CN115441719A

CN115441719A - Starting protection module for DC-DC converter

Info

Publication number: CN115441719A
Application number: CN202211382233.3A
Authority: CN
Inventors: 梁其才
Original assignee: Paisheng Core Suzhou Technology Co ltd
Current assignee: Paisheng Core Suzhou Technology Co ltd
Priority date: 2022-11-07
Filing date: 2022-11-07
Publication date: 2022-12-06
Anticipated expiration: 2042-11-07
Also published as: CN115441719B

Abstract

The invention belongs to the technical field of analog integrated circuits, and particularly relates to a starting protection module for a DC-DC converter, which comprises a soft starting circuit, an MOS feedback loop and a capacitor C, wherein the MOS feedback loop comprises an MP module and an MN module, the soft starting circuit is respectively connected with the MP module and the MN module, the MP module and the MN module are both connected with the capacitor C, and the soft starting circuit comprises a PMOS module, an NMOS module and a control module. According to the invention, when the DC-DC converter is turned off or short-circuit protection and over-temperature protection are carried out, the capacitor C is discharged through the MOS feedback loop, so that the voltage of the capacitor C is slightly lower than the voltage of the MOS feedback loop, a soft start voltage slightly higher than the voltage of the MOS feedback loop is generated by adopting the negative MOS feedback loop, a soft start function is realized, voltage overshoot is avoided, the soft start function after the soft turn-off and short-circuit protection of the DC-DC converter is realized, and output voltage overshoot when the DC-DC circuit recovers under the conditions of short circuit, over-temperature and the like is effectively avoided.

Description

Starting protection module for DC-DC converter

Technical Field

The invention belongs to the technical field of analog integrated circuits, and particularly relates to a starting protection module for a DC-DC converter.

Background

The DC/DC converter is a voltage converter that converts an input voltage and effectively outputs a fixed voltage. DC/DC converters are divided into three categories: step-up DC/DC converters, step-down DC/DC converters, and step-up/step-down DC/DC converters. The DC-DC converter is generally composed of a control chip, an inductor, a diode, a transistor, and a capacitor. The PFM control type has an advantage of low power consumption even when used for a long time, particularly when used under a small load. The PWM/PFM switching type PFM control is carried out at the time of a small load, and is automatically switched to the PWM control at the time of a heavy load. The DC-DC converter is widely applied to products such as mobile phones, MP3 s, digital cameras, portable media players and the like. Belonging to chopper circuits in circuit type classification.

In a soft start circuit and a short-circuit protection circuit of a conventional DC-DC converter, if the output voltage (A400) of a module is too high, when the voltage of a restart signal (A105, A106) inside a chip arrives, the capacitor needs to be discharged for a long time, so that ground overshoot caused in the restart process of the chip can be caused, the error of the chip is caused, and if the voltage of the A400 is too low, the output voltage of the chip cannot reach a target value, and the start fails.

Disclosure of Invention

The invention aims to provide a starting protection module for a DC-DC converter, which can realize the soft shutdown of the DC-DC converter and the soft starting function after short-circuit protection, and effectively avoid the overshoot of output voltage when a DC-DC circuit recovers under the conditions of short circuit, over-temperature and the like.

The technical scheme adopted by the invention is as follows:

a starting protection module for a DC-DC converter comprises a soft start circuit, an MOS feedback loop and a capacitor C;

the MOS feedback loop comprises an MP module and an MN module, the soft start circuit is respectively connected with the MP module and the MN module, and the MP module and the MN module are both connected with a capacitor C;

the soft start circuit comprises a PMOS module, an NMOS module and a control module, wherein the PMOS module is connected with the NMOS module, the MP module, the MN module and the control module, the NMOS module is connected with the PMOS module, the MN module, a capacitor C and the control module, and the control module is also connected with the capacitor C and the MN module;

when the DC-DC converter is closed or abnormal protection is carried out, the MP module and the MN module discharge a capacitor C, so that the voltage C of the capacitor is lower than the voltage of an MOS feedback loop.

In a preferred scheme, the MP module includes a PMOS transistor VR8, a PMOS transistor VR9 and a PMOS transistor VR10, the G-pole of the PMOS transistor VR8 is connected to the input FB, the S-pole of the PMOS transistor VR8 is connected to the S-pole of the PMOS transistor VR9, the S-pole of the PMOS transistor VR10 and the PMOS module, the D-pole of the PMOS transistor VR8 is connected to the MN module, the G-pole of the PMOS transistor VR9 is connected to the MN module, the D-pole of the PMOS transistor VR9 is connected to the D-pole of the PMOS transistor VR10 and the MN module, and the G-pole of the PMOS transistor VR10 is connected to the output a502.

In a preferred embodiment, the MN module includes an NMOS transistor VR18, an NMOS transistor VR19, an NMOS transistor VR20, an NMOS transistor VR21, an NMOS transistor VR22, an NMOS transistor VR23, an NMOS transistor VR24, an NMOS transistor VR25, an NMOS transistor VR26, a resistor R2, and a resistor R3, a G-pole of the NMOS transistor VR18 is connected to a D-pole of the NMOS transistor VR18, one end of the capacitor C, a G-pole of the NMOS transistor VR19, and a control module, an S-pole of the NMOS transistor VR18 is connected to a D-pole of the NMOS transistor VR21, a D-pole of the NMOS transistor VR25, and a D-pole of the NMOS transistor VR26, a D-pole of the NMOS transistor VR19 is connected to a PMOS module, an S-pole of the NMOS transistor VR19 is connected to one end of the resistor R2, an S-pole of the NMOS transistor VR19 is connected to an output terminal a400, a G-pole of the NMOS transistor VR20 is connected to an NMOS module, the D pole of NMOS transistor VR20 is connected with the other end of resistance R2 and the one end of resistance R3, the S pole of NMOS transistor VR20 and the S pole of NMOS transistor VR21, the S pole of NMOS transistor VR23, the S pole of NMOS transistor VR24, the S pole of NMOS transistor VR25 and the S pole of NMOS transistor VR26 are connected, the S pole of NMOS transistor VR20 is grounded, the other end of resistance R3 is connected with the G pole of PMOS transistor VR9, the G pole of NMOS transistor VR21 is connected with the D pole of PMOS transistor VR8 of NMOS transistor VR22, the G pole of NMOS transistor VR22 is connected with the G pole of NMOS transistor VR23, the G pole of NMOS transistor VR24, the D pole of NMOS transistor VR24 and the D pole of PMOS transistor VR9, the S pole of NMOS transistor VR22 is connected with the D pole of NMOS transistor VR23, the G pole of NMOS transistor VR25 is connected with input terminal A106, and the G pole of NMOS transistor VR26 is connected with input terminal A105.

In a preferred embodiment, the PMOS module includes PMOS transistor VR1, PMOS transistor VR2, PMOS transistor VR3, PMOS transistor VR4, PMOS transistor VR5, PMOS transistor VR6, PMOS transistor VR7, and resistor R1, the S pole of PMOS transistor VR1 is connected to the S pole of PMOS transistor VR2, the S pole of PMOS transistor VR1 is connected to the power input, the G pole of PMOS transistor VR1 is connected to the G pole of PMOS transistor VR2, the G pole of PMOS transistor VR3, the D pole of PMOS transistor VR3, and the NMOS module, the D pole of PMOS transistor VR1 is connected to the control module, the D pole of PMOS transistor VR2 is connected to the S pole of PMOS transistor VR8, the S pole of PMOS transistor VR3 is connected to one end of resistor R1, the S pole of PMOS transistor VR4, the S pole of PMOS transistor VR5, the D pole of NMOS transistor VR19, the other end of resistor R1 is connected to the output, the G pole of PMOS transistor VR4 is connected to the D pole of PMOS transistor VR4, the S pole of PMOS transistor VR5, the D pole of PMOS transistor VR5 is connected to the D pole of PMOS transistor VR6, and the D pole of PMOS transistor VR4 is connected to the D pole of PMOS transistor VR4, the PMOS transistor VR6, and the D pole of PMOS transistor VR6 is connected to the PMOS transistor VR6, and the D pole of PMOS transistor VR transistor.

In a preferred embodiment, the NMOS module includes an NMOS transistor VR11, an NMOS transistor VR12, an NMOS transistor VR13, an NMOS transistor VR14, an NMOS transistor VR15, an NMOS transistor VR16, and an NMOS transistor VR17, a G pole of the NMOS transistor VR11 is connected to a D pole of the NMOS transistor VR11, a G pole of the NMOS transistor VR12, a G pole of the NMOS transistor VR17, a G pole of the NMOS transistor VR16, a G pole of the NMOS transistor VR15, a G pole of the NMOS transistor VR14, a G pole of the NMOS transistor VR13, and a G pole of the NMOS transistor VR20, a D pole of the NMOS transistor VR11 is connected to the input IB, a S pole of the NMOS transistor VR11 is connected to a S pole of the NMOS transistor VR12, a S pole of the NMOS transistor VR17, the other end of the capacitor C, and a S pole of the NMOS transistor VR20, a D pole of the NMOS transistor VR12 is connected to a D pole of the PMOS transistor VR3, a D pole of the NMOS transistor VR13 is connected to a D pole of the PMOS transistor VR4, a S pole of the NMOS transistor VR13 is connected to a D pole of the NMOS transistor VR14, and a D pole of the NMOS transistor VR16 is connected to the NMOS transistor VR 16.

In a preferred scheme, the control module comprises a switch S1 and a switch S2, one end of the switch S1 is connected with a D pole of a PMOS transistor VR1, the other end of the switch S1 is connected with one end of the switch S2 and a D pole of an NMOS transistor VR18, and the other end of the switch S2 is connected with a D pole of a PMOS transistor VR 7.

In a preferred embodiment, the S-pole of the PMOS transistor VR1 and the S-pole of the PMOS transistor VR3 are connected to the NTC thermistor RT.

The invention has the technical effects that:

according to the invention, when the DC-DC converter is turned off or short-circuit protection and over-temperature protection are carried out, the capacitor C is discharged through the MOS feedback loop, so that the voltage of the capacitor C is slightly lower than the voltage of the MOS feedback loop, the negative MOS feedback loop is adopted to generate a soft start voltage slightly higher than the voltage of the MOS feedback loop, the soft start function is realized, voltage overshoot is avoided, the soft start function after the soft turn-off and short-circuit protection of the DC-DC converter is realized, and the output voltage overshoot of the DC-DC converter during recovery under the conditions of short circuit, over-temperature and the like is effectively avoided.

Drawings

Fig. 1 is a schematic diagram of the circuit structure of the present invention.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.

Furthermore, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation of the invention. The appearances of the phrase "in one preferred embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.

Furthermore, the present invention is described in detail with reference to the drawings, and in the detailed description of the embodiments of the present invention, the drawings are only examples for convenience of illustration, and should not be construed as limiting the scope of the present invention.

Referring to fig. 1, a first embodiment of the present invention provides a start protection module for a DC-DC converter, which includes a soft start circuit, a MOS feedback loop and a capacitor C, where the MOS feedback loop includes an MP module and an MN module, the soft start circuit is connected to the MP module and the MN module respectively, the MP module and the MN module are both connected to the capacitor C, the soft start circuit includes a PMOS module, an NMOS module and a control module, the PMOS module is connected to the NMOS module, the MP module, the MN module and the control module, the NMOS module is connected to the PMOS module, the MN module, the capacitor C and the control module, and the control module is further connected to the capacitor C and the MN module, where in soft start, the negative MOS feedback loop generates a soft start voltage higher than a voltage of the MOS feedback loop, and in shutdown or abnormal protection of the DC-DC converter, the MP module and the MN module discharge the capacitor C, so that the capacitor voltage C is lower than the voltage of the MOS feedback loop.

Specifically, when the DC-DC converter is turned off or short-circuit protection and over-temperature protection are carried out, the capacitor C is discharged through the MOS feedback loop, so that the voltage of the capacitor C is slightly lower than the voltage of the MOS feedback loop, a negative MOS feedback loop is adopted to generate a soft start voltage which is slightly higher than the voltage of the MOS feedback loop, the soft start function is realized, voltage overshoot is avoided, the soft start function after the soft turn-off and short-circuit protection of the DC-DC converter is realized, and the output voltage overshoot of the DC-DC circuit during recovery under the conditions of short circuit, over-temperature and the like is effectively avoided.

In a preferred embodiment, the MP module includes a PMOS transistor VR8, a PMOS transistor VR9 and a PMOS transistor VR10, wherein a G-pole of the PMOS transistor VR8 is connected to the input FB, an S-pole of the PMOS transistor VR8 is connected to an S-pole of the PMOS transistor VR9, an S-pole of the PMOS transistor VR10 is connected to the PMOS module, a D-pole of the PMOS transistor VR8 is connected to the MN module, a G-pole of the PMOS transistor VR9 is connected to the MN module, a D-pole of the PMOS transistor VR9 is connected to a D-pole of the PMOS transistor VR10 and the MN module, and a G-pole of the PMOS transistor VR10 is connected to the output a502.

Secondly, the MN module comprises an NMOS transistor VR18, an NMOS transistor VR19, an NMOS transistor VR20, an NMOS transistor VR21, an NMOS transistor VR22, an NMOS transistor VR23, an NMOS transistor VR24, an NMOS transistor VR25, an NMOS transistor VR26, a resistor R2 and a resistor R3;

the G pole of the NMOS transistor VR18 is connected with the D pole of the NMOS transistor VR18, one end of the capacitor C, the G pole of the NMOS transistor VR19 and the control module, the S pole of the NMOS transistor VR18 is connected with the D pole of the NMOS transistor VR21, the D pole of the NMOS transistor VR25 and the D pole of the NMOS transistor VR26, the D pole of the NMOS transistor VR19 is connected with the PMOS module, the S pole of the NMOS transistor VR19 is connected with one end of the resistor R2, the S pole of the NMOS transistor VR19 is connected with the output end A400, the G pole of the NMOS transistor VR20 is connected with the NMOS module, the D pole of the NMOS transistor VR20 is connected with the other end of the resistor R2 and one end of the resistor R3, the S pole of the NMOS transistor VR20 is connected with the S pole of the NMOS transistor VR21, the S pole of the NMOS transistor VR23, the S pole of the NMOS transistor VR24, the S pole of the NMOS transistor VR25 is connected with the S pole of the NMOS transistor VR26, the S pole of the NMOS transistor VR20 is grounded, the other end of the resistor R3 is connected with the G pole of the PMOS transistor VR9, the G pole of the NMOS transistor VR21 is connected with the D pole of the PMOS transistor VR8 of the NMOS transistor VR22, the G pole of the NMOS transistor VR22 is connected with the G pole of the NMOS transistor VR23, the G pole of the NMOS transistor VR24, the D pole of the NMOS transistor VR24 is connected with the D pole of the PMOS transistor VR9, the S pole of the NMOS transistor VR22 is connected with the D pole of the NMOS transistor VR23, the G pole of the NMOS transistor VR25 is connected with the input end A106, and the G pole of the NMOS transistor VR26 is connected with the input end A105.

It should be noted that the input terminal a105 and the input terminal a106 are connected to a control chip, and in the DC-DC converter, the application of the control chip is relatively wide, wherein circuit control is relatively common, and is a mature technology in the prior art, and redundant description is not repeated here.

It should be noted that the output voltage a400 of the module can be stabilized at a voltage higher than the output voltage FB by a feedback loop formed by the MP module and the MN module.

Secondly, the PMOS module comprises a PMOS transistor VR1, a PMOS transistor VR2, a PMOS transistor VR3, a PMOS transistor VR4, a PMOS transistor VR5, a PMOS transistor VR6, a PMOS transistor VR7 and a resistor R1;

the S pole of the PMOS transistor VR1 is connected with the S pole of the PMOS transistor VR2, the S pole of the PMOS transistor VR1 is connected with the power input end, the G pole of the PMOS transistor VR1 is connected with the G pole of the PMOS transistor VR2, the G pole of the PMOS transistor VR3, the D pole of the PMOS transistor VR3 is connected with the NMOS module, the D pole of the PMOS transistor VR1 is connected with the control module, the D pole of the PMOS transistor VR2 is connected with the S pole of the PMOS transistor VR8, the S pole of the PMOS transistor VR3 is connected with one end of the resistor R1, the S pole of the PMOS transistor VR4, the S pole of the PMOS transistor VR5 is connected with the D pole of the NMOS transistor VR19, the other end of the resistor R1 is connected with the output end, the G pole of the PMOS transistor VR4 is connected with the D pole of the PMOS transistor VR4, the NMOS module, the G pole of the PMOS transistor VR5, the G pole of the PMOS transistor VR6, the G pole of the PMOS transistor VR7 is connected with the G pole of the PMOS transistor VR7, the D pole of the PMOS transistor VR5 is connected with the S pole of the PMOS transistor VR6, and the control module.

Still further, the S-pole of the PMOS transistor VR1 and the S-pole of the PMOS transistor VR3 are connected to the power input terminal with an NTC thermistor RT.

In the embodiment, before the current is input at the power input end, because the NTC thermistor RT has low temperature, the surge current when the current is input at the power input end can be well limited, after the current is input at the power input end, the NTC thermistor RT has high temperature and greatly reduced resistance, and excessive loss can not be generated, so that when the power input end is started to input the current, the large current generated in the process is subjected to current limiting protection through the NTC thermistor RT, and when the NTC thermistor RT enters the PMOS module, the NTC thermistor RT rapidly heats along with the temperature rise, the resistance value of the NTC thermistor can be rapidly reduced to a very small level within millisecond-level time, generally, the resistance value is only a few tenths of zero to a few ohms, and compared with the situation that the power lost on the resistor is reduced by dozens of times or even hundreds of times, the capability of inhibiting the surge current is strong, the reliability is high, the service life is long, and the residual resistance is small.

Secondly, the NMOS module comprises an NMOS transistor VR11, an NMOS transistor VR12, an NMOS transistor VR13, an NMOS transistor VR14, an NMOS transistor VR15, an NMOS transistor VR16 and an NMOS transistor VR17;

the G pole of the NMOS transistor VR11 is connected with the D pole of the NMOS transistor VR11, the G pole of the NMOS transistor VR12, the G pole of the NMOS transistor VR17, the G pole of the NMOS transistor VR16, the G pole of the NMOS transistor VR15, the G pole of the NMOS transistor VR14, the G pole of the NMOS transistor VR13 and the G pole of the NMOS transistor VR20, the D pole of the NMOS transistor VR11 is connected with the input terminal IB, the S pole of the NMOS transistor VR11 is connected with the S pole of the NMOS transistor VR12, the S pole of the NMOS transistor VR17, the other end of the capacitor C is connected with the S pole of the NMOS transistor VR20, the D pole of the NMOS transistor VR12 is connected with the D pole of the PMOS transistor VR3, the D pole of the NMOS transistor VR13 is connected with the D pole of the PMOS transistor VR4, the S pole of the NMOS transistor VR13 is connected with the D pole of the NMOS transistor VR14, the S pole of the NMOS transistor VR14 is connected with the D pole of the NMOS transistor VR15, the S pole of the NMOS transistor VR15 is connected with the NMOS transistor VR15, the D pole of the NMOS transistor VR15 is connected with the D pole of the NMOS transistor VR15, and the S pole of the NMOS transistor VR16 is connected with the NMOS transistor VR 16.

It should be noted that the input end IB is connected to the control chip, and in the DC-DC converter, the application of the control chip is relatively wide, where circuit control is common and is a mature technology in the prior art, and therefore, redundant description is not repeated here.

And the control module comprises a switch S1 and a switch S2, one end of the switch S1 is connected with the D pole of the PMOS transistor VR1, the other end of the switch S1 is connected with one end of the switch S2 and the D pole of the NMOS transistor VR18, and the other end of the switch S2 is connected with the D pole of the PMOS transistor VR 7.

It should be noted that one end of the switch S1 is connected to the soft start terminal SS for transmitting the soft start signal.

As described above, the feedback loop formed by the MP module and the MN module stabilizes the output voltage a400 of the module at a voltage higher than the output voltage FB by a certain amount, and when the voltage of a400 is too high, and when the voltages of a105 and a106 (restart signals inside the chip) come, the discharging process of the capacitor C is reduced, so that the overshoot caused during the restart of the chip is avoided, and when the voltage of a400 is too low, the output voltage of the chip can reach the target value, and the start is completed.

The working principle of the invention is as follows: when the DC-DC converter is turned off or short-circuit protection and over-temperature protection are carried out, the capacitor C is discharged through the MOS feedback loop, so that the voltage of the capacitor C is slightly lower than that of the MOS feedback loop, a negative MOS feedback loop is adopted to generate a soft start voltage which is slightly higher than that of the MOS feedback loop, a soft start function is realized, voltage overshoot is avoided, the soft start function after the soft turn-off and short-circuit protection of the DC-DC converter is realized, and output voltage overshoot when the DC-DC circuit recovers under the conditions of short circuit, over-temperature protection and the like is effectively avoided.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and amendments can be made without departing from the principle of the present invention, and these modifications and amendments should also be considered as the protection scope of the present invention. Structures, devices, and methods of operation not specifically described or illustrated herein are not specifically illustrated or described, but are instead contemplated to be practiced in the art by those skilled in the art.

Claims

1. A start-up protection module for a DC-DC converter, characterized by: the soft start circuit comprises a soft start circuit, an MOS feedback loop and a capacitor C;

when the DC-DC converter is closed or is abnormally protected, the MP module and the MN module discharge a capacitor C, so that the capacitor voltage C is lower than the voltage of an MOS feedback loop.

2. The startup protection module for a DC-DC converter according to claim 1, characterized in that: the MP module comprises a PMOS transistor VR8, a PMOS transistor VR9 and a PMOS transistor VR10, the G pole of the PMOS transistor VR8 is connected with the input end FB, the S pole of the PMOS transistor VR8 is connected with the S pole of the PMOS transistor VR9, the S pole of the PMOS transistor VR10 and the PMOS module, the D pole of the PMOS transistor VR8 is connected with the MN module, the G pole of the PMOS transistor VR9 is connected with the MN module, the D pole of the PMOS transistor VR9 is connected with the D pole of the PMOS transistor VR10 and the MN module, and the G pole of the PMOS transistor VR10 is connected with the output end A502.

3. A start-up protection module for a DC-DC converter according to claim 2, characterized in that: the MN module comprises an NMOS transistor VR18, an NMOS transistor VR19, an NMOS transistor VR20, an NMOS transistor VR21, an NMOS transistor VR22, an NMOS transistor VR23, an NMOS transistor VR24, an NMOS transistor VR25, an NMOS transistor VR26, a resistor R2 and a resistor R3, the G pole of the NMOS transistor VR18 is connected with the D pole of the NMOS transistor VR18, one end of a capacitor C, the G pole of the NMOS transistor VR19 and a control module, the S pole of the NMOS transistor VR18 is connected with the D pole of the NMOS transistor VR21, the D pole of the NMOS transistor VR25 and the D pole of the NMOS transistor VR26, the D pole of the NMOS transistor VR19 is connected with a PMOS module, the S pole of the NMOS transistor VR19 is connected with one end of the resistor R2, the S pole of the NMOS transistor VR19 is connected with an output end A400, the G pole of the NMOS transistor VR20 is connected with the NMOS module, the D pole of the NMOS transistor VR20 is connected with the other end of the resistor R2 and one end of the resistor R3, the S pole of the NMOS transistor VR20 is connected with the S pole of the NMOS transistor VR21, the S pole of the NMOS transistor VR23, the S pole of the NMOS transistor VR24, the S pole of the NMOS transistor VR25 and the S pole of the NMOS transistor VR26, the S pole of the NMOS transistor VR20 is grounded, the other end of the resistor R3 is connected with the G pole of the PMOS transistor VR9, the G pole of the NMOS transistor VR21 is connected with the D pole of the PMOS transistor VR8 of the NMOS transistor VR22, the G pole of the NMOS transistor VR22 is connected with the G pole of the NMOS transistor VR23, the G pole of the NMOS transistor VR24, the D pole of the NMOS transistor VR24 and the D pole of the PMOS transistor VR9, the S pole of the NMOS transistor VR22 is connected with the D pole of the NMOS transistor VR23, the G pole of the NMOS transistor VR25 is connected with the input end A106, and the G pole of the NMOS transistor VR26 is connected with the input end A105.

4. A start-up protection module for a DC-DC converter according to claim 3, wherein: the PMOS module comprises a PMOS transistor VR1, a PMOS transistor VR2, a PMOS transistor VR3, a PMOS transistor VR4, a PMOS transistor VR5, a PMOS transistor VR6, a PMOS transistor VR7 and a resistor R1, the S pole of the PMOS transistor VR1 is connected with the S pole of the PMOS transistor VR2, the S pole of the PMOS transistor VR1 is connected with the power input end, the G pole of the PMOS transistor VR1 is connected with the G pole of the PMOS transistor VR2, the G pole of the PMOS transistor VR3, the D pole of the PMOS transistor VR3 and the NMOS module, the D pole of the PMOS transistor VR1 is connected with the control module, the D pole of the PMOS transistor VR2 is connected with the S pole of the PMOS transistor VR8, the S pole of the PMOS transistor VR3 is connected with one end of the resistor R1, the S pole of the PMOS transistor VR4, the S pole of the PMOS transistor VR5 and the D pole of the NMOS transistor VR19, the other end of the resistor R1 is connected with the output end, the G pole of the PMOS transistor VR4 is connected with the D pole of the PMOS transistor VR4, the NMOS module, the G pole of the PMOS transistor VR5, the G pole of the PMOS transistor VR6 is connected with the D pole of the PMOS transistor VR6, the PMOS transistor VR6 is connected with the S pole of the PMOS transistor VR6, and the S pole of the PMOS transistor VR6 are connected with the PMOS transistor VR6, and the S pole of the PMOS transistor VR6, and the PMOS transistor VR6 are connected with the S pole of the PMOS transistor VR6, and the S pole of the PMOS transistor VR6 are connected with the PMOS transistor.

5. The start-up protection module for a DC-DC converter according to claim 4, wherein: the NMOS module comprises an NMOS transistor VR11, an NMOS transistor VR12, an NMOS transistor VR13, an NMOS transistor VR14, an NMOS transistor VR15, an NMOS transistor VR16 and an NMOS transistor VR17, the G pole of the NMOS transistor VR11 is connected with the D pole of the NMOS transistor VR11, the G pole of the NMOS transistor VR12, the G pole of the NMOS transistor VR17, the G pole of the NMOS transistor VR16, the G pole of the NMOS transistor VR15, the G pole of the NMOS transistor VR14, the G pole of the NMOS transistor VR13 and the G pole of the NMOS transistor VR20, the D pole of the NMOS transistor VR11 is connected with an input end IB, the S pole of the NMOS transistor VR11 is connected with the S pole of the NMOS transistor VR12, the S pole of the NMOS transistor VR17, the other end of the capacitor C and the S pole of the NMOS transistor VR20, the D pole of the NMOS transistor VR12 is connected with the D pole of the PMOS transistor VR3, the D pole of the NMOS transistor VR13 is connected with the D pole of the PMOS transistor VR4, the S pole of the NMOS transistor VR13 is connected with the D pole of the NMOS transistor VR14, and the NMOS transistor VR14 is connected with the S pole of the NMOS transistor VR15, and the NMOS transistor VR16 is connected with the NMOS transistor D pole of the NMOS transistor VR 15.

6. The start-up protection module for a DC-DC converter according to claim 4, wherein: the control module comprises a switch S1 and a switch S2, one end of the switch S1 is connected with the D pole of the PMOS transistor VR1, the other end of the switch S1 is connected with one end of the switch S2 and the D pole of the NMOS transistor VR18, and the other end of the switch S2 is connected with the D pole of the PMOS transistor VR 7.

7. The start-up protection module for a DC-DC converter according to claim 4, wherein: and the S pole of the PMOS transistor VR1 and the S pole of the PMOS transistor VR3 are connected with a power supply input end by an NTC thermistor RT.