A protection circuit and a power supply device

Abstract

The utility model discloses a kind of protection circuit and power supply device. The circuit includes: linear voltage stabilizing module, input voltage is converted into target output voltage;Overvoltage protection module is connected with linear voltage stabilizing module and input power respectively, for transmission target output voltage, output current is collected, when input voltage reaches first preset threshold, target output voltage reaches second preset threshold or receives overcurrent protection signal, output overvoltage protection signal;Overcurrent protection module, when the sampling signal of output current reaches first preset reference voltage, output overcurrent protection signal;Conduction control module is connected with overvoltage protection module and main control chip, and it is turned on in response to target output voltage, and it is turned off in response to overvoltage protection signal. By the above-mentioned mode, the utility model embodiment can overcome the problem that TVS tube breakdown voltage drifts with temperature, avoid protector device permanent damage due to long time overvoltage, improve the safety and reliability of MCU power supply circuit.

Description

Technical Field

[0001] This utility model relates to the field of overvoltage protection, and in particular to a protection circuit and power supply device. Background Technology

[0002] As the core control chip of electronic devices, microcontroller units (MCUs) require a stable and reliable power supply to ensure the normal operation of the system. In practical applications, the power supply circuit of MCUs often faces problems such as input voltage fluctuations, overvoltage surges, and sudden changes in load current. These abnormal conditions may damage the MCU or even cause the entire system to fail.

[0003] Currently, the most common overvoltage protection scheme in MCU power supply circuits mainly adopts a Transient Voltage Suppression (TVS) diode clamping circuit. Its working principle is that when the input voltage exceeds the breakdown voltage of the TVS diode, the TVS diode conducts and clamps the overvoltage within a safe range, thereby protecting the subsequent circuits. This scheme has the advantages of simple structure and low cost, and can provide basic overvoltage protection in general application scenarios.

[0004] However, traditional TVS diode clamping protection schemes have the following technical drawbacks: First, the breakdown voltage of a TVS diode is easily affected by ambient temperature. Temperature changes can cause the protection threshold to drift, affecting protection accuracy. In high or low temperature environments, the TVS diode may not operate at the accurate voltage point, leading to untimely or false protection. Second, when the input voltage is under overvoltage for an extended period, the TVS diode needs to remain on and withstand significant power consumption. If the overvoltage duration is too long or the overvoltage amplitude is too large, the TVS diode may be permanently damaged due to overheating. Once the TVS diode fails, the downstream linear regulator and MCU will be directly exposed to the overvoltage threat, which can easily cause irreversible damage, leading to the failure of the entire system. Utility Model Content

[0005] The main technical problem solved by this utility model embodiment is to provide a protection circuit and power supply device that can solve at least some of the defects of existing MCU protection circuits.

[0006] In a first aspect, this utility model provides a protection circuit, comprising: a linear voltage regulator module connected to an input power supply, used to convert the input voltage of the input power supply into a target output voltage; an overvoltage protection module connected to both the linear voltage regulator module and the input power supply, used to transmit the target output voltage, acquire the output current of the linear voltage regulator module, and output the overvoltage protection signal when the input voltage reaches a first preset threshold, the target output voltage reaches a second preset threshold, or an overcurrent protection signal is received; an overcurrent protection module connected to the overvoltage protection module, used to receive a sampling signal of the output current, and output the overcurrent protection signal when the sampling signal reaches a first preset reference voltage; and a conduction control module connected to both the overvoltage protection module and a main control chip, used to transmit the target output voltage to the main control chip in response to the target output voltage being turned on, and to turn off in response to the overvoltage protection signal.

[0007] Optionally, the overvoltage protection module includes a current sampling unit, a first detection unit, a second detection unit, and a signal output unit. The current sampling unit is connected to the linear voltage regulator module, the overcurrent protection module, and the conduction control module, respectively, and is used to transmit the target output voltage, collect the output current, and convert the output current into the sampling signal. The first detection unit is connected to the input power supply and is used to output a first detection signal when the input voltage reaches the first preset threshold. The second detection unit is connected to the linear voltage regulator module and is used to output a second detection signal when the target output voltage reaches the second preset threshold. The signal output unit is connected to the first detection unit, the second detection unit, the overcurrent protection module, and the conduction control module, respectively, and is used to output the overvoltage protection signal when at least one of the first detection signal, the second detection signal, and the overcurrent protection signal is received.

[0008] Optionally, the current sampling unit includes a fifth resistor and a second capacitor; the first end of the fifth resistor is connected to the first end of the second capacitor, the output end of the linear voltage regulator module, and the first input end of the overcurrent protection module, and the second end of the fifth resistor is connected to the second end of the second capacitor, the second input end of the overcurrent protection module, and the input end of the conduction control module.

[0009] Optionally, the first detection unit includes a first Zener diode, the cathode of which is connected to the input power supply, and the anode of which is connected to the signal terminal of the signal output unit; the second detection unit includes a second Zener diode, the cathode of which is connected to the output terminal of the linear voltage regulator module, and the anode of which is connected to the signal terminal of the signal output unit.

[0010] Optionally, the signal output unit includes a first capacitor, a first resistor, a third resistor, a sixth resistor, a second switch, and a fourth switch; the first end of the first resistor is connected to the emitter of the second switch and the input terminal of the conduction control module; the second end of the first resistor is connected to the first end of the third resistor and the base of the second switch; the second end of the third resistor is connected to the collector of the fourth switch; the collector of the second switch is connected to the signal terminal of the conduction control module; the base of the fourth switch is connected to the second end of the sixth resistor and the first end of the first capacitor; the first end of the sixth resistor is connected to the output terminal of the first detection unit, the output terminal of the second detection unit, and the output terminal of the overcurrent protection module; and the emitter of the fourth switch and the second end of the first capacitor are connected to reference ground.

[0011] Optionally, the overcurrent protection module includes an operational amplifier unit and a comparison unit; the operational amplifier unit is connected to the overvoltage protection module and is used to amplify the sampled signal into a comparison voltage; the comparison unit is connected to the operational amplifier unit and the overvoltage protection module and is used to output the overcurrent protection signal when the comparison voltage is greater than a second preset reference voltage; the ratio of the second preset reference voltage to the first preset reference voltage is the voltage amplification factor of the operational amplifier unit.

[0012] Optionally, the operational amplifier unit includes a third capacitor, a fourth capacitor, an eighth capacitor, a ninth resistor, a tenth resistor, a twelfth resistor, a fourteenth resistor, a sixteenth resistor, and an operational amplifier; the first terminal of the twelfth resistor is connected to the first terminal of the current sampling unit, the second terminal of the twelfth resistor is connected to the second terminal of the tenth resistor, the second terminal of the fourth capacitor, and the non-inverting input terminal of the operational amplifier, the first terminal of the fourth capacitor, the second terminal of the third capacitor, and the first terminal of the ninth resistor are connected to a first supply voltage, the second terminal of the ninth resistor is connected to the first terminal of the tenth resistor, and the first terminal of the third capacitor is connected to a reference ground; the first terminal of the fourteenth resistor is connected to the second terminal of the current sampling unit, the second terminal of the fourteenth resistor is connected to the first terminal of the sixteenth resistor, the first terminal of the eighth capacitor, and the inverting input terminal of the operational amplifier, and the output terminal of the operational amplifier is connected to the second terminal of the sixteenth resistor, the second terminal of the eighth capacitor, and the input terminal of the comparator unit.

[0013] Optionally, the comparison unit includes a fifth capacitor, a sixth capacitor, a seventh capacitor, a seventh resistor, an eighth resistor, an eleventh resistor, a thirteenth resistor, a fifteenth resistor, a first Schottky diode, a second Schottky diode, and a comparator; the anode of the first Schottky diode is connected to the output terminal of the operational amplifier unit and the first terminal of the sixth capacitor; the cathode of the first Schottky diode is connected to the first terminal of the thirteenth resistor; the second terminal of the thirteenth resistor is connected to the first terminal of the seventh capacitor, the first terminal of the fifteenth resistor, and the inverting input terminal of the comparator; the second terminal of the sixth capacitor, the second terminal of the seventh capacitor, and the first... The second terminal of the fifteenth resistor is connected to the reference ground; the first terminal of the eighth resistor is connected to the first supply voltage, and the second terminal of the eighth resistor is connected to the first terminal of the seventh resistor, the second terminal of the eleventh resistor, the second terminal of the fifth capacitor, and the non-inverting input terminal of the comparator. The first terminal of the fifth capacitor and the first terminal of the eleventh resistor are connected to the reference ground; the second terminal of the seventh resistor is connected to the anode of the second Schottky diode; the positive terminal of the comparator is connected to the second supply voltage; the negative terminal of the comparator is connected to the reference ground; and the output terminal of the comparator is connected to the cathode of the second Schottky diode and the signal terminal of the overvoltage protection module.

[0014] Optionally, the conduction control module includes a second resistor, a fourth resistor, a second electrolytic capacitor, and a third switching transistor; the first end of the second resistor is connected to the voltage output terminal of the overvoltage protection module and the source of the third switching transistor; the second end of the second resistor is connected to the signal output terminal of the overvoltage protection module, the gate of the third switching transistor, and the first end of the fourth resistor; the drain of the third switching transistor is connected to the first end of the second electrolytic capacitor and the input terminal of the main control chip; and the second end of the fourth resistor and the second end of the second electrolytic capacitor are connected to reference ground.

[0015] Secondly, embodiments of the present invention provide a power supply device, including: a protection circuit as described in the first aspect.

[0016] The beneficial effects of this utility model embodiment are as follows: Unlike the prior art, this utility model embodiment collects the output current and detects the input voltage and output voltage through the overvoltage protection module. When an abnormal input overvoltage, output overvoltage, or overcurrent is detected, the conduction control module is controlled to actively shut off the power supply path, thereby achieving active circuit breaking protection. This overcomes the problem of TVS tube breakdown voltage drift with temperature, avoids permanent damage to the protection device due to long-term overvoltage, and can automatically recover after the fault is eliminated, achieving repeatable protection and improving the safety and reliability of the MCU power supply circuit. Attached Figure Description

[0017] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0018] Figure 1 This is a schematic diagram of the structure of a protection circuit provided by an embodiment of this utility model; Figure 2 This is a structural schematic diagram of an overvoltage protection module provided by an embodiment of this utility model; Figure 3 This is a schematic diagram of the structure of an overcurrent protection module provided by an embodiment of the present invention; Figure 4 This is a circuit diagram of a protection circuit provided by an embodiment of the present invention. Detailed Implementation

[0019] To facilitate understanding of this utility model, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. It should be noted that when an element is described as being "fixed to" another element, it can be directly on the other element, or one or more intermediate elements may exist between them. When an element is described as being "connected" to another element, it can be directly connected to the other element, or one or more intermediate elements may exist between them. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this specification are for illustrative purposes only.

[0020] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0021] In some embodiments of this application, a protection circuit 10 is provided, see [link to relevant documentation]. Figure 1 As shown, the protection circuit 10 includes a linear voltage regulator module 110, an overvoltage protection module 120, an overcurrent protection module 140, and a conduction control module 130.

[0022] Specifically, the linear regulator module 110 is connected to the input power supply 20 and is used to convert the input voltage of the input power supply 20 into a target output voltage. By way of example and not limitation, the linear regulator module 110 uses its internal regulating transistor and feedback control circuit to convert an unstable input voltage into a stable target output voltage, providing a stable power supply voltage for subsequent circuits. When the input voltage fluctuates within a certain range, the linear regulator module 110 can automatically adjust to maintain the stability of the output voltage.

[0023] The overvoltage protection module 120 is connected to the linear regulator module 110 and the input power supply 20, respectively. It is used to transmit the target output voltage, acquire the output current of the linear regulator module 110, and output an overvoltage protection signal when the input voltage reaches a first preset threshold, the target output voltage reaches a second preset threshold, or an overcurrent protection signal is received. It is easy to understand that by monitoring the voltage status at the input and output terminals and receiving the overcurrent protection signal, the overvoltage protection module 120 can promptly output an overvoltage protection signal when any of the following abnormal conditions occur: the input voltage reaches the first preset threshold, the target output voltage reaches the second preset threshold, or an overcurrent protection signal is received, thereby triggering protection action.

[0024] The overcurrent protection module 140 is connected to the overvoltage protection module 120 and is used to receive the sampling signal of the output current. When the sampling signal reaches a first preset reference voltage, it outputs an overcurrent protection signal. In some embodiments of this application, the overcurrent protection module 140 detects and compares the sampling signal. When it detects that the current exceeds the set safety range, it immediately outputs an overcurrent protection signal to trigger protection action and prevent damage to subsequent circuits due to excessive current.

[0025] The conduction control module 130 is connected to both the overvoltage protection module 120 and the main control chip 30. It is used to transmit the target output voltage to the main control chip 30 in response to a target output voltage, and to turn off in response to an overvoltage protection signal. As a controlled switch, the conduction control module 130 conducts to supply power to the main control chip 30 during normal operation, and immediately turns off upon receiving an overvoltage protection signal, cutting off the power supply path and protecting the main control chip 30.

[0026] Specifically, when the protection circuit 10 is working normally, the input voltage of the input power supply 20 is converted into the target output voltage by the linear voltage regulator module 110, the overvoltage protection module 120 transmits the target output voltage and monitors the voltage and current status, and the conduction control module 130 responds to the target output voltage and conducts the target output voltage to the main control chip 30 to supply power to the main control chip 30 normally.

[0027] As an example and not a limitation, when an input overvoltage occurs, the overvoltage protection module 120 detects that the input voltage has reached a first preset threshold and outputs an overvoltage protection signal; when an output overvoltage occurs, the overvoltage protection module 120 detects that the target output voltage has reached a second preset threshold and outputs an overvoltage protection signal; when an overcurrent occurs, the overcurrent protection module 140 detects that the sampled signal has reached a first preset reference voltage and outputs an overcurrent protection signal to the overvoltage protection module 120, which then outputs an overvoltage protection signal upon receiving the overcurrent protection signal. When any protection condition is triggered, the turn-on control module 130 responds to the overvoltage protection signal by turning off, cutting off the power supply path to the main control chip 30.

[0028] Once the abnormal situation is resolved, the input voltage and target output voltage return to normal range, the overcurrent condition is released, the overvoltage protection module 120 stops outputting the overvoltage protection signal, and the conduction control module 130 resumes conduction in response to the target output voltage, restoring normal power supply to the main control chip 30. The protection circuit 10 can automatically resume normal operation, realizing a repeatable protection function and effectively preventing permanent damage to the main control chip 30 due to overvoltage and overcurrent.

[0029] In other embodiments of this application, see Figure 2As shown, the overvoltage protection module 120 includes a current sampling unit 121, a first detection unit 122, a second detection unit 123, and a signal output unit 124.

[0030] Specifically, the current sampling unit 121 is connected to the linear regulator module 110, the overcurrent protection module 140, and the turn-on control module 130, respectively, for transmitting the target output voltage, acquiring the output current, and converting the output current into a sampling signal. As an example and not a limitation, the current sampling unit 121 is connected in series in the output path of the linear regulator module 110. On the one hand, it allows the target output voltage to pass through and be transmitted to the turn-on control module 130; on the other hand, it converts the flowing output current into a voltage-form sampling signal through the sampling element for detection and processing by the overcurrent protection module 140.

[0031] The first detection unit 122 is connected to the input power supply 20 and is used to output a first detection signal when the input voltage reaches a first preset threshold. By way of example and not limitation, the first detection unit 122 continuously monitors the voltage state of the input power supply 20. When the input voltage abnormally rises and reaches the first preset threshold, the first detection unit 122 activates and outputs the first detection signal, thereby detecting the overvoltage state at the input terminal. The first preset threshold is set according to the safe operating voltage range of the linear regulator module 110 and the main control chip 30.

[0032] The second detection unit 123 is connected to the linear voltage regulator module 110 and is used to output a second detection signal when the target output voltage reaches a second preset threshold. As an example and not a limitation, the second detection unit 123 monitors the target output voltage output by the linear voltage regulator module 110. When the target output voltage abnormally increases for some reason and reaches the second preset threshold, the second detection unit 123 activates and outputs the second detection signal, thereby detecting the overvoltage state at the output terminal. The second preset threshold is set according to the maximum allowable operating voltage of the main control chip 30.

[0033] The signal output unit 124 is connected to the first detection unit 122, the second detection unit 123, the overcurrent protection module 140, and the conduction control module 130, respectively, and is used to output an overvoltage protection signal when at least one of the first detection signal, the second detection signal, and the overcurrent protection signal is received. By way of example and not limitation, the signal output unit 124 implements a logic OR function to comprehensively process the protection signals from different detection units, ensuring that an overvoltage protection signal can be reliably output to the conduction control module 130 when any protection condition is triggered.

[0034] Specifically, under normal operating conditions, neither the first detection unit 122 nor the second detection unit 123 outputs a detection signal, the overcurrent protection module 140 does not output an overcurrent protection signal, the signal output unit 124 does not output an overvoltage protection signal, the conduction control module 130 remains in the conduction state, and the target output voltage is normally transmitted to the main control chip 30.

[0035] When an input overvoltage occurs, the first detection unit 122 outputs a first detection signal to the signal output unit 124; when an output overvoltage occurs, the second detection unit 123 outputs a second detection signal to the signal output unit 124; when an overcurrent occurs, the overcurrent protection module 140 outputs an overcurrent protection signal to the signal output unit 124. Upon receiving any of the above signals, the signal output unit 124 immediately outputs an overvoltage protection signal to the turn-on control module 130, triggering the turn-on control module 130 to turn off and cut off the power supply path to the main control chip 30.

[0036] In this embodiment, the overvoltage protection module 120, by setting up a first detection unit 122 and a second detection unit 123 respectively, realizes independent overvoltage detection at the input and output terminals. Combined with the overcurrent detection function of the current sampling unit 121, this constitutes a complete overvoltage and overcurrent protection system. The signal output unit 124 processes multiple protection signals uniformly, ensuring that any abnormal situation can trigger protection action, thus improving the reliability and safety of the protection circuit 10.

[0037] Once the abnormal situation is eliminated, the first detection unit 122 and the second detection unit 123 stop outputting detection signals, the overcurrent protection module 140 stops outputting overcurrent protection signals, the signal output unit 124 stops outputting overvoltage protection signals, and the conduction control module 130 is turned on again to restore normal power supply to the main control chip 30, thereby realizing the automatic recovery function of the protection circuit 10.

[0038] In other embodiments of this application, see Figure 3 As shown, the overcurrent protection module 140 includes an operational amplifier unit 141 and a comparison unit 142.

[0039] Specifically, the operational amplifier unit 141 is connected to the overvoltage protection module 120 and is used to amplify the sampled signal into a comparison voltage. By way of example and not limitation, the operational amplifier unit 141 receives a sampled signal from the current sampling unit 121 in the overvoltage protection module 120, the sampled signal reflecting the output current of the linear regulator module 110. Since the sampled signal is usually relatively weak, the operational amplifier unit 141 amplifies the sampled signal by a predetermined voltage amplification factor to obtain a comparison voltage for subsequent comparison and judgment.

[0040] Comparison unit 142 is connected to operational amplifier unit 141 and overvoltage protection module 120, and is used to output an overcurrent protection signal when the comparison voltage is greater than a second preset reference voltage. By way of example and not limitation, comparison unit 142 receives the comparison voltage output by operational amplifier unit 141 and compares the comparison voltage with the second preset reference voltage. When the comparison voltage is greater than the second preset reference voltage, it indicates that the output current exceeds the safe range, and comparison unit 142 immediately outputs an overcurrent protection signal to signal output unit 124 of overvoltage protection module 120.

[0041] As an example and not a limitation, the ratio of the second preset reference voltage to the first preset reference voltage is the voltage amplification factor of the operational amplifier unit 141. Specifically, the first preset reference voltage corresponds to the actual overcurrent protection threshold, and the second preset reference voltage is set accordingly based on the voltage amplification factor of the operational amplifier unit 141. For example, if the voltage amplification factor of the operational amplifier unit 141 is 10 times and the first preset reference voltage is 0.1V (corresponding to a certain overcurrent value), then the second preset reference voltage is set to 1V to ensure that the comparison unit 142 can accurately determine the overcurrent state.

[0042] In some embodiments of this application, the overcurrent protection module 140 operates as follows: During normal operation, the output current is within a safe range, and the sampling signal generated by the current sampling unit 121 is relatively small. After amplification by the operational amplifier unit 141, the comparison voltage obtained is still less than the second preset reference voltage, and the comparison unit 142 does not output an overcurrent protection signal. When the output current increases, the sampling signal increases accordingly, and the comparison voltage also increases. When the output current reaches the overcurrent threshold, the sampling signal reaches the first preset reference voltage, and the comparison voltage amplified by the operational amplifier unit 141 reaches the second preset reference voltage. The comparison unit 142 detects that the comparison voltage is greater than the second preset reference voltage and immediately outputs an overcurrent protection signal.

[0043] By amplifying the sampled signal using the operational amplifier unit 141, the sensitivity and accuracy of overcurrent detection can be improved. Weak sampled signals, after amplification, are more easily detected and judged accurately by the comparison unit 142. Simultaneously, by appropriately setting the relationship between the first preset reference voltage, the second preset reference voltage, and the voltage amplification factor, the trigger point of the overcurrent protection can be precisely controlled, ensuring that the protection action is triggered in time before the output current reaches a dangerous value.

[0044] After the overcurrent protection signal is output to the signal output unit 124 of the overvoltage protection module 120, the signal output unit 124 outputs an overvoltage protection signal. The conduction control module 130 responds to the overvoltage protection signal by turning off, cutting off the power supply to the main control chip 30 to prevent damage to the main control chip 30 due to overcurrent. When the overcurrent condition is eliminated and the output current returns to normal, the sampling signal decreases, the comparison voltage drops below the second preset reference voltage, the comparison unit 142 stops outputting the overcurrent protection signal, and the protection circuit 10 resumes normal operation.

[0045] In some other embodiments of this application, a circuit schematic of a protection circuit is provided, such as... Figure 4 As shown. Specifically, the linear regulator module 110 includes a linear regulator U1 and a first electrolytic capacitor CE1. The input terminal of the linear regulator U1 and the first terminal of the first electrolytic capacitor CE1 are connected to the input power supply VCC1. The output terminal of the linear regulator U1 is connected to the second input terminal of the overvoltage protection module 120. The ground terminal of the linear regulator U1 and the second terminal of the first electrolytic capacitor CE1 are connected to the reference ground GND.

[0046] In some embodiments of this application, the current sampling unit 121 includes a fifth resistor R5 and a second capacitor C2. The first terminal of the fifth resistor R5 is connected to the first terminal of the second capacitor C2, and the output terminal of the linear regulator module 110 (i.e.,...) Figure 4 The output terminal of the linear regulator U1 shown) and the first input terminal of the overcurrent protection module 140 (i.e. Figure 4 The first terminal of the twelfth resistor R12 is connected to the second terminal of the fifth resistor R5, and the second terminal of the second capacitor C2 is connected to the second input terminal of the overcurrent protection module 140 (i.e., the second terminal of the first resistor R12). Figure 4 The first terminal of the fourteenth resistor R14 shown) and the input terminal of the conduction control module 130 (i.e. Figure 4 The source of the third switch Q3 is connected as shown. The fifth resistor R5 serves as the current sampling resistor; when the output current flows through it, a voltage drop is generated across it, and this voltage drop is the sampling signal. The second capacitor C2 is connected in parallel across the fifth resistor R5 to filter out high-frequency noise and improve the stability of the sampling signal.

[0047] The first detection unit 122 includes a first Zener diode ZD1. The cathode of the first Zener diode ZD1 is connected to the input power supply VCC1, and the anode of the first Zener diode ZD1 is connected to the signal terminal of the signal output unit 124 (i.e., Figure 4 The first terminal of the sixth resistor R6 shown is connected. The second detection unit 123 includes a second Zener diode ZD2, the cathode of which is connected to the output terminal of the linear regulator module 110 (i.e., the first terminal of the sixth resistor R6 shown). Figure 4 The output terminal of the linear regulator U1 shown is connected to the signal terminal of the signal output unit 124 (i.e., the anode of the second Zener diode ZD2 is connected to the signal terminal of the signal output unit 124). Figure 4 The first terminal of the sixth resistor R6 shown is connected. It is easy to understand that the Zener diodes ZD1 and ZD2 are selected according to the target input overvoltage action voltage and output overvoltage action voltage, respectively. When the corresponding voltage reaches the breakdown voltage of the Zener diode, the Zener diode conducts and outputs a detection signal.

[0048] The signal output unit 124 includes a first capacitor C1, a first resistor R1, a third resistor R3, a sixth resistor R6, a second switch Q2, and a fourth switch Q4. The first terminal of the first resistor R1 is connected to the emitter of the second switch Q2 and the input terminal of the conduction control module 130 (i.e.,...). Figure 4 The source of the third switch Q3 is connected to the source of the second switch Q2. The second end of the first resistor R1 is connected to the first end of the third resistor R3 and the base of the second switch Q2. The second end of the third resistor R3 is connected to the collector of the fourth switch Q4. The collector of the second switch Q2 is connected to the signal terminal of the conduction control module 130 (i.e., the source of the third switch Q3). Figure 4 The gate of the third switch Q3 is connected to the gate of the fourth switch Q4. The base of the fourth switch Q4 is connected to the second terminal of the sixth resistor R6 and the first terminal of the first capacitor C1. The first terminal of the sixth resistor R6 is connected to the output terminal of the first detection unit 122 (i.e., the gate of the third switch Q3 is connected to the gate of the fourth switch Q4). Figure 4 The anode of the first Zener diode ZD1 shown), and the output terminal of the second detection unit 123 (i.e. Figure 4 The anode of the second Zener diode ZD2 (shown) is connected to the output terminal of the overcurrent protection module 140, and the emitter of the fourth switch Q4 is connected to the second terminal of the first capacitor C1 to the reference ground GND.

[0049] Specifically, when any protection signal is triggered (the first Zener diode ZD1 or the second Zener diode ZD2 breaks down, or the overcurrent protection module 140 outputs a high level), the base voltage of the fourth switch Q4 increases and it turns on, its collector voltage is pulled down, which in turn turns on the second switch Q2, and the collector of the second switch Q2 outputs a high level as an overvoltage protection signal.

[0050] In some embodiments of this application, the operational amplifier unit 141 includes a third capacitor C3, a fourth capacitor C4, an eighth capacitor C8, a ninth resistor R9, a tenth resistor R10, a twelfth resistor R12, a fourteenth resistor R14, a sixteenth resistor R16, and an operational amplifier U2B. The comparator unit 142 includes a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, a seventh resistor R7, an eighth resistor R8, an eleventh resistor R11, a thirteenth resistor R13, a fifteenth resistor R15, a first Schottky diode DS1, a second Schottky diode DS2, and a comparator U2A.

[0051] As an example, and not a limitation, the non-inverting and inverting inputs of operational amplifier U2B are connected to the two ends of resistor R5 via resistors R12 (twelfth resistor) and R14 (fourteenth resistor), respectively, to detect the sampled signal and perform differential amplification. The non-inverting input of comparator U2A is set with a second preset reference voltage via a voltage divider circuit, while the inverting input receives the amplified comparison voltage. When the comparison voltage exceeds the second preset reference voltage, comparator U2A outputs an overcurrent protection signal.

[0052] In some embodiments of this application, the conduction control module 130 includes a second resistor R2, a fourth resistor R4, a second electrolytic capacitor CE2, and a third switching transistor Q3. The first terminal of the second resistor R2 is connected to the voltage output terminal of the overvoltage protection module 120 (i.e., Figure 4 The second terminal of the fifth resistor R5 (shown) is connected to the source of the third switch Q3, and the second terminal of the second resistor R2 is connected to the signal output terminal of the overvoltage protection module 120 (i.e., Figure 4 The collector of the second switch Q2, the gate of the third switch Q3, and the first end of the fourth resistor R4 are connected. The drain of the third switch Q3 is connected to the first end of the second electrolytic capacitor CE2 and the input terminal of the main control chip 30. The second end of the fourth resistor R4 and the second end of the second electrolytic capacitor CE2 are connected to the reference ground GND.

[0053] During normal operation, the voltage divider between the second resistor R2 and the fourth resistor R4 turns on the third switch Q3, and the target output voltage is transmitted to the main control chip 30 through the third switch Q3. When an overvoltage protection signal is generated, the gate voltage of the third switch Q3 is pulled up to the source voltage, the gate-source voltage difference is zero, the third switch Q3 turns off, and the power supply path is cut off. The second electrolytic capacitor CE2 is used to stabilize the power supply voltage of the main control chip 30.

[0054] Unlike existing technologies, this utility model embodiment uses an overvoltage protection module to collect output current, detect input voltage and output voltage. When an abnormal input overvoltage, output overvoltage or overcurrent is detected, the conduction control module is controlled to actively shut off the power supply path, realizing active circuit breaking protection. This overcomes the problem of TVS tube breakdown voltage drift with temperature, avoids permanent damage to protection devices due to long-term overvoltage, and can automatically recover after the fault is cleared, realizing repeatable protection and improving the safety and reliability of the MCU power supply circuit.

[0055] Based on the protection circuit provided in the above embodiments, this application also provides a power supply device, which includes the protection circuit provided in any of the above embodiments.

[0056] It should be noted that while the preferred embodiments of this utility model are provided in the specification and accompanying drawings, this utility model can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are not intended to impose additional limitations on the content of this utility model; their purpose is to provide a more thorough and comprehensive understanding of the disclosure of this utility model. Furthermore, the above-described technical features can be combined with each other to form various embodiments not listed above, all of which are considered to be within the scope of this utility model specification. Moreover, those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A protection circuit, characterized in that, include: A linear voltage regulator module, connected to an input power supply, is used to convert the input voltage of the input power supply into a target output voltage; An overvoltage protection module is connected to the linear voltage regulator module and the input power supply, respectively, and is used to transmit the target output voltage, collect the output current of the linear voltage regulator module, and output an overvoltage protection signal when the input voltage reaches a first preset threshold, the target output voltage reaches a second preset threshold, or an overcurrent protection signal is received. An overcurrent protection module, connected to the overvoltage protection module, is used to receive the sampling signal of the output current and output the overcurrent protection signal when the sampling signal reaches a first preset reference voltage; The conduction control module is connected to the overvoltage protection module and the main control chip respectively, and is used to transmit the target output voltage to the main control chip in response to the target output voltage being turned on; And shut down in response to the overvoltage protection signal.

2. The circuit according to claim 1, characterized in that, The overvoltage protection module includes a current sampling unit, a first detection unit, a second detection unit, and a signal output unit; The current sampling unit is connected to the linear voltage regulator module, the overcurrent protection module, and the conduction control module respectively, and is used to transmit the target output voltage, collect the output current, and convert the output current into the sampling signal; The first detection unit is connected to the input power supply and is used to output a first detection signal when the input voltage reaches the first preset threshold. The second detection unit is connected to the linear voltage regulator module and is used to output a second detection signal when the target output voltage reaches the second preset threshold. The signal output unit is connected to the first detection unit, the second detection unit, the overcurrent protection module, and the conduction control module, respectively, and is used to output the overvoltage protection signal when at least one of the first detection signal, the second detection signal, and the overcurrent protection signal is received.

3. The circuit according to claim 2, characterized in that, The current sampling unit includes a fifth resistor and a second capacitor; The first end of the fifth resistor is connected to the first end of the second capacitor, the output end of the linear voltage regulator module, and the first input end of the overcurrent protection module. The second end of the fifth resistor is connected to the second end of the second capacitor, the second input end of the overcurrent protection module, and the input end of the conduction control module.

4. The circuit according to claim 2, characterized in that, The first detection unit includes a first Zener diode, the cathode of which is connected to the input power supply, and the anode of which is connected to the signal terminal of the signal output unit. The second detection unit includes a second Zener diode, the cathode of which is connected to the output terminal of the linear voltage regulator module, and the anode of which is connected to the signal terminal of the signal output unit.

5. The circuit according to claim 2, characterized in that, The signal output unit includes a first capacitor, a first resistor, a third resistor, a sixth resistor, a second switch, and a fourth switch. The first end of the first resistor is connected to the emitter of the second switch and the input terminal of the conduction control module; the second end of the first resistor is connected to the first end of the third resistor and the base of the second switch; the second end of the third resistor is connected to the collector of the fourth switch; and the collector of the second switch is connected to the signal terminal of the conduction control module. The base of the fourth switching transistor is connected to the second end of the sixth resistor and the first end of the first capacitor. The first end of the sixth resistor is connected to the output end of the first detection unit, the output end of the second detection unit, and the output end of the overcurrent protection module. The emitter of the fourth switching transistor is connected to the second end of the first capacitor and grounded.

6. The circuit according to claim 2, characterized in that, The overcurrent protection module includes an operational amplifier unit and a comparison unit; The operational amplifier unit is connected to the overvoltage protection module and is used to amplify the sampled signal into a comparison voltage; The comparison unit is connected to the operational amplifier unit and the overvoltage protection module, and is used to output the overcurrent protection signal when the comparison voltage is greater than the second preset reference voltage; The ratio of the second preset reference voltage to the first preset reference voltage is the voltage amplification factor of the operational amplifier unit.

7. The circuit according to claim 6, characterized in that, The operational amplifier unit includes a third capacitor, a fourth capacitor, an eighth capacitor, a ninth resistor, a tenth resistor, a twelfth resistor, a fourteenth resistor, a sixteenth resistor, and an operational amplifier; The first end of the twelfth resistor is connected to the first end of the current sampling unit. The second end of the twelfth resistor is connected to the second end of the tenth resistor, the second end of the fourth capacitor, and the non-inverting input of the operational amplifier. The first end of the fourth capacitor, the second end of the third capacitor, and the first end of the ninth resistor are connected to the first power supply voltage. The second end of the ninth resistor is connected to the first end of the tenth resistor. The first end of the third capacitor is connected to the reference ground. The first end of the fourteenth resistor is connected to the second end of the current sampling unit, the second end of the fourteenth resistor is connected to the first end of the sixteenth resistor, the first end of the eighth capacitor and the inverting input of the operational amplifier, and the output of the operational amplifier is connected to the second end of the sixteenth resistor, the second end of the eighth capacitor and the input of the comparator unit.

8. The circuit according to claim 6, characterized in that, The comparison unit includes a fifth capacitor, a sixth capacitor, a seventh capacitor, a seventh resistor, an eighth resistor, an eleventh resistor, a thirteenth resistor, a fifteenth resistor, a first Schottky diode, a second Schottky diode, and a comparator; The anode of the first Schottky diode is connected to the output terminal of the operational amplifier unit and the first terminal of the sixth capacitor. The cathode of the first Schottky diode is connected to the first terminal of the thirteenth resistor. The second terminal of the thirteenth resistor is connected to the first terminal of the seventh capacitor, the first terminal of the fifteenth resistor, and the inverting input terminal of the comparator. The second terminals of the sixth capacitor, the seventh capacitor, and the fifteenth resistor are connected to reference ground. The first end of the eighth resistor is connected to the first supply voltage, and the second end of the eighth resistor is connected to the first end of the seventh resistor, the second end of the eleventh resistor, the second end of the fifth capacitor, and the non-inverting input of the comparator. The first end of the fifth capacitor and the first end of the eleventh resistor are connected to the reference ground. The second terminal of the seventh resistor is connected to the anode of the second Schottky diode, the positive terminal of the comparator is connected to the second power supply voltage, the negative terminal of the comparator is connected to the reference ground, and the output terminal of the comparator is connected to the cathode of the second Schottky diode and the signal terminal of the overvoltage protection module.

9. The circuit according to claim 1, characterized in that, The conduction control module includes a second resistor, a fourth resistor, a second electrolytic capacitor, and a third switching transistor; The first end of the second resistor is connected to the voltage output terminal of the overvoltage protection module and the source of the third switching transistor. The second end of the second resistor is connected to the signal output terminal of the overvoltage protection module, the gate of the third switching transistor, and the first end of the fourth resistor. The drain of the third switching transistor is connected to the first end of the second electrolytic capacitor and the input terminal of the main control chip. The second end of the fourth resistor and the second end of the second electrolytic capacitor are connected to the reference ground.

10. A power supply device, characterized in that, include: The protection circuit as described in any one of claims 1-9.

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