A controllable current limiting inrush current suppression circuit on ground

Abstract

The application provides a controllable current-limiting impact current suppression circuit on a ground wire and relates to the technical field of an airborne computer direct-current power supply, and comprises a main power MOSFET and a driving circuit thereof connected between a DC / DC power supply end and a Vin end, a current sampling detection circuit, a voltage amplification circuit and a negative feedback circuit based on a three-terminal voltage regulator; the current sampling detection circuit is connected in series on the ground wire of the main power MOSFET and the driving circuit thereof, the output end of the current sampling detection circuit is connected with the input end of the voltage amplification circuit, the output end of the voltage amplification circuit is connected with the feedback input end of the negative feedback circuit, and the feedback output end of the negative feedback circuit is connected with the gate of the main power MOSFET in the main power MOSFET and the driving circuit thereof. The application can realize the suppression of the impact current of the input end at any moment in the normal working of the circuit, and the electronic equipment power supply system and the electronic equipment circuit are protected to the maximum extent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of on-board computer direct current power supply, in particular to a controllable current-limiting inrush current suppression circuit on ground wire. BACKGROUND

[0002] The input end of the internal power supply of an electronic device needs a capacitor with a large capacitance value for filtering and power failure maintenance. These devices will cause a large inductive current, i.e. inrush current, to the power supply system at the moment of power supply voltage change. The inrush current not only has a serious impact on the power supply system, but also causes damage to the internal electronic devices and circuit boards of the electronic device.

[0003] In traditional circuit design, in order to suppress the inrush current on the line at the moment of device power-on, a soft start circuit is added to the input end of the power supply circuit. However, the existing design often has problems such as high power consumption, low safety level, only applicable to the moment of power-on, or unable to accurately control the limited current. In order to alleviate the above limitations, a new controllable current-limiting inrush current suppression circuit on ground wire is proposed, which can accurately suppress the inrush current at any time during normal operation of the circuit. SUMMARY

[0004] Therefore, the embodiments of the present application provide a controllable current-limiting inrush current suppression circuit on ground wire, which can suppress the inrush current at the input end at any time during normal operation of the circuit, solving the shortcoming that the inrush current suppression can only be realized at the moment of starting the circuit in the traditional protection method, and protecting the power supply system of the electronic device and the electronic device circuit to the greatest extent.

[0005] The embodiments of the present application provide the following technical solutions: a controllable current-limiting inrush current suppression circuit on ground wire, comprising: a main power MOSFET and a driving circuit thereof connected between a DC / DC power supply end and a Vin end, a current sampling and detection circuit, a voltage amplification circuit, and a negative feedback circuit based on a three-terminal voltage regulator.

[0006] The current sampling detection circuit is connected in series with the ground of the main power MOSFET and its driving circuit loop, and is used for collecting the current signal on the main power MOSFET and its driving circuit and voltage conversion; the output end of the current sampling detection circuit is connected with the input end of the voltage amplification circuit, and is used for inputting the converted voltage signal into the voltage amplification circuit; the output end of the voltage amplification circuit is connected with the feedback input end of the negative feedback circuit, and is used for inputting the amplified voltage signal into the negative feedback circuit and comparing with the reference voltage inside the negative feedback circuit to determine whether overcurrent occurs in the main loop; and the feedback output end of the negative feedback circuit is connected with the gate of the main power MOSFET in the main power MOSFET and its driving circuit, and is used for controlling the driving voltage of the main power MOSFET and its driving circuit, and further controlling the opening degree of the main power MOSFET in the main power MOSFET and its driving circuit, so as to realize the suppression of the inrush current.

[0007] According to an embodiment of the present application, the drain and source of the main power MOSFET Q1 in the main power MOSFET and its driving circuit are connected in series with the ground of the main power loop, wherein the driving circuit comprises a gate driving resistor R9 and a gate discharge resistor R10; the gate driving resistor R9 is connected in parallel between the main power MOSFET Q1 and the cathode of the voltage reference chip in the negative feedback circuit; and the gate discharge resistor R10 is connected in parallel between the gate and the drain of the main power MOSFET Q1.

[0008] According to an embodiment of the present application, the current sampling detection circuit comprises a sampling resistor R1 connected in series between the source of the main power MOSFET Q1 and the negative end of the input power supply.

[0009] According to an embodiment of the present application, the voltage amplification circuit comprises an operational amplifier N1, input voltage dividing resistors R2 and R3, output voltage dividing resistors R4 and R5, filter capacitors C1 and C2, and an output current limiting resistor R11.

[0010] The voltage dividing resistors R2 and R3 input the voltage of the sampling resistor R1 into the positive input end of the operational amplifier N1 after voltage division; the filter capacitor C1 is connected in parallel with the voltage dividing resistor R3; the voltage dividing resistor R5 is connected in parallel between the negative input end of the operational amplifier N1 and the ground; the voltage dividing resistor R4 is connected in parallel between the negative input end and the output end of the operational amplifier N1; the filter capacitor C2 is connected in parallel with the voltage dividing resistor R4; the output end of the operational amplifier N1 amplifies the voltage between the sampling resistor R1 according to the resistance voltage division ratio; and the output signal of the operational amplifier N1 is input into the 2.5V reference end of the voltage reference chip in the negative feedback circuit through the output current limiting resistor R11.

[0011] According to one embodiment of this application, the operational amplifier N1 of the voltage amplifier circuit is a rail-to-rail operational amplifier.

[0012] According to one embodiment of this application, the negative feedback circuit includes a voltage reference chip, a Zener diode V2, a current-limiting resistor R8, a bus voltage divider resistor R6 and a voltage divider resistor R7, and a charging capacitor C3; the voltage divider resistors R6 and R7 are connected in series and then connected in parallel with the input power supply; the current-limiting resistor R8 is connected between the midpoint of the voltage divider resistors R6 and R7 and the cathode of the voltage reference chip; the anode of the voltage reference chip is connected to the input power supply ground; the charging capacitor C3 is connected in parallel between the cathode and the reference terminal of the voltage reference chip; and the Zener diode V2 is connected in parallel between the cathode and the anode of the voltage reference chip.

[0013] According to one embodiment of this application, the negative feedback circuit adopts a negative feedback circuit based on a three-terminal regulator.

[0014] According to one embodiment of this application, the voltage reference chip is a voltage reference chip TL431.

[0015] Compared with the prior art, the beneficial effects achieved by at least one of the above-mentioned technical solutions adopted in the embodiments of this specification include at least the following: The embodiments of this invention design a controllable current-limiting inrush current suppression circuit on the ground wire. This circuit only requires a power switch and a current detection circuit connected in series on the ground wire of the main power supply circuit, and an external voltage amplification circuit and a feedback circuit to control the turn-on degree of the power switch, ensuring that the inrush current is limited to below a set value, and the subsequent DC / DC conversion circuit can operate normally. This circuit design avoids the shortcomings of previous designs where the main power supply circuit can only achieve inrush current suppression at the moment of power-on, and also avoids the problem that the inrush current limit value cannot be accurately controlled. It achieves precise suppression of inrush current at any time during normal operation, improving circuit reliability. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Fig. 1 This is a schematic diagram of the overall structure of the controllable current-limiting inrush current suppression circuit according to an embodiment of the present invention;

[0018] Fig. 2This is a schematic diagram of the controllable current-limiting inrush current suppression circuit according to an embodiment of the present invention. Detailed Implementation

[0019] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0020] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] like Figs. 1-2 As shown, this embodiment of the invention provides a controllable current-limiting inrush current suppression circuit on the ground line, including: a main power MOSFET and its driving circuit 1 connected between the DC / DC power supply terminal and the Vin terminal, a current sampling and detection circuit 2, a voltage amplification circuit 3, and a negative feedback circuit 4 based on a three-terminal regulator; the current sampling and detection circuit 2 is connected in series on the ground line of the main power MOSFET and its driving circuit 1 loop, and is used to collect the current signal on the main power MOSFET and its driving circuit 1 and convert it to voltage; the output terminal of the current sampling and detection circuit 2 is connected to the input terminal of the voltage amplification circuit 3, and is used to input the converted voltage signal to the ground line. The voltage amplifier circuit 3 is described above. The output terminal of the voltage amplifier circuit 3 is connected to the feedback input terminal of the negative feedback circuit 4. It is used to input the amplified voltage signal into the negative feedback circuit 4 and compare it with the reference voltage inside the negative feedback circuit 4 to determine whether an overcurrent occurs in the main circuit. The feedback output terminal of the negative feedback circuit 4 is connected to the gate of the main power MOSFET in the main power MOSFET and its driving circuit 1. It is used to control the driving voltage of the main power MOSFET and its driving circuit 1, thereby controlling the turn-on degree of the main power MOSFET in the main power MOSFET and its driving circuit 1 to achieve the suppression of inrush current.

[0022] This invention discloses a controllable inrush current suppression circuit on the ground wire. The circuit connects a power MOSFET and a current detection circuit in series on the ground wire of the main power supply circuit. The detected current is converted into a voltage signal and input to a voltage amplifier circuit. After amplification, the signal is compared with the internal reference voltage of the core component of the negative feedback circuit to determine whether an overcurrent has occurred in the main circuit. The output signal is then sent to the gate of the power switch to adjust its on-state, thereby suppressing the inrush current. The inrush current limit value can be precisely adjusted by changing the amplification factor of the voltage amplifier circuit. This invention enables precise suppression of inrush current at any time during normal operation, improving circuit reliability.

[0023] In one specific implementation of this invention, the drain and source of the main power MOSFET Q1 in the main power MOSFET and its driving circuit are connected in series on the ground line of the main power circuit, wherein the drain D is close to the DC / DC power supply terminal and the source S is close to the Vin terminal; the driving circuit includes a gate driving resistor R9 and a gate bleed resistor R10, wherein the gate driving resistor R9 is connected in parallel across the cathode of the main power MOSFET Q1 and the voltage reference chip TL431 V1 in the negative feedback circuit, and the gate bleed resistor R10 is connected in parallel across the gate and drain of the main power MOSFET Q1.

[0024] In one specific implementation of this invention, the current sampling and detection circuit includes a sampling resistor R1, which is connected in series between the source of the main power MOSFET Q1 and the negative terminal of the input power supply. The current sampling and detection circuit is capable of detecting the magnitude of the current and converting it into a voltage signal, and includes, but is not limited to, sampling resistors, Hall sensors, and any other analog or digital circuits used to detect the magnitude of the current and convert it into a voltage signal.

[0025] In one specific implementation of this invention, the voltage amplification circuit includes an operational amplifier N1, input voltage divider resistors R2 and R3, output voltage divider resistors R4 and R5, filter capacitors C1 and C2, and output current limiting resistor R11.

[0026] The voltage divided by resistors R2 and R3 is used to input the voltage of the sampling resistor R1 to the positive input terminal of operational amplifier N1. The filter capacitor C1 is connected in parallel with the voltage divider resistor R3. Voltage divider resistor R5 is connected in parallel between the negative input terminal of operational amplifier N1 and ground. Voltage divider resistor R4 is connected in parallel between the negative input terminal and the output terminal of operational amplifier N1. The filter capacitor C2 is connected in parallel with the voltage divider resistor R4. The output terminal of operational amplifier N1 amplifies the voltage across the sampling resistor R1 according to the resistor division ratio. The output signal of operational amplifier N1 is input to the 2.5V reference terminal of the voltage reference chip TL431 V1 in the negative feedback circuit through the output current limiting resistor R11. The operational amplifier N1 in the voltage amplification circuit is a rail-to-rail operational amplifier.

[0027] In one specific implementation of this invention, the negative feedback circuit includes a voltage reference chip TL431 V1, a Zener diode V2, a current-limiting resistor R8, a bus voltage divider resistor R6 and a voltage divider resistor R7, and a charging capacitor C3. The voltage divider resistors R6 and R7 are connected in series and then in parallel with the input power supply. The current-limiting resistor R8 is connected between the midpoint of the voltage divider resistors R6 and R7 and the cathode of the voltage reference chip TL431 V1. The anode of the voltage reference chip TL431 V1 is connected to the input power supply ground. The charging capacitor C3 is connected in parallel between the cathode and the reference terminal of the voltage reference chip TL431 V1. The Zener diode V2 is connected in parallel between the cathode and the anode of the voltage reference chip TL431 V1. The negative feedback circuit is based on a three-terminal voltage regulator.

[0028] This invention utilizes a reference voltage chip and a power switch as the core of the circuit, which can accurately suppress inrush current and avoid damage to the subsequent DC / DC conversion circuit caused by inrush current induced by circuit voltage changes.

[0029] The circuit with inrush current suppression function in this invention is suitable for products that have limitations on the magnitude of inrush current, requirements for transient operation characteristics of DC power supply, and requirements for power interruption. The circuit mainly consists of: a main power MOSFET and its driving circuit, a current sampling and detection circuit, a voltage amplification circuit, and a negative feedback circuit based on a three-terminal regulator. Its specific circuit principle is as follows:

[0030] 1. Current sampling and detection circuit

[0031] The current sampling and detection circuit is connected in series with the ground wire of the main power circuit. Its main function is to convert the magnitude of the current in the main power circuit into a voltage signal according to a certain ratio. The magnitude of the voltage signal can be expressed as:

[0032] V1=R1·I

[0033] In the formula: I represents the magnitude of the current in the main power circuit, V1 represents the magnitude of the voltage signal obtained from sampling, and R1 is the conversion ratio coefficient, which is related to the sampling circuit parameters. To avoid large losses in the current sampling resistor, a power resistor with a small resistance value is usually used.

[0034] 2. Voltage Amplifier Circuit

[0035] The voltage amplifier circuit is used to amplify the current sampling signal. The current sampling signal V1 is divided by resistors R2 and R3 and then input to amplifier N1. After being amplified by resistors R4 and R5, an output voltage is obtained. The amplified output voltage value V2 can be expressed as:

[0036]

[0037] Let R2 + R3 = R4 + R5, which can be simplified to:

[0038]

[0039] The input voltage of the negative feedback circuit based on the three-terminal regulator can be adjusted by adjusting the ratio of resistor R3 to resistor R5, thereby adjusting the inrush current limit value.

[0040] 3. Negative feedback circuit based on a three-terminal regulator

[0041] The negative feedback circuit based on a three-terminal regulator is used to compare the sampled and amplified voltage with a reference voltage and feed it back to the gate of the MOSFET Q1 to control the turn-on level, thereby controlling the main power circuit current. The core component of this circuit is the TL431. Vin is powered by the TL431 after being divided by resistors R6 and R7, and R8 is a current-limiting resistor. The amplified sampled voltage is input to the 2.5V reference voltage terminal of the TL431, and the cathode is connected to the gate drive resistor R9 of Q1.

[0042] Based on the comparator's working principle, the magnitude of the inrush current that the feedback circuit can limit can be calculated as follows:

[0043]

[0044] When the detected current is less than the set limit, V2 is lower than the reference voltage VREF (VREF is the 2.5V internal reference voltage of TL431), the internal transistor of TL431 is in the off state, and Q1 is normally turned on; when the detected current is greater than the set limit, V2 is higher than the reference voltage, the internal transistor of TL431 conducts, causing the drive voltage of Q1 to be pulled low, according to the u of Q1. GS -i DThe curve shows that the current flowing through Q1 decreases until the current drops to the set limit value, that is, V2 equals the reference voltage value.

[0045] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A controllable current-limiting inrush current suppression circuit on a ground wire, characterized in that, include: The main power MOSFET and its driving circuit, current sampling and detection circuit, voltage amplification circuit, and negative feedback circuit based on a three-terminal regulator are connected between the DC / DC power supply terminal and the Vin terminal. The current sampling and detection circuit is connected in series with the ground wire of the main power MOSFET and its driving circuit loop. It is used to collect the current signal on the main power MOSFET and its driving circuit and convert it into voltage. The output terminal of the current sampling and detection circuit is connected to the input terminal of the voltage amplification circuit. It is used to input the converted voltage signal into the voltage amplification circuit. The output terminal of the voltage amplification circuit is connected to the feedback input terminal of the negative feedback circuit. It is used to input the amplified voltage signal into the negative feedback circuit and compare it with the reference voltage inside the negative feedback circuit to determine whether an overcurrent has occurred in the main circuit. The feedback output terminal of the negative feedback circuit is connected to the gate of the main power MOSFET in the main power MOSFET and its driving circuit. It is used to control the driving voltage of the main power MOSFET and its driving circuit, thereby controlling the turn-on degree of the main power MOSFET in the main power MOSFET and its driving circuit, and realizing the suppression of inrush current. The drain and source of the main power MOSFET Q1 in the main power MOSFET and its driving circuit are connected in series on the ground line of the main power circuit. The driving circuit includes a gate driving resistor R9 and a gate discharge resistor R10. The gate driving resistor R9 is connected in parallel across the main power MOSFET Q1 and the cathode of the voltage reference chip in the negative feedback circuit. The gate discharge resistor R10 is connected in parallel across the gate and drain of the main power MOSFET Q1. The current sampling and detection circuit includes a sampling resistor R1, which is connected in series between the source of the main power MOSFET Q1 and the negative terminal of the input power supply. The voltage amplifier circuit includes an operational amplifier N1, input voltage divider resistors R2 and R3, output voltage divider resistors R4 and R5, filter capacitors C1 and C2, and output current limiting resistor R11. The voltage divider resistors R2 and R3 divide the voltage and input the voltage of the sampling resistor R1 to the positive input terminal of the operational amplifier N1. The filter capacitor C1 and the voltage divider resistor R3 are connected in parallel. The voltage divider resistor R5 is connected in parallel between the negative input terminal of the operational amplifier N1 and ground. The voltage divider resistor R4 is connected in parallel between the negative input terminal and the output terminal of the operational amplifier N1. The filter capacitor C2 and the voltage divider resistor R4 are connected in parallel. The output terminal of the operational amplifier N1 amplifies the voltage across the sampling resistor R1 according to the resistor voltage division ratio. The output signal of the operational amplifier N1 is input to the 2.5V reference terminal of the voltage reference chip in the negative feedback circuit through the output current limiting resistor R11.

2. The controllable current-limiting inrush current suppression circuit on the ground wire according to claim 1, characterized in that, The operational amplifier N1 of the voltage amplifier circuit is a rail-to-rail operational amplifier.

3. The controllable current-limiting inrush current suppression circuit on the ground wire according to claim 1, characterized in that, The negative feedback circuit includes a voltage reference chip, a Zener diode V2, a current-limiting resistor R8, a bus voltage divider resistor R6 and a voltage divider resistor R7, and a charging capacitor C3. The voltage divider resistors R6 and R7 are connected in series and then in parallel with the input power supply. The current-limiting resistor R8 is connected between the midpoint of the voltage divider resistors R6 and R7 and the cathode of the voltage reference chip. The anode of the voltage reference chip is connected to the input power supply ground. The charging capacitor C3 is connected in parallel between the cathode and the reference terminal of the voltage reference chip. The Zener diode V2 is connected in parallel between the cathode and the anode of the voltage reference chip.

4. The controllable current-limiting inrush current suppression circuit on the ground wire according to claim 3, characterized in that, The negative feedback circuit adopts a negative feedback circuit based on a three-terminal voltage regulator.

5. The controllable current-limiting inrush current suppression circuit on the ground wire according to claim 3, characterized in that, The voltage reference chip used is the TL431 voltage reference chip.

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