A direct current voltage reducing circuit

Abstract

The utility model relates to the field of power electronics, especially a direct current step-down circuit, including MOS pipe Q1, reference module, self -excitation switch tube and sampling module, MOS pipe Q1 is in target loop through drain and source series connection, the drain of MOS pipe Q1 is used as input, the source of MOS pipe Q1 is used as output, self -excitation switch tube is coupled between the gate of MOS pipe Q1 and reference module, sampling module is coupled between target loop and self -excitation switch tube, when the sampling voltage that sampling module samples is greater than the sum of the conduction voltage of self -excitation switch tube and the reference voltage of reference module, self -excitation switch tube and MOS pipe Q1 are conducted, solved the various reliability problems that traditional direct current step-down circuit used capacitor and inductance charge and discharge to realize step-down to cause.

Description

Technical Field

[0001] This utility model relates to the field of power electronics technology, and in particular to a DC step-down circuit. Background Technology

[0002] Currently, DC step-down circuits are commonly used in the lighting industry. They are coupled with a switching transistor in the circuit loop, and the voltage is reduced by using the self-excitation of the switching transistor to control the charging and discharging of the capacitor and inductor. Frequent charging and discharging will lead to large output voltage ripple and generate relatively large noise, which will greatly reduce the signal quality received by the active filter at the receiving end and reduce the sensitivity of the receiving end. Therefore, they cannot be used in high-voltage environments or military communication products with strict power supply requirements. Utility Model Content

[0003] To address the aforementioned shortcomings, the purpose of this invention is to propose a DC step-down circuit that solves various reliability problems caused by the traditional DC step-down circuit's reliance on capacitors and inductors for voltage reduction.

[0004] To achieve this objective, the present invention adopts the following technical solution: A DC step-down circuit includes a MOSFET Q1, a reference module, a self-excited switch, and a sampling module; the MOSFET Q1 is connected in series with its drain and source in the target circuit, the drain of the MOSFET Q1 is used as the input terminal, and the source of the MOSFET Q1 is used as the output terminal; The self-excited switch is coupled between the gate of the MOS transistor Q1 and the reference module, and the sampling module is coupled between the target circuit and the self-excited switch. When the sampling voltage sampled by the sampling module is greater than the sum of the turn-on voltage of the self-excited switch and the reference voltage of the reference module, the self-excited switch and the MOS transistor Q1 are turned on.

[0005] Furthermore, the self-excited switching transistor is a MOS transistor Q2; the drain of the MOS transistor Q2 is electrically connected to the gate of the MOS transistor Q1, the gate of the MOS transistor Q2 is electrically connected to the sampling module, and the source of the MOS transistor Q2 is electrically connected to the reference module.

[0006] Furthermore, the reference module includes a Zener diode D1 and a resistor R3; one end of the resistor R3 is electrically connected to the source of the MOSFET Q1, and the other end of the resistor R3 and the cathode of the Zener diode D1 are both electrically connected to the source of the MOSFET Q2, and the anode of the Zener diode D1 is grounded.

[0007] Furthermore, the sampling module includes resistors R2, R5, and R6; one end of resistor R2 is electrically connected to the source of MOS transistor Q1, the other end of resistor R2 and one end of resistor R5 are both electrically connected to the gate of MOS transistor Q2, and the other end of resistor R5 is grounded through resistor R6.

[0008] Furthermore, it also includes a resistor R4; the resistor R4 is connected in parallel between the drain and gate of the MOS transistor Q1.

[0009] Furthermore, it also includes diodes D2 and D3; the anode and cathode of diode D2 are electrically connected to the source and gate of MOS transistor Q1, respectively, and the anode and cathode of diode D3 are electrically connected to the source and gate of MOS transistor Q2, respectively.

[0010] Furthermore, it also includes capacitors C1, C2, and C3; capacitor C1 is connected in parallel between the drain of the MOS transistor Q1 and ground, and capacitors C2 and C3 are both connected in parallel between the source of the MOS transistor Q1 and ground.

[0011] The technical solution provided by this utility model can include the following beneficial effects: Utilizing the characteristics of MOSFET Q1, after it is turned on, the conduction channel becomes smaller and the conduction resistance becomes larger, thus reducing the output voltage at the source (i.e., output terminal) of MOSFET Q1, thereby achieving voltage reduction in the target circuit. Specifically, a self-oscillating control system, consisting of a reference module, a self-oscillating switch, and a sampling module, follows the output voltage of the target circuit. When voltage reduction is required, the self-oscillating switch is turned on, thereby driving MOSFET Q1 to achieve voltage reduction.

[0012] More importantly, the reference module provides the reference voltage for the self-excited switching transistor instead of the traditional capacitor and inductor charging and discharging to provide the reference voltage for the self-excited switching transistor. This avoids the problems of large output voltage ripple, high noise, and serious impact on receiving devices caused by frequent charging and discharging, and is more suitable for high-voltage environments and military communication products. Attached Figure Description

[0013] Figure 1 This is a circuit diagram of a DC step-down circuit according to one embodiment of the present invention.

[0014] The components include: MOSFET Q1, reference module 1, self-excited switch 2, sampling module 3, MOSFET Q2, Zener diode D1, resistors R3, R2, R5, R6, R4, diode D2, diode D3, capacitors C1, C2, and C3. Detailed Implementation

[0015] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0016] In the description of embodiments of this utility model, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of embodiments of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0017] In the description of the embodiments of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this utility model according to the specific circumstances.

[0018] The following is combined with Figure 1 This describes a DC step-down circuit according to an embodiment of the present invention.

[0019] A DC step-down circuit includes a MOSFET Q1, a reference module 1, a self-excited switch 2, and a sampling module 3; the MOSFET Q1 is connected in series with the drain and source of the target circuit, the drain of the MOSFET Q1 is used as the input terminal, and the source of the MOSFET Q1 is used as the output terminal. The self-excited switch 2 is coupled between the gate of the MOS transistor Q1 and the reference module 1, and the sampling module 3 is coupled between the target circuit and the self-excited switch 2; When the sampling voltage sampled by the sampling module 3 is greater than the sum of the turn-on voltage of the self-excited switch 2 and the reference voltage of the reference module 1, the self-excited switch 2 and the MOS transistor Q1 are turned on.

[0020] This utility model proposes a preferred embodiment of a DC step-down circuit, such as... Figure 1As shown, utilizing the characteristics of MOSFET Q1, after it is turned on, the conduction channel becomes smaller and the on-resistance becomes larger, causing the output voltage at the source (i.e., output terminal) of MOSFET Q1 to decrease, thereby achieving voltage reduction in the target circuit. Specifically, the reference module 1, the self-oscillating switch 2, and the sampling module 3 constitute a self-oscillating control that follows the output voltage of the target circuit. When voltage reduction is required, the self-oscillating switch 2 will self-oscillate and turn on, thereby driving MOSFET Q1 to achieve voltage reduction.

[0021] More importantly, the reference module 1 provides the reference voltage for the self-excited switch 2 instead of the traditional capacitor and inductor charging and discharging to provide the reference voltage for the self-excited switch 2. This avoids the problems of large output voltage ripple, high noise, and serious impact on receiving devices caused by frequent charging and discharging, and is more suitable for high-voltage environments and military communication products.

[0022] Furthermore, the self-excited switch 2 is a MOSFET Q2; the drain of MOSFET Q2 is electrically connected to the gate of MOSFET Q1, the gate of MOSFET Q2 is electrically connected to the sampling module 3, and the source of MOSFET Q2 is electrically connected to the reference module 1.

[0023] In this embodiment, since the sampling module 3 directly samples from the target circuit (especially the high-voltage circuit) to drive the self-excited switch 2 to conduct, the self-excited switch 2 needs to withstand higher voltage and greater current. Therefore, the self-excited switch 2 preferably adopts a MOS transistor Q2, which can withstand higher voltage and greater current, effectively prevents the self-excited switch 2 from being broken down, and has low loss.

[0024] Furthermore, the reference module 1 includes a Zener diode D1 and a resistor R3; one end of the resistor R3 is electrically connected to the source of the MOSFET Q1, and the other end of the resistor R3 and the cathode of the Zener diode D1 are both electrically connected to the source of the MOSFET Q2, and the anode of the Zener diode D1 is grounded.

[0025] In this embodiment, reference module 1 utilizes the characteristics of Zener diode D1 to provide a stable reference voltage for self-excited switching transistor 2 (i.e., MOSFET Q2). Resistor R3 primarily serves as the input resistance between the source of MOSFET Q2 and the cathode of Zener diode D1, ensuring that the output voltage of the target circuit can form a loop with Zener diode D1, guaranteeing the normal operation of Zener diode D1 and providing a stable reference voltage for MOSFET Q2.

[0026] Furthermore, the sampling module 3 includes resistors R2, R5, and R6; one end of resistor R2 is electrically connected to the source of MOSFET Q1, the other end of resistor R2 and one end of resistor R5 are both electrically connected to the gate of MOSFET Q2, and the other end of resistor R5 is grounded through resistor R6.

[0027] In this embodiment, the sampling module 3 preferably uses a voltage divider circuit composed of resistors R2, R5 and R6 to perform sampling. The timing of voltage reduction can be adjusted by selecting different resistance values ​​for resistors R2, R5 and R6 respectively.

[0028] Furthermore, it also includes resistor R4; resistor R4 is connected in parallel between the drain and gate of MOSFET Q1.

[0029] In this embodiment, resistor R4 is the input resistance of the gate of MOSFET Q1 and the drain of MOSFET Q2. It mainly serves as an isolation device to prevent the input voltage of the target circuit from affecting MOSFET Q1 and MOSFET Q2.

[0030] Furthermore, it also includes diodes D2 and D3; the anode and cathode of diode D2 are electrically connected to the source and gate of MOSFET Q1, respectively, and the anode and cathode of diode D3 are electrically connected to the source and gate of MOSFET Q2, respectively.

[0031] In this embodiment, adding a diode between the source and gate of the two MOSFETs serves as a clamping protection for the MOSFETs, preventing high voltage or interference signals from causing the gate-source voltage to exceed the rated value, thus avoiding damage to the MOSFETs and making them more suitable for high voltage environments.

[0032] In addition, diode D3 can suppress the reverse current between the gate and source of MOSFET Q2, preventing the reverse current from affecting the Zener diode D1 in reference module 1 and ensuring the stability of the reference voltage.

[0033] Furthermore, it also includes capacitors C1, C2, and C3; capacitor C1 is connected in parallel between the drain of MOSFET Q1 and ground, and capacitors C2 and C3 are both connected in parallel between the source of MOSFET Q1 and ground.

[0034] In this embodiment, capacitors C1, C2, and C3 are mainly used to filter the input and output terminals of MOSFET Q1 after it is connected in series in the target circuit, so as to ensure that MOSFET Q1 is normally turned on or off.

[0035] Other configurations and operations of the DC buck circuit according to the embodiments of this utility model are known to those skilled in the art and will not be described in detail here.

[0036] In this specification, the terms "embodiment," "example," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0037] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A DC step-down circuit, characterized in that: It includes a MOSFET Q1, a reference module, a self-excited switch, and a sampling module; the MOSFET Q1 is connected in series with the drain and source in the target circuit, the drain of the MOSFET Q1 is used as the input terminal, and the source of the MOSFET Q1 is used as the output terminal; The self-excited switch is coupled between the gate of the MOS transistor Q1 and the reference module, and the sampling module is coupled between the target circuit and the self-excited switch. When the sampling voltage sampled by the sampling module is greater than the sum of the turn-on voltage of the self-excited switch and the reference voltage of the reference module, the self-excited switch and the MOS transistor Q1 are turned on.

2. The DC step-down circuit according to claim 1, characterized in that: The self-excited switching transistor is a MOS transistor Q2; the drain of the MOS transistor Q2 is electrically connected to the gate of the MOS transistor Q1, the gate of the MOS transistor Q2 is electrically connected to the sampling module, and the source of the MOS transistor Q2 is electrically connected to the reference module.

3. The DC step-down circuit according to claim 2, characterized in that: The reference module includes a Zener diode D1 and a resistor R3; one end of the resistor R3 is electrically connected to the source of the MOSFET Q1, and the other end of the resistor R3 and the cathode of the Zener diode D1 are both electrically connected to the source of the MOSFET Q2. The anode of the Zener diode D1 is grounded.

4. The DC step-down circuit according to claim 2, characterized in that: The sampling module includes resistors R2, R5, and R6; one end of resistor R2 is electrically connected to the source of MOS transistor Q1, the other end of resistor R2 and one end of resistor R5 are both electrically connected to the gate of MOS transistor Q2, and the other end of resistor R5 is grounded through resistor R6.

5. A DC step-down circuit according to claim 2, characterized in that: It also includes resistor R4; resistor R4 is connected in parallel between the drain and gate of the MOS transistor Q1.

6. A DC step-down circuit according to claim 3, characterized in that: It also includes diodes D2 and D3; the anode and cathode of diode D2 are electrically connected to the source and gate of MOS transistor Q1, respectively, and the anode and cathode of diode D3 are electrically connected to the source and gate of MOS transistor Q2, respectively.

7. The DC step-down circuit according to claim 1, characterized in that: It also includes capacitors C1, C2, and C3; capacitor C1 is connected in parallel between the drain of the MOS transistor Q1 and ground, and capacitors C2 and C3 are both connected in parallel between the source of the MOS transistor Q1 and ground.

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