Overvoltage protection circuit, DC-DC converter, electric equipment and air conditioning unit

Abstract

The invention discloses an overvoltage protection circuit, a DC-DC converter, electric equipment and an air conditioning unit. The overvoltage protection circuit comprises a sampling module, the first end of which is connected with an input power supply of a DC-DC chip, and the second end of which is grounded; the first input end of the comparator is connected with the third end of the sampling module; the input end of the reference voltage source is connected with a power supply of the overvoltage protection circuit, and the output end of the reference voltage source is connected with the second input end of the comparator; the reference circuit is used for outputting reference voltage, and the value of the reference voltage is adjustable; and the input end of the switching tube is connected with the enabling pin of the DC-DC chip, the output end of the switching tube is grounded, the control end of the switching tube is connected with the output end of the comparator, and the switching tube is switched on or switched off according to the signal output by the comparator. According to the overvoltage protection circuit, variable reference voltages can be output according to different types of DC-DC chips, protection delay or advanced false triggering is avoided, and the reliability of the overvoltage protection circuit is improved.

Description

Technical Field

[0001] This invention relates to the field of electronic power technology, and more specifically, to an overvoltage protection circuit, a DC-DC converter, electrical equipment, and an air conditioning unit. Background Technology

[0002] DC-DC converters are widely used in power management, especially in portable devices, industrial control modules, and smart terminals. Their core function is to efficiently and stably convert the input voltage into the required output voltage. However, in practical applications, the input power supply may momentarily or continuously exceed the rated input voltage range of the DC-DC chip due to external interference, abnormal power switching, or user misconnection. This can lead to internal circuit breakdown, MOSFET damage, thermal runaway, or even permanent failure.

[0003] Common overvoltage protection solutions in existing technologies mainly include the following three types: 1. Setting an external TVS (Transient Voltage Suppressor): It can absorb transient overvoltages, but the response speed is limited and it cannot cope with continuous overvoltages; 2. Setting a current-limiting protection circuit, which cuts off the power supply by detecting abnormal input current, but it has no direct suppression capability for the input voltage itself; 3. A DC-DC chip with built-in overvoltage protection function, but its protection threshold is fixed, which cannot adapt to application scenarios with a wide input voltage range, and there is a risk of protection delay or false triggering when the voltage changes suddenly.

[0004] There is currently no effective solution to the problem that the overvoltage protection threshold of existing DC-DC chips is fixed, which cannot adapt to application scenarios with a wide input voltage range, and there is a risk of protection delay or false triggering when the voltage changes. Summary of the Invention

[0005] This invention provides an overvoltage protection circuit, a DC-DC converter, electrical equipment, and an air conditioning unit to solve the problems in the prior art where the overvoltage protection threshold of DC-DC chips is fixed, which cannot adapt to application scenarios with a wide input voltage range, and there is a risk of protection delay or false triggering when the voltage changes.

[0006] To solve the above-mentioned technical problems, the present invention provides an overvoltage protection circuit applied to a DC-DC chip, the overvoltage protection circuit comprising:

[0007] The sampling module has its first terminal connected to the input power supply of the DC-DC chip and its second terminal grounded.

[0008] A comparator, the first input of which is connected to the third terminal of the sampling module;

[0009] A reference voltage source, whose input terminal is connected to the power supply of the overvoltage protection circuit, and whose output terminal is connected to the second input terminal of the comparator; is used to output a reference voltage, the value of which is adjustable;

[0010] The switching transistor has its input terminal connected to the enable pin of the DC-DC chip, its output terminal grounded, and its control terminal connected to the output terminal of the comparator. It is used to turn on or off according to the signal output by the comparator.

[0011] Furthermore, the reference voltage source includes:

[0012] An adjustable voltage regulator, the input of which is connected to the power supply of the overvoltage protection circuit;

[0013] A first voltage divider resistor and a second voltage divider resistor are connected in series. The first voltage divider resistor is connected to the output terminal of the adjustable voltage regulator, and the second voltage divider resistor is grounded. The line between the first voltage divider resistor and the second voltage divider resistor is connected to the second input terminal of the comparator. The resistance values ​​of the first voltage divider resistor and / or the second voltage divider resistor are adjustable.

[0014] Furthermore, the overvoltage protection circuit also includes:

[0015] A buffer is disposed between the sampling module and the comparator. Its first input terminal is connected to the third terminal of the sampling module, its second input terminal is connected to its own output terminal, and its output terminal is connected to the comparator.

[0016] Furthermore, the overvoltage protection circuit also includes:

[0017] A first hysteresis resistor and a second hysteresis resistor are connected in series. The first hysteresis resistor is connected to the output terminal of the comparator, and the second hysteresis resistor is grounded.

[0018] Furthermore, the sampling module includes:

[0019] A third voltage divider resistor and a fourth voltage divider resistor are connected in series. The third voltage divider resistor is connected to the input power supply of the DC-DC chip, and the fourth voltage divider resistor is grounded. The line between the third voltage divider resistor and the fourth voltage divider resistor is connected to the comparator.

[0020] Furthermore, the enable pin of the DC-DC chip is also connected to the input power supply of the DC-DC chip via a pull-up resistor.

[0021] Furthermore, the overvoltage protection circuit also includes:

[0022] A unidirectional diode, the positive terminal of which is connected to the pull-up resistor, and the negative terminal of which is connected to the enable pin of the DC-DC chip.

[0023] Furthermore, the overvoltage protection circuit also includes:

[0024] The decoupling capacitor has its first end connected to the power supply of the overvoltage protection circuit, and its second end grounded.

[0025] Furthermore, the overvoltage protection circuit also includes:

[0026] The LED indicator has its positive terminal connected to the control terminal of the switching transistor, and its negative terminal grounded.

[0027] Furthermore, the overvoltage protection circuit is packaged using an SMD (Surface Mount Device) package.

[0028] The present invention also provides a DC-DC converter, including a DC-DC chip and the overvoltage protection circuit described above.

[0029] The present invention also provides an electrical device including the above-described DC-DC converter.

[0030] Furthermore, the electrical equipment is a compressor or a fan.

[0031] The present invention also provides an air conditioning unit, including the above-mentioned electrical equipment.

[0032] Applying the technical solution of this invention, the sampling module generates a sampling voltage based on the input voltage of the DC-DC chip, outputs an adjustable reference voltage through a reference voltage source, and the comparator generates a high-level or low-level signal based on the sampling voltage and the reference voltage, thereby controlling the level of the enable pin of the DC-DC chip. When the input voltage of the DC-DC chip is normal, the sampling voltage is less than the reference voltage, the comparator outputs a low level, the switch is off, the enable pin of the DC-DC chip is high, and the DC-DC chip operates normally. When an overvoltage occurs, the input voltage of the DC-DC chip surges, making the sampling voltage greater than the reference voltage. The comparator flips to output a high level, turning on the switch and grounding the enable pin of the DC-DC chip, causing the voltage to be pulled low and the DC-DC chip to turn off for a short time. When the input voltage of the DC-DC chip drops back, making the sampling voltage less than the reference voltage, the comparator output returns to a low level, the switch is off, the enable pin of the DC-DC chip returns to a high level, and the system can restart. This embodiment enables the output of a variable reference voltage for different DC-DC chip models, avoiding protection delays or premature triggering. This ensures that the input voltage of different DC-DC chips always operates below their maximum withstand voltage, ensuring accurate overvoltage protection timing and improving the reliability of the overvoltage protection circuit. Attached Figure Description

[0033] Figure 1 This is a structural block diagram of an overvoltage protection circuit according to an embodiment of the present invention;

[0034] Figure 2 This is a structural diagram of an overvoltage protection circuit according to another embodiment of the present invention;

[0035] Figure 3 This is a structural diagram of an overvoltage protection circuit according to another embodiment of the present invention;

[0036] Figure 4 This is a structural diagram of an overvoltage protection circuit according to another embodiment of the present invention;

[0037] Figure 5 This is a structural diagram of an overvoltage protection circuit according to another embodiment of the present invention;

[0038] Figure 6 This is a structural diagram of an overvoltage protection circuit according to another embodiment of the present invention;

[0039] Figure 7 This is a structural diagram of an overvoltage protection circuit according to another embodiment of the present invention;

[0040] Figure 8 This is a structural diagram of an overvoltage protection circuit according to another embodiment of the present invention;

[0041] Figure 9 This is a structural diagram of an overvoltage protection circuit according to another embodiment of the present invention;

[0042] Figure 10 This is a schematic diagram illustrating the operation of a comparator according to an embodiment of the present invention. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0044] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0045] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0046] It should be understood that although the terms first, second, third, etc., may be used to describe voltage divider resistors in the embodiments of the present invention, these voltage divider resistors should not be limited to these terms. These terms are only used to distinguish different voltage divider resistors. For example, without departing from the scope of the embodiments of the present invention, a first voltage divider resistor may also be referred to as a second voltage divider resistor, and similarly, a second voltage divider resistor may also be referred to as a first voltage divider resistor.

[0047] Depending on the context, the words “if” or “suppose” as used here can be interpreted as “when” or “in response to determination” or “in response to detection.” Similarly, depending on the context, the phrases “if determination” or “if detection (of the stated condition or event)” can be interpreted as “when determination” or “in response to determination” or “when detection (of the stated condition or event)” or “in response to detection (of the stated condition or event).”

[0048] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0049] The optional embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0050] Example 1

[0051] In practical applications, the input power supply of a DC-DC chip may be affected by external interference, abnormal power switching, or user misconnection, causing the input voltage to momentarily or continuously exceed the rated input voltage range of the DC-DC chip, thereby causing internal circuit breakdown, MOSFET damage, thermal runaway, or even permanent failure.

[0052] Common overvoltage protection solutions in existing technologies mainly include the following three types: 1. Setting an external TVS (Transient Voltage Suppressor): It can absorb transient overvoltages, but the response speed is limited and it cannot cope with continuous overvoltages; 2. Setting a current-limiting protection circuit, which cuts off the power supply by detecting abnormal input current, but it has no direct suppression capability for the input voltage itself; 3. A DC-DC chip with built-in overvoltage protection function, but its protection threshold is fixed, which cannot adapt to application scenarios with a wide input voltage range, and there is a risk of protection delay or false triggering when the voltage changes suddenly.

[0053] To address the issues of fixed overvoltage protection thresholds in existing DC-DC chips, which are unsuitable for applications with wide input voltage ranges and pose risks of protection delays or false triggering during voltage surges, this embodiment provides an overvoltage protection circuit for DC-DC chips. Figure 1 This is a structural block diagram of an overvoltage protection circuit according to an embodiment of the present invention, such as... Figure 1 As shown, the overvoltage protection circuit includes: a sampling module 10, whose first terminal is connected to the input power supply of the DC-DC chip and whose second terminal is grounded, for generating a sampling voltage based on the input voltage of the DC-DC chip; a comparator U1, whose first input terminal (non-inverting input terminal) is connected to the third terminal of the sampling module 10, for generating a high-level or low-level signal based on the above-mentioned sampling voltage and reference voltage; a reference voltage source 20, whose input terminal is connected to the power supply of the overvoltage protection circuit and whose output terminal is connected to the second input terminal (inverting input terminal) of the comparator U1, for outputting a reference voltage V_ref, the value of which is adjustable; and a switching transistor Q, whose input terminal is connected to the input power supply of the DC-DC chip through a pull-up resistor, whose output terminal is grounded, and whose control terminal is connected to the output terminal of the comparator U1, the switching transistor Q being used to turn on or off according to the signal output by the comparator U1.

[0054] Since different models of DC-DC chips have different maximum withstand voltages, the overvoltage thresholds that need to be set are also different. In this embodiment, the reference voltage source 20 can output a variable reference voltage V_ref. For different models of DC-DC chips with different maximum withstand voltages, the value of the reference voltage V_ref can be flexibly adjusted to ensure that the input voltage of different models of DC-DC chips is always below their maximum withstand voltage, thus ensuring that the chips work normally.

[0055] When the input voltage VIN of the DC-DC chip is normal (e.g., 12V), the sampling voltage V_sample < the reference voltage V_ref, the comparator U1 outputs a low level, the switching transistor Q is cut off, the EN pin is at a high level, and the DC-DC chip operates normally; when overvoltage occurs, the input voltage VIN of the DC-DC chip will suddenly increase, causing the sampling voltage V_sample > V_ref, the comparator flips and outputs a high level, causing the switching transistor Q to conduct, EN is grounded, resulting in the voltage being pulled down by the ground, and the DC-DC chip is turned off within 10 μs. When the input voltage VIN of the DC-DC chip drops back to V_sample < V_ref, the comparator resumes a low level, the switching transistor Q is cut off, the EN resumes a high level, and the system can restart.

[0056] In the overvoltage protection circuit of this embodiment, the sampling module 10 generates a sampling voltage based on the input voltage of the DC-DC chip, the reference voltage source 20 outputs an adjustable reference voltage V_ref, and the comparator U1 generates a high-level or low-level signal based on the sampling voltage and the reference voltage, thereby controlling the level of the enable pin of the DC-DC chip. When the input voltage VIN of the DC-DC chip is normal (e.g., 12V), the sampling voltage V_sample is less than the reference voltage V_ref, the comparator U1 outputs a low level, the switching transistor Q is cut off, and the enable pin EN of the DC-DC chip is at a high level, and the DC-DC chip operates normally; when overvoltage occurs, the input voltage VIN of the DC-DC chip will suddenly increase, causing the sampling voltage V_sample to be greater than the reference voltage V_ref, the output of the comparator U1 flips and outputs a high level, causing the switching transistor Q to conduct, and the enable pin EN of the DC-DC chip is grounded, resulting in the voltage being pulled down by the ground, and the DC-DC chip is turned off within 10 μs. When the input voltage VIN of the DC-DC chip drops back, causing the sampling voltage V_sample < the reference voltage V_ref, the output of the comparator U1 resumes a low level, the switching transistor Q is cut off, and the enable pin EN of the DC-DC chip resumes a high level, and the system can restart. Through this embodiment, it is possible to output a variable reference voltage for different models of DC-DC chips, avoid protection delay or premature false triggering, and thus ensure that the input voltages of different models of DC-DC chips always operate below their maximum tolerance voltages, ensuring accurate overvoltage protection timing and improving the reliability of the overvoltage protection circuit.

[0057] Figure 2 As the structural diagram of the overvoltage protection circuit according to another embodiment of the present invention, in order to achieve the adjustment of the reference voltage, such as Figure 2As shown, the aforementioned reference voltage source 20 includes: an adjustable voltage regulator 201, the input of which is connected to the power supply of the overvoltage protection circuit; a first voltage divider resistor R1 and a second voltage divider resistor R2 connected in series, the first voltage divider resistor R1 being connected to the output of the adjustable voltage regulator, the second voltage divider resistor R2 being grounded, and the line between the first voltage divider resistor R1 and the second voltage divider resistor R2 being connected to the second input (inverting input) of the comparator U1; the resistance values ​​of the first voltage divider resistor R1 and / or the second voltage divider resistor R2 are adjustable. In specific implementations, the resistance values ​​of the first voltage divider resistor R1 and / or the second voltage divider resistor R2 can be adjusted by replacing the resistor element, or by configuring the first voltage divider resistor R1 and / or the second voltage divider resistor R2 as variable resistors.

[0058] Under overvoltage conditions, the input voltage of a DC-DC chip may be too high, which could impact downstream components and cause damage. Therefore, to avoid this situation, such as... Figure 2 As shown, the sampling module 10 includes a third voltage divider resistor R3 and a fourth voltage divider resistor connected in series. The third voltage divider resistor R3 is connected to the input power supply of the DC-DC chip, and the fourth voltage divider resistor is grounded. The line between the third voltage divider resistor R3 and the fourth voltage divider resistor R4 is connected to the comparator U1.

[0059] In addition, to ensure the normal operation of components such as comparator U1, an overvoltage protection circuit is provided with a power supply, such as... Figure 2 As shown, the positive terminal of comparator U1 is connected to the power supply (which can provide 5V voltage), and the negative terminal of comparator U1 is grounded.

[0060] Figure 3 This is a structural diagram of an overvoltage protection circuit according to another embodiment of the present invention. To avoid the load effect affecting the sampling accuracy, the overvoltage protection circuit further includes:

[0061] Buffer U2 is located between sampling module 10 and comparator U1. Its first input terminal (non-inverting input terminal) is connected to the third terminal of sampling module, its second input terminal (inverting input terminal) is connected to its own output terminal, and its output terminal is connected to comparator U1.

[0062] To ensure the normal operation of buffer U2, such as Figure 3 As shown, the positive terminal of buffer U2 is connected to the power supply (which can provide 5V voltage), and the negative terminal of buffer U2 is grounded.

[0063] Figure 4 This is a structural diagram of an overvoltage protection circuit according to another embodiment of the present invention. In practical applications, if the voltage output of the comparator fluctuates, it will cause the switching state of the switching transistor to repeatedly change, which can easily lead to damage to the components in the circuit. To avoid the above situation, such as... Figure 4As shown, the above overvoltage protection circuit further includes: a first hysteresis resistor R5 and a second hysteresis resistor R6 connected in series. The first hysteresis resistor R5 is connected to the output terminal of comparator U1, and the second hysteresis resistor R6 is grounded. The first hysteresis resistor R5 and the second hysteresis resistor R6 form a hysteresis window, which effectively prevents the switching transistor from repeatedly switching due to voltage fluctuations at the comparator output, thus stabilizing the power-on and power-off state of the DC-DC chip.

[0064] Figure 5 This is a structural diagram of an overvoltage protection circuit according to another embodiment of the present invention. To enable the DC-DC chip to operate normally when the input voltage is normal, or to restart the DC-DC chip after overvoltage protection when the input voltage drops back to its normal value, as shown below... Figure 5 As shown, the enable pin of the DC-DC chip is also connected to the input power supply of the DC-DC chip through a pull-up resistor R7.

[0065] Figure 6 The diagram shows the structure of an overvoltage protection circuit according to another embodiment of the present invention. To prevent the enable pin EN of the DC-DC chip from generating a reverse voltage at the moment of turn-off, the overvoltage protection circuit further includes:

[0066] The unidirectional diode D has its positive terminal connected to the aforementioned pull-up resistor R7, and its negative terminal connected to the enable pin of the DC-DC chip. This is used to achieve unidirectional conduction and prevent the enable pin EN of the DC-DC chip from generating a reverse voltage at the moment of turn-off.

[0067] Figure 7 This is a structural diagram of an overvoltage protection circuit according to another embodiment of the present invention. In order to suppress high-frequency noise interference generated by the power supply, such as... Figure 7 As shown, the above-mentioned overvoltage protection circuit also includes:

[0068] The decoupling capacitor C has its first terminal connected to the power supply of the overvoltage protection circuit, and its second terminal grounded. The decoupling capacitor C serves as a filter, suppressing high-frequency noise interference generated by the power supply.

[0069] Figure 8 This is a structural diagram of an overvoltage protection circuit according to another embodiment of the present invention. For ease of observation and recording of overvoltage faults, as shown... Figure 8 As shown, the above-mentioned overvoltage protection circuit also includes:

[0070] The LED indicator has its positive terminal connected to the control terminal of the switching transistor Q, and its negative terminal grounded. When an overvoltage occurs, the input voltage VIN of the DC-DC chip will suddenly rise, causing the comparator to flip and output a high level when the sampling voltage V_sample > V_ref, and the LED indicator will light up.

[0071] The above-mentioned overvoltage protection circuit is packaged using SMD packaging, with an overall circuit area of ​​less than 50mm², making it suitable for high-density PCB layouts.

[0072] Example 2

[0073] This invention provides another overvoltage protection circuit. Figure 9 This is a structural diagram of an overvoltage protection circuit according to another embodiment of the present invention, as shown below. Figure 9 As shown, the reference voltage source 20 includes: an adjustable voltage regulator 201, the input of which is connected to the power supply of the overvoltage protection circuit; a first voltage divider resistor R1 and a second voltage divider resistor R2 connected in series, the first voltage divider resistor R1 being connected to the output of the adjustable voltage regulator, the second voltage divider resistor R2 being grounded, and the line between the first voltage divider resistor R1 and the second voltage divider resistor R2 being connected to the second input (inverting input) of the comparator U1; the resistance values ​​of the first voltage divider resistor R1 and / or the second voltage divider resistor R2 are adjustable. In specific implementations, the resistance values ​​of the first voltage divider resistor R1 and / or the second voltage divider resistor R2 can be adjusted by replacing the resistor element, or by configuring the first voltage divider resistor R1 and / or the second voltage divider resistor R2 as variable resistors.

[0074] The sampling module 10 includes a third voltage divider resistor R3 and a fourth voltage divider resistor connected in series. The third voltage divider resistor R3 is connected to the input power supply of the DC-DC chip, and the fourth voltage divider resistor is grounded. The line between the third voltage divider resistor R3 and the fourth voltage divider resistor R4 is connected to the comparator U1.

[0075] The positive terminal of comparator U1 is connected to the power supply (which can provide 5V voltage), and the negative terminal of comparator U1 is grounded.

[0076] The overvoltage protection circuit described above also includes: a buffer U2, disposed between the sampling module 10 and the comparator U1. Its first input terminal (non-inverting input terminal) is connected to the third terminal of the sampling module, its second input terminal (inverting input terminal) is connected to its own output terminal, and its output terminal is connected to the comparator U1. The positive terminal of the buffer U2 is connected to the power supply (which can provide 5V voltage), and the negative terminal of the buffer U2 is grounded.

[0077] The overvoltage protection circuit described above also includes a first hysteresis resistor R5 and a second hysteresis resistor R6 connected in series. The first hysteresis resistor R5 is connected to the output terminal of comparator U1, and the second hysteresis resistor R6 is grounded. The first hysteresis resistor R5 and the second hysteresis resistor R6 form a hysteresis window, which effectively prevents the switching transistor from repeatedly switching due to voltage fluctuations at the comparator output, thus stabilizing the power-on and power-off state of the DC-DC chip.

[0078] The enable pin of the DC-DC chip is also connected to the input power supply of the DC-DC chip via a pull-up resistor R7. This allows the DC-DC chip to operate normally when the input voltage is normal, or to restart the DC-DC chip after overvoltage protection and when the input voltage drops back to its normal value.

[0079] The overvoltage protection circuit mentioned above also includes: a unidirectional diode D, whose positive terminal is connected to the pull-up resistor R7, and whose negative terminal is connected to the enable pin of the DC-DC chip, to achieve unidirectional conduction and prevent the enable pin EN of the DC-DC chip from generating reverse voltage at the moment of turn-off.

[0080] The overvoltage protection circuit described above also includes a decoupling capacitor C, whose first terminal is connected to the power supply of the overvoltage protection circuit, and whose second terminal is grounded. The decoupling capacitor C performs a filtering function to suppress high-frequency noise interference generated by the power supply.

[0081] The overvoltage protection circuit mentioned above also includes an LED indicator, whose positive terminal is connected to the control terminal of the switching transistor Q and whose negative terminal is grounded. When an overvoltage occurs, the input voltage VIN of the DC-DC chip will suddenly rise, causing the comparator to flip and output a high level when the sampling voltage V_sample > V_ref, and the LED indicator will light up.

[0082] The above-mentioned overvoltage protection circuit is packaged using SMD packaging, with an overall circuit area of ​​less than 50mm², making it suitable for high-density PCB layouts.

[0083] The specific working principle of the overvoltage protection circuit in this embodiment is as follows:

[0084] 1. Input Voltage Sampling: A voltage divider network consisting of two high-precision, low-temperature-drift metal film resistors, R1 and R2, connected in series between the input power supply VIN and ground GND. The sampled voltage is then isolated and amplified by a low-noise buffer U2 to prevent load effects from affecting sampling accuracy. The output of buffer U2 is connected to the non-inverting input of comparator U1.

[0085] 2. Voltage Comparison: A comparator U1 with hysteresis is used. Its inverting input receives the reference voltage V_ref, and its non-inverting input receives the sampled voltage V_sample. The reference voltage source 20 consists of an adjustable voltage regulator TL431 and resistors R3 and R4, allowing for adjustable overvoltage protection threshold settings. The output of comparator U1 is connected to the switching transistor Q. A first hysteresis resistor and resistors R5 and R6 are placed between the output of comparator U1 and ground to form a hysteresis window, effectively preventing repeated voltage fluctuations.

[0086] 3. Overvoltage Protection: An NPN transistor switch Q1 and a pull-up resistor R7 are used. When comparator U1 outputs a high level, switch Q1 is turned on, pulling the protection signal line low. This signal line is connected to the enable pin EN of the DC-DC chip. When the enable pin EN is low, the DC-DC chip immediately enters the shutdown state, stopping the output and thus protecting the DC-DC chip. Simultaneously, an LED is connected to the output of comparator U1 to achieve real-time reporting of fault status, facilitating fault recording or automatic restart of the system.

[0087] 4. Output Execution: A fast recovery diode D (such as 1N4148) is connected in parallel with the enable pin EN of the DC-DC chip to prevent reverse voltage from being generated on the EN pin during turn-off. Additionally, a decoupling capacitor C is added to the power input of the protection circuit to suppress high-frequency noise interference.

[0088] The sampled voltage is isolated and amplified by a low-noise buffer U2 to avoid the load effect affecting sampling accuracy. The first hysteresis resistor R5 and the second hysteresis resistor R6 generate a hysteresis voltage, forming a hysteresis window to effectively prevent repeated voltage jumps caused by voltage fluctuations. A fast recovery diode D1 is connected in parallel with the enable pin EN of the DC-DC chip to prevent reverse voltage from being generated at the moment of turn-off. A decoupling capacitor C1 is added to the power input of the protection circuit to suppress high-frequency noise interference.

[0089] Figure 10 This is a schematic diagram illustrating the operation of a comparator according to an embodiment of the present invention, such as... Figure 10 As shown, the operation of comparator U1 is as follows:

[0090] V_sample is the sampling voltage. When the input voltage is normal (e.g., 12V), V_sample < V_ref, comparator U1 outputs a low level, switch Q1 is turned off, and the voltage of the enable pin EN is pulled high by pull-up resistor R7, allowing the DC-DC chip to operate normally. When V_sample = V_ref, the output level of comparator U1 does not flip, switch Q remains off, and the DC-DC chip remains operational. When the input voltage suddenly rises to V_sample > V_ref, the output of comparator U1 flips to a high level, switch Q turns on, the voltage of the enable pin EN is pulled low by ground, and the DC-DC chip turns off within 10μs, ceasing operation.

[0091] When VIN falls back to V_sample < V_ref, the output of comparator U1 returns to low level, switch Q1 is turned off, enable EN returns to high level, and the system can be restarted (requires external reset or manual restart).

[0092] The overvoltage protection circuit of this embodiment is inventive in that it performs real-time voltage division sampling of the input voltage through a first-stage high-precision sampling circuit; and achieves anti-jitter capability of voltage comparison through a second-stage comparator circuit with hysteresis characteristics, avoiding malfunctions caused by power supply fluctuations or noise. The protection threshold is configured by an external adjustable resistor, enabling dynamic adjustment of the protection voltage threshold to adapt to different application scenarios (such as 5V / 12V / 24V input systems). When overvoltage is detected, the protection circuit outputs a shutdown signal to the enable pin (EN) of the DC-DC chip within 10μs and outputs a fault status signal, facilitating system fault diagnosis and automatic recovery. Through the overvoltage protection circuit of this embodiment, fast, accurate, and configurable shutdown protection is achieved when the input voltage of the DC-DC chip exceeds the reference voltage value, effectively preventing permanent damage to the DC-DC chip due to overvoltage. The dual-stage voltage sampling and hysteresis comparison mechanism significantly improves anti-interference capability, ensuring the reliability and stability of protection action. Users can dynamically set the protection threshold through an external resistor or digital interface, achieving flexible adaptation to different power supply environments. 1. Solved the technical problems of delayed protection response, unadjustable protection threshold, and weak anti-interference capability when the input voltage of existing DC-DC chips is overvoltage; 2. Solved the technical problems of false triggering or missed protection of traditional protection circuits in high noise environment; 3. Solved the technical problem that the overvoltage protection threshold of existing protection circuits is fixed and cannot adapt to multiple application scenarios.

[0093] Example 3

[0094] This embodiment provides a DC-DC converter, including a DC-DC chip and the overvoltage protection circuit described in the above embodiment.

[0095] Example 4

[0096] This embodiment provides an electrical device, including the DC-DC converter described in the above embodiment.

[0097] In some embodiments of the present invention, the aforementioned electrical equipment is a compressor or a fan.

[0098] Example 5

[0099] This embodiment provides an air conditioning unit, including the electrical equipment described in the above embodiment.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An overvoltage protection circuit, applied to a DC-DC chip, characterized in that, The overvoltage protection circuit includes: The sampling module has its first terminal connected to the input power supply of the DC-DC chip and its second terminal grounded. A comparator, the first input of which is connected to the third terminal of the sampling module; A reference voltage source, whose input terminal is connected to the power supply of the overvoltage protection circuit, and whose output terminal is connected to the second input terminal of the comparator; is used to output a reference voltage, the value of which is adjustable; The switching transistor has its input terminal connected to the enable pin of the DC-DC chip, its output terminal grounded, and its control terminal connected to the output terminal of the comparator. It is used to turn on or off according to the signal output by the comparator.

2. The overvoltage protection circuit according to claim 1, characterized in that, The reference voltage source includes: An adjustable voltage regulator, the input of which is connected to the power supply of the overvoltage protection circuit; A first voltage divider resistor and a second voltage divider resistor are connected in series. The first voltage divider resistor is connected to the output terminal of the adjustable voltage regulator, and the second voltage divider resistor is grounded. The line between the first voltage divider resistor and the second voltage divider resistor is connected to the second input terminal of the comparator. The resistance values ​​of the first voltage divider resistor and / or the second voltage divider resistor are adjustable.

3. The overvoltage protection circuit according to claim 1, characterized in that, The overvoltage protection circuit also includes: A buffer is disposed between the sampling module and the comparator. Its first input terminal is connected to the third terminal of the sampling module, its second input terminal is connected to its own output terminal, and its output terminal is connected to the comparator.

4. The overvoltage protection circuit according to claim 1, characterized in that, The overvoltage protection circuit also includes: A first hysteresis resistor and a second hysteresis resistor are connected in series. The first hysteresis resistor is connected to the output terminal of the comparator, and the second hysteresis resistor is grounded.

5. The overvoltage protection circuit according to claim 1, characterized in that, The sampling module includes: A third voltage divider resistor and a fourth voltage divider resistor are connected in series. The third voltage divider resistor is connected to the input power supply of the DC-DC chip, and the fourth voltage divider resistor is grounded. The line between the third voltage divider resistor and the fourth voltage divider resistor is connected to the comparator.

6. The overvoltage protection circuit according to claim 1, characterized in that, The enable pin of the DC-DC chip is also connected to the input power supply of the DC-DC chip via a pull-up resistor.

7. The overvoltage protection circuit according to claim 6, characterized in that, The overvoltage protection circuit also includes: A unidirectional diode, the positive terminal of which is connected to the pull-up resistor, and the negative terminal of which is connected to the enable pin of the DC-DC chip.

8. The overvoltage protection circuit according to claim 1, characterized in that, The overvoltage protection circuit also includes: The decoupling capacitor has its first end connected to the power supply of the overvoltage protection circuit, and its second end grounded.

9. The overvoltage protection circuit according to claim 1, characterized in that, The overvoltage protection circuit also includes: The LED indicator has its positive terminal connected to the control terminal of the switching transistor, and its negative terminal grounded.

10. The overvoltage protection circuit according to any one of claims 1 to 9, characterized in that, The overvoltage protection circuit is packaged using SMD packaging.

11. A DC-DC converter, comprising a DC-DC chip, characterized in that, It also includes the overvoltage protection circuit according to any one of claims 1 to 9.

12. An electrical device comprising the DC-DC converter of claim 11.

13. The electrical equipment according to claim 12, characterized in that, The electrical equipment is a compressor or a fan.

14. An air conditioning unit, characterized in that, Includes the electrical equipment as described in claim 12.

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