Linear slow start circuit and control method

Abstract

The invention provides a linear slow start circuit and a control method. The circuit comprises a pre-start module, a constant current module, a slow start module and a slow start NMOS tube. Wherein the pre-starting module is used for receiving an input voltage and carrying out rapid pre-charging on the slow starting module through delayed power-on, so that the output voltage of the slow starting module is a reverse input voltage; the constant-current module is used for performing a constant-current discharging process based on a reverse input voltage after the rapid pre-charging is finished; the slow start module is used for obtaining a reverse input voltage through rapid pre-charging and carrying out a constant-current discharging process through the constant-current module based on the reverse input voltage after the rapid pre-charging is finished, so that the output voltage of the slow start module is linearly reduced, and the slow start NMOS tube enters a linear opening state; therefore, the output voltage of the slow start circuit is linearly increased, and the linear slow start of the circuit is realized. The invention provides a linear slow start circuit and a control method. The linear characteristic of slope climbing of output voltage of the slow start circuit is achieved.

Description

Technical Field

[0001] The present invention relates to the field of electrical technology and power supply technology, and in particular to a linear slow-start circuit and a control method. Background Art

[0002] In the design of 12V and 28V low-voltage DC power supply systems, it is usually necessary to place anti-reverse connection and slow start circuits at the DC power supply input port. At present, most of the industry adopts a nonlinear simple solution to achieve input reverse connection protection and output slow start. At the beginning of startup, the output voltage rising slope (V / us) of this circuit is unstable, and the curve with a local rise that is too fast causes surge current. The curve that is too slow is prone to MOS tube damage. It does not meet the reliability requirements of actual projects, nor is it conducive to the reliability design of DC power supply system applications, resulting in difficulties in the design of low-voltage DC power supply systems, poor suppression of power-on impact current, and low reliability.

[0003] In order to solve this difficulty, it is necessary to propose an anti-reverse connection slow start circuit that can realize linear slow start to meet the design requirements of most low-voltage DC power supply systems and obtain more and more extensive applications. Summary of the invention

[0004] The present invention aims to provide a linear slow start circuit and a control method to solve the above technical problems and realize linear slow start.

[0005] In order to solve the above technical problems, the present invention provides a linear slow start circuit, which includes: a pre-start module, a constant current module, a slow start module and a slow start NMOS tube; wherein:

[0006] The positive input end of the pre-start module serves as the positive input end of the slow-start circuit, the negative input end of the pre-start module serves as the negative input end of the slow-start circuit, the positive input end of the pre-start module is electrically connected to the input end of the constant current module, the constant current end of the pre-start module is electrically connected to the pre-start end of the constant current module, the negative output end of the pre-start module is electrically connected to the output end of the constant current module, and the positive output end of the pre-start module is electrically connected to the source of the slow-start NMOS tube;

[0007] The output end of the constant current module is electrically connected to the gate of the slow-start NMOS tube, and the input end of the constant current module serves as the positive output end of the slow-start circuit;

[0008] The gate of the slow-start NMOS tube is electrically connected to the input end of the slow-start module, and the drain of the slow-start NMOS tube is electrically connected to the output end of the slow-start module;

[0009] The output end of the slow start module serves as the negative output end of the slow start circuit;

[0010] The pre-start module is used to receive an input voltage and quickly pre-charge the slow-start module by delaying power-on, so that the output voltage of the slow-start module is the reverse input voltage;

[0011] The constant current module is used to perform a constant current discharge process based on a reverse input voltage after the fast pre-charging is completed;

[0012] The slow start module is used to perform fast pre-charging through the pre-start module, so that when the fast pre-charging ends, the output voltage of the slow start module is the reverse input voltage, and after the fast pre-charging ends, a constant current discharge process is performed through the constant current module based on the reverse input voltage, so that the output voltage of the slow start module decreases linearly, and the slow start NMOS tube enters a linear on state, so that the output voltage of the slow start circuit increases linearly, realizing the linear characteristic of the output voltage slope climbing of the slow start circuit.

[0013] The circuit provided by the above scheme first uses the input voltage to perform rapid pre-charging through the pre-start module, so that the slow-start capacitor reaches a certain amount of charge in a short time, ensuring that the slow-start process can start quickly and reducing the start-up delay; and after the pre-charging is completed, the constant current module discharges the slow-start capacitor at a constant current rate, so that the output voltage of the slow-start module decreases linearly, and then the slow-start NMOS tube is controlled to enter a linear on state, thereby realizing a linear increase in the output voltage of the slow-start circuit. The slow-start circuit has a simple structure and can realize linear slow-start of the DC power supply while making the DC power supply system design more concise.

[0014] Further, the pre-start module includes: a pre-start diode group, a pre-start capacitor, a first voltage-dividing resistor, a second voltage-dividing resistor, a third voltage-dividing resistor, a pre-start transistor and a clamping diode, wherein:

[0015] The anode of the pre-start diode group serves as the positive input terminal of the pre-start module, the cathode of the pre-start diode group serves as the constant current terminal of the pre-start module, the cathode of the pre-start diode group is electrically connected to the first end of the pre-start capacitor, and the cathode of the pre-start diode group is electrically connected to the first end of the third voltage-dividing resistor;

[0016] The second end of the pre-start capacitor is electrically connected to the first end of the first voltage-dividing resistor;

[0017] The second end of the first voltage-dividing resistor is electrically connected to the first end of the second voltage-dividing resistor;

[0018] The first end of the second voltage-dividing resistor is electrically connected to the anode of the clamping diode, the second end of the second voltage-dividing resistor is electrically connected to the cathode of the clamping diode, and the second end of the second voltage-dividing resistor is electrically connected to the base of the pre-starting transistor;

[0019] The emitter of the pre-start transistor is electrically connected to the second end of the third voltage-dividing resistor, the emitter of the pre-start transistor serves as the positive output end of the pre-start module, and the collector of the pre-start transistor serves as the negative output end of the pre-start module;

[0020] The second end of the third voltage-dividing resistor serves as a negative input end of the pre-start module;

[0021] The pre-start module receives the input voltage and quickly pre-charges the slow start module by delaying power-on, so that the output voltage of the slow start module is the reverse input voltage. The process includes:

[0022] The input voltage passes through the pre-start diode group and is divided by the third voltage-dividing resistor, and then the pre-start capacitor is charged. The first voltage-dividing resistor and the second voltage-dividing resistor are used to divide the pre-start capacitor, thereby driving the base of the pre-start transistor, and the base voltage of the pre-start transistor is clamped by the clamping diode, so that the pre-start transistor enters the on state, so that the voltage across the slow-start module is the reverse input voltage, and the fast pre-charging of the slow-start module is realized;

[0023] After the fast pre-charge is completed, the pre-start transistor is in the cut-off state.

[0024] In the above scheme, a pre-start circuit is composed of a pre-start diode group, a pre-start capacitor, a voltage-dividing resistor, a clamping diode and a pre-start transistor to achieve rapid pre-charging of the slow-start module. During this process, the clamping diode clamps the base voltage of the pre-start transistor to make it in a conducting state, and the slow-start module enters the dead time. At this time, the positive and negative output ends of the slow-start circuit are equipotential points, and the emitter and collector of the pre-start transistor are also equipotential points, so that the voltage of the slow-start module is the reverse input voltage. After the pre-start capacitor is fully charged, that is, after the rapid pre-charging is completed, the pre-start transistor is cut off. At this time, current continues to exist on the pre-start diode group, forming a fixed series voltage drop value.

[0025] Furthermore, the constant current module includes: a constant current resistor and a constant current transistor, wherein:

[0026] The output end of the constant current resistor is electrically connected to the emitter of the constant current transistor, the input end of the constant current resistor serves as the input end of the constant current module, the collector of the constant current transistor serves as the output end of the constant current module, and the base of the constant current transistor serves as the pre-start end of the constant current module;

[0027] The constant current module is used to perform a constant current discharge process to the constant current resistor and the constant current transistor based on the reverse input voltage after the fast pre-charging is completed.

[0028] In the above scheme, the reverse input voltage discharges the constant current module through the virtually shorted positive and negative output terminals of the slow-start circuit, causing the reverse input voltage to drop linearly, thereby causing the voltage between the positive and negative output terminals of the slow-start circuit to rise linearly.

[0029] Furthermore, the constant current module also includes: a protection diode, an anode of the protection diode is electrically connected to the base of the constant current transistor, and a cathode of the protection diode is electrically connected to the emitter of the constant current transistor.

[0030] In the above scheme, a protection diode is added to the constant current module to protect the constant current transistor from reverse voltage damage caused by a small leakage current generated during reverse voltage and from high voltage damage.

[0031] Further, the slow start module includes: a slow start capacitor, wherein:

[0032] The first end of the slow-start capacitor is used as the input end of the slow-start module, and the second end of the slow-start capacitor is used as the output end of the slow-start module;

[0033] The slow-start capacitor is used to perform fast pre-charging through the pre-start module, so that when the fast pre-charging is completed, the output voltage of the slow-start module is the reverse input voltage, and after the fast pre-charging is completed, a constant current discharge is performed through the constant current module based on the reverse input voltage, so that the output voltage of the slow-start module decreases linearly, and the slow-start NMOS tube enters the linear region and turns on, so that the output voltage of the DC power supply rises linearly, realizing the linear slow start of the slow-start circuit.

[0034] In the above scheme, the slow start module performs the charging and discharging process through the slow start capacitor. First, the reverse input voltage is obtained by fast pre-charging based on the pre-start module. Then, the reverse input voltage of the slow start capacitor passes through the virtually shorted positive and negative output terminals of the slow start circuit and performs a constant current discharge process through the constant current module. During the constant current discharge process, the reverse input voltage of the slow start capacitor decreases linearly, so that the voltage between the positive and negative output terminals of the slow start circuit produces a linear increase of the same amplitude, thereby realizing the linear slow start of the slow start circuit.

[0035] Furthermore, a linear slow start circuit also includes: a voltage stabilizing module, wherein:

[0036] The voltage stabilizing module includes a voltage stabilizing tube and a voltage stabilizing capacitor;

[0037] The anode of the voltage regulator tube is used as the input end of the voltage regulator module, the anode of the voltage regulator tube is electrically connected to the source of the slow-start NMOS tube, and the anode of the voltage regulator tube is electrically connected to the first end of the voltage regulator capacitor;

[0038] The cathode of the voltage regulator tube serves as the output end of the voltage regulator module, the cathode of the voltage regulator tube is electrically connected to the gate of the slow-start NMOS tube, and the cathode of the voltage regulator tube is electrically connected to the second end of the voltage regulator capacitor;

[0039] The voltage regulator module is used to control the slow-start output voltage within the preset voltage threshold through the clamping voltage of the voltage regulator tube during the fast pre-charging process, and after the slow-start is completed, the voltage regulator tube clamps the voltage across the voltage regulator capacitor to charge the voltage regulator capacitor to the preset voltage threshold, thereby making the slow-start NMOS tube fully turned on, and finally realizing the regulated output of the slow-start circuit.

[0040] In the above scheme, the voltage stabilizing module ensures that the slow-start NMOS tube will not be damaged by controlling the slow-start output voltage within the preset voltage threshold and clamping the voltage after the slow-start is completed to make the slow-start NMOS tube fully turned on, thereby achieving the regulated output of the slow-start circuit and achieving the equal potential of the positive output terminal and the positive input terminal, and the equal potential of the negative output terminal and the negative input terminal of the slow-start circuit.

[0041] Furthermore, a linear slow start circuit also includes: an anti-reverse connection NMOS tube, wherein:

[0042] The source of the reverse connection protection NMOS tube is electrically connected to the source of the slow start NMOS tube, the source of the reverse connection protection NMOS tube is electrically connected to the negative input terminal of the pre-start module, the gate of the reverse connection protection NMOS tube is electrically connected to the gate of the slow start NMOS tube, and at this time, the drain of the reverse connection protection NMOS tube replaces the negative input terminal of the pre-start module as the negative input terminal of the slow start circuit;

[0043] The anti-reverse connection NMOS tube is used to enter the fully conductive state after the linear slow start is completed;

[0044] The anti-reverse connection NMOS tube is used for when the input voltage is reversed, the drain of the anti-reverse connection NMOS tube is in a reverse bias state, so that the anti-reverse connection NMOS tube is in a cut-off state, thereby realizing the anti-reverse connection protection of the slow start circuit.

[0045] In the above scheme, the input voltage is reversed by adding an anti-reverse NMOS tube. When the input voltage is reversed, since the anti-reverse NMOS tube is in a reverse bias state, its internal diode is not turned on, and the back-end circuit cannot obtain voltage and current. The anti-reverse NMOS tube remains in the cut-off state, that is, the circuit enters the anti-reverse protection state.

[0046] The present invention provides a linear slow-start circuit, which firstly uses an input voltage to perform rapid pre-charging through a pre-start module, so that a slow-start capacitor reaches a certain charge amount in a short time, thereby ensuring that the slow-start process can start quickly and reducing the start delay; and after the pre-charging is completed, a constant current module discharges the slow-start capacitor at a constant current rate, so that the output voltage of the slow-start module decreases linearly, and then controls the slow-start NMOS tube to enter a linear on state, thereby realizing a linear increase in the output voltage of the slow-start circuit, and realizes a voltage-stabilizing output through a voltage-stabilizing module, and adds an anti-reverse connection NMOS tube to make the circuit have an anti-reverse connection effect; the linear slow-start circuit has a simple structure, has an anti-reverse connection effect, and can realize a linear slow-start of a DC power supply while making the design of a DC power supply system more concise.

[0047] The present invention also provides a control method for a linear slow start circuit, which is implemented by using a linear slow start circuit and includes the following steps:

[0048] Receiving an input voltage, and performing delayed power-on based on the input voltage to quickly pre-charge the slow-start module until the output voltage of the slow-start module is the reverse input voltage;

[0049] Then, the constant current module performs a constant current discharge process based on the reverse input voltage, so that the output voltage of the slow start module decreases linearly, and the slow start NMOS tube is controlled to enter a linear on state, so that the output voltage of the slow start circuit increases linearly, realizing linear slow start.

[0050] After receiving the input voltage, the above scheme realizes a linear rise of the output voltage through a simple delayed power-on, fast pre-charging and constant current discharge process, thereby achieving a linear slow start.

[0051] Furthermore, during the fast pre-charging process, the voltage is clamped by the voltage stabilizing module to control the output voltage of the slow start module within a preset voltage threshold, and after the slow start is completed, the voltage is clamped to make the slow start NMOS tube fully turned on, ultimately achieving a regulated output of the slow start circuit.

[0052] In the above scheme, by controlling the slow-start output voltage within a preset voltage threshold and performing voltage clamping after the slow-start is completed to make the slow-start NMOS tube fully turned on, it is ensured that the slow-start NMOS tube will not be damaged, and ultimately the slow-start circuit achieves a regulated output, achieving equal potential between the positive output terminal and the positive input terminal of the slow-start circuit, and equal potential between the negative output terminal and the negative input terminal.

[0053] Furthermore, when the input voltage is reversely connected, the drain of the anti-reverse-connection NMOS tube is in a reverse bias state, so that the anti-reverse-connection NMOS tube is in a cut-off state, thereby realizing the anti-reverse-connection protection of the slow start circuit.

[0054] In the above scheme, the input voltage reverse connection is prevented by the reverse connection NMOS tube. When the input voltage is reversed, since the reverse connection NMOS tube is in a reverse bias state, its internal diode is not turned on, and the back-end circuit cannot obtain voltage and current. The reverse connection NMOS tube remains in the cut-off state, that is, the circuit enters the reverse connection protection state.

[0055] The present invention provides a control method for a linear slow-start circuit. First, a quick pre-charging is performed based on an input voltage, so that a slow-start module reaches a certain amount of charge in a short time, thereby ensuring that the slow-start process can start quickly and reducing the start delay. After the pre-charging is completed, the method discharges at a constant current rate, so that the output voltage of the slow-start module decreases linearly. Then, a slow-start NMOS tube is controlled to enter a linear on state, thereby realizing a linear increase in the output voltage of the slow-start circuit. The circuit realizes a regulated output through a voltage stabilizing module, and an anti-reverse NMOS tube with an anti-reverse effect is added, thereby realizing a linear slow-start with an anti-reverse effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 A schematic diagram of a linear slow start circuit provided by an embodiment of the present invention;

[0057] Figure 2 A schematic diagram of a linear slow-start circuit with reverse connection protection provided by an embodiment of the present invention;

[0058] Figure 3 A schematic diagram of a linear slow start test waveform provided by an embodiment of the present invention;

[0059] Figure 4 A schematic diagram of a linear slow-start circuit with reverse connection protection provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0060] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0061] Embodiment 1:

[0062] This embodiment provides a linear slow start circuit, which includes: a pre-start module, a constant current module, a slow start module and a slow start NMOS tube; wherein:

[0063] The positive input end of the pre-start module serves as the positive input end of the slow-start circuit, the negative input end of the pre-start module serves as the negative input end of the slow-start circuit, the positive input end of the pre-start module is electrically connected to the input end of the constant current module, the constant current end of the pre-start module is electrically connected to the pre-start end of the constant current module, the negative output end of the pre-start module is electrically connected to the output end of the constant current module, and the positive output end of the pre-start module is electrically connected to the source of the slow-start NMOS tube;

[0064] The output end of the constant current module is electrically connected to the gate of the slow-start NMOS tube, and the input end of the constant current module serves as the positive output end of the slow-start circuit;

[0065] The gate of the slow-start NMOS tube is electrically connected to the input end of the slow-start module, and the drain of the slow-start NMOS tube is electrically connected to the output end of the slow-start module;

[0066] The output end of the slow start module serves as the negative output end of the slow start circuit;

[0067] The pre-start module is used to receive an input voltage and quickly pre-charge the slow-start module by delaying power-on, so that the output voltage of the slow-start module is the reverse input voltage;

[0068] The constant current module is used to perform a constant current discharge process based on a reverse input voltage after the fast pre-charging is completed;

[0069] The slow start module is used to perform fast pre-charging through the pre-start module, so that when the fast pre-charging ends, the output voltage of the slow start module is the reverse input voltage, and after the fast pre-charging ends, a constant current discharge process is performed through the constant current module based on the reverse input voltage, so that the output voltage of the slow start module decreases linearly, and the slow start NMOS tube enters a linear on state, so that the output voltage of the slow start circuit increases linearly, realizing the linear slow start of the circuit.

[0070] The circuit provided in this embodiment first uses the input voltage to perform rapid pre-charging through the pre-start module, so that the slow-start capacitor reaches a certain amount of charge in a short time, ensuring that the slow-start process can start quickly and reducing the start-up delay; and after the pre-charging is completed, the constant current module discharges the slow-start capacitor at a constant current rate, so that the output voltage of the slow-start module decreases linearly, and then the slow-start NMOS tube is controlled to enter a linear on state, thereby achieving a linear increase in the output voltage of the slow-start circuit. The slow-start circuit has a simple structure, which can realize the linear slow start of the DC power supply and make the DC power supply system design more concise.

[0071] In the specific implementation process, Figure 1As shown, +Vi represents the positive input terminal, -Vi represents the negative input terminal, +Vo represents the positive output terminal, -Vo represents the negative output terminal, and the input voltage slope starts vertically to enter this circuit: first, the pre-start module and the constant current module are used to form a control unit, and the slow start module is quickly pre-charged by delaying the power-on of the pre-start module when powered on; when the delayed power-on of the pre-start module ends, the slow start module is controlled to perform constant current discharge through the constant current module, so that the voltage Vc of the slow start module presents a linear decline state; in this circuit, it satisfies: Vgs = Vi-Vo-Vc (where: Vgs represents the voltage between the gate and the source of the slow start NMOS tube, Vi represents the input voltage, and Vo represents Output voltage, Vc represents the slow-start module voltage), Vi remains unchanged, Vc decreases slowly, so at this time Vo slowly increases with the slow decrease of Vc, Vgs is basically stable at 3~4V, that is, it is slowly turned on in the amplification range, thereby realizing the function of linear increase of output voltage (only when the Vgs voltage is at Vth (3~4V) can the slow-start NMOS tube be in the amplification range, and if Vgs suddenly becomes larger, it will cause full conduction, Vo will be equal to Vi, at this time Vgs conduction = -Vc conduction will cause the slow-start NMOS tube to be closed, which is contradictory); when the output voltage rises to the highest voltage (input voltage), the slow-start process ends.

[0072] Optionally, the pre-start module includes: a pre-start diode group, a pre-start capacitor, a first voltage-dividing resistor, a second voltage-dividing resistor, a third voltage-dividing resistor, a pre-start transistor and a clamping diode, wherein: the anode of the pre-start diode group serves as the positive input terminal of the pre-start module, the cathode of the pre-start diode group serves as the constant current terminal of the pre-start module, the cathode of the pre-start diode group is electrically connected to the first end of the pre-start capacitor, and the cathode of the pre-start diode group is electrically connected to the first end of the third voltage-dividing resistor; the second end of the pre-start capacitor is electrically connected to the first end of the first voltage-dividing resistor; the second end of the first voltage-dividing resistor is electrically connected to the first end of the second voltage-dividing resistor; the first end of the second voltage-dividing resistor is electrically connected to the anode of the clamping diode, the second end of the second voltage-dividing resistor is electrically connected to the cathode of the clamping diode, and the second end of the second voltage-dividing resistor is electrically connected to the base of the pre-start transistor; the emitter of the pre-start transistor is electrically connected to the second end of the third voltage-dividing resistor, and the emitter of the pre-start transistor is electrically connected to the second end of the The first electrode is used as the positive output terminal of the pre-start module, and the collector of the pre-start transistor is used as the negative output terminal of the pre-start module; the second end of the third voltage-dividing resistor is used as the negative input terminal of the pre-start module; the pre-start module receives the input voltage, and quickly pre-charges the slow-start module by delaying power-on, so that the output voltage of the slow-start module is the reverse input voltage process, including: the input voltage passes through the pre-start diode group, and after the input voltage is divided by the third voltage-dividing resistor, the pre-start capacitor is charged, and the first voltage-dividing resistor and the second voltage-dividing resistor are used to divide the pre-start capacitor, thereby driving the base of the pre-start transistor, and clamping the base voltage of the pre-start transistor by the clamping diode, so that the pre-start transistor enters the on state, so that the voltage across the slow-start module is the reverse input voltage, and the slow-start module is quickly pre-charged; after the fast pre-charging is completed, the pre-start transistor is in the off state.

[0073] In the specific implementation process, a pre-start circuit is composed of a pre-start diode group, a pre-start capacitor, a voltage-dividing resistor, a clamping diode and a pre-start transistor to achieve rapid pre-charging of the slow-start module. During this process, the clamping diode clamps the base voltage of the pre-start transistor to make it in an on state, and the slow-start module enters the dead time. At this time, the positive and negative output ends of the slow-start circuit are equipotential points, and the emitter and collector of the pre-start transistor are also equipotential points, so that the voltage of the slow-start module is the reverse input voltage. After the pre-start capacitor is fully charged, that is, after the rapid pre-charging is completed, the pre-start transistor is cut off. At this time, current continues to exist on the pre-start diode group, forming a fixed series voltage drop value.

[0074] Optionally, the constant current module includes: a constant current resistor and a constant current transistor, wherein:

[0075] The output end of the constant current resistor is electrically connected to the emitter of the constant current transistor, the input end of the constant current resistor serves as the input end of the constant current module, the collector of the constant current transistor serves as the output end of the constant current module, and the base of the constant current transistor serves as the pre-start end of the constant current module;

[0076] The constant current module is used to perform a constant current discharge process to the constant current resistor and the constant current transistor based on the reverse input voltage after the fast pre-charging is completed.

[0077] In the specific implementation process, the reverse input voltage performs constant current discharge on the constant current module through the virtually shorted positive and negative output terminals of the slow start circuit, causing the reverse input voltage to drop linearly, thereby causing the voltage between the positive and negative output terminals of the slow start circuit to rise linearly.

[0078] Optionally, the constant current module further includes: a protection diode, wherein the anode of the protection diode is electrically connected to the base of the constant current transistor, and the cathode of the protection diode is electrically connected to the emitter of the constant current transistor.

[0079] In the specific implementation process, a protection diode is added to the constant current module to protect the constant current transistor from reverse pressure damage caused by a small leakage current generated during reverse pressure and from high voltage damage.

[0080] Optionally, the slow start module includes: a slow start capacitor, wherein:

[0081] The first end of the slow-start capacitor is used as the input end of the slow-start module, and the second end of the slow-start capacitor is used as the output end of the slow-start module;

[0082] The slow-start capacitor is used to perform fast pre-charging through the pre-start module, so that when the fast pre-charging is completed, the output voltage of the slow-start module is the reverse input voltage, and after the fast pre-charging is completed, a constant current discharge is performed through the constant current module based on the reverse input voltage, so that the output voltage of the slow-start module decreases linearly, and the slow-start NMOS tube enters the linear region and turns on, so that the output voltage of the DC power supply rises linearly, realizing the linear slow start of the slow-start circuit.

[0083] In the specific implementation process, the slow start module performs a charging and discharging process through the slow start capacitor. First, a quick pre-charging is performed based on the pre-start module to obtain a reverse input voltage. Then, the reverse input voltage of the slow start capacitor passes through the virtually shorted positive and negative output terminals of the slow start circuit and performs a constant current discharge process through the constant current module. During the constant current discharge process, the reverse input voltage of the slow start capacitor decreases linearly, so that the voltage between the positive and negative output terminals of the slow start circuit produces a linear increase of the same amplitude, thereby realizing a linear slow start of the slow start circuit.

[0084] Optionally, a linear slow start circuit further includes: a voltage stabilizing module, wherein:

[0085] The voltage stabilizing module includes a voltage stabilizing tube and a voltage stabilizing capacitor;

[0086] The anode of the voltage regulator tube is used as the input end of the voltage regulator module, the anode of the voltage regulator tube is electrically connected to the source of the slow-start NMOS tube, and the anode of the voltage regulator tube is electrically connected to the first end of the voltage regulator capacitor;

[0087] The cathode of the voltage regulator tube serves as the output end of the voltage regulator module, the cathode of the voltage regulator tube is electrically connected to the gate of the slow-start NMOS tube, and the cathode of the voltage regulator tube is electrically connected to the second end of the voltage regulator capacitor;

[0088] The voltage regulator module is used to control the slow-start output voltage within the preset voltage threshold through the clamping voltage of the voltage regulator tube during the fast pre-charging process, and after the slow-start is completed, the voltage regulator tube clamps the voltage across the voltage regulator capacitor to charge the voltage regulator capacitor to the preset voltage threshold, thereby making the slow-start NMOS tube fully turned on, and finally realizing the regulated output of the slow-start circuit.

[0089] During the specific implementation process, the voltage stabilizing module controls the slow-start output voltage within the preset voltage threshold and performs voltage clamping after the slow-start is completed to make the slow-start NMOS tube fully turned on, thereby ensuring that the slow-start NMOS tube will not be damaged, and ultimately achieving a regulated output of the slow-start circuit, and achieving equal potential between the positive output terminal and the positive input terminal, and equal potential between the negative output terminal and the negative input terminal.

[0090] Optionally, a linear slow start circuit further includes: an anti-reverse connection NMOS tube, wherein:

[0091] The source of the reverse connection protection NMOS tube is electrically connected to the source of the slow start NMOS tube, the source of the reverse connection protection NMOS tube is electrically connected to the negative input terminal of the pre-start module, the gate of the reverse connection protection NMOS tube is electrically connected to the gate of the slow start NMOS tube, and at this time, the drain of the reverse connection protection NMOS tube replaces the negative input terminal of the pre-start module as the negative input terminal of the slow start circuit;

[0092] The anti-reverse connection NMOS tube is used to enter the fully conductive state after the linear slow start is completed;

[0093] The anti-reverse connection NMOS tube is used for when the input voltage is reversed, the drain of the anti-reverse connection NMOS tube is in a reverse bias state, so that the anti-reverse connection NMOS tube is in a cut-off state, thereby realizing the anti-reverse connection protection of the slow start circuit.

[0094] In the specific implementation process, the input voltage is reversed by adding an anti-reverse NMOS tube. When the input voltage is reversed, since the anti-reverse NMOS tube is in a reverse bias state, its internal diode is not turned on, and the back-end circuit cannot obtain voltage and current. The anti-reverse NMOS tube remains in the cut-off state, that is, the circuit enters the anti-reverse protection state.

[0095] A linear slow-start circuit provided in the present embodiment firstly performs fast pre-charging using the input voltage through the pre-start module, so that the slow-start capacitor reaches a certain amount of charge in a short time, thereby ensuring that the slow-start process can start quickly and reducing the start-up delay; and after the pre-charging is completed, the constant current module discharges the slow-start capacitor at a constant current rate, so that the output voltage of the slow-start module decreases linearly, and then the slow-start NMOS tube is controlled to enter a linear on state, thereby realizing a linear increase in the output voltage of the slow-start circuit, and the circuit realizes a regulated output through the voltage stabilizing module, and an anti-reverse NMOS tube is added to make the circuit have an anti-reverse effect; the linear slow-start circuit has a simple structure, has an anti-reverse effect, and can realize the linear slow-start of the DC power supply while making the DC power supply system design more concise.

[0096] Embodiment 2:

[0097] This embodiment also provides a control method for a linear slow start circuit, which is implemented by using a linear slow start circuit and includes the following steps:

[0098] Receiving an input voltage, and performing delayed power-on based on the input voltage to quickly pre-charge the slow-start module until the output voltage of the slow-start module is the reverse input voltage;

[0099] Then, the constant current module performs a constant current discharge process based on the reverse input voltage, so that the output voltage of the slow start module decreases linearly, and the slow start NMOS tube is controlled to enter a linear on state, so that the output voltage of the slow start circuit increases linearly, realizing linear slow start.

[0100] After receiving the input voltage, the above scheme realizes a linear rise of the output voltage through a simple delayed power-on, fast pre-charging and constant current discharge process, thereby achieving a linear slow start.

[0101] Optionally, during the fast pre-charging process, the voltage is clamped by the voltage stabilizing module to control the output voltage of the slow-start module within a preset voltage threshold, and after the slow-start is completed, the voltage is clamped to make the slow-start NMOS tube fully turned on, ultimately achieving a regulated output of the slow-start circuit.

[0102] In the specific implementation process, by controlling the slow-start output voltage within the preset voltage threshold and performing voltage clamping after the slow-start is completed to make the slow-start NMOS tube fully turned on, it is ensured that the slow-start NMOS tube will not be damaged, and finally the regulated output of the slow-start circuit is achieved, and the positive output terminal of the slow-start circuit is equal to the positive input terminal, and the negative output terminal is equal to the negative input terminal.

[0103] Optionally, when the input voltage is reversed, the drain of the anti-reverse NMOS tube is in a reverse bias state, so that the anti-reverse NMOS tube is in a cut-off state, thereby realizing anti-reverse protection of the slow start circuit.

[0104] In the specific implementation process, the input voltage is reversed through an anti-reverse NMOS tube. When the input voltage is reversed, since the anti-reverse NMOS tube is in a reverse bias state, its internal diode is not turned on, and the back-end circuit cannot obtain voltage and current. The anti-reverse NMOS tube remains in the cut-off state, that is, the circuit enters the anti-reverse protection state.

[0105] A control method for a linear slow-start circuit provided in the present embodiment first performs fast pre-charging based on the input voltage so that the slow-start module reaches a certain amount of charge in a short time, thereby ensuring that the slow-start process can start quickly and reducing the start-up delay; and after the pre-charging is completed, the discharge is performed at a constant current rate so that the output voltage of the slow-start module decreases linearly, and then the slow-start NMOS tube is controlled to enter a linear on state, thereby realizing a linear increase in the output voltage of the slow-start circuit, and the circuit realizes a regulated output through a voltage stabilizing module, and an anti-reverse NMOS tube with an anti-reverse effect is added to realize a linear slow-start with an anti-reverse effect.

[0106] Embodiment three:

[0107] This embodiment provides a linear slow-start circuit schematic diagram with reverse connection protection, which includes: pre-start diode group D1, D3, pre-start capacitor C1, first voltage-dividing resistor R2, second voltage-dividing resistor R4, third voltage-dividing resistor R3, pre-start transistor N1, clamping diode D4, constant current resistor R1, constant current transistor P1, protection diode D2, slow-start capacitor C3, voltage-stabilizing module including voltage-stabilizing tube Z1, voltage-stabilizing capacitor C2, slow-start NMOS tube Q1 and reverse connection protection NMOS tube Q2. The circuit schematic diagram is shown in FIG. Figure 2 As shown, +Vout represents the positive output terminal, -Vout represents the negative output terminal, +Vin represents the positive output terminal, and -Vin represents the negative output terminal.

[0108] In the specific implementation process, the input voltage Vi passes through D1 and D3 and then is divided by R3 to charge C1, thereby making R2 and R4 in a divided voltage state to drive N1. b pole, and clamp the b pole voltage of N1 through D4, so that N1 enters the on state, so that the slow start circuit enters the dead time, +Vout and -Vout are equipotential points, the emitter and collector of N1 are equipotential points, and the voltage of C3 is equal to the reverse input voltage value; after C1 is fully charged, the Vbe voltage between the base and emitter of N1 will drop below 0.7V, so that it is in the cut-off state; due to the existence of R3, current will continue to flow through D1 and D3, and its series voltage drop is about 1.4V. Through the circuit connection relationship, it can be seen that: the voltage across R1 plus the Veb voltage of P1 (0.7V) is equal to the series voltage of D1 and D3, then R1 will maintain a stable voltage of about 0.7V, that is, R1, P1 combined with D1, D3, R3 constitute a constant current circuit, and the constant current i=0.7V / R1; after N1 is cut off, the reverse voltage of C3 passes through the virtual short Vo The two ends discharge to the constant current load composed of R1 and P1, and the reverse voltage of C3 decreases slowly and linearly. The speed calculation formula of its voltage decrease is: dU / dt=i / C. Due to the principle of Vgs=Vi-Vo-Vc, Q1 enters the linear region and turns on at this time. The voltage of C3 capacitor decreases, and the voltage of Vo increases accordingly. The amplitude of its decrease and increase is equal. Therefore, the output of Vo is a linear rising voltage curve. When the input voltage is determined, its linear slow start time should be t=Vi*C / i; after the slow start, Vi passes through the constant current circuit and clamps C2 through the Z1 voltage regulator (12V) to make Q1 fully turned on. The maximum positive charging voltage is 12V to ensure that Q1 is not damaged. Finally, -Vout is equal to -Vin value and +Vout is equal to +Vin value, that is, it presents a linear slow start characteristic. The input voltage and output voltage test waveforms are as follows Figure 3 As shown, the dotted line represents the input voltage and the solid line represents the output voltage.

[0109] In the specific implementation process, Figure 4As shown, the pre-start diode group D1, D3, the pre-start capacitor C1, the first voltage-dividing resistor R2, the second voltage-dividing resistor R4, the third voltage-dividing resistor R3, the pre-start transistor N1 and the clamping diode D4 constitute a pre-start module; the constant current resistor R1, the constant current transistor P1 and the protection diode D2 constitute a constant current module; the slow start capacitor C3 constitutes a slow start module; the voltage stabilizing module includes a voltage stabilizing tube Z1 and a voltage stabilizing capacitor C2 to constitute a voltage stabilizing module. +Vi represents the positive input terminal, -Vi represents the negative input terminal, +Vo represents the positive output terminal, -Vo represents the negative output terminal, and the input voltage slope starts vertically to enter this circuit: first, the pre-start module and the constant current module are used to form a control unit, and the slow start module is quickly pre-charged by delaying the power-on of the pre-start module when powered on; when the delayed power-on of the pre-start module ends, the slow start module is controlled to perform constant current discharge through the constant current module, so that the voltage Vc of the slow start module presents a linear decline state; in this circuit, it satisfies: Vgs = Vi-Vo-Vc, Vi remains unchanged, and Vc decreases slowly, so at this time Vo decreases with the slow decline of Vc And it rises slowly accordingly, Vgs is basically stable at 3-4V, that is, it is slowly turned on within the amplification range, thereby realizing the function of linear increase of output voltage; when the output voltage rises to the highest voltage (input voltage), the slow start process ends, and the slow start capacitor changes from discharge to charging state due to the drive of the constant current module, and the gate-source voltage exceeds Vth and continues to rise until the voltage is clamped by the voltage stabilizing diode of the voltage stabilizing circuit. At this time, the slow start N-mosfet (i.e. slow start NMOS tube) and the anti-reverse connection N-mosfet (i.e. anti-reverse connection NMOS tube) obtain a sufficiently high gate-source voltage and enter a fully turned-on saturation state.

[0110] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A linear slow start circuit, characterized in that: include: Pre-start module, constant current module, slow start module and slow start NMOS tube; among which: The positive input end of the pre-start module serves as the positive input end of the slow-start circuit, the negative input end of the pre-start module serves as the negative input end of the slow-start circuit, the positive input end of the pre-start module is electrically connected to the input end of the constant current module, the constant current end of the pre-start module is electrically connected to the pre-start end of the constant current module, the negative output end of the pre-start module is electrically connected to the output end of the constant current module, and the positive output end of the pre-start module is electrically connected to the source of the slow-start NMOS tube; The output end of the constant current module is electrically connected to the gate of the slow-start NMOS tube, and the input end of the constant current module serves as the positive output end of the slow-start circuit; The gate of the slow-start NMOS tube is electrically connected to the input end of the slow-start module, and the drain of the slow-start NMOS tube is electrically connected to the output end of the slow-start module; The output end of the slow start module serves as the negative output end of the slow start circuit; The pre-start module is used to receive an input voltage and quickly pre-charge the slow-start module by delaying power-on, so that the output voltage of the slow-start module is the reverse input voltage; The constant current module is used to perform a constant current discharge process based on a reverse input voltage after the fast pre-charging is completed; The slow start module is used to perform fast pre-charging through the pre-start module, so that when the fast pre-charging ends, the output voltage of the slow start module is the reverse input voltage, and after the fast pre-charging ends, a constant current discharge process is performed through the constant current module based on the reverse input voltage, so that the output voltage of the slow start module decreases linearly, and the slow start NMOS tube enters a linear on state, so that the output voltage of the slow start circuit increases linearly, realizing the linear slow start of the circuit.

2. A linear slow start circuit according to claim 1, characterized in that: The pre-start module includes: a pre-start diode group, a pre-start capacitor, a first voltage-dividing resistor, a second voltage-dividing resistor, a third voltage-dividing resistor, a pre-start transistor and a clamping diode, wherein: The anode of the pre-start diode group serves as the positive input terminal of the pre-start module, the cathode of the pre-start diode group serves as the constant current terminal of the pre-start module, the cathode of the pre-start diode group is electrically connected to the first end of the pre-start capacitor, and the cathode of the pre-start diode group is electrically connected to the first end of the third voltage-dividing resistor; The second end of the pre-start capacitor is electrically connected to the first end of the first voltage-dividing resistor; The second end of the first voltage-dividing resistor is electrically connected to the first end of the second voltage-dividing resistor; The first end of the second voltage-dividing resistor is electrically connected to the anode of the clamping diode, the second end of the second voltage-dividing resistor is electrically connected to the cathode of the clamping diode, and the second end of the second voltage-dividing resistor is electrically connected to the base of the pre-start transistor; The emitter of the pre-start transistor is electrically connected to the second end of the third voltage-dividing resistor, the emitter of the pre-start transistor serves as the positive output end of the pre-start module, and the collector of the pre-start transistor serves as the negative output end of the pre-start module; The second end of the third voltage-dividing resistor serves as the negative input end of the pre-start module; The pre-start module receives an input voltage and quickly pre-charges the slow start module by delaying power-on, so that the output voltage of the slow start module is the reverse input voltage, including: The input voltage passes through the pre-start diode group, and after the input voltage is divided by the third voltage-dividing resistor, the pre-start capacitor is charged, and the first voltage-dividing resistor and the second voltage-dividing resistor are used to divide the pre-start capacitor, thereby driving the pre-start transistor base, and the pre-start transistor base voltage is clamped by the clamping diode, so that the pre-start transistor enters the on state, so that the voltage across the slow-start module is the reverse input voltage, and the slow-start module is quickly pre-charged; After the fast pre-charging is completed, the pre-start transistor is in a cut-off state.

3. A linear slow start circuit according to claim 1, characterized in that: The constant current module comprises: a constant current resistor and a constant current transistor, wherein: The output end of the constant current resistor is electrically connected to the emitter of the constant current transistor, the input end of the constant current resistor serves as the input end of the constant current module, the collector of the constant current transistor serves as the output end of the constant current module, and the base of the constant current transistor serves as the pre-start end of the constant current module; The constant current module is used to perform a constant current discharge process to the constant current resistor and the constant current triode based on the reverse input voltage after the fast pre-charging is completed.

4. A linear slow start circuit according to claim 3, characterized in that: The constant current module further includes: a protection diode, wherein the anode of the protection diode is electrically connected to the base of the constant current transistor, and the cathode of the protection diode is electrically connected to the emitter of the constant current transistor.

5. A linear slow start circuit according to claim 1, characterized in that: The slow start module includes a slow start capacitor, wherein: The first end of the slow-start capacitor is used as the input end of the slow-start module, and the second end of the slow-start capacitor is used as the output end of the slow-start module; The slow-start capacitor is used to perform fast pre-charging through the pre-start module, so that when the fast pre-charging ends, the output voltage of the slow-start module is the reverse input voltage, and after the fast pre-charging ends, constant current discharge is performed through the constant current module based on the reverse input voltage, so that the output voltage of the slow-start module decreases linearly, and the slow-start NMOS tube enters the linear region and turns on, so that the output voltage of the DC power supply increases linearly, realizing the linear slow start of the slow-start circuit.

6. A linear slow start circuit according to claim 1, characterized in that: Also includes: Voltage regulator module, including: The voltage stabilizing module includes a voltage stabilizing tube and a voltage stabilizing capacitor; The anode of the voltage regulator tube is used as the input end of the voltage regulator module, the anode of the voltage regulator tube is electrically connected to the source of the slow-start NMOS tube, and the anode of the voltage regulator tube is electrically connected to the first end of the voltage regulator capacitor; The cathode of the voltage regulator tube serves as the output end of the voltage regulator module, the cathode of the voltage regulator tube is electrically connected to the gate of the slow-start NMOS tube, and the cathode of the voltage regulator tube is electrically connected to the second end of the voltage regulator capacitor; The voltage stabilizing module is used to control the slow-start output voltage within a preset voltage threshold through the clamping voltage of the voltage regulator tube during the fast pre-charging process, and after the slow-start is completed, clamp the voltage across the voltage regulator capacitor through the voltage regulator tube to charge the voltage regulator capacitor to the preset voltage threshold, thereby making the slow-start NMOS tube fully turned on, and finally realizing the voltage stabilization output of the slow-start circuit.

7. A linear slow start circuit according to claim 1, characterized in that: Also includes: Anti-reverse connection NMOS tube, where: The source of the reverse connection protection NMOS tube is electrically connected to the source of the slow start NMOS tube, the source of the reverse connection protection NMOS tube is electrically connected to the negative input terminal of the pre-start module, the gate of the reverse connection protection NMOS tube is electrically connected to the gate of the slow start NMOS tube, and the drain of the reverse connection protection NMOS tube replaces the negative input terminal of the pre-start module as the negative input terminal of the slow start circuit; The anti-reverse connection NMOS tube is used to enter a fully-on state after the linear slow start is completed; The anti-reverse connection NMOS tube is used for when the input voltage is reversed, the drain of the anti-reverse connection NMOS tube is in a reverse bias state, so that the anti-reverse connection NMOS tube is in a cut-off state, thereby realizing the anti-reverse connection protection of the soft start circuit.

8. A control method for a linear slow start circuit, implemented by using a linear slow start circuit as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: Receiving an input voltage, and performing delayed power-on based on the input voltage to quickly pre-charge the slow-start module until the output voltage of the slow-start module is the reverse input voltage; Then, the constant current module performs a constant current discharge process based on the reverse input voltage, so that the output voltage of the slow start module decreases linearly, and the slow start NMOS tube is controlled to enter a linear on state, so that the output voltage of the slow start circuit increases linearly, realizing linear slow start.

9. A control method for a linear slow start circuit according to claim 8, characterized in that: Also includes: During the fast pre-charging process, the voltage is clamped by the voltage stabilizing module to control the output voltage of the slow-start module within the preset voltage threshold. After the slow-start is completed, the voltage is clamped to make the slow-start NMOS tube fully turned on, ultimately achieving a regulated output of the slow-start circuit.

10. The control method of a linear slow start circuit according to claim 8, characterized in that: Also includes: When the input voltage is reversed, the drain of the anti-reverse NMOS tube is in a reverse bias state, so that the anti-reverse NMOS tube is in a cut-off state, thereby realizing the anti-reverse protection of the slow start circuit.

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