Current protection circuit and voltage stabilized power supply

Abstract

The present application is applicable to the field of power management, and provides a current protection circuit and a voltage-stabilized power supply. The current protection circuit includes a reference voltage unit, a collection unit, a logic unit, and a first three-terminal voltage-stabilizing tube. The collection unit is arranged on the power supply line between the power supply and the load. The reference voltage unit is used to provide a reference voltage. The collection unit is used to collect the working current on the power supply line. When the working current is greater than a preset value, the collection unit outputs a first signal according to the working current and the reference voltage, so that the cathode of the first three-terminal voltage-stabilizing tube outputs a second signal. The logic unit outputs a target logic signal according to the second signal, and the target logic signal is used to control the switch unit to shut down. The current protection circuit provided in the embodiment of the present application solves the problem that in the existing low-voltage difference linear voltage-stabilized power supply, due to the "input-output pulse response time" of the integrated comparator being too long, the large current flows through the field effect transistor for too long, causing the junction temperature of the field effect transistor to be too high and fail.

Description

Technical Field

[0001] The present application belongs to the technical field of power management, and in particular, relates to a current protection circuit and a voltage-stabilized power supply. Background Art

[0002] At present, the DC power supply used by high-precision equipment generally requires the output voltage ripple of the power supply to be extremely small, the high-frequency interference to be extremely small, and the voltage stability to be extremely high. At the same time, the temperature rise of the components of the DC power supply is required to be low when working at full load. In order to meet the above requirements, the DC power supply used by high-precision equipment usually adopts a low-voltage difference linear voltage regulator. The low-voltage difference linear voltage regulator needs to have a safe and reliable abnormal situation protection function. For example: when the positive pole of the output DC voltage and the negative pole of the output DC voltage of the low-voltage difference linear voltage regulator are overcurrent or short-circuited, the current protection control circuit module inside the low-voltage difference linear voltage regulator should shut down the current flowing from the positive pole of the output DC voltage to the negative pole of the output DC voltage without damaging any circuit components. The existing current protection control circuit module uses a general-purpose integrated comparator as the core functional device, but the "input and output pulse response time" of the integrated comparator is too long, resulting in a large current flowing through the field effect transistor in the low-voltage difference linear voltage regulator for too long, causing the junction temperature of the field effect transistor to be too high and fail, causing safety hazards such as smoke and fire. Summary of the invention

[0003] The embodiments of the present application provide a current protection circuit and a voltage-stabilized power supply, which can solve the problem in the existing low-voltage difference linear voltage-stabilized power supply that the "input-output pulse response time" of the integrated comparator is too long, resulting in the large current flowing through the field effect transistor in the low-voltage difference linear voltage-stabilized power supply for too long, causing the junction temperature of the field effect transistor to be too high and fail.

[0004] In a first aspect, an embodiment of the present application provides a current protection circuit, comprising a reference voltage unit, a collection unit, a logic unit and a first three-terminal voltage regulator; the collection unit is arranged on a power supply line between a power supply and a load, the reference voltage unit and the reference end of the first three-terminal voltage regulator are respectively electrically connected to the collection unit, the anode of the first three-terminal voltage regulator is used to be electrically connected to the negative electrode of the power supply, the cathode of the first three-terminal voltage regulator is electrically connected to the logic unit, and the logic unit is respectively used to be electrically connected to a switch unit in a voltage regulator and the power supply;

[0005] The reference voltage unit is used to provide a reference voltage; the acquisition unit is used to acquire the working current on the power supply line; when the working current is greater than a preset value, the acquisition unit is used to output a first signal according to the working current and the reference voltage, so that the cathode of the first three-terminal voltage regulator tube outputs a second signal; the logic unit is used to output a target logic signal according to the second signal, and the target logic signal is used to control the switch unit to shut down.

[0006] In a possible implementation of the first aspect, the reference voltage unit includes a second three-terminal voltage regulator and a twelfth resistor; the first end of the twelfth resistor is used to be electrically connected to the positive electrode of the first power supply, the second end of the twelfth resistor is respectively electrically connected to the cathode of the second three-terminal voltage regulator, the reference end of the second three-terminal voltage regulator and the acquisition unit, the anode of the second three-terminal voltage regulator is used to be electrically connected to the negative electrode of the first power supply, and the negative electrode of the first power supply is electrically connected to the negative electrode of the power supply.

[0007] In a possible implementation manner of the first aspect, the acquisition unit includes a tenth resistor, an eleventh resistor, and a sampling resistor;

[0008] The first end of the tenth resistor is electrically connected to the reference voltage unit, the second end of the tenth resistor is electrically connected to the first end of the eleventh resistor and the reference end of the first three-terminal voltage regulator respectively, the second end of the eleventh resistor is electrically connected to the first end of the sampling resistor, the first end of the sampling resistor is used to be electrically connected to the negative electrode of the load, and the second end of the sampling resistor is used to be electrically connected to the negative electrode of the power supply.

[0009] In a possible implementation manner of the first aspect, the logic unit includes a first logic unit and a second logic unit; the first logic unit is electrically connected to the cathode of the first three-terminal voltage regulator and the second logic unit respectively, the first logic unit is used to be electrically connected to the power supply, and the second logic unit is used to be electrically connected to the switch unit;

[0010] The first logic unit is used to output a first logic signal according to the second signal; the second logic unit is used to output a target logic signal according to the first logic signal.

[0011] In a possible implementation manner of the first aspect, the first logic unit includes a first switch tube, a third resistor, a fourth resistor, and a fifth resistor;

[0012] The first end of the third resistor is used to be electrically connected to the positive electrode of the power supply, the second end of the third resistor is respectively electrically connected to the first end of the fourth resistor and the cathode of the first three-terminal voltage regulator tube, the second end of the fourth resistor is electrically connected to the control end of the first switch tube, the first end of the first switch tube is used to be electrically connected to the positive electrode of the power supply, the second end of the first switch tube is respectively electrically connected to the second logic unit and the first end of the fifth resistor, and the second end of the fifth resistor is used to be electrically connected to the negative electrode of the power supply.

[0013] In a possible implementation manner of the first aspect, the second logic unit includes a first diode; an anode of the first diode is electrically connected to the first logic unit, and a cathode of the first diode is used to be electrically connected to the switch unit.

[0014] In a possible implementation of the first aspect, the second logic unit includes a seventh resistor and a second switch tube; the first end of the seventh resistor is electrically connected to the first logic unit, the second end of the seventh resistor is electrically connected to the control end of the second switch tube, the first end of the second switch tube is used to be electrically connected to the switch unit, and the second end of the second switch tube is used to be electrically connected to the negative pole of the power supply.

[0015] In a possible implementation manner of the first aspect, the current protection circuit further includes a current protection time locking unit; the current protection time locking unit is electrically connected to the reference end of the first three-terminal voltage regulator and the logic unit respectively;

[0016] When the operating current is greater than a preset value, the current protection time locking unit is used to lock the current protection circuit in a protection state.

[0017] In a possible implementation of the first aspect, the current protection time locking unit includes a fourth capacitor, a second diode and a ninth resistor; the first end of the fourth capacitor is electrically connected to the first end of the ninth resistor and the negative electrode of the second diode, respectively, the second end of the ninth resistor is electrically connected to the reference end of the first three-terminal voltage regulator, the second end of the fourth capacitor is electrically connected to the logic unit, and the positive electrode of the second diode is used to be electrically connected to the negative electrode of the power supply.

[0018] In a second aspect, an embodiment of the present application provides a voltage-stabilized power supply, comprising a current protection circuit as described in any one of the first aspects.

[0019] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0020] The embodiment of the present application provides a current protection circuit, including a reference voltage unit, a collection unit, a logic unit and a first three-terminal voltage regulator. The collection unit is arranged on the power supply line between the power supply and the load. The reference voltage unit and the reference end of the first three-terminal voltage regulator are electrically connected to the collection unit respectively. The anode of the first three-terminal voltage regulator is used to be electrically connected to the negative electrode of the power supply, and the cathode of the first three-terminal voltage regulator is electrically connected to the logic unit. The logic unit is used to be electrically connected to the switch unit and the power supply in the voltage regulator respectively. The reference voltage unit is used to provide a reference voltage. The collection unit is used to collect the working current on the power supply line. The current protection circuit provided in the embodiment of the present application adopts the first three-terminal voltage regulator as the core component, and the "input and output pulse response time" of the first three-terminal voltage regulator is less than 100nS, which is one tenth of the "input and output pulse response time" of the general integrated comparator. When the working current collected by the collection unit is greater than the preset value, the collection unit outputs a first signal according to the working current and the reference voltage, so that the cathode of the first three-terminal voltage regulator quickly outputs a second signal. The logic unit outputs a target logic signal according to the second signal, and the target logic signal is used to control the switch unit to turn off. Compared to a voltage-stabilizing power supply using a general-purpose integrated comparator, the current protection circuit provided in the embodiment of the present application can shut down the switch unit in a shorter time, thereby preventing a large current from flowing through the switch unit for too long, causing the switch unit to overheat and fail, resulting in safety hazards such as smoke and fire. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0022] Figure 1 is a principle block diagram of a current protection circuit provided in an embodiment of the present application;

[0023] Figure 2 is a circuit connection diagram of a current protection circuit provided in an embodiment of the present application;

[0024] Figure 3 is a circuit connection diagram of a current protection circuit provided by another embodiment of the present application;

[0025] Figure 4 is a circuit connection diagram of a current protection circuit provided by another embodiment of the present application;

[0026] Figure 5 is a circuit connection diagram of a current protection circuit provided by another embodiment of the present application;

[0027] Figure 6 is a circuit connection diagram of a current protection circuit provided by another embodiment of the present application;

[0028] Figure 7 This is a circuit connection diagram of a voltage-stabilized power supply provided in one embodiment of the present application;

[0029] Figure 8 is a circuit connection diagram of a voltage-stabilized power supply provided in another embodiment of the present application;

[0030] Fig. 9 It is the working waveform of the voltage-stabilized power supply provided in one embodiment of the present application.

[0031] In the figure: 20, power supply; 30, load; 100, current protection circuit; 110, reference voltage unit; 120, acquisition unit; 130, logic unit; 1301, first logic unit; 1302, second logic unit; 200, voltage feedback circuit; 300, switch unit. DETAILED DESCRIPTION

[0032] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0033] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0034] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0035] As used in the specification and appended claims of this application, the term "if" can be interpreted as "when" or "uponce" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "uponce it is determined" or "in response to determining" or "uponce [described condition or event] is detected" or "in response to detecting [described condition or event]", depending on the context.

[0036] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0037] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0038] like Figure 1 As shown, an embodiment of the present application provides a current protection circuit, including a reference voltage unit 110, a collection unit 120, a logic unit 130 and a first three-terminal voltage regulator IC1. The collection unit 120 is arranged on the power supply line between the power supply 20 and the load 30. The reference voltage unit 110 and the reference end of the first three-terminal voltage regulator IC1 are electrically connected to the collection unit 120 respectively. The anode of the first three-terminal voltage regulator IC1 is used to be electrically connected to the negative electrode VI- of the power supply 20, and the cathode of the first three-terminal voltage regulator IC1 is electrically connected to the logic unit 130. The logic unit 130 is used to be electrically connected to the switch unit 300 and the power supply 20 in the voltage regulator, respectively.

[0039] Specifically, the reference voltage unit 110 is used to provide a reference voltage. The acquisition unit 120 is used to acquire the working current on the power supply line, which is the line between the negative electrode of the power supply 20 and the negative electrode of the load 30. The current protection circuit provided in the embodiment of the present application uses the first three-terminal voltage regulator IC1 as the core component, and the "input and output pulse response time" of the first three-terminal voltage regulator IC1 is less than 100nS, which is one tenth of the "input and output pulse response time" of the general integrated comparator. When the working current collected by the acquisition unit 120 is greater than the preset value, that is, when the voltage regulator has an overcurrent or short circuit, the acquisition unit 120 outputs a first signal according to the working current and the reference voltage, so that the cathode of the first three-terminal voltage regulator IC1 quickly outputs a second signal. The logic unit 130 outputs a target logic signal according to the second signal, and the target logic signal is used to control the switch unit 300 to turn off. After the switch unit 300 is turned off, the voltage regulator turns off the voltage output loop, and the output current drops to 0A, that is, the working current on the power supply line drops to 0A. When the working current on the power supply line is 0A, the second signal outputted by the cathode of the first three-terminal voltage regulator IC1 controls the logic unit 130 to turn off, the switch unit 300 resumes conduction, and the voltage regulator is turned on again. Compared with the voltage regulator using a general integrated comparator, the current protection circuit provided in the embodiment of the present application can turn off the switch unit in a shorter time, avoiding the high current flowing through the switch unit for too long, causing the temperature of the switch unit to be too high and fail, causing safety hazards such as smoke and fire.

[0040] like Figure 2 As shown, the reference voltage unit 110 includes a second three-terminal voltage regulator IC2 and a twelfth resistor R12. The first end of the twelfth resistor R12 is used to be electrically connected to the positive electrode V1+ of the first power supply. The second end of the twelfth resistor R12 is electrically connected to the cathode of the second three-terminal voltage regulator IC2, the reference end of the second three-terminal voltage regulator IC2 and the acquisition unit 120 respectively. The anode of the second three-terminal voltage regulator IC2 is used to be electrically connected to the negative electrode V1- of the first power supply, and the negative electrode V1- of the first power supply is electrically connected to the negative electrode VI- of the power supply 20.

[0041] Specifically, when the switch unit 300 is a P-channel field effect transistor or a PNP transistor, the first power source may be the power supply 20. When the switch unit 300 is an N-channel field effect transistor or an NPN transistor, the first power source is an auxiliary power source.

[0042] The negative electrode V1- of the first power source is used as the reference 0 potential, and the twelfth resistor R12 is used to power the second three-terminal voltage regulator IC2. The reference terminal of the second three-terminal voltage regulator IC2 outputs a reference voltage Vref, which is the internal reference voltage of the second three-terminal voltage regulator IC2.

[0043] For example, Figure 4As shown, the second three-terminal voltage regulator IC2 can be replaced by a first voltage regulator diode Z1. The cathode of the first voltage regulator diode Z1 is electrically connected to the second end of the twelfth resistor R12 and the acquisition unit 120 respectively, and the anode of the first voltage regulator diode Z1 is used to be electrically connected to the negative electrode V1- of the first power supply, and the negative electrode V1- of the first power supply is electrically connected to the negative electrode VI- of the power supply 20.

[0044] With the negative electrode V1- of the first power supply as the reference 0 potential, the cathode of the first voltage zener diode Z1 outputs a reference voltage Vref, and the reference voltage Vref is the rated voltage of the first voltage zener diode Z1.

[0045] For example, Figure 5 As shown, the reference voltage unit 110 also includes a fifth capacitor C5, a sixth capacitor C6, a thirteenth resistor R13 and a fourteenth resistor R14. The first end of the fifth capacitor C5, the first end of the sixth capacitor C6 and the first end of the thirteenth resistor R13 are all electrically connected to the cathode of the second three-terminal voltage regulator IC2. The second end of the sixth capacitor C6 is electrically connected to the anode of the second three-terminal voltage regulator IC2. The second end of the fifth capacitor C5, the second end of the thirteenth resistor R13 and the first end of the fourteenth resistor R14 are all electrically connected to the reference end of the second three-terminal voltage regulator IC2. The second end of the fourteenth resistor R14 is electrically connected to the anode of the second three-terminal voltage regulator IC2. The fifth capacitor C5 and the sixth capacitor C6 have the functions of smoothing filtering and anti-interference.

[0046] like Figure 2 As shown, the acquisition unit 120 includes a tenth resistor R10, an eleventh resistor R11 and a sampling resistor RS1. The first end of the tenth resistor R10 is electrically connected to the reference voltage unit 110. The second end of the tenth resistor R10 is electrically connected to the first end of the eleventh resistor R11 and the reference end of the first three-terminal voltage regulator IC1 respectively. The second end of the eleventh resistor R11 is electrically connected to the first end of the sampling resistor RS1. The first end of the sampling resistor RS1 is used to be electrically connected to the negative electrode VO- of the load 30. The second end of the sampling resistor RS1 is used to be electrically connected to the negative electrode VI- of the power supply 20.

[0047] Specifically, the first end of the tenth resistor R10 is electrically connected to the second end of the twelfth resistor R12 in the reference voltage unit 110. The sampling resistor RS1 is used to collect the working current on the power supply line. The first end of the tenth resistor R10 receives the reference voltage Vref. The second end of the tenth resistor R10 outputs the first signal VR. It is set that the reference voltage Vref is greater than the voltage VIS on the first end of the sampling resistor RS1. According to the circuit structure of the acquisition unit 120, it can be obtained that VR = VIS + (Vref - VIS) * R11 / (R10 + R11). For the convenience of analysis, the coefficient K = R11 / (R10 + R11) is set. The tenth resistor R10 and the eleventh resistor R11 are fixed values, so the coefficient K is a fixed value and 0 < K < 1. Therefore, the first signal VR can be expressed as VR = K * Vref + (1 - K) * VIS. From this formula, it can be obtained that the first signal VR is a monotonic function of the voltage VIS. When the voltage VIS increases, the first signal VR also increases. When the voltage VIS decreases, the first signal VR also decreases.

[0048] When the working current collected by the sampling resistor RS1 is greater than the preset value, that is, when the regulated power supply has overcurrent or short - circuit, the voltage VIS will increase, resulting in an increase in the first signal VR. When the first signal VR is greater than the internal reference voltage of the first three - terminal voltage - regulating diode IC1, the second signal output from the cathode of the first three - terminal voltage - regulating diode IC1 starts to decrease. The control logic unit 130 is turned on and outputs a target logic signal. The target logic signal controls the switch unit 300 to turn off. After the switch unit 300 is turned off, the regulated power supply turns off the voltage output loop, and the output current drops to 0A, preventing the switch unit 300 from being burned due to flowing through a large current for a long time and avoiding safety hazards such as smoking and fire. When the working current is 0A, the voltage VIS decreases to 0V, and the first signal VR decreases accordingly. When the first signal VR is less than the internal reference voltage of the first three - terminal voltage - regulating diode IC1, the second signal output from the cathode of the first three - terminal voltage - regulating diode IC1 starts to rise, so that the control logic unit 130 is turned off, the switch unit 300 resumes conduction, and the regulated power supply is restarted.

[0049] As Figure 2 shown, the logic unit 130 includes a first logic unit 1301 and a second logic unit 1302. The first logic unit 1301 is electrically connected to the cathode of the first three - terminal voltage - regulating diode IC1 and the second logic unit 1302 respectively. The first logic unit 1301 is used to be electrically connected to the power supply 20. The second logic unit 1302 is used to be electrically connected to the switch unit 300.

[0050] Specifically, when the working current is greater than the preset value, that is, when the voltage-stabilized power supply has an overcurrent or short circuit, the second signal outputted from the cathode of the first three-terminal voltage-stabilizing tube IC1 begins to decrease, controlling the first logic unit 1301 to turn on, and then controlling the second logic unit 1302 to turn on, so that the first logic unit 1301 outputs the first logic signal, and the second logic unit 1302 outputs the target logic signal according to the first logic signal. The target logic signal is used to control the switch unit 300 to turn off. After the switch unit 300 is turned off, the voltage-stabilized power supply turns off the voltage output circuit, and the output current drops to 0A.

[0051] When the working current is 0A, the second signal outputted from the cathode of the first three-terminal voltage regulator IC1 starts to rise, thereby controlling the first logic unit 1301 to shut down. After the first logic unit 1301 is shut down, the second logic unit 1302 is also shut down, the switch unit 300 resumes conduction, and the voltage regulator power supply is turned on again.

[0052] like Figure 2 As shown, the first logic unit 1301 includes a first switch tube M1, a third resistor R3, a fourth resistor R4 and a fifth resistor R5. The first end of the third resistor R3 is used to be electrically connected to the positive electrode of the power supply 20. The second end of the third resistor R3 is electrically connected to the first end of the fourth resistor R4 and the cathode of the first three-terminal voltage regulator IC1 respectively. The second end of the fourth resistor R4 is electrically connected to the control end of the first switch tube M1. The first end of the first switch tube M1 is used to be electrically connected to the positive electrode of the power supply 20. The second end of the first switch tube M1 is electrically connected to the second logic unit 1302 and the first end of the fifth resistor R5 respectively. The second end of the fifth resistor R5 is used to be electrically connected to the negative electrode of the power supply 20.

[0053] Specifically, the third resistor R3 is used to supply power to the first three-terminal voltage regulator IC1.

[0054] When the working current is greater than the preset value, that is, when the voltage regulator power supply has an overcurrent or short circuit, the second signal outputted from the cathode of the first three-terminal voltage regulator IC1 begins to decrease, causing the voltage on the control end of the first switch tube M1 to begin to decrease, causing the voltage difference between the first end and the control end of the first switch tube M1 to begin to increase. When the voltage difference is greater than the turn-on voltage of the first switch tube M1 (the PN junction voltage of the PNP-type transistor or the gate threshold voltage of the P-channel field effect transistor), the first switch tube M1 is turned on, causing the first logic signal outputted from the second end of the first switch tube M1 to increase, thereby controlling the second logic unit 1302 to turn on and output a target logic signal. The target logic signal is used to control the switch unit 300 to turn off. After the switch unit 300 is turned off, the voltage regulator power supply turns off the voltage output loop, and the output current drops to 0A.

[0055] When the operating current is 0A, the second signal outputted from the cathode of the first three-terminal voltage regulator IC1 begins to rise, causing the voltage on the control terminal of the first switch tube M1 to begin to rise, so that the voltage difference between the first terminal and the control terminal of the first switch tube M1 begins to decrease. When the voltage difference is less than the on-voltage of the first switch tube M1 (the PN junction voltage of the PNP transistor or the gate threshold voltage of the P-channel field effect transistor), the first switch tube M1 is turned off, thereby controlling the second logic unit 1302 to turn off, the switch unit 300 resumes conduction, and the voltage regulator power supply is restarted.

[0056] Exemplarily, the first switch tube M1 is a P-channel field effect transistor or a PNP transistor.

[0057] When the first switch tube M1 is a P-channel field effect transistor, the control end of the first switch tube M1 is the gate, the first end of the first switch tube M1 is the source, and the second end of the first switch tube M1 is the drain.

[0058] When the first switch tube M1 is a PNP transistor, the control end of the first switch tube M1 is the base, the first end of the first switch tube M1 is the emitter, and the second end of the first switch tube M1 is the collector.

[0059] For example, Figure 5 As shown, the first logic unit 1301 also includes a sixth resistor R6. The first end of the sixth resistor R6 is electrically connected to the control end of the first switch tube M1. The second end of the sixth resistor R6 is electrically connected to the first end of the first switch tube M1. The function of the sixth resistor R6 is to provide a discharge loop (the first switch tube M1 is a P-channel field effect transistor at this time) or a PN junction current bypass (the first switch tube M1 is a PNP type transistor at this time) for the parasitic capacitance between the control end and the first end of the first switch tube M1, so as to ensure the reliable shutdown of the first switch tube M1.

[0060] For example, Figure 5 As shown, the current protection circuit also includes a third capacitor C3. The first end of the third capacitor C3 is electrically connected to the reference end of the first three-terminal voltage regulator IC1. The second end of the third capacitor C3 is electrically connected to the cathode of the first three-terminal voltage regulator IC1. The function of the third capacitor C3 is to resist electromagnetic noise interference and ensure the reliability of the current protection circuit.

[0061] like Figure 2 and Figure 4 As shown, when the switch unit 300 is a P-channel field effect transistor or a PNP transistor, the switch unit 300 is arranged on the line between the positive electrode VI+ of the power supply 20 and the positive electrode VO+ of the load 30 .

[0062] The second logic unit 1302 includes a first diode D1. An anode of the first diode D1 is electrically connected to the first logic unit 1301. A cathode of the first diode D1 is electrically connected to the switch unit 300.

[0063] Specifically, the anode of the first diode D1 is electrically connected to the second end of the first switch tube M1 in the first logic unit 1301 .

[0064] When the working current is greater than the preset value, that is, when the voltage regulator power supply has an overcurrent or short circuit, the second signal outputted from the cathode of the first three-terminal voltage regulator IC1 begins to decrease, causing the voltage on the control end of the first switch tube M1 to begin to decrease, so that the voltage difference between the first end and the control end of the first switch tube M1 begins to increase. When the voltage difference is greater than the turn-on voltage of the first switch tube M1 (the PN junction voltage of the PNP-type transistor or the gate threshold voltage of the P-channel field effect transistor), the first switch tube M1 is turned on, so that the first logic signal outputted from the second end of the first switch tube M1 increases, thereby controlling the first diode D1 to turn on and output a target logic signal. The target logic signal is at a high level and is used to control the switch unit 300 to turn off. After the switch unit 300 is turned off, the voltage regulator power supply turns off the voltage output loop, and the output current drops to 0A.

[0065] When the operating current is 0A, the second signal outputted from the cathode of the first three-terminal voltage regulator IC1 begins to rise, causing the voltage on the control terminal of the first switch tube M1 to begin to rise, so that the voltage difference between the first terminal and the control terminal of the first switch tube M1 begins to decrease. When the voltage difference is less than the turn-on voltage of the first switch tube M1 (the PN junction voltage of the PNP transistor or the gate threshold voltage of the P-channel field effect transistor), the first switch tube M1 is turned off, thereby turning off the first diode D1, and the switch unit 300 resumes conduction, and the voltage regulator power supply is restarted.

[0066] like Figure 3 As shown, when the switch unit 300 is an N-channel field effect transistor or an NPN-type transistor, the switch unit 300 is arranged on the line between the negative electrode VI- of the power supply 20 and the negative electrode VO- of the load 30.

[0067] like Figure 3 As shown, the second logic unit 1302 includes a seventh resistor R7 and a second switch tube M2. The first end of the seventh resistor R7 is electrically connected to the first logic unit 1301. The second end of the seventh resistor R7 is electrically connected to the control end of the second switch tube M2. The first end of the second switch tube M2 is used to be electrically connected to the switch unit 300. The second end of the second switch tube M2 is used to be electrically connected to the negative electrode VI- of the power supply 20.

[0068] Specifically, a first end of the seventh resistor R7 is electrically connected to a second end of the first switch tube M1 in the first logic unit 1301 .

[0069] When the working current is greater than the preset value, that is, when the voltage regulator power supply has an overcurrent or short circuit, the second signal outputted from the cathode of the first three-terminal voltage regulator IC1 begins to decrease, causing the voltage on the control end of the first switch tube M1 to begin to decrease, so that the voltage difference between the first end and the control end of the first switch tube M1 begins to increase. When the voltage difference is greater than the turn-on voltage of the first switch tube M1 (the PN junction voltage of the PNP type transistor or the gate threshold voltage of the P-channel field effect transistor), the first switch tube M1 is turned on, so that the first logic signal outputted from the second end of the first switch tube M1 increases, thereby increasing the voltage on the control end of the second switch tube M2, turning on the second switch tube M2, and the first end of the second switch tube M2 outputs a target logic signal, which is at a low level and is used to control the switch unit 300 to turn off. After the switch unit 300 is turned off, the voltage regulator power supply turns off the voltage output loop, and the output current drops to 0A.

[0070] When the operating current is 0A, the second signal outputted from the cathode of the first three-terminal voltage regulator IC1 starts to rise, causing the voltage on the control terminal of the first switch tube M1 to start to rise, so that the voltage difference between the first terminal and the control terminal of the first switch tube M1 starts to decrease. When the voltage difference is less than the turn-on voltage of the first switch tube M1 (the PN junction voltage of the PNP transistor or the gate threshold voltage of the P-channel field effect transistor), the first switch tube M1 is turned off, thereby turning off the second switch tube M2, and the switch unit 300 resumes conduction, and the voltage regulator power supply is restarted.

[0071] Exemplarily, the second switch tube M2 is an N-channel field effect transistor or an NPN transistor.

[0072] When the second switch tube M2 is an N-channel field effect transistor, the control end of the second switch tube M2 is the gate, the first end of the second switch tube M2 is the drain, and the second end of the second switch tube M2 is the source.

[0073] When the second switch tube M2 is an NPN transistor, the control end of the second switch tube M2 is the base, the first end of the second switch tube M2 is the collector, and the second end of the second switch tube M2 is the emitter.

[0074] For example, Figure 5 As shown, the second logic unit 1302 further includes an eighth resistor R8. A first end of the eighth resistor R8 is electrically connected to the control end of the second switch tube M2. A second end of the eighth resistor R8 is electrically connected to the second end of the second switch tube M2.

[0075] like Figure 6 As shown, the current protection circuit further includes a current protection time locking unit 140. The current protection time locking unit 140 is electrically connected to the reference terminal of the first three-terminal voltage regulator IC1 and the logic unit 130 respectively.

[0076] Specifically, when the operating current is greater than a preset value, the current protection time locking unit 140 is used to lock the current protection circuit in a protection state.

[0077] like Figure 6 As shown, the current protection time locking unit 140 includes a fourth capacitor C4, a second diode D2 and a ninth resistor R9. The first end of the fourth capacitor C4 is electrically connected to the first end of the ninth resistor R9 and the cathode of the second diode D2, respectively. The second end of the ninth resistor R9 is electrically connected to the reference end of the first three-terminal voltage regulator IC1. The second end of the fourth capacitor C4 is electrically connected to the logic unit 130. The anode of the second diode D2 is used to be electrically connected to the cathode VI- of the power supply 20.

[0078] Specifically, the second end of the fourth capacitor C4 is electrically connected to the first end of the fifth resistor R5 in the logic unit 130. The principle of the current protection time locking unit 140 is explained by taking the switch unit 300 as an N-channel field effect transistor or an NPN transistor.

[0079] When the working current is greater than the preset value, the voltage-stabilized power supply has an overcurrent or short circuit. Combined with the above analysis, when the first switch tube M1 is turned on, the fourth capacitor C4 starts to charge, and the charging current flows through the ninth resistor R9 and the eleventh resistor R11, and flows to the first end of the sampling resistor RS1. This charging current generates a voltage drop across the eleventh resistor R11, which in turn causes the first signal VR to rise, so that when the voltage VIS of the voltage-stabilized power supply drops to 0V after overcurrent or short circuit protection, the first signal VR is still greater than the internal reference voltage of the first three-terminal voltage-stabilized tube IC1, so that the current protection circuit is maintained in a protection state.

[0080] When the first switch tube M1 is in the on state, the charging current of the fourth capacitor C4 will gradually decrease. When the charging current drops to 0A, the charging process ends.

[0081] When the charging current of the fourth capacitor C4 starts to decrease, the first signal VR starts to decrease. When the first signal VR is less than the internal reference voltage of the first three-terminal voltage regulator IC1, the second signal output from the cathode of the first three-terminal voltage regulator IC1 increases, and the first switch tube M1 is turned off.

[0082] When the first switch tube M1 is turned off, the fourth capacitor C4 starts to discharge, and the discharge current passes through the high-voltage end of the fourth capacitor C4, the fifth resistor R5 and the second diode D2, and then returns to the low-voltage end of the fourth capacitor C4. When the discharge current of the fourth capacitor C4 begins to decrease, the voltage at the second end of the first switch tube M1 decreases. At this time, the voltage difference between the control end and the second end of the second switch tube M2 begins to decrease. When the voltage difference is less than the conduction voltage of the second switch tube M2 (the threshold voltage of the N-channel field effect transistor or the PN junction voltage of the NPN-type transistor), the second switch tube M2 is turned off. At this time, the current protection circuit exits the protection state, and the voltage-stabilized power supply is turned on again.

[0083] like Figure 7 As shown, the embodiment of the present application also provides a voltage-stabilized power supply, including a first capacitor C1, a second capacitor C2, a first resistor R1, a second resistor R2, a switch unit, a current protection circuit 100, and a voltage feedback circuit 200. The switch unit is a P-channel field effect transistor or a PNP-type transistor, and the switch unit adopts a P-channel field effect transistor, which is represented by Q1.

[0084] The first end of the first capacitor C1 is used to be electrically connected to the positive electrode VI+ of the power supply, the second end of the first capacitor C1 is used to be electrically connected to the negative electrode VI- of the power supply, and the second end of the first capacitor C1 is also electrically connected to the current protection circuit 100. The current protection circuit 100 is used to be electrically connected to the positive electrode VI+ of the power supply and the negative electrode VI- of the power supply. The current protection circuit 100 is also used to be electrically connected to the negative electrode VO+ of the load. The source of the field effect transistor Q1 is used to be electrically connected to the positive electrode VI+ of the power supply, the drain of the field effect transistor Q1 is used to be electrically connected to the positive electrode VO+ of the load, and the gate of the field effect transistor Q1 is electrically connected to the first end of the second resistor R2 and the first end of the first resistor R1 respectively. The second end of the first resistor R1 is electrically connected to the current protection circuit 100. The second end of the second resistor R2 is electrically connected to the voltage feedback circuit 200. The first end of the second capacitor C2 is used to be electrically connected to the positive electrode VO+ of the load, and the second end of the second capacitor C2 is used to be electrically connected to the negative electrode VO- of the load. The voltage feedback circuit 200 is used to be electrically connected to a positive electrode VO+ of the load and a negative electrode VO- of the load.

[0085] Specifically, when the voltage-stabilized power supply is overcurrent or short-circuited, the working current collected by the sampling resistor inside the current protection circuit 100 is greater than the preset value, and the reference voltage unit inside the current protection circuit 100 generates a reference voltage. The collection unit outputs a first signal according to the working current and the reference voltage, so that the cathode of the first three-terminal voltage regulator tube quickly outputs a second signal. Since the first signal increases with the increase of the working current, when the first signal is greater than the internal reference voltage of the first three-terminal voltage regulator tube, the second signal output by the cathode of the first three-terminal voltage regulator tube begins to decrease. The second logic unit in the logic unit uses a first diode, and the logic unit outputs a high-level target logic signal according to the second signal. The high-level target logic signal is transmitted to the gate of the field effect transistor Q1 through the first resistor R1, so that the gate voltage of the field effect transistor Q1 increases, and at this time, the voltage difference between the source and the gate of the field effect transistor Q1 begins to decrease. When this voltage difference is less than the gate threshold voltage of the field effect transistor Q1, the field effect transistor Q1 is turned off. When the field effect transistor Q1 is turned off, the voltage regulator shuts off the voltage output circuit, and the output current drops to 0A, that is, the working current on the power supply line is 0A. This prevents the field effect transistor Q1 from being burned due to a large current flowing through it for a long time, and also avoids potential safety hazards such as smoke and fire.

[0086] When the operating current is 0A and the current protection time locking unit also stops working, the current protection circuit 100 exits the protection state, the voltage feedback circuit 200 controls the field effect transistor Q1 to resume conduction, and the regulated power supply is restarted.

[0087] like Figure 8 As shown, the embodiment of the present application also provides a voltage-stabilized power supply, including a first capacitor C1, a second capacitor C2, a first resistor R1, a second resistor R2, a switch unit, a current protection circuit 100, and a voltage feedback circuit 200. The switch unit is an N-channel field effect transistor or an NPN-type transistor, and the switch unit adopts an N-channel field effect transistor, which is represented by Q1.

[0088] The first end of the first capacitor C1 is used to be electrically connected to the positive electrode VI+ of the power supply, the second end of the first capacitor C1 is used to be electrically connected to the negative electrode VI- of the power supply, and the second end of the first capacitor C1 is also electrically connected to the current protection circuit 100. The current protection circuit 100 is used to be electrically connected to the positive electrode V1+ and the negative electrode V1- of the first power supply, and the negative electrode V1- of the first power supply is electrically connected to the negative electrode VI- of the power supply, and the first power supply is an auxiliary power supply. The current protection circuit 100 is electrically connected to the source of the field effect transistor Q1. The drain of the field effect transistor Q1 is used to be electrically connected to the negative electrode VO- of the load, and the gate of the field effect transistor Q1 is electrically connected to the first end of the second resistor R2 and the first end of the first resistor R1 respectively. The second end of the first resistor R1 is electrically connected to the current protection circuit 100. The second end of the second resistor R2 is electrically connected to the voltage feedback circuit 200. The first end of the second capacitor C2 is used to be electrically connected to the positive electrode VO+ of the load, and the second end of the second capacitor C2 is used to be electrically connected to the negative electrode VO- of the load. The voltage feedback circuit 200 is used to be electrically connected to a positive electrode VO+ of the load, a negative electrode VO− of the load, a positive electrode V1+ of the first power source, and a negative electrode V1− of the first power source.

[0089] Specifically, when the voltage-stabilized power supply has an overcurrent or short circuit, the working current collected by the sampling resistor inside the current protection circuit 100 is greater than the preset value, and the reference voltage unit inside the current protection circuit 100 generates a reference voltage. The collection unit outputs a first signal according to the working current and the reference voltage, so that the cathode of the first three-terminal voltage-stabilizing tube quickly outputs a second signal. Since the first signal increases with the increase of the working current, when the first signal is greater than the internal reference voltage of the first three-terminal voltage-stabilizing tube, the second signal output by the cathode of the first three-terminal voltage-stabilizing tube begins to decrease. The second logic unit in the logic unit uses a second switch tube. The logic unit outputs a low-level target logic signal according to the second signal, and the gate of the field effect transistor Q1 begins to discharge through the first resistor R1, so that the gate voltage of the field effect transistor Q1 decreases. At this time, the voltage difference between the source and the gate of the field effect transistor Q1 begins to decrease. When this voltage difference is less than the gate threshold voltage of the field effect transistor Q1, the field effect transistor Q1 is turned off. When the field effect transistor Q1 is turned off, the voltage-stabilized power supply turns off the voltage output loop, and the output current drops to 0A, that is, the working current is 0A. This is to prevent the field effect transistor Q1 from being burned due to a large current flowing through it for a long time, and to avoid safety hazards such as smoke and fire.

[0090] When the operating current is 0A and the current protection time locking unit also stops working, the current protection circuit 100 exits the protection state, the voltage feedback circuit 200 controls the field effect transistor Q1 to resume conduction, and the regulated power supply is restarted.

[0091] Fig. 9The working waveform diagram of the voltage-stabilized power supply provided in the embodiment of the present application, V in the figure is the voltage axis, A is the current axis, and t is the time axis. I_Q1_s is the DS pole current of the field effect transistor Q1 when the voltage-stabilized power supply is short-circuited. U(VO+, VO-) is the output voltage of the voltage-stabilized power supply. T_s is the duration from the short circuit of the voltage-stabilized power supply to the shutdown of the voltage-stabilized power supply. W1: Schematic diagram of the output voltage waveform when a short circuit occurs at the output end of the voltage-stabilized power supply. W2: Schematic diagram of the short-circuit current waveform at the output end of the voltage-stabilized power supply using a universal integrated comparator. W3: Schematic diagram of the short-circuit current waveform at the output end of the voltage-stabilized power supply provided in the embodiment of the present application. Time period 0-t1: The voltage-stabilized power supply works normally. Time period t1-t2: A short circuit occurs at the output end of the voltage-stabilized power supply. After time period t2: The voltage-stabilized power supply works normally.

[0092] from Fig. 9 It can be seen that compared with the voltage-stabilized power supply using a general-purpose integrated comparator, the voltage-stabilized power supply provided in the embodiment of the present application can shut down the field effect transistor Q1 in a shorter time when an overcurrent or short circuit occurs, thereby preventing the large current from flowing through the field effect transistor Q1 for too long, causing the junction temperature of the field effect transistor Q1 to be too high and fail, resulting in safety hazards such as smoke and fire.

[0093] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0094] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A current protection circuit, characterized in that: It includes a reference voltage unit, a collection unit, a logic unit and a first three-terminal voltage regulator; the collection unit is arranged on the power supply line between the power supply and the load, the reference voltage unit and the reference end of the first three-terminal voltage regulator are respectively electrically connected to the collection unit, the anode of the first three-terminal voltage regulator is used to be electrically connected to the negative electrode of the power supply, the cathode of the first three-terminal voltage regulator is electrically connected to the logic unit, and the logic unit is respectively used to be electrically connected to the switch unit in the voltage regulator and the power supply; The reference voltage unit is used to provide a reference voltage; The acquisition unit is used to collect the working current on the power supply line; when the working current is greater than a preset value, the acquisition unit is used to output a first signal according to the working current and the reference voltage, so that the cathode of the first three-terminal voltage regulator tube outputs a second signal; the logic unit is used to output a target logic signal according to the second signal, and the target logic signal is used to control the switch unit to turn off; The acquisition unit includes a tenth resistor, an eleventh resistor and a sampling resistor; The first end of the tenth resistor is electrically connected to the reference voltage unit, the second end of the tenth resistor is electrically connected to the first end of the eleventh resistor and the reference end of the first three-terminal voltage regulator, the second end of the eleventh resistor is electrically connected to the first end of the sampling resistor, the first end of the sampling resistor is used to be electrically connected to the negative electrode of the load, and the second end of the sampling resistor is used to be electrically connected to the negative electrode of the power supply; The logic unit includes a first logic unit and a second logic unit; the first logic unit is electrically connected to the cathode of the first three-terminal voltage regulator and the second logic unit respectively, the first logic unit is used to be electrically connected to the power supply, and the second logic unit is used to be electrically connected to the switch unit; The first logic unit is used to output a first logic signal according to the second signal; the second logic unit is used to output a target logic signal according to the first logic signal; The first logic unit includes a first switch tube, a third resistor, a fourth resistor and a fifth resistor; The first end of the third resistor is used to be electrically connected to the positive electrode of the power supply, the second end of the third resistor is electrically connected to the first end of the fourth resistor and the cathode of the first three-terminal voltage regulator tube respectively, the second end of the fourth resistor is electrically connected to the control end of the first switch tube, the first end of the first switch tube is used to be electrically connected to the positive electrode of the power supply, the second end of the first switch tube is electrically connected to the second logic unit and the first end of the fifth resistor respectively, and the second end of the fifth resistor is used to be electrically connected to the negative electrode of the power supply; The second logic unit includes a seventh resistor and a second switch tube; the first end of the seventh resistor is electrically connected to the first logic unit, the second end of the seventh resistor is electrically connected to the control end of the second switch tube, the first end of the second switch tube is used to be electrically connected to the switch unit, and the second end of the second switch tube is used to be electrically connected to the negative electrode of the power supply; The current protection circuit also includes a current protection time locking unit; The current protection time locking unit is electrically connected to the reference end of the first three-terminal voltage regulator tube and the logic unit respectively; When the working current is greater than a preset value, the current protection time locking unit is used to lock the current protection circuit in a protection state; The reference voltage unit includes a second three-terminal voltage regulator and a twelfth resistor; the first end of the twelfth resistor is used to be electrically connected to the positive electrode of the first power supply, the second end of the twelfth resistor is respectively electrically connected to the cathode of the second three-terminal voltage regulator, the reference end of the second three-terminal voltage regulator and the acquisition unit, the anode of the second three-terminal voltage regulator is used to be electrically connected to the negative electrode of the first power supply, and the negative electrode of the first power supply is electrically connected to the negative electrode of the power supply.

2. The current protection circuit according to claim 1, characterized in that: The second logic unit includes a first diode; an anode of the first diode is electrically connected to the first logic unit, and a cathode of the first diode is electrically connected to the switch unit.

3. The current protection circuit according to claim 1, characterized in that: The current protection time locking unit includes a fourth capacitor, a second diode and a ninth resistor; the first end of the fourth capacitor is electrically connected to the first end of the ninth resistor and the negative electrode of the second diode, the second end of the ninth resistor is electrically connected to the reference end of the first three-terminal voltage regulator, the second end of the fourth capacitor is electrically connected to the logic unit, and the positive electrode of the second diode is used to be electrically connected to the negative electrode of the power supply.

4. A voltage-stabilized power supply, characterized in that: The invention comprises the current protection circuit as described in any one of claims 1 to 3.

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