CN220857923U - DC voltage-reducing circuit, DC voltage-reducing chip and switching power supply - Google Patents

Abstract

The application provides a direct-current voltage-reducing circuit, a direct-current voltage-reducing chip and a switching power supply, and relates to the technical field of electronic circuits. The direct current step-down circuit comprises a first switch circuit, a second switch circuit, a step-down circuit and a voltage conversion circuit. The first switch circuit is used for outputting an input voltage signal to the voltage conversion circuit; the second switch circuit is used for controlling the first switch circuit to be disconnected when the voltage amplitude of the input voltage signal is larger than a preset voltage threshold value; the voltage reducing circuit is used for reducing the input voltage signal when the first switch circuit is in an off state, so as to obtain a first voltage reducing signal and output the first voltage reducing signal to the voltage converting circuit; the voltage conversion circuit is used for converting an input voltage signal or a first voltage-reducing signal into a target voltage signal. The direct current voltage reduction circuit provided by the application has a large application range, and when the voltage amplitude of the input voltage signal exceeds the voltage threshold value of the voltage conversion circuit, the first switch circuit is in an off state, so that the voltage loss is reduced.

Description

DC voltage-reducing circuit, DC voltage-reducing chip and switching power supply

Technical Field

The present application relates to the field of electronic circuits, and in particular, to a dc voltage reduction circuit, a dc voltage reduction chip, and a switching power supply.

Background

In a switching power supply, the voltage amplitude conversion from a dc voltage to a dc voltage is often required to be applied to a dc voltage step-down circuit, so as to obtain a stable low-voltage dc supply voltage. The core of the buck circuit is a conversion control integrated circuit (INTEGRATED CIRCUIT, IC). The conversion control IC is an application specific integrated circuit for the step-down circuit. It is generally responsible for monitoring the input voltage and the output voltage and controlling the switching frequency and the duty cycle of the switching tube based on these voltage signals to maintain a stable output voltage.

The input voltage range of the existing conversion control IC is small, so that the application of the direct current voltage reduction circuit is limited.

Disclosure of utility model

In view of the above, the present application is directed to a dc voltage reduction circuit, a dc voltage reduction chip and a switching power supply, which can increase the input voltage range of the dc voltage reduction circuit, thereby expanding the application range of the dc voltage reduction circuit.

The technical scheme adopted by the application for solving the technical problems is as follows:

In a first aspect, the present application provides a dc voltage reduction circuit including a first switch circuit, a second switch circuit, a voltage reduction circuit, and a voltage conversion circuit. The first switch circuit is electrically connected with the voltage conversion circuit and is used for outputting the input voltage signal to the voltage conversion circuit when the voltage amplitude of the input voltage signal of the direct current voltage reduction circuit is smaller than or equal to a preset voltage threshold value; the second switch circuit is electrically connected with the first switch circuit and is used for controlling the first switch circuit to be switched from an on state to an off state when the voltage amplitude of the input voltage signal is larger than a preset voltage threshold value; the voltage reducing circuit is electrically connected with the voltage converting circuit and is used for carrying out voltage reducing treatment on the input voltage signal when the first switch circuit is in an off state, so that a first voltage reducing signal is obtained and is output to the voltage converting circuit, and the voltage amplitude of the first voltage reducing signal is smaller than or equal to a preset voltage threshold value; the voltage conversion circuit is used for converting an input voltage signal or a first voltage-reducing signal into a target voltage signal.

In one possible implementation of the application, the first switching circuit comprises a first impedance unit and a first switching unit. The first impedance unit is used for generating a first starting voltage signal based on the input voltage signal; the first switch unit is used for conducting based on the first starting voltage signal and outputting an input voltage signal to the voltage conversion circuit.

In one possible implementation of the present application, the first impedance unit includes a first resistor circuit, and the first switching unit includes a first switching tube; the input end of the first resistor circuit is connected with the input end of the direct current voltage reduction circuit and the first end of the first switch tube, the output end of the first resistor circuit is connected with the third end of the first switch tube, and the second end of the first switch tube is connected with the input end of the voltage conversion circuit.

In one possible implementation of the present application, the first switching circuit further includes a first protection unit connected between the second end of the first switching tube and the third end of the first switching tube.

In one possible implementation of the present application, the second switching circuit includes a second protection unit, a second impedance unit, a third impedance unit, and a second switching unit; the second protection unit is used for carrying out step-down processing on the input voltage signal to obtain a second step-down signal and outputting the second step-down signal to the second impedance unit; the second impedance unit is used for generating a second starting voltage signal based on a second voltage reduction signal when the voltage amplitude of the input voltage signal is larger than a preset voltage threshold value; the second switch unit is used for conducting based on the second starting voltage signal and outputting a voltage signal to ground to the third impedance unit; the third impedance unit is used for generating an off signal based on the voltage signal to ground and outputting the off signal to the first switch circuit so as to enable the first switch circuit to be switched from an on state to an off state.

In one possible implementation of the present application, the second protection unit includes a first zener diode, the second impedance unit includes a second resistance circuit, the third impedance unit includes a third resistance circuit, and the second switching unit includes a second switching tube; the second end of the first voltage stabilizing diode is connected with the input end of the direct current voltage reducing circuit; the input end of the second resistor circuit is connected with the first end of the first voltage stabilizing diode, and the output end of the second resistor circuit is connected with the third end of the second switching tube; the second end of the second switching tube is grounded, and the first end of the second switching tube is connected with the first switching circuit through the third resistor circuit.

In one possible implementation of the present application, the second switching circuit further includes a third protection unit connected between the second end of the second switching tube and the third end of the second switching tube.

In one possible implementation of the present application, the voltage step-down circuit includes a second zener diode, a second end of the second zener diode is connected to the input terminal of the dc voltage step-down circuit, and a first end of the second zener diode is connected to the input terminal of the voltage conversion circuit.

In one possible implementation of the present application, the dc voltage step-down circuit further includes a voltage feedback circuit, and the voltage feedback circuit is connected to the voltage conversion circuit, and is configured to generate a feedback voltage signal based on the target voltage signal and feedback the feedback voltage signal to the voltage conversion circuit.

In a second aspect, the present application provides a dc buck chip, which includes the dc buck circuit described above.

In a third aspect, the present application further provides a switching power supply, which includes the dc voltage step-down circuit described above.

In summary, due to the adoption of the technical scheme, the application at least comprises the following beneficial effects:

When the voltage amplitude of an input voltage signal is smaller than or equal to a preset voltage threshold, the direct-current voltage reducing circuit outputs the input voltage signal to the voltage converting circuit through the first switch circuit so as to convert the input voltage signal into a target voltage signal; when the voltage amplitude of the input voltage signal is larger than a preset voltage threshold, the second switch circuit is used for controlling the first switch circuit to switch from an on state to an off state, then the voltage reduction circuit is used for carrying out voltage reduction processing on the input voltage signal, and the first voltage reduction signal is output to the voltage conversion circuit so as to be converted into a target voltage signal by the voltage conversion circuit. Therefore, the input voltage range of the voltage conversion circuit is enlarged, and the application range of the direct current voltage reduction circuit is enlarged.

Drawings

For a clearer description of an embodiment of the application, reference will be made to the accompanying drawings of embodiments, which are given for clarity, wherein:

FIG. 1 is a schematic diagram of a general structure of a voltage step-down circuit in the related art;

fig. 2 is a schematic diagram of a dc voltage step-down circuit according to an embodiment of the present application;

fig. 3 is a schematic diagram of another structure of a dc voltage step-down circuit according to an embodiment of the present application;

Fig. 4 is a schematic diagram of another structure of a dc voltage step-down circuit according to an embodiment of the present application;

Fig. 5 is a schematic diagram of a structure of a first switch circuit according to an embodiment of the application;

FIG. 6 is a schematic circuit diagram of a first switch circuit according to an embodiment of the present application;

fig. 7 is a schematic diagram of a structure of a second switch circuit according to an embodiment of the application;

FIG. 8 is a schematic diagram of a second switch circuit according to an embodiment of the present application;

fig. 9 is a schematic diagram of another structure of a dc voltage step-down circuit according to an embodiment of the present application;

fig. 10 is a schematic circuit diagram of a dc voltage step-down circuit according to an embodiment of the present application.

Detailed Description

The technical solutions of the embodiments of the present application will be clearly and fully described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to fall within the scope of the application.

In the description of the present application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and are not to be interpreted as indicating or implying any relative importance or order of inclusion in the indicated technical feature. Thus, a feature defining "a first" or "a second" may include one or more features, either explicitly or implicitly.

In the present application, the term "exemplary" is used to mean "serving as an example, instance, or illustration. Any embodiment described as exemplary in this disclosure is not necessarily to be construed as preferred or advantageous over other embodiments. The following description is presented to enable any person skilled in the art to make and use the application. In the following description, details are set forth for purposes of explanation. It will be apparent to one of ordinary skill in the art that the present application may be practiced without these specific details. In other instances, well-known structures and processes have not been described in detail so as not to obscure the description of the application with unnecessary detail. Thus, the present application is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles disclosed herein.

In addition, the term "plurality" in the embodiments of the present application means two or more, and in view of this, the term "plurality" may be understood as "at least two" in the embodiments of the present application. "at least one" may be understood as one or more, for example as one, two or more. For example, including at least one means including one, two or more, and not limiting what is included, e.g., including at least one of A, B and C, then what may be included is A, B, C, A and B, A and C, B and C, or A and B and C.

It should be noted that in embodiments of the present application, "connected" may be understood as electrically connected, and two electrical components may be connected directly or indirectly between the two electrical components. For example, a may be directly connected to B, or indirectly connected to B via one or more other electrical components.

The first pole/first end of each switching tube used in the embodiment of the application is one of a source electrode and a drain electrode, and the second pole/second end of each switching tube is the other of the source electrode and the drain electrode. Since the source and drain of the switching tube may be symmetrical in structure, the source and drain thereof may be indistinguishable in structure, that is, the first pole/first end and the second pole/second end of the switching tube in the embodiments of the present application may be indistinguishable in structure. Illustratively, in the case where the switching tube is a P-type switching tube, the first pole/first end of the switching tube is a source and the second pole/second end is a drain; illustratively, in the case where the switching tube is an N-type switching tube, the first pole/first end of the switching tube is a drain electrode and the second pole/second end is a source electrode.

Before describing the dc voltage-reducing circuit and the dc voltage-reducing chip of the present application, first, relevant background information of the embodiments of the present application is described.

The direct current step-down circuit is an indispensable circuit unit in modern electronic products and chips, especially in switching power supplies. The voltage amplitude of the working voltage required by the partial load is lower than that of the input voltage, so that the partial load needs to be reduced and then output to the corresponding load. Since the voltage amplitude of the input voltage varies, in order to make the load operate normally, the present step-down circuit generally adopts the structure shown in fig. 1.

The step-down circuit as shown in fig. 1 includes an input terminal of a direct-current step-down circuit, a conversion control IC, a filter circuit, a voltage stabilizing circuit, and a feedback circuit. The input end of the direct current voltage reduction circuit is connected with the 1 pin of the conversion control IC and the filter circuit, the voltage stabilizing circuit is connected with the 3 pin of the conversion control IC, and the feedback circuit is connected with the voltage stabilizing circuit and the 4 pin of the conversion control IC. The input end of the direct current voltage reduction circuit generates an input voltage signal and outputs the input voltage signal to the conversion control IC, and the conversion control IC reduces the input voltage signal to obtain a target voltage signal and outputs the target voltage signal to a corresponding load through the voltage stabilizing circuit. The feedback circuit generates a feedback voltage signal based on the target voltage signal and feeds back the feedback voltage signal to the conversion control IC.

The voltage amplitude of the input voltage signal acceptable by the voltage reducing circuit is limited, and the applicable variable range of the voltage amplitude of the input voltage signal is tens of volts. If the voltage amplitude of the input voltage signal exceeds the input voltage of the conversion control IC, the step-down circuit cannot be employed. The input voltage of the conversion control IC is the working voltage of the conversion control IC.

Based on this, the embodiment of the application provides a dc voltage reduction circuit and a dc voltage reduction chip, which are described in detail below.

Referring to fig. 2, fig. 2 is a schematic diagram of a dc voltage step-down circuit 100 according to an embodiment of the application. The embodiment of the present application provides a dc voltage reducing circuit 100, where the dc voltage reducing circuit 100 includes a first switch circuit 30, a second switch circuit 20, a voltage reducing circuit 40, and a voltage converting circuit 50.

The first switch circuit 30 is electrically connected to the voltage conversion circuit 50. The first switch circuit is configured to output the input voltage signal to the voltage conversion circuit 50 when the voltage amplitude of the input voltage signal of the dc voltage reduction circuit is less than or equal to a preset voltage threshold.

The second switching circuit 20 is electrically connected to the first switching circuit 30. When the voltage amplitude of the input voltage signal is greater than the preset voltage threshold, the second switch circuit 20 is configured to control the first switch circuit 30 to switch from the on state to the off state.

The step-down circuit 40 is electrically connected to the voltage conversion circuit 50. When the first switch circuit 30 is in an off state, the voltage-reducing circuit 40 is configured to perform voltage-reducing processing on the input voltage signal, obtain a first voltage-reducing signal, and output the first voltage-reducing signal to the voltage conversion circuit 50; the voltage amplitude of the first voltage reduction signal is smaller than or equal to a preset voltage threshold value.

The voltage conversion circuit 50 is configured to convert an input voltage signal or a first step-down signal into a target voltage signal, and output the target voltage signal to the output terminal 90 of the dc step-down circuit.

It will be appreciated that the input voltage signal of the dc voltage reduction circuit is the voltage signal that needs to be reduced, which is generated by the input 10 of the dc voltage reduction circuit. The voltage conversion circuit 50 is a conversion control IC. Alternatively, the model of the shift control IC is OB2107MP.

The preset voltage threshold is the maximum voltage value at which the voltage conversion circuit 50 can operate normally.

When the voltage amplitude of the input voltage signal is less than or equal to the preset voltage threshold, the first switch circuit 30 is in a conducting state, and outputs the input voltage signal from the input terminal 10 of the dc voltage reduction circuit to the voltage conversion circuit 50, and the voltage conversion circuit 50 performs voltage reduction processing on the input voltage signal to obtain a target voltage signal, and outputs the target voltage signal to the load.

When the voltage amplitude of the input voltage signal is greater than the preset voltage threshold, if the input voltage signal is still output to the voltage conversion circuit 50 through the first switch circuit 30, damage to the voltage conversion circuit 50 may be caused. Therefore, at this time, the first switch circuit 30 can be controlled by the second switch circuit 20 to switch from the on state to the off state. The voltage-reducing circuit 40 then performs a voltage-reducing process on the input voltage signal to obtain a first voltage-reduced signal, and then outputs the first voltage-reduced signal to the voltage conversion circuit 50. The voltage conversion circuit 50 performs a step-down process on the first step-down signal to obtain a target voltage signal, and outputs the target voltage signal to the load.

For example, when the operating voltage range of the voltage conversion circuit 50 is 36-70V, the preset voltage threshold is 70V correspondingly.

When the voltage amplitude of the input voltage signal is 36-70V, the first switch circuit 30 is in a conductive state, and outputs the input voltage signal to the voltage conversion circuit 50, and the voltage conversion circuit 50 performs step-down processing on the input voltage signal to obtain a target voltage signal.

When the voltage amplitude of the input voltage signal is 70-95V, the voltage-reducing circuit 40 performs voltage-reducing processing on the input voltage signal, where the voltage amplitude that can be reduced is the maximum voltage amplitude of the input voltage signal minus the voltage amplitude of the maximum operating voltage of the voltage conversion circuit 50, that is, 95V-70 v=25v. The voltage-reducing circuit 40 reduces the input voltage signal with the voltage amplitude of 70-95V to obtain a first voltage-reducing signal with the voltage amplitude of 45-70V. The first step-down signal is then output to the voltage conversion circuit 50, and the voltage conversion circuit 50 performs step-down processing on the first step-down signal to obtain a target voltage signal.

In the dc voltage reduction circuit provided by the embodiment of the present application, when the voltage amplitude of the input voltage signal is less than or equal to the preset voltage threshold, the input voltage signal is output to the voltage conversion circuit 50 through the first switch circuit 30, so that the voltage conversion circuit 50 converts the input voltage signal into the target voltage signal; when the voltage amplitude of the input voltage signal is greater than the preset voltage threshold, the second switch circuit 20 controls the first switch circuit 30 to switch from the on state to the off state, and the step-down circuit 40 steps down the input voltage signal to output the first step-down signal to the voltage conversion circuit 50, so that the voltage conversion circuit 50 converts the input voltage signal into the target voltage signal, and the input voltage range of the voltage conversion circuit 50 is enlarged, thereby expanding the application range of the direct current step-down circuit.

And, when the voltage amplitude of the input voltage signal exceeds the voltage conversion circuit 50, the first switching circuit 30 is in an off state, thereby reducing voltage loss.

In addition, when the voltage amplitude of the input voltage signal is less than or equal to the preset voltage threshold value, the first switch circuit 30 is used for conveying the voltage signal; when the voltage amplitude of the input voltage signal is greater than the preset voltage threshold, the voltage signal is delivered by the step-down circuit 40. Therefore, different circuits are adopted for voltage input in different states, so that the control is simple and direct, and two circuits are adopted for inputting voltage signals, so that the two circuits share the working time, and the service life of the voltage reduction circuit is prolonged.

In implementation, the step-down circuit 40 can be made into an external structure, so that the step-down circuit can be quickly replaced according to the amplitude values of different input voltage signals, the application range of the direct-current step-down circuit is wider, the operation is simple and direct, and the cost is low. A plurality of step-down circuits may be employed, and the step-down circuits may be connected in series, and a switch may be provided for the remaining step-down circuits to perform switching of the step-down lines. So that the number of step-down circuits of the access circuit can be selected according to the actual situation.

Referring to fig. 3, fig. 3 is a schematic diagram of a dc voltage step-down circuit 100 according to an embodiment of the application. In some embodiments of the present application, the dc voltage reducing circuit 100 further includes a filter circuit 60, and the filter circuit 60 is connected to the output terminal of the first switch circuit 30 and the output terminal of the voltage reducing circuit 40. The first switching circuit 30 outputs the input voltage signal to the filter circuit 60; the step-down circuit 40 outputs the first step-down signal to the filter circuit 60.

The filter circuit 60 may perform multiple filtering rectification on the input voltage signal or the first step-down signal, so that the voltage signal input to the voltage conversion circuit 50 is gentle and stable, thereby improving the stability and reliability of the target voltage signal output by the voltage conversion circuit 50.

Alternatively, the filter circuit 60 may include a third capacitor, which may be a ceramic chip capacitor, and one end of the third capacitor is connected to the first switch circuit 30 and the step-down circuit 40, and the other end is grounded.

Referring to fig. 4, fig. 4 is a schematic diagram of another structure of a dc voltage reduction circuit 100 according to an embodiment of the application. In some embodiments of the present application, the dc voltage reduction circuit 100 further includes a first tank circuit 70, where the first tank circuit 70 is connected to the input terminal 10 of the dc voltage reduction circuit, and is used for storing the voltage of the input voltage signal. The electrical energy stored in the first tank circuit 70 may be used for high power loads.

Alternatively, the first tank circuit 70 comprises a first capacitance, in particular the first capacitance may be an electrolytic capacitance. The positive terminal of the voltage regulator is connected with the input terminal 10 of the direct current voltage reducing circuit, and the negative terminal of the voltage regulator is grounded.

Referring to fig. 5, fig. 5 is a schematic diagram of a first switch circuit according to an embodiment of the application. In some embodiments of the present application, the first switching circuit 30 includes a first impedance unit 302 and a first switching unit 301. The first impedance unit 302 is configured to generate a first start voltage signal based on the input voltage signal; the first switching unit 301 is configured to be turned on based on the first start voltage signal to output an input voltage signal to the voltage conversion circuit 50.

In this embodiment, the first impedance unit 302 is configured to sample the input voltage signal to obtain a first starting voltage signal for starting the first switch unit 301.

In some embodiments of the present application, the first impedance unit 302 includes a first resistance circuit, and the first switching unit 301 includes a first switching tube; the input end of the first resistor circuit is connected with the input end 10 of the direct current step-down circuit and the first end of the first switch tube, the output end of the first resistor circuit is connected with the third end of the first switch tube, and the second end of the first switch tube is connected with the input end of the voltage conversion circuit 50.

The first switching tube can be a triode, a thyristor, a MOS tube, an IGBT tube and other switching tubes.

Referring to fig. 6, fig. 6 is a schematic circuit diagram of a first switch circuit according to an embodiment of the application. In this embodiment, optionally, the first switching tube is a first MOS tube Q1. The drain electrode of the first MOS tube Q1 is a first end, the source electrode of the first MOS tube Q1 is a second end, and the grid electrode of the first MOS tube Q1 is a third end. The first resistor circuit may include a first resistor R1, which may be understood that the first resistor circuit may also include a plurality of resistors sequentially connected in series, which may be specifically determined according to an actual application scenario, and is not limited herein.

As shown in fig. 5, in some embodiments of the present application, the first switching circuit 30 further includes a first protection unit 303, and the first protection unit 303 is connected between the second terminal of the first switching tube and the third terminal of the first switching tube.

In this embodiment, the first protection unit 303 is configured to limit the voltage between the second end of the first switching tube and the third end of the first switching tube, so that the voltage amplitude between the second end of the first switching tube and the third end of the first switching tube does not exceed the specification of the first switching tube.

As shown in fig. 6, the first protection unit is optionally a third zener diode ZD3. The first end, namely the anode, of the third zener diode ZD3 is connected with the second end of the first MOS transistor Q1, and the second end, namely the cathode, of the third zener diode ZD3 is connected with the third end of the first MOS transistor Q1. In other examples, the first protection unit may further be a voltage-dropping element such as a resistor, which is connected between the second end of the first MOS transistor Q1 and the third end of the first MOS transistor Q1 to limit the voltage between the second end of the first MOS transistor Q1 and the third end of the first MOS transistor Q1.

Referring to fig. 7, fig. 7 is a schematic diagram of a structure of a second switching circuit according to an embodiment of the application. In some embodiments of the present application, the second switching circuit 20 includes a second protection unit 201, a second impedance unit 202, a third impedance unit 203, and a second switching unit 204; the second protection unit 201 is configured to perform a step-down process on the input voltage signal, and obtain a second step-down signal, and output the second step-down signal to the second impedance unit 202; the second impedance unit 202 is configured to generate a second start voltage signal based on the second step-down signal when the voltage amplitude of the input voltage signal is greater than a preset voltage threshold; the second switch unit 204 is configured to be turned on based on the second start voltage signal, and output a voltage signal to ground to the third impedance unit 203; the third impedance unit 203 is configured to generate an off signal based on the voltage signal to ground and output the off signal to the first switch circuit 30, so that the first switch circuit 30 is switched from an on state to an off state.

The second impedance unit 202 is configured to sample the input voltage signal to obtain a second start voltage signal for starting the second switch unit 204, so that the second switch unit 204 is turned on, thereby outputting a voltage signal to ground to the first switch circuit 30 through the third impedance unit 203, and pull down the voltage of the first switch circuit 30 based on the third impedance unit 203, thereby turning off the first switch circuit 30.

Referring to fig. 8, fig. 8 is a schematic circuit diagram of a second switch circuit according to an embodiment of the application. In some embodiments of the present application, the second protection unit 201 includes a first zener diode ZD1; the second impedance unit 202 includes a second resistance circuit, which may include a second resistance R2; the third impedance unit 203 includes a third resistance circuit, which may include a third resistance R3, and the second switching unit 204 includes a second switching tube. The second switching tube is a second MOS tube Q2. The drain electrode of the second MOS tube Q2 is a first end, the source electrode of the second MOS tube Q2 is a second end, and the grid electrode of the second MOS tube Q2 is a third end.

The second switching tube can be a triode, a thyristor, a MOS tube, an IGBT tube and other switching tubes.

The second end of the first zener diode ZD1 is connected with the input end 10 of the direct current voltage reduction circuit; the input end of the second resistor R2 is connected with the first end of the first zener diode ZD1, and the output end of the second resistor R2 is connected with the third end of the second MOS tube Q2; the second end of the second MOS transistor Q2 is grounded, and the first end of the first zener diode ZD1 is connected to the first switch circuit 30 through the third resistor R3.

The cathode terminal of the first zener diode ZD1 is a first terminal, and the anode terminal of the first zener diode ZD1 is a second terminal, which is turned on when the voltage amplitude of the input voltage signal exceeds a preset voltage threshold.

It can be appreciated that the second resistor circuit and the third resistor circuit may further include a plurality of resistors connected in series, and the resistance value of each resistor may be determined according to an actual application scenario, which is not limited herein.

As shown in fig. 7, in some embodiments of the present application, the second switch circuit 20 further includes a third protection unit 205, and the third protection unit 205 is connected to the second switch unit 204, specifically, between the second end of the second MOS transistor Q2 and the third end of the second MOS transistor Q2.

The third protection unit 205 is configured to limit a voltage between the second end of the second MOS transistor Q2 and the third end of the second MOS transistor Q2, so that a voltage amplitude between the second end of the second MOS transistor Q2 and the third end of the second MOS transistor Q2 does not exceed a specification of the second MOS transistor Q2.

Optionally, the third protection unit 205 is a zener diode and/or a resistor.

In some embodiments of the present application, the voltage step-down circuit 40 includes a second zener diode ZD2, a second terminal of the second zener diode ZD2 is connected to the input terminal 10 of the dc voltage step-down circuit, and a first terminal of the second zener diode ZD2 is connected to the input terminal of the voltage conversion circuit 50.

The cathode terminal of the second zener diode ZD2 is a first terminal, and the anode terminal of the second zener diode ZD2 is a second terminal, which is turned on when the voltage amplitude of the input voltage signal exceeds a preset voltage threshold.

Referring to fig. 9, fig. 9 is a schematic diagram of a dc voltage reduction circuit 100 according to an embodiment of the application. In some embodiments of the present application, the dc voltage step-down circuit 100 further includes a voltage feedback circuit 80, where the voltage feedback circuit 80 is connected to the voltage conversion circuit 50, and the voltage feedback circuit 80 is configured to generate a feedback voltage signal based on the target voltage signal and feedback the feedback voltage signal to the voltage conversion circuit 50.

The voltage feedback circuit 80 includes a fourth impedance unit and a fifth impedance unit, wherein one end of the fourth impedance unit is connected to the output end of the voltage feedback circuit 80, and the other end of the fourth impedance unit is connected to one end of the fifth impedance unit and the feedback end of the voltage feedback circuit 80. The other end of the fifth impedance unit is grounded.

Optionally, the fourth impedance unit and the fifth impedance unit are resistors.

Referring to fig. 10, fig. 10 is a schematic circuit diagram of a dc voltage reduction circuit 100 according to an embodiment of the application. The embodiment of the present application provides a dc voltage reducing circuit 100, where the dc voltage reducing circuit 100 includes a first switch circuit 30, a second switch circuit 20, a voltage reducing circuit 40, a voltage converting circuit 50, and a filter circuit 60.

The voltage conversion circuit 50 is a conversion control IC, and hereinafter, the chip U1 is referred to as the voltage conversion circuit 50.

The first switch circuit 30 includes a first MOS transistor Q1 and a first resistor R1, where an input end of the first resistor R1 is connected to the input end 10 of the dc voltage reduction circuit and a first end of the first MOS transistor Q1, an output end of the first resistor R1 is connected to a third end of the first MOS transistor Q1, and a second end of the first MOS transistor Q1 is connected to a voltage input end of the chip U1.

The second switching circuit 20 includes a first zener diode ZD1, a second resistor R2, a third resistor R3, and a second MOS transistor Q2. The cathode end of the first zener diode ZD1 is connected with the input end 10 of the direct current voltage reduction circuit, the anode end of the first zener diode ZD1 is connected with the input end of the second resistor R2, the output end of the second resistor R2 is connected with the third end of the second MOS tube Q2, the second end of the second MOS tube Q2 is grounded, the first end of the second MOS tube Q2 is connected with the output end of the third resistor R3, and the input end of the third resistor R3 is connected with the third end of the first MOS tube Q1.

The step-down circuit 40 includes a second zener diode ZD2, wherein a cathode terminal of the second zener diode ZD2 is connected to the input terminal 10 of the dc step-down circuit, and an anode terminal of the second zener diode ZD2 is connected to the voltage input terminal of the chip U1.

The filter circuit 60 includes a third capacitor C3, an input end of the third capacitor C3 is connected to the second end of the first MOS transistor Q1 and the anode end of the second zener diode ZD2, and an output end of the third capacitor C3 is grounded.

When the input voltage is within the operating voltage of the chip U1, the gate of the second MOS transistor Q2 is in an off state due to the barrier of the first zener diode ZD1 not having a driving voltage. The input voltage signal v_bull is sent to the gate of the first MOS transistor Q1 through the first resistor R1, so that the first MOS transistor Q1 is in a conducting state. The second zener diode ZD2 is now bypassed and is not connected in series to the supply loop of the chip U1. The input voltage signal v_bull is sent to Pin1 of the chip U1 and the third capacitor C3 after passing through pins 1 and 2 of the first MOS transistor Q1. The voltage amplitude of Pin1 Pin of the chip U1 is consistent with the voltage amplitude of the input voltage signal v_bulk. The input voltage signal V_bulk is in the normal input voltage range of the chip U1, and the chip U1 can stably convert the target voltage signal after voltage reduction.

When the input voltage exceeds the working voltage of the chip U1, the input voltage signal v_bull is sent to the gate of the second MOS transistor Q2 through the first zener diode ZD1, so that the second MOS transistor Q2 is in a conductive state. The negative end of the third resistor R3 is in a short circuit state to the ground through the second MOS tube Q2, so that the third zener diode ZD3 is conducted in the positive direction. At this time, the gate voltage of the first MOS transistor Q1 is pulled down to be in an off state. The input voltage signal v_bulk is reduced by the second zener diode ZD2 and then sent to the third capacitor C3 and Pin1 of the chip U1.

Assuming that the maximum value of the operating voltage of the chip U1 is 70V, the input voltage signal v_bulk is 80V, and the regulated value of the zener diode ZD2 is 25V. At this time, the input voltage signal v_bulk is first reduced in voltage by the second zener diode ZD2 and then transferred to Pin1 of the chip U1. The Pin1 Pin voltage of the chip U1 is 80V-25 v=55v. By configuring the second zener diode ZD2 and other related components, the input voltage amplitude of the chip U1 is within the specification range, so that the chip U1 can stably convert the target voltage after voltage reduction, and stable operation of the chip U1 is realized.

In the dc voltage reduction circuit provided in this embodiment, the voltage amplitude range of the input voltage signal that can be used is not limited. Which can adjust the voltage amplitude of the input chip U1 by adjusting the regulated value of the second zener diode ZD 2. I.e. the highest voltage amplitude voltage of the input voltage signal v_bulk is equal to the sum of the highest input voltage of the chip U1 and the regulated voltage of the second zener diode ZD 2.

As shown in fig. 10, the dc voltage reducing circuit 100 further includes a first tank circuit 70, a voltage stabilizing circuit, and a voltage feedback circuit 80.

The first tank circuit 70 includes a first capacitor C1, where the positive terminal of the first capacitor C1 is connected to the input terminal 10 of the dc voltage reduction circuit, and the negative terminal of the first capacitor C1 is grounded.

The voltage stabilizing circuit comprises a first inductor L1 and a second capacitor C2, wherein the input end of the first inductor L1 is connected with the output end of the voltage converting circuit, the output end of the first inductor L1 is connected with the positive end of the second capacitor C2, and the negative end of the second capacitor C2 is grounded.

The feedback circuit comprises a fourth resistor R4, a sixth resistor R6 and a fourth capacitor C4, wherein the input end of the fourth resistor R4 is connected with the output end of the first inductor L1, and the output end of the fourth resistor R4 is connected with the input end of the sixth resistor R6 and the feedback end of the chip U1. The output end of the sixth resistor R6 is grounded. The fourth capacitor C4 is connected in parallel with the resistor R6.

Correspondingly, the application also provides a direct-current voltage reduction chip, which comprises the direct-current voltage reduction circuit 100. The chip may be an integrated circuit (INTEGRATED CIRCUIT, IC), or microcircuit (microcircuit), microchip (microchip), wafer/chip (chip). The Chip may be, but is not limited to, a System On Chip (SOC), a System on package (SYSTEM IN PACKAGE, SIP) Chip.

The step-down circuit of the chip obtains a target voltage signal by processing an input voltage signal of the input terminal 10 of the direct current step-down circuit. Specifically, when the voltage amplitude of the input voltage signal is less than or equal to a preset voltage threshold, the voltage converting circuit performs step-down processing on the input voltage signal to obtain a target voltage signal. When the voltage amplitude of the input voltage signal is larger than a preset voltage threshold value, the voltage reducing circuit performs voltage reducing processing on the input voltage signal to obtain a first voltage reducing signal, and the first voltage reducing signal is output to the voltage converting circuit. The voltage conversion circuit performs a step-down process on the first step-down signal to obtain a target voltage signal. The application range of the direct current voltage reduction chip is effectively expanded by reducing the voltage of an input voltage signal exceeding the working voltage of the voltage reduction circuit and then processing the signal; the direct current voltage reduction chip is simple in structure and direct in control.

Correspondingly, the application also provides a switching power supply, which comprises the direct current voltage reduction circuit 100.

In the switching power supply, by configuring the dc voltage reduction circuit 100, the input voltage can be converted into a stable dc voltage suitable for the electronic device, and the voltage feedback circuit 80 can respond to the load change in an instant, so as to output a stable voltage, and further ensure the normal operation of the related electronic device.

While the basic concepts have been described above, it will be apparent to those skilled in the art that the foregoing detailed disclosure is by way of example only and is not intended to be limiting. Although not explicitly described herein, various modifications, improvements and adaptations of the application may occur to one skilled in the art. Such modifications, improvements, and modifications are intended to be suggested within the present disclosure, and therefore, such modifications, improvements, and adaptations are intended to be within the spirit and scope of the exemplary embodiments of the present disclosure.

Claims (11)

1. The direct-current voltage reduction circuit is characterized by comprising a first switch circuit, a second switch circuit, a voltage reduction circuit and a voltage conversion circuit;

The first switch circuit is electrically connected with the voltage conversion circuit, and is used for outputting the input voltage signal of the direct-current voltage reduction circuit to the voltage conversion circuit when the voltage amplitude of the input voltage signal is smaller than or equal to a preset voltage threshold value;

The second switch circuit is electrically connected with the first switch circuit, and is used for controlling the first switch circuit to be switched from an on state to an off state when the voltage amplitude of the input voltage signal is larger than the preset voltage threshold value;

The voltage reducing circuit is electrically connected with the voltage converting circuit, and is used for reducing the input voltage signal when the first switch circuit is in an off state, so that a first voltage reducing signal is obtained and output to the voltage converting circuit, and the voltage amplitude of the first voltage reducing signal is smaller than or equal to a preset voltage threshold value;

The voltage conversion circuit is used for converting the input voltage signal or the first voltage reduction signal into a target voltage signal.

2. The dc voltage reduction circuit of claim 1, wherein the first switching circuit comprises:

A first impedance unit for generating a first start voltage signal based on the input voltage signal;

And the first switch unit is used for conducting based on the first starting voltage signal and outputting the input voltage signal to the voltage conversion circuit.

3. The direct current step-down circuit according to claim 2, wherein the first impedance unit includes a first resistance circuit, and the first switching unit includes a first switching tube; the input end of the first resistor circuit is connected with the input end of the direct current voltage reduction circuit and the first end of the first switch tube, the output end of the first resistor circuit is connected with the third end of the first switch tube, and the second end of the first switch tube is connected with the input end of the voltage conversion circuit.

4. The dc voltage reduction circuit of claim 3, wherein the first switching circuit further comprises a first protection unit connected between the second terminal of the first switching tube and the third terminal of the first switching tube.

5. The direct current step-down circuit according to claim 1, wherein the second switching circuit includes a second protection unit, a second impedance unit, a third impedance unit, and a second switching unit;

the second protection unit is used for performing step-down processing on the input voltage signal to obtain a second step-down signal and outputting the second step-down signal to the second impedance unit;

The second impedance unit is used for generating a second starting voltage signal based on the second voltage reduction signal when the voltage amplitude of the input voltage signal is larger than the preset voltage threshold value;

The second switch unit is used for conducting based on the second starting voltage signal and outputting a voltage signal to ground to the third impedance unit;

The third impedance unit is configured to generate an off signal to the first switch circuit based on the voltage signal to ground, so that the first switch circuit is switched from an on state to an off state.

6. The dc voltage reduction circuit of claim 5, wherein the second protection unit comprises a first zener diode, the second impedance unit comprises a second resistance circuit, the third impedance unit comprises a third resistance circuit, and the second switching unit comprises a second switching tube;

The second end of the first voltage stabilizing diode is connected with the input end of the direct current voltage reducing circuit;

The input end of the second resistor circuit is connected with the first end of the first zener diode, and the output end of the second resistor circuit is connected with the third end of the second switching tube;

the second end of the second switching tube is grounded, and the first end of the second switching tube is connected with the first switching circuit through the third resistance circuit.

7. The dc voltage reduction circuit of claim 6, wherein the second switching circuit further comprises a third protection unit connected between the second terminal of the second switching tube and the third terminal of the second switching tube.

8. The dc voltage reduction circuit of claim 1, wherein the voltage reduction circuit comprises a second zener diode, a second terminal of the second zener diode being connected to the input terminal of the dc voltage reduction circuit, and a first terminal of the second zener diode being connected to the input terminal of the voltage conversion circuit.

9. The direct current voltage reduction circuit according to any one of claims 1 to 8, further comprising a voltage feedback circuit connected to the voltage conversion circuit, the voltage feedback circuit being configured to generate a feedback voltage signal based on the target voltage signal and to feed back the feedback voltage signal to the voltage conversion circuit.

10. A direct current step-down chip comprising the direct current step-down circuit according to any one of claims 1 to 9.

11. A switching power supply comprising a dc voltage reducing circuit as claimed in any one of claims 1 to 9.