises: a first voltage stabilizing diode, with an anode connected to the ground terminal and a cathode connected to the first node; The second voltage stabilizing module comprises: The second voltage stabilizing diode has an anode connected to the ground terminal and a cathode connected to the second node.

5. The power supply startup circuit according to claim 1, characterized in that: The power supply startup circuit also includes: An energy storage module is connected to the second node and the ground terminal, and is used to store the voltage signal written into the second node.

6. A power module, characterized in that: It comprises a power supply module, a control module and a power supply start-up circuit according to any one of claims 1 to 5; The power supply startup circuit is used to supply power to the control module during the startup phase of the power module; The power supply end of the control module is connected to the second node, and the output end is connected to the start control end of the power supply module, and the control module is used to output a start control signal to the start control end through the output end to start the power supply module; The first voltage output terminal of the power supply module is connected to the feedback input terminal of the control module, and the second voltage output terminal is connected to the power supply terminal of the control module. The power supply module is used to supply power to the control module after the power module is started.

7. The power module according to claim 6, characterized in that: The power supply module includes a second capacitor, a first switch, a third resistor, a transformer, a first diode, a second diode, a third capacitor, a fourth resistor and a fourth capacitor; Wherein, one end of the second capacitor is connected to the signal input end, and the other end is connected to the ground end; The positive pole and negative pole of the primary coil of the transformer are connected to the signal input terminal and the fourth node respectively, the positive pole and negative pole of the secondary coil are connected to the fifth node and one end of the third capacitor respectively, the other end of the third capacitor is connected to the first voltage output terminal, and the positive pole and negative pole of the feedback winding of the transformer are connected to the third node and the ground terminal respectively; The anode of the first diode is connected to the fifth node, and the cathode is connected to the first voltage output terminal; The anode of the second diode is connected to the third node, the cathode is connected to the second voltage output terminal through the fourth resistor, and the fourth capacitor is connected to the second voltage output terminal and the ground terminal; The control end of the first switch serves as the start-up control end of the power supply module, the first end is connected to the fourth node, the second end is respectively connected to one end of the third resistor and the sampling end of the control module, and the other end of the third resistor is connected to the ground end.

8. The power module according to claim 7, characterized in that: The control module includes a chip; The power pin of the chip serves as the power end of the control module, the feedback pin of the chip serves as the feedback input end of the control module, the output pin of the chip is connected to the sixth resistor and serves as the output end of the control module, the sampling pin of the chip is respectively connected to one end of the fifth resistor and one end of the fifth capacitor, the other end of the fifth capacitor is connected to the ground end, and the other end of the fifth resistor serves as the sampling end of the control module.

9. The power module according to claim 8, characterized in that: The power module further comprises: The sampling circuit is connected in series between the first voltage output terminal and the feedback pin of the chip.

10. The power module according to claim 6, characterized in that: The current limiting value of the second current limiting module is greater than the minimum starting current; The voltage stabilization values ​​of the first voltage stabilization module and the second voltage stabilization module are greater than or equal to the working voltage of the control module.

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