Controllable current-limiting impulse current suppression circuit on ground wire

Abstract

The invention provides a controllable current-limiting impulse current suppression circuit on a ground wire, which relates to the technical field of airborne computer direct-current power supplies and comprises a main power MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) connected between a DC / DC (Direct Current / Direct Current) power supply end and a Vin end, a driving circuit of the main power MOSFET, a current sampling detection circuit, a voltage amplification circuit and a negative feedback circuit based on a three-terminal regulator, the current sampling detection circuit is connected in series with a ground wire of a main power MOSFET and a driving circuit loop thereof, the output end of the current sampling detection circuit is connected with the input end of the voltage amplification circuit, and the output end of the voltage amplification circuit is connected with the feedback input end of the negative feedback circuit. The feedback output end of the negative feedback circuit is connected with the main power MOSFET and the grid electrode of the main power MOSFET in the driving circuit of the main power MOSFET. According to the invention, suppression of the impact current of the input end can be realized at any time during normal operation of the circuit, and the power supply system of the electronic equipment and the circuit of the electronic equipment are protected to the greatest extent.

Description

Technical Field

[0001] The invention relates to the technical field of direct current power supply for airborne computers, and in particular to a controllable current-limiting impulse current suppression circuit on a ground line. Background Art

[0002] The input end of the internal power supply of electronic equipment requires a capacitor with a large capacitance for filtering and power-off maintenance. These devices will bring a large inductive current to the power supply system when the power supply voltage changes. The impact current not only has a serious impact on the power supply system, but also causes damage to the electronic components and circuit boards inside the electronic equipment.

[0003] In traditional circuit design, in order to suppress the surge current on the line when the device is powered on, a soft start circuit is added to the input end of the power supply circuit. However, existing designs often have problems such as high power consumption, low safety level, only applicable to the power-on moment, or inability to accurately control the current limit. In order to alleviate the above limitations, a new controllable current limiting surge current suppression circuit on the ground line is proposed, which can achieve accurate suppression of the surge current at any time during the normal operation of the circuit. Summary of the invention

[0004] In view of this, an embodiment of the present application provides a controllable current limiting surge current suppression circuit on the ground line, which can suppress the input surge current at any time during the normal operation of the circuit, solving the shortcoming of the traditional protection method that the surge current suppression can only be achieved at the moment of circuit startup, and protecting the electronic equipment power supply system and the electronic equipment circuit to the greatest extent.

[0005] The embodiment of the present application provides the following technical solution: a controllable current-limiting inrush current suppression circuit on a ground line, comprising: a main power MOSFET and its driving circuit connected between a DC / DC power supply terminal and a Vin terminal, a current sampling detection circuit, a voltage amplification circuit, and a negative feedback circuit based on a three-terminal regulator;

[0006] The current sampling detection circuit is connected in series to the ground line of the main power MOSFET and its drive circuit loop, and is used to collect the current signal on the main power MOSFET and its drive circuit and convert it into voltage. The output end of the current sampling detection circuit is connected to the input end of the voltage amplifier circuit, and is used to input the converted voltage signal into the voltage amplifier circuit. The output end of the voltage amplifier circuit is connected to the feedback input end of the negative feedback circuit, and 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 overcurrent occurs in the main loop. The feedback output end of the negative feedback circuit is connected to the gate of the main power MOSFET and its drive circuit, and is used to control the drive voltage of the main power MOSFET and its drive circuit, and then control the opening degree of the main power MOSFET and its drive circuit to suppress the impact 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 to the ground line of the main power loop, wherein the driving circuit includes a gate drive resistor R9 and a gate discharge resistor R10, the gate drive resistor R9 is connected in parallel to 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 to the gate and drain of the main power MOSFET Q1.

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

[0009] According to an embodiment of the present application, the voltage amplification circuit includes 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] After voltage division by the voltage-dividing resistor R2 and the voltage-dividing resistor R3, the input voltage of the sampling resistor R1 is input into the positive input terminal of the operational amplifier N1, and the filter capacitor C1 and the voltage-dividing resistor R3 are connected in parallel; the voltage-dividing resistor R5 is connected in parallel between the negative input terminal and the ground of the operational amplifier N1, and the voltage-dividing 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-dividing resistor R4 are connected in parallel, and the output terminal of the operational amplifier N1 amplifies the voltage across the sampling resistor R1 according to the resistor voltage division ratio, and the output signal of the operational amplifier N1 is input into the 2.5V reference terminal of the voltage reference chip in the negative feedback circuit through the output current-limiting resistor R11.

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

[0012] According to an embodiment of the present application, the negative feedback circuit includes a voltage reference chip, a voltage regulator tube 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 resistor R6 and the voltage divider resistor 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 resistor R6 and the voltage divider resistor R7 and the cathode of the voltage reference chip, the anode of the voltage reference chip is connected to the input power ground, the charging capacitor C3 is connected in parallel to the cathode and the reference end of the voltage reference chip, and the voltage regulator tube V2 is connected in parallel between the cathode and the anode of the voltage reference chip.

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

[0014] According to an embodiment of the present application, the voltage reference chip adopts the voltage reference chip TL431.

[0015] Compared with the prior art, the beneficial effects that can be achieved by at least one of the above technical solutions adopted in the embodiments of this specification include at least the following: The embodiments of the present invention design a controllable current limiting inrush current suppression circuit on the ground line. The circuit only needs to connect a power switch tube and a current detection circuit in series on the ground line of the main power supply circuit, and set a voltage amplifier circuit and a feedback circuit externally, so as to control the opening degree of the power switch tube, ensure that the inrush current is limited to below the set value, and the subsequent DC / DC conversion circuit can work normally. This circuit design avoids the shortcomings of the previous design that the main power supply circuit can only realize the inrush current suppression function at the moment of power-on, and also avoids the problem that the inrush current limit value cannot be accurately controlled, and realizes that the circuit can accurately suppress the inrush current at any time during normal operation, thereby improving the circuit reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

[0018] Figure 2The figure is a connection diagram of a controllable current limiting inrush current suppression circuit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0020] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0021] like Figure 1-Figure 2 As shown, an embodiment of the present invention provides a controllable current limiting impact current suppression circuit on a ground line, comprising: a main power MOSFET and its driving circuit 1 connected between a DC / DC power supply terminal and a Vin terminal, a current sampling detection circuit 2, a voltage amplifier circuit 3, and a negative feedback circuit 4 based on a three-terminal regulator; the current sampling detection circuit 2 is connected in series to 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 into voltage, and the output end of the current sampling detection circuit 2 is connected to the input end of the voltage amplifier circuit 3, and is used to input the converted voltage signal into the ground line. The voltage amplifier circuit 3, the output end of the voltage amplifier circuit 3 is connected to the feedback input end of the negative feedback circuit 4, and 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 overcurrent occurs in the main circuit. The feedback output end of the negative feedback circuit 4 is connected to the gate of the main power MOSFET and the main power MOSFET in the driving circuit 1, and is used to control the driving voltage of the main power MOSFET and the driving circuit 1, and then control the opening degree of the main power MOSFET and the main power MOSFET in the driving circuit 1, so as to suppress the impact current.

[0022] A controllable current limiting surge current suppression circuit on a ground wire in an embodiment of the present invention has a power field effect tube and a current detection circuit connected in series on the ground wire of the main power supply circuit. The detected current is converted into a voltage signal and input into the voltage amplifier circuit. After amplification, the input feedback circuit is compared with the internal reference voltage of the core device of the negative feedback circuit to determine whether there is overcurrent in the main circuit. The signal is output to the gate of the power switch tube to adjust the opening degree of the power switch tube to suppress the surge current. The surge current limit value can be accurately adjusted by adjusting the amplification factor of the voltage amplifier circuit. The invention can realize accurate suppression of surge current at any time during normal operation of the circuit, thereby improving the reliability of the circuit.

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

[0024] In a specific implementation of the embodiment of the present invention, the current sampling detection circuit includes a sampling resistor R1, and the sampling resistor R1 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 detection circuit is a form that can detect the current size and convert it into a voltage signal, including but not limited to a sampling resistor, a Hall sensor, and all other analog and digital circuit forms for detecting the current size and converting it into a voltage signal.

[0025] In a specific implementation of the embodiment of the present invention, the voltage amplification circuit includes 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;

[0026] After the voltage-dividing resistors R2 and R3 divide the voltage, the input voltage of the sampling resistor R1 is input to the positive input terminal of the operational amplifier N1, and the filter capacitor C1 and the voltage-dividing resistor R3 are connected in parallel; the voltage-dividing resistor R5 is connected in parallel between the negative input terminal and the ground of the operational amplifier N1, and the voltage-dividing resistor R4 is connected in parallel between the negative input terminal and the output terminal of the operational amplifier N1, and the filter capacitor C2 and the voltage-dividing 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-dividing ratio, and the output signal of the 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. Among them, the operational amplifier N1 of the voltage amplifier circuit adopts a rail-to-rail operational amplifier.

[0027] In a specific implementation of the embodiment of the present invention, the negative feedback circuit includes a voltage reference chip TL431 V1, a voltage regulator tube 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 resistor R6 and the voltage divider resistor 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 resistor R6 and the voltage divider resistor R7 and the cathode of the voltage reference chip TL431 V1, the anode of the voltage reference chip TL431V1 is connected to the input power ground, the charging capacitor C3 is connected in parallel to the cathode and the reference end of the voltage reference chip TL431 V1, and the voltage regulator tube V2 is connected in parallel between the cathode and the anode of the voltage reference chip TL431 V1. Wherein, the negative feedback circuit adopts a negative feedback circuit based on a three-terminal voltage regulator.

[0028] The embodiment of the present invention utilizes a reference voltage chip and a power switch tube as the circuit core, which can realize accurate suppression of the impact current and avoid damage to the subsequent DC / DC conversion circuit caused by the impact current induced by the circuit voltage change.

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

[0030] 1. Current sampling detection circuit

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

[0032] V1=R1·I

[0033] In the formula: I is the current in the main power circuit, V1 is the voltage signal obtained by sampling, and R1 is the conversion ratio coefficient, which is related to the sampling circuit parameters. In order to avoid large losses on the current sampling resistor, a power resistor with a smaller resistance 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 input into the amplifier N1. After being amplified by resistors R4 and R5, an output voltage can be 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] By adjusting the ratio of the resistor R3 to the resistor R5, the voltage value of the negative feedback circuit based on the three-terminal regulator can be adjusted, thereby adjusting the impact current limit value.

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

[0041] The negative feedback circuit based on the three-terminal voltage regulator is used to compare the current sampling and amplified voltage with the reference voltage, and feed it back to the gate of the field effect tube Q1 to control the degree of opening, thereby controlling the current of the main power loop. The core component of the negative feedback circuit based on the three-terminal voltage regulator is TL431. Vin is divided by resistors R6 and R7 to power TL431, and R8 is a current limiting resistor. The amplified sampling voltage is input to the 2.5V reference voltage terminal of TL431, and the cathode is connected to the gate drive resistor R9 of Q1.

[0042] According to the working principle of the comparator, the magnitude of the impact current that the feedback circuit can limit can be calculated as:

[0043]

[0044] When the detected current is less than the set limit value, V2 is lower than the reference voltage VREF (VREF is the 2.5V reference voltage inside TL431), the internal transistor of TL431 is in the cut-off state, and Q1 is turned on normally; when the detected current is greater than the set limit value, V2 is higher than the reference voltage, the internal transistor of TL431 is turned on, so that the driving voltage of Q1 is pulled down. GS -i DCurve, the current flowing through Q1 decreases until the current drops to the set limit value, that is, V2 is equal to the reference voltage value.

[0045] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A controllable current limiting impulse current suppression circuit on a ground line, characterized in that: include: The main power MOSFET and its driving circuit, current sampling detection circuit, voltage amplifier circuit, and negative feedback circuit based on a three-terminal regulator connected between the DC / DC power supply terminal and the Vin terminal; The current sampling detection circuit is connected in series to the ground line of the main power MOSFET and its drive circuit loop, and is used to collect the current signal on the main power MOSFET and its drive circuit and convert it into voltage. The output end of the current sampling detection circuit is connected to the input end of the voltage amplifier circuit, and is used to input the converted voltage signal into the voltage amplifier circuit. The output end of the voltage amplifier circuit is connected to the feedback input end of the negative feedback circuit, and 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 overcurrent occurs in the main loop. The feedback output end of the negative feedback circuit is connected to the gate of the main power MOSFET and its drive circuit, and is used to control the drive voltage of the main power MOSFET and its drive circuit, and then control the opening degree of the main power MOSFET and its drive circuit to suppress the impact current.

2. The controllable current limiting impulse current suppression circuit on the ground line according to claim 1, characterized in that: The drain and source of the main power MOSFET Q1 in the main power MOSFET and its driving circuit are connected in series to the ground line of the main power loop, wherein the driving circuit includes a gate driving resistor R9 and a gate discharge resistor R10, wherein the gate driving resistor R9 is connected in parallel to 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 to the gate and drain of the main power MOSFET Q1.

3. The controllable current limiting impulse current suppression circuit on the ground line according to claim 2, characterized in that: The current sampling detection circuit comprises a sampling resistor R1, and the sampling resistor R1 is connected in series between the source of the main power MOSFET Q1 and the negative terminal of the input power supply.

4. The controllable current limiting surge current suppression circuit on the ground line according to claim 3, characterized in that: The voltage amplification circuit includes 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; After voltage division by the voltage-dividing resistor R2 and the voltage-dividing resistor R3, the input voltage of the sampling resistor R1 is input into the positive input terminal of the operational amplifier N1, and the filter capacitor C1 and the voltage-dividing resistor R3 are connected in parallel; the voltage-dividing resistor R5 is connected in parallel between the negative input terminal and the ground of the operational amplifier N1, and the voltage-dividing 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-dividing resistor R4 are connected in parallel, and the output terminal of the operational amplifier N1 amplifies the voltage across the sampling resistor R1 according to the resistor voltage division ratio, and the output signal of the operational amplifier N1 is input into the 2.5V reference terminal of the voltage reference chip in the negative feedback circuit through the output current-limiting resistor R11.

5. The controllable current limiting surge current suppression circuit on the ground line according to claim 4, characterized in that: The operational amplifier N1 of the voltage amplifying circuit is a rail-to-rail operational amplifier.

6. The controllable current limiting surge current suppression circuit on the ground line according to claim 4, characterized in that: The negative feedback circuit includes a voltage reference chip, a voltage regulator tube V2, a current limiting resistor R8, a bus voltage dividing resistor R6 and a voltage dividing resistor R7, and a charging capacitor C3; the voltage dividing resistor R6 and the voltage dividing resistor 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 dividing resistor R6 and the voltage dividing resistor R7 and the cathode of the voltage reference chip, the anode of the voltage reference chip is connected to the input power ground, the charging capacitor C3 is connected in parallel to the cathode and the reference end of the voltage reference chip, and the voltage regulator tube V2 is connected in parallel between the cathode and the anode of the voltage reference chip.

7. The controllable current limiting surge current suppression circuit on the ground line according to claim 6, characterized in that: The negative feedback circuit adopts a negative feedback circuit based on a three-terminal regulator.

8. The controllable current limiting surge current suppression circuit on the ground line according to claim 6, characterized in that: The voltage reference chip adopts the voltage reference chip TL431.

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