Input overvoltage protection circuit and switching power supply

Abstract

The utility model discloses an input overvoltage protection circuit and a switching power supply, and relates to the technical field of overvoltage protection, the input overvoltage protection circuit comprises a sampling circuit configured to collect an input voltage and convert the input voltage into a sampling signal; the comparison circuit is connected with the sampling circuit and is configured to compare the voltage of the sampling signal with a reference voltage to generate a switching signal; and the control circuit is connected with the comparison circuit and is configured to generate a control signal according to the switching signal and output the control signal. According to the input overvoltage protection circuit and the switching power supply provided by the utility model, input overvoltage protection without a return difference circuit can be provided for the AC / DC switching power supply, the circuit is simple, the return difference circuit is not needed, the occupied area of the input overvoltage protection circuit on a printed circuit board is reduced, and the manufacturing cost is reduced at the same time.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of overvoltage protection technical field, and particularly, it is related to an input overvoltage protection circuit and switching power supply. BACKGROUND

[0002] In today's switching power supply products, various protection functions of the product can be applied to various environments, and can ensure the reliability of the product, and input overvoltage protection is one of the protection functions.

[0003] The current input overvoltage protection circuit has many circuit devices, and the comparator is not single, but two comparators are collected together to make an integrated circuit (IC), and the circuit also includes a hysteresis circuit, so the current input overvoltage protection circuit occupies a larger area of the printed circuit board, and the cost is higher.

[0004] This section aims to provide background or context for the utility model embodiments stated in the claims. The description in this section is not admitted to be prior art merely because it is included in this section. UTILITY MODEL CONTENT

[0005] The utility model aims to provide an input overvoltage protection circuit and switching power supply, which can at least solve one of the above technical problems of the current input overvoltage protection circuit.

[0006] The utility model embodiment provides an input overvoltage protection circuit, which comprises:

[0007] A sampling circuit configured to collect an input voltage and convert the input voltage into a sampling signal;

[0008] A comparison circuit connected to the sampling circuit and configured to compare the voltage of the sampling signal with a reference voltage and generate a switching signal;

[0009] A control circuit connected to the comparison circuit and configured to generate a control signal according to the switching signal and output the control signal.

[0010] In some embodiments, the sampling circuit comprises:

[0011] A first resistance module, the first end of the first resistance module is configured to collect the input voltage;

[0012] A second resistance module, the first end of the second resistance module is connected to the second end of the first resistance module, and the second end of the second resistance module is grounded;

[0013] A first capacitance module, the first end of the first capacitance module is connected to the first end of the second resistance module, and the second end of the first capacitance module is grounded.

[0014] In some embodiments, the first resistance module comprises a first resistance, a second resistance and a third resistance connected in series.

[0015] The second resistance module comprises a fourth resistance and a fifth resistance connected in parallel.

[0016] In some embodiments, the comparison circuit comprises:

[0017] a diode, a first end of the diode configured to input a reference voltage;

[0018] a third resistance module, a first end of the third resistance module connected to a second end of the diode;

[0019] an adjustable shunt regulator, a first end of the adjustable shunt regulator connected to a second end of the third resistance module, a second end of the adjustable shunt regulator connected to a first end of the first capacitance module, a third end of the adjustable shunt regulator grounded.

[0020] In some embodiments, the control circuit comprises:

[0021] a first MOS transistor, a first end of the first MOS transistor configured to output the control signal, a second end of the first MOS transistor grounded, a third end of the first MOS transistor inputting a first voltage;

[0022] a second MOS transistor, a first end of the second MOS transistor connected to the third end of the first MOS transistor, a second end of the second MOS transistor grounded;

[0023] a fourth resistance module, a first end of the fourth resistance module connected to the third end of the first MOS transistor, a second end of the fourth resistance module connected to the first end of the third resistance module;

[0024] a fifth resistance module, a first end of the fifth resistance module connected to the third end of the second MOS transistor, a second end of the fifth resistance module connected to the second end of the third resistance module;

[0025] a sixth resistance module, a first end of the sixth resistance module connected to the third end of the second MOS transistor, a second end of the sixth resistance module grounded;

[0026] a second capacitance module, a first end of the second capacitance module connected to the third end of the first MOS transistor, a second end of the second capacitance module grounded;

[0027] a seventh resistance module, a first end of the seventh resistance module connected to the third end of the first MOS transistor, a second end of the seventh resistance module connected to the first end of the second resistance module;

[0028] a third capacitor module, a first end of the third capacitor module being connected with a second end of the fifth resistor module, and a second end of the third capacitor module being grounded.

[0029] In some embodiments, the third capacitor module comprises a first capacitor and a second capacitor connected in parallel with each other.

[0030] The control circuit further comprises a fourth capacitor module, a first end of the fourth capacitor module being connected with a third end of the second MOS tube, and a second end of the fourth capacitor module being grounded.

[0031] In some embodiments, when the voltage at the second end of the adjustable shunt regulator is lower than the reference voltage, the adjustable shunt regulator remains off, the first end of the third capacitor module is at a high voltage level, the second MOS tube is turned on at a high level, the first MOS tube is turned off at a low level, and the first end of the first MOS tube outputs a low level control signal.

[0032] In some embodiments, when the voltage at the second end of the adjustable shunt regulator is higher than the reference voltage, the first end of the adjustable shunt regulator outputs a low level voltage, the second MOS tube is turned off at a low level, and the first MOS tube is turned on at a high level while pulling down the voltage of the control signal outputted at the first end.

[0033] In some embodiments, the charging time / discharge time of the third capacitor module is greater than half of the cycle period of the alternating current.

[0034] The utility model embodiment further provides a switching power supply, including the input overvoltage protection circuit that any embodiment described above, the input end of sampling circuit is connected with the input positive pole of switching power supply, the output end of control circuit is connected with the control chip of switching power supply.

[0035] The input overvoltage protection circuit and the switching power supply provided by the utility model embodiment acquire the input voltage of the switching power supply through the input end of the sampling circuit, and convert the input voltage into a sampling signal output, the comparison circuit compares the sampling signal with the reference voltage, generates a switching signal according to the comparison result, and the control circuit generates a control signal (high level or low level) according to the switching signal. It can be seen that the utility model can provide input overvoltage protection without a return difference circuit for AC / DC switching power supply, the circuit is simple, does not need a return difference circuit, reduces the area occupied by the input overvoltage protection circuit on the printed circuit board, and reduces the manufacturing cost. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor based on these drawings.

[0037] Figure 1 A structure diagram of an input overvoltage protection circuit provided by the embodiment of the present application.

[0038] Figure 2 A structure diagram of an input overvoltage protection circuit provided by the embodiment of the present application. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0040] The specific embodiments of the present application are disclosed in detail in the following with reference to the description and drawings, and the principles of the present application can be adopted. It should be understood that the embodiments of the present application are not limited in scope. The embodiments of the present application include many changes, modifications and equivalents within the spirit and clauses of the appended claims.

[0041] The features described and / or illustrated with respect to one embodiment can be used in the same or similar manner in one or more other embodiments, in combination with features in other embodiments, or in place of features in other embodiments.

[0042] It should be emphasized that the term "comprises / comprising" used herein refers to the presence of a feature, item, step or component, but does not exclude the presence or addition of one or more other features, items, steps or components.

[0043] In order to solve at least one of the above problems in the prior art, in a first aspect, the present application provides an input overvoltage protection circuit, as shown in the figure, the input overvoltage protection circuit 100 comprises: Figure 1

[0044] The sampling circuit 10 is configured to collect an input voltage HV1 and convert the input voltage HV1 into a sampling signal;

[0045] ​The comparison circuit 20 is connected with the sampling circuit 10, configured to compare the voltage of the sampling signal with a reference voltage, and generate a switching signal;

[0046] The control circuit 30 is connected with the comparison circuit 20, configured to generate a control signal according to the switching signal, and output the control signal.

[0047] The input overvoltage protection circuit 100 provided by the utility model, through the input end of sampling circuit 10 gathers the input HV (High Voltage) voltage (after rectification, generally 127V-380V) of switching power supply, and converts into sampling signal output, comparison circuit 20 compares the sampling signal with reference voltage, generates switching signal according to comparison result, control circuit 30 generates control signal (high level or low level) according to the switching signal. Therefore, the utility model can provide AC / DC switching power supply with input overvoltage protection without back difference circuit, and the circuit is simple, without back difference circuit, reduces the area occupied by input overvoltage protection circuit on the printed circuit board, and reduces the manufacturing cost.

[0048] As shown in the figure, Figure 2 In some embodiments, the sampling circuit 10 comprises: a first resistance module 11, a first end of the first resistance module 11 is configured to collect the input voltage; a second resistance module 12, a first end of the second resistance module 12 is connected with a second end of the first resistance module 11, and a second end of the second resistance module 12 is grounded; and a first capacitor module C103, a first end of the first capacitor module C103 is connected with the first end of the second resistance module 12, and a second end of the first capacitor module C103 is grounded.

[0049] As shown in the figure, Figure 2 In some embodiments, the first resistance module 11 comprises a first resistance R130B, a second resistance R130A and a third resistance R130 connected in series; and the second resistance module 12 comprises a fourth resistance R145 and a fifth resistance R145A connected in parallel.

[0050] As shown in the figure, Figure 2 In some embodiments, the comparison circuit 20 comprises: a diode D106, a first end of the diode D106 is configured to input a reference voltage; a third resistance module R142, a first end of the third resistance module R142 is connected with a second end of the diode D106; and an adjustable parallel voltage stabilizer U105, a first end of the adjustable parallel voltage stabilizer U105 is connected with a second end of the third resistance module R142, a second end of the adjustable parallel voltage stabilizer U105 is connected with the first end of the first capacitor module C103, and a third end of the adjustable parallel voltage stabilizer U105 is grounded.

[0051] As Figure 2 shown in some embodiments, the control circuit 30 comprises: a first MOS tube Q103, a first end of the first MOS tube Q103 is configured to output the control signal, a second end of the first MOS tube Q103 is grounded, a third end of the first MOS tube Q103 inputs a first voltage V1, the first voltage V1 is used to turn on the first MOS tube Q103 at high level; a second MOS tube Q104, a first end of the second MOS tube Q104 is connected with the third end of the first MOS tube Q103, a second end of the second MOS tube Q104 is grounded; a fourth resistance module R143, a first end of the fourth resistance module R143 is connected with the third end of the first MOS tube Q103, a second end of the fourth resistance module R143 is connected with a first end of the third resistance module R142; a fifth resistance module R144, a first end of the fifth resistance module R144 is connected with a third end of the second MOS tube Q104, a second end of the fifth resistance module R144 is connected with a second end of the third resistance module R142; a sixth resistance module R146, a first end of the sixth resistance module R146 is connected with the third end of the second MOS tube Q104, a second end of the sixth resistance module R146 is grounded; a second capacitor module C120, a first end of the second capacitor module C120 is connected with the third end of the first MOS tube Q103, a second end of the second capacitor module C120 is grounded; a seventh resistance module R133, a first end of the seventh resistance module R133 is connected with the third end of the first MOS tube Q103, a second end of the seventh resistance module R133 is connected with a first end of the second resistance module 12; a third capacitor module 31, a first end of the third capacitor module 31 is connected with the second end of the fifth resistance module R144, a second end of the third capacitor module 31 is grounded.

[0052] As Figure 2 shown in some embodiments, the third capacitor module 31 comprises a first capacitor C118 and a second capacitor C118A connected in parallel with each other; the control circuit 30 further comprises a fourth capacitor module C119, a first end of the fourth capacitor module C119 is connected with the third end of the second MOS tube Q104, a second end of the fourth capacitor module C119 is grounded.

[0053] As Figure 2As shown, in some embodiments, when the voltage at the second terminal of the adjustable parallel regulator U105 is lower than the reference voltage, the adjustable parallel regulator U105 remains off, the first terminal of the third capacitor module 31 is at a high voltage level, the second MOSFET Q104 is turned on at a high level, the first MOSFET Q103 is turned off at a low level, and the first terminal of the first MOSFET Q103 outputs a low-level control signal.

[0054] Specifically, in one embodiment, under normal conditions, the R terminal (second terminal) of the adjustable parallel regulator U105 is below 1.24V, the adjustable parallel regulator U105 remains off, the reference voltage Vcc is powered through the third resistor module R142, the first capacitor C118 / second capacitor C118A is at a high voltage level, the second MOSFET Q104 is turned on at a high level, the first MOSFET Q103 is turned off at a low level, and the control chip of the switching power supply (e.g., PWM chip) works normally.

[0055] like Figure 2 As shown, in some embodiments, when the voltage at the second terminal of the adjustable parallel regulator U105 is higher than the reference voltage, the first terminal of the adjustable parallel regulator U105 outputs a low-level voltage, the second MOSFET Q104 is turned off at a low level, and the first MOSFET Q103 is turned on at a high level and simultaneously pulls down the voltage of the control signal output from the first terminal.

[0056] Specifically, in one embodiment, when the peak voltage at the R terminal (second terminal) of the adjustable parallel regulator U105 exceeds 1.24V, the adjustable parallel regulator U105 pulls down the drive terminal K (first terminal), the second MOSFET Q104 is turned off at a low level, and the first MOSFET Q103 is turned on at a high level, simultaneously pulling down the voltage at the FB1 terminal. When the voltage at the FB1 terminal is lower than 0.7V, the control chip of the switching power supply (e.g., a PWM chip) enters the OVP (Over Voltage Protection) state. At the same time, the flyback converter of the switching power supply will also enter the OVP state due to the action of the PWM chip, stopping or reducing the output voltage. Because the charging time / discharging time τ of the first capacitor C118 and the second capacitor C118A is much greater than half of the AC cycle period, the first capacitor C118 and the second capacitor C118A will keep the K terminal in a low voltage state until the power supply resumes operation before the next peak AC voltage arrives.

[0057] In conclusion, the input overvoltage protection circuit provided by the utility model can provide input overvoltage protection without a return difference circuit for an AC / DC switching power supply, and has simple circuit, less components, easy design, convenient debugging and low cost.

[0058] Based on the same inventive concept, the utility model embodiment further provides a switching power supply, the switching power supply includes the input overvoltage protection circuit of any one embodiment described above, the input end of the sampling circuit is connected with the input positive pole of the switching power supply, and the output end of the control circuit is connected with the control chip of the switching power supply.

[0059] It should be noted that, in this document, the terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or sequence between these entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the statement "including a" does not exclude the presence of another identical element in the process, method, article or device including the element. The orientation or position relationship indicated by the terms "upper", "lower" and the like is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the utility model. Unless otherwise explicitly specified and limited, the terms "mount", "connect", "connect" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection, it can be mechanical connection, or electrical connection, it can be direct connection, or indirect connection through intermediate medium, or the communication between two elements. For ordinary skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0060] The various embodiments in the specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the difference from other embodiments. In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of the specification. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0061] The principle and implementation mode of the specific embodiments applied in the utility model are described, and the above embodiment is only used to help understand the method and core idea of the utility model; at the same time, for the general technical personnel in the art, according to the idea of the utility model, there will be changes in the specific implementation mode and application range, and the above is not understood as the limitation of the utility model.

Claims

1. An input overvoltage protection circuit, characterized in that, include: A sampling circuit is configured to acquire an input voltage and convert the input voltage into a sampling signal; A comparator circuit, connected to the sampling circuit, is configured to compare the voltage of the sampled signal with a reference voltage to generate a switching signal; A control circuit, connected to the comparator circuit, is configured to generate a control signal based on the switch signal and output the control signal.

2. The input overvoltage protection circuit according to claim 1, characterized in that, The sampling circuit includes: A first resistor module, wherein a first terminal of the first resistor module is configured to acquire the input voltage; The second resistor module has a first terminal connected to the second terminal of the first resistor module, and the second terminal of the second resistor module is grounded. A first capacitor module, wherein the first end of the first capacitor module is connected to the first end of the second resistor module, and the second end of the first capacitor module is grounded.

3. The input overvoltage protection circuit according to claim 2, characterized in that, The first resistor module includes a first resistor, a second resistor, and a third resistor connected in series. The second resistor module includes a fourth resistor and a fifth resistor connected in parallel.

4. The input overvoltage protection circuit according to claim 2, characterized in that, The comparison circuit includes: A diode, wherein the first terminal of the diode is configured to receive a reference voltage; A third resistor module, wherein the first end of the third resistor module is connected to the second end of the diode; An adjustable parallel voltage regulator is provided, wherein the first terminal of the adjustable parallel voltage regulator is connected to the second terminal of the third resistor module, the second terminal of the adjustable parallel voltage regulator is connected to the first terminal of the first capacitor module, and the third terminal of the adjustable parallel voltage regulator is grounded.

5. The input overvoltage protection circuit according to claim 4, characterized in that, The control circuit includes: A first MOSFET, wherein a first terminal of the first MOSFET is configured to output the control signal, a second terminal of the first MOSFET is grounded, and a first voltage is input to the third terminal of the first MOSFET; The second MOSFET has its first terminal connected to the third terminal of the first MOSFET, and its second terminal grounded. A fourth resistor module, wherein the first end of the fourth resistor module is connected to the third end of the first MOS transistor, and the second end of the fourth resistor module is connected to the first end of the third resistor module; The fifth resistor module has its first terminal connected to the third terminal of the second MOS transistor, and its second terminal connected to the second terminal of the third resistor module. The sixth resistor module has its first terminal connected to the third terminal of the second MOS transistor, and its second terminal grounded. The second capacitor module has its first terminal connected to the third terminal of the first MOS transistor, and its second terminal grounded. A seventh resistor module, wherein the first end of the seventh resistor module is connected to the third end of the first MOS transistor, and the second end of the seventh resistor module is connected to the first end of the second resistor module; The third capacitor module has its first terminal connected to the second terminal of the fifth resistor module, and the second terminal of the third capacitor module is grounded.

6. The input overvoltage protection circuit according to claim 5, characterized in that, The third capacitor module includes a first capacitor and a second capacitor connected in parallel. The control circuit also includes a fourth capacitor module, the first end of which is connected to the third end of the second MOS transistor, and the second end of which is grounded.

7. The input overvoltage protection circuit according to claim 5, characterized in that, When the voltage at the second terminal of the adjustable parallel regulator is lower than the reference voltage, the adjustable parallel regulator remains off, the first terminal of the third capacitor module is at a high voltage level, the second MOSFET is turned on at a high level, the first MOSFET is turned off at a low level, and the first terminal of the first MOSFET outputs a low-level control signal.

8. The input overvoltage protection circuit according to claim 5, characterized in that, When the voltage at the second terminal of the adjustable parallel regulator is higher than the reference voltage, the first terminal of the adjustable parallel regulator outputs a low-level voltage, the second MOSFET is turned off at a low level, the first MOSFET is turned on at a high level and simultaneously pulls down the voltage of the control signal output from the first terminal.

9. The input overvoltage protection circuit according to any one of claims 5-8, characterized in that, The charging / discharging time of the third capacitor module is greater than half of the AC cycle period.

10. A switching power supply, characterized in that, The circuit includes the input overvoltage protection circuit according to any one of claims 1 to 9, wherein the input terminal of the sampling circuit is connected to the positive input terminal of the switching power supply, and the output terminal of the control circuit is connected to the control chip of the switching power supply.

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