Protection circuit and electric equipment thereof

Abstract

The utility model provides a protection circuit, which is applied to a DC interface circuit when an external adapter is connected with electric equipment, and comprises a discharge circuit, an under-voltage protection circuit, an overvoltage protection circuit and a delay switch circuit, the delay switch circuit is connected between the power supply input end and the power supply output end and is used for slowly conducting the power supply input end and the power supply output end under a preset condition, the under-voltage protection circuit and the overvoltage protection circuit are connected between the power supply input end and the delay switch circuit, and the under-voltage protection circuit and the overvoltage protection circuit are used for monitoring the voltage of the power supply input end. When the voltage of the power supply input end meets a preset condition, the time-delay switch circuit is switched on; the discharging circuit is connected to the power supply output end and used for being disconnected when power supply input exists and being connected for discharging when no power supply input exists. The utility model further provides the electric equipment comprising the protection circuit. According to the protection circuit and the electric equipment provided by the invention, the problems of spark prevention, rapid discharge and voltage protection are comprehensively solved, and the output voltage of the adapter is monitored in real time.

Description

Technical Field

[0001] This application belongs to the field of power protection circuit technology, specifically relating to a protection circuit and its electrical equipment. Background Technology

[0002] When the adapter's DC plug (e.g., 5.3mm) is inserted into the device, the large-capacity capacitors inside the device (e.g., electrolytic capacitors) will generate a large current due to instantaneous charging, which may cause electric sparks between the metal contacts of the DC socket, posing a safety hazard and leading to user complaints. Existing anti-spark circuits typically use a time-delay switching scheme, but the following problems still exist: 1. Under frequent plugging and unplugging, the residual charge in the capacitor cannot be released in time, which may still cause sparks upon secondary plugging and unplugging; 2. The output voltage of the external adapter may fluctuate, and undervoltage or overvoltage conditions may damage the device's circuitry; 3. Existing solutions fail to simultaneously address the issues of spark prevention, rapid discharge, and voltage protection, lacking a real-time monitoring and protection mechanism for abnormal adapter output voltage. Using a time-delay switching method can slowly turn on the circuit, reducing transient current and effectively suppressing the generation of electric sparks, but further optimization is needed to improve overall safety and reliability. Summary of the Invention

[0003] The purpose of this application is to overcome the shortcomings of the prior art and to provide a protection circuit and its electrical equipment.

[0004] To address the aforementioned technical problems, this application provides a protection circuit for use in the DC interface circuit of an external adapter connected to a power device. The circuit includes a discharge circuit, an undervoltage protection circuit, an overvoltage protection circuit, and a time-delay switch circuit. The time-delay switch circuit is connected between the power input terminal and the power output terminal, and is used to slowly connect the power input terminal and the power output terminal under preset conditions. The undervoltage protection circuit and the overvoltage protection circuit are connected between the power input terminal and the time-delay switch circuit. The undervoltage protection circuit and the overvoltage protection circuit monitor the voltage at the power input terminal, and the time-delay switch circuit is activated when the voltage at the power input terminal meets the preset conditions. The discharge circuit is connected to the power output terminal and is used to disconnect when there is power input and to discharge when there is no power input.

[0005] The discharge circuit consists of a switch socket J1 and a first resistor R1 connected in parallel. When no power is inserted, the switch socket J1 is closed and the first resistor R1 is connected to the circuit; when power is inserted, the switch socket J1 is open and the first resistor R1 is not connected to the circuit.

[0006] The undervoltage protection circuit consists of a second resistor R5, a first diode D1, and a third resistor R6 connected in series. The anode of the first diode D1 is connected to the ground terminal, and the cathode is connected to the power output terminal.

[0007] The overvoltage protection circuit consists of a fourth resistor R7, a fifth resistor R8, a second diode D2, and a first transistor Q2. One end of the fifth resistor R8 is electrically connected to the base of the first transistor Q2, and the other end is electrically connected to the cathode of the second diode D2. One end of the fourth resistor R7 is electrically connected to the cathode of the second diode D2, and the other end is electrically connected to the emitter of the first transistor Q2. The anode of the second diode D2 is grounded.

[0008] The delay switch circuit comprises a sixth resistor R2, a seventh resistor R3, an eighth resistor R4, a ninth resistor R9, a first capacitor C1, a second capacitor C2, a field-effect transistor Q1, and a third transistor Q3. The field-effect transistor Q1 is a MOSFET. The sixth resistor R2 and the first capacitor C1 are connected in parallel between the source and gate of the field-effect transistor Q1, with one end connected to the emitter of the first transistor Q2 and the other end connected to the collector of the first transistor Q2. One end of the seventh resistor R3 is connected to the collector of the first transistor Q2 and the other end is connected to the collector of the third transistor Q3. One end of the eighth resistor R4 is connected to the base of the third transistor Q3 and the other end is connected to the anode of the first diode D1. The ninth resistor and the second capacitor are connected in parallel between the base of the third transistor Q3 and ground.

[0009] The circuit also includes a third capacitor C3, which is connected between the drain of the field-effect transistor Q1 and ground.

[0010] On the other hand, this application provides an electrical device, the power input interface circuit of which includes the above-mentioned protection circuit.

[0011] The protection circuit and electrical equipment provided in this application, on the one hand, quickly release the residual charge of the capacitor when the power adapter is quickly plugged in and out, avoiding possible sparks during secondary plugging and unplugging; on the other hand, when the output voltage of the power adapter is unstable, it has undervoltage or overvoltage protection functions, allowing the electrical equipment to operate within the normal voltage range and protecting the normal operation of the electrical equipment; the solution provided in this application comprehensively solves the problems of spark prevention, rapid discharge and voltage protection, and provides real-time monitoring and protection against abnormal adapter output voltage. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a logic block diagram of the protection circuit in an embodiment of this application;

[0014] Figure 2 This is a specific circuit structure diagram of the protection circuit in one embodiment of this application. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0016] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0017] It should also be noted that the directional terms such as left, right, up, and down in the embodiments of this application are only relative concepts or are based on the normal use state of the product, and should not be considered as restrictive.

[0018] Please refer to Figure 1 The diagram shows a logic block diagram of the protection circuit in an embodiment of this application. The protection circuit is applied to the DC interface circuit when the external adapter is connected to the power device. The protection circuit includes a discharge circuit, an undervoltage protection circuit, an overvoltage protection circuit, and a time-delay switch circuit. The time-delay switch circuit is connected between the power input terminal and the power output terminal and is used to slowly turn on the power input terminal and the power output terminal under preset conditions. The undervoltage protection circuit and the overvoltage protection circuit are connected between the power input terminal and the time-delay switch circuit. The undervoltage protection circuit and the overvoltage protection circuit are used to monitor the voltage at the power input terminal. When the voltage at the power input terminal meets the preset conditions, the time-delay switch circuit is turned on. The discharge circuit is connected to the power output terminal and is used to disconnect when there is power input and to discharge when there is no power input.

[0019] In one implementation, the preset condition refers to an operating voltage of 16V ≤ V. in≤22V. When the working voltage is less than 16V, the undervoltage protection circuit is activated, thus preventing the power input to the delay switch circuit and the power output circuit from conducting. When the working voltage is greater than 22V, the overvoltage protection circuit is activated, thus preventing the power input to the delay switch circuit and the power output circuit from conducting, thereby protecting the safety of the electrical equipment. If the working voltage is within the normal operating range, the delay switch circuit slowly turns on, and the voltage gradually increases, slowly charging the third capacitor C3, reducing the transient conduction current, thereby avoiding electric sparks when the power is plugged in.

[0020] Please refer to Figure 2 The diagram shown is a specific circuit structure diagram of the protection circuit in one embodiment of this application.

[0021] The discharge circuit consists of a switch socket J1 connected in parallel with a first resistor R1. When no power is supplied, the switch socket J1 is closed, and the first resistor R1 is connected in the circuit; when power is supplied, the switch socket J1 is open, and the first resistor R1 is disconnected. The undervoltage protection circuit consists of a second resistor R5, a first diode D1, and a third resistor R6 connected in series. The anode of the first diode D1 is connected to the ground terminal, and the cathode is connected to the power output terminal. The overvoltage protection circuit consists of a fourth resistor R7, a fifth resistor R8, a second diode D2, and a first transistor Q2. One end of the fifth resistor R8 is electrically connected to the base of the first transistor Q2, and the other end is electrically connected to the cathode of the second diode D2. One end of the fourth resistor R7 is electrically connected to the cathode of the second diode D2, and the other end is electrically connected to the emitter of the first transistor Q2. The anode of the second diode D2 is grounded. The time-delay switch circuit consists of a sixth resistor R2, a seventh resistor R3, an eighth resistor R4, a ninth resistor R9, a first capacitor C1, a second capacitor C2, a field-effect transistor Q1, and a third transistor Q3. The field-effect transistor Q1 is a MOSFET. The sixth resistor R2 and the first capacitor C1 are connected in parallel between the source and gate of the field-effect transistor Q1, with one end connected to the emitter of the first transistor Q2 and the other end connected to the collector of the first transistor Q2. One end of the seventh resistor R3 is connected to the collector of the first transistor Q2, and the other end is connected to the collector of the third transistor Q3. One end of the eighth resistor R4 is connected to the base of the third transistor Q3, and the other end is connected to the anode of the first diode D1. The ninth resistor and the second capacitor are connected in parallel between the base of the third transistor Q3 and ground. The circuit also includes a third capacitor C3, which is connected between the drain of the field-effect transistor Q1 and ground.

[0022] Its working principle is as follows: When the power is plugged in and socket J1 is opened, R1 is disconnected from ground, and the fast discharge circuit is broken. The undervoltage protection circuit, composed of the second resistor R5, the first diode D1, and the third resistor R6 connected in series, starts to work. If the voltage is lower than 16V, the first diode D1 is cut off and does not conduct, the base of the third transistor Q3 is at a low level and does not conduct, the gate of the second diode Q1 is at a high level, and Q1 is also cut off, so the circuit is not open, thus providing undervoltage protection. If the voltage is higher than 16V, the first diode D1 conducts, the base of the third transistor Q3 is at a high level and begins to conduct, the gate of the field-effect transistor Q1 is at a low level, and the field-effect transistor Q1 conducts, so the power is output to the electrical equipment through the field-effect transistor Q1. At the same time, the overvoltage protection circuit starts working. If the voltage is lower than 22V, the second diode D2 does not conduct, the base of the first transistor Q2 is at a high level, equal to the emitter level, and the first transistor Q2 is cut off and does not conduct, having no effect on the field-effect transistor Q1. If the voltage is higher than 22V, the second diode D2 conducts, the base level of the first transistor Q2 is lower than the emitter level, the first transistor Q2 conducts, and its collector is also at a high level, thus causing the field-effect transistor Q1 to be cut off, playing an overvoltage protection role. The principle of the time-delay switch circuit is as follows: When the input voltage is within the range, the first diode D1 conducts, and the voltage charges the second capacitor C2 through the eighth resistor R4, causing the third transistor Q3 to slowly conduct. After the third transistor Q3 conducts, the gate of the second diode Q1 is at a low level, and the second diode Q1 begins to conduct. According to the principle that the capacitor voltage does not change abruptly, at the instant the third transistor Q3 conducts, the first capacitor C1 begins to slowly discharge, the voltage at the gate of the second diode Q1 slowly decreases, the second diode Q1 slowly conducts, and its drain voltage slowly rises, charging the third capacitor C3, thereby avoiding the occurrence of large current and preventing electric sparks caused by DC insertion. When the DC power supply is unplugged, the switch socket J1 closes, the first resistor R1 is connected to ground, and the third capacitor C3 begins to discharge rapidly through the reverse diode inside the second diode Q1. At the same time, the second capacitor C2 also discharges through the ninth resistor R9, quickly reducing the internal voltage to a low level, and the circuit returns to its initial state, thus avoiding electric sparks caused by rapid plugging and unplugging of the DC socket.

[0023] In addition, this application also provides an electrical device whose power input interface circuit includes the aforementioned protection circuit.

[0024] The protection circuit and electrical equipment provided in this application, on the one hand, quickly release the residual charge of the capacitor when the power adapter is quickly plugged in and out, avoiding possible sparks during secondary plugging and unplugging; on the other hand, when the output voltage of the power adapter is unstable, it has undervoltage or overvoltage protection functions, allowing the electrical equipment to operate within the normal voltage range and protecting the normal operation of the electrical equipment; the solution provided in this application comprehensively solves the problems of spark prevention, rapid discharge and voltage protection, and provides real-time monitoring and protection against abnormal adapter output voltage.

[0025] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A protection circuit applied to a DC interface circuit when an external adapter is connected to an electrical device, characterized in that, The discharge circuit, the under-voltage protection circuit, the over-voltage protection circuit and the delay switch circuit are connected in series. The delay switch circuit is connected between the power input terminal and the power output terminal, and is used for slowly turning on the power input terminal and the power output terminal under a preset condition. The discharge circuit is connected to the power output terminal, and is used for being turned off when there is power input and being turned on when there is no power input.

2. The protection circuit of claim 1, wherein, The discharge circuit is composed of the switch socket J1 and the first resistor R1 connected in parallel.

3. The protection circuit of claim 1, wherein, The under-voltage protection circuit is composed of the second resistor R5, the first diode D1 and the third resistor R6 connected in series.

4. The protection circuit of claim 1, wherein, The over-voltage protection circuit is composed of the fourth resistor R7, the fifth resistor R8, the second diode D2 and the first triode Q2.

5. The protection circuit of claim 1, wherein, The delay switch circuit is composed of the sixth resistor R2, the seventh resistor R3, the eighth resistor R4, the ninth resistor R9, the first capacitor C1, the second capacitor C2, the field effect tube Q1 and the third triode Q3.

6. The protection circuit of claim 1, wherein, The circuit further comprises a third capacitor C3 connected between the drain of the field effect tube Q1 and the ground.

7. An electric device, characterized by The power input interface circuit of the electric device comprises the protection circuit according to any one of claims 1-6.

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