A protection circuit for a power supply and a power supply

Abstract

The application relates to a protection circuit and a power supply. The protection circuit comprises a detection module, an input end of the detection module being used for acquiring a fault signal of the power supply, and an output end of the detection module; a response module, at least one first switch device being used for controlling the turn-off of a slow-start switch tube, and a control end of the first switch device being connected to the output end of the detection module. The application adopts the detection module to detect the fault signal of the power supply; the response module is used for receiving the fault signal and outputting an action signal according to the fault signal, so as to control the turn-off of the slow-start switch tube of the power supply. The slow-start switch tube can be turned off quickly when a fault occurs, and the stress requirement of the slow-start switch tube is effectively reduced.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to, but are not limited to, the technical field of power supply, and particularly relate to a protection circuit for a power supply. BACKGROUND

[0002] In the design of a power supply circuit, in order to limit the impact current, a slow start circuit, which can also be called a soft start circuit, is usually designed in the input loop. There are four common forms of implementation of the slow start circuit: one is to use a resistor for slow start, two is to use a MOS (Metal Oxide Semiconductor) tube for slow start, three is to use a resistor and a relay for slow start, and four is to use a resistor and a switch tube (such as a MOS tube) for slow start.

[0003] In the structure of the existing slow start circuit using a resistor and a switch tube for slow start, when a short circuit occurs between the power supply bus, whether the input loop can be quickly turned off and whether the parallel switch tubes can be protected from being damaged by the rapidly rising large current are the keys to ensuring whether the protection can be achieved. Otherwise, the long-time large current can cause the power supply to smoke and catch fire, causing a safety accident. In particular, the larger the power is and the more the parallel switch tubes are, the more serious the situation is. Normally, to turn off the switch tube (such as a MOS tube) in the on state, the drive voltage (such as the gate-source voltage Vgs) thereof needs to be reduced to below the threshold for turning on. Therefore, the time when the switch is turned off and the time required for turning off determine the timeliness of the protection and the stress requirement on the switch tube device.

[0004] At present, the conventional method is: on the one hand, a single-chip microcomputer is used to run control software, and when a fault is detected, an instruction is output to turn off the drive voltage of the switch tube; on the other hand, a switch tube with strong impact resistance is selected. However, on the one hand, the single-chip microcomputer is used to run control software, and from the detection of a signal to the judgment of the software to the completion of the switching action of the switch tube, a long time is consumed; and once a short circuit occurs between the power supply bus, the current will sharply rise in a short time, which can still cause the power supply to smoke and catch fire, causing a safety accident. On the other hand, since the current will sharply rise in a short time when a fault occurs, even if a switch tube with large size and strong impact resistance is selected, the safety hazard of the power supply bus smoking and catching fire when an abnormal short circuit occurs cannot be fundamentally eliminated. SUMMARY

[0005] Embodiments of the present application provide a protection circuit for a power supply and a power supply, which can quickly turn off the slow start switch tube when a fault occurs and effectively reduce the stress requirement on the slow start switch tube.

[0006] In a first aspect, embodiments of the present application provide a protection circuit for a power supply, the power supply comprising a power supply bus and a slow start switch tube, and characterized in that the protection circuit comprises:

[0007] The detection module includes a detection input terminal and a detection output terminal, wherein the detection input terminal is electrically connected to the power bus.

[0008] The response module includes at least one first switching device for controlling the turn-off of the soft-start switch transistor, wherein the control terminal of the first switching device is connected to the detection output terminal.

[0009] Secondly, embodiments of this application provide a power supply, including:

[0010] Power input terminal;

[0011] A power bus, which is connected to the power input terminal;

[0012] Power output terminal;

[0013] A soft-start circuit is provided at the power bus for soft-starting the power supply; the soft-start circuit includes a soft-start resistor and a soft-start switch connected in parallel.

[0014] A protection circuit for a power supply as described in the first aspect.

[0015] This application embodiment includes: using a detection module to detect a fault signal of the power supply; using a response module to receive the fault signal and output an action signal based on the fault signal to control the slow-start switch of the power supply to turn off. This achieves rapid shutdown of the slow-start switch when a fault occurs and effectively reduces the stress requirements on the slow-start switch.

[0016] Other features and advantages of this application will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures particularly pointed out in the description, claims and drawings. Attached Figure Description

[0017] The accompanying drawings are used to provide a further understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0018] Figure 1a , 1b 1c and 1d are schematic diagrams of four commonly used soft-start circuit implementation forms;

[0019] Figure 2 This is a schematic diagram showing the location and implementation of a soft-start circuit in a switching power supply in related technologies;

[0020] Figure 3This is a schematic diagram showing the location and implementation of a soft-start circuit structure using a resistor and a MOSFET for soft start in a switching power supply.

[0021] Figure 4 This is a schematic diagram of the protection circuit provided in one embodiment of this application;

[0022] Figure 5 This is a schematic diagram of the location and structure of the protection circuit in the power supply according to an embodiment of this application;

[0023] Figure 6 This is a schematic diagram of the protection circuit provided in another embodiment of this application;

[0024] Figure 7 This is a schematic diagram of the protection circuit provided in another embodiment of this application;

[0025] Figure 8 This is a schematic diagram showing the location and structure of the protection circuit in the power supply according to another embodiment of this application;

[0026] Figure 9 This is a schematic diagram of the protection circuit provided in another embodiment of this application;

[0027] Figure 10 This is a schematic diagram of the structure of a power supply provided in an embodiment of this application;

[0028] Figure 11 This is a schematic diagram of the power supply structure provided in another embodiment of this application;

[0029] Figure 12 This is a schematic diagram comparing the effects before and after the implementation of the embodiments of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. Unless otherwise specified, the embodiments and features described herein can be arbitrarily combined with each other.

[0031] It should be noted that although functional modules are divided in the device schematic diagram and a logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than the module division in the device or the order in the flowchart. The terms "first," "second," etc., in the specification, claims, and the aforementioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0032] In power supply circuit design, to limit inrush current, a soft-start circuit, also known as a soft-start circuit, is usually designed in the input circuit. There are four common implementation methods for soft-start circuits: one is using a resistor for soft-start (see...). Figure 1a Secondly, the MOSFET is used for soft start (refer to...). Figure 1b Thirdly, a resistor plus a relay is used for soft start (refer to...). Figure 1c Fourth, use a resistor and a switching transistor (such as a MOSFET) for soft start (see [reference]). Figure 1d ).For example, Figure 2 The diagram illustrates the location and implementation of the soft-start circuit in the switching power supply; Figure 3 This diagram illustrates the location and implementation of a soft-start circuit structure using a resistor and a MOSFET for soft start in a switching power supply.

[0033] In existing slow-start circuit structures using resistors and switching transistors, the key to ensuring protection effectiveness lies in the ability to quickly shut off the input circuit and prevent damage to the parallel switching transistors from rapidly rising large currents when a short circuit occurs between power buses. Otherwise, prolonged high current may cause the power supply to smoke and catch fire, leading to a safety accident. This is especially true for higher power ratings and more parallel switching transistors. Under normal circumstances, to turn off a switching transistor (such as a MOSFET), its drive voltage (such as the gate-source voltage Vgs) must be reduced below its turn-on threshold. Therefore, the timing of shutdown and the required shutdown time determine the timeliness of the protection and the stress requirements on the switching transistors.

[0034] Currently, the conventional approach is twofold: firstly, using a microcontroller-based control software to output a command to shut down the driving voltage of the switching transistor upon fault detection; and secondly, selecting a switching transistor with high surge resistance. However, the process is lengthy. Firstly, the microcontroller-based control software takes considerable time, from signal detection and software-defined switching command to the transistor's actual switching action. Secondly, a short circuit between power buses can cause a rapid increase in current, potentially leading to smoke and fire, and posing a safety hazard. Thirdly, because the current surges dramatically during a fault, even selecting a large-sized, surge-resistant switching transistor cannot completely eliminate the safety risk of smoke and fire during a short circuit in the power bus.

[0035] For example, the soft-start circuit structure of the switching power supply in related technologies is as follows: Figure 3As shown in the diagram. This circuit structure is typically used in high-power switching power supplies. The soft-start circuit includes multiple soft-start MOSFETs Q1 and soft-start resistors R1. The multiple soft-start MOSFETs Q1 and soft-start resistors R1 are connected in parallel, and the on / off state of each soft-start MOSFET Q1 is controlled by a soft-start MOSFET driver unit (soft-start switch driver circuit). This scheme not only meets the requirements for limiting inrush current but also greatly helps improve power supply efficiency. In this soft-start circuit structure, the soft-start resistor R1 limits the inrush current during power-up. When the voltage of the input bus capacitor on the power bus reaches a certain value, the soft-start MOSFET driver unit outputs a drive command to control the soft-start MOSFET Q1 to conduct; when a fault (such as a short circuit on the power bus) occurs, the soft-start MOSFET driver unit outputs a drive command to turn off the soft-start MOSFET Q1. The soft-start MOSFET driver unit typically uses a microcontroller or discrete components to detect the electrical signals of the power bus or the temperature signals of the soft-start circuit to determine the power supply fault state. From the detection of electrical signals from the power bus or the temperature signal from the soft-start circuit, to the microcontroller's software judgment, to the issuance of the drive command, and then to the completion of the switching action of the soft-start MOSFET Q1, it usually takes tens or hundreds of milliseconds. However, once a short circuit occurs between the power buses during normal operation, the current will rise to hundreds of amperes in a short period of tens to hundreds of nanoseconds. Under such rapid conditions, the microcontroller cannot complete the protection action. The large current of hundreds or even thousands of amperes can easily damage the soft-start MOSFET Q1, causing a short circuit and failing to disconnect the input circuit. The continuous large current will cause the power supply temperature to rise sharply. Therefore, even if a large-sized soft-start MOSFET Q1 with strong impact resistance is selected, it cannot fundamentally solve the safety hazard of smoke and fire when there is an abnormal short circuit inside the power supply.

[0036] Based on this, embodiments of this application provide a protection circuit and a power supply for a power supply. Specifically, addressing the problem that the delayed shutdown of the slow-start switch during a short-circuit fault may cause significant safety hazards, embodiments of this application add a protection circuit to the normal switching of the slow-start switch. This circuit enables the slow-start switch to be shut down as soon as a fault occurs, achieving rapid shutdown of the slow-start switch during a fault and effectively reducing the stress requirements on the slow-start switch.

[0037] It should be noted that in the following embodiments, the power supply can be a switching power supply or other types of power supply (such as a linear power supply); the power supply can be a DC power supply or an AC power supply. The following explanation uses a DC switching power supply as an example. The soft-start circuit uses a soft-start resistor and a soft-start switch transistor for soft-start. The soft-start resistor can be any type of resistor, such as a constant resistor or a thermistor; the soft-start switch transistor can be any type of switch transistor, such as a transistor or a MOSFET. The number of soft-start resistors and soft-start switch transistors can be arbitrarily set according to actual conditions. The following explanation uses an example where the soft-start switch transistor is a MOSFET and the soft-start resistor is a positive temperature coefficient thermistor. The soft-start resistor and soft-start switch transistor can be set on the positive line (positive input line) of the power supply bus, or on the negative line (negative input line), or simultaneously on both the positive and negative lines of the power supply bus (the positive line has a soft-start resistor and a soft-start switch transistor, and the negative line also has a soft-start resistor and a soft-start switch transistor). The following explanation uses an example where the soft-start resistor and soft-start switch transistor are set on the negative line of the power supply bus. Fault signals can be electrical fault signals or over-temperature signals, etc. For example, a detection module can obtain an electrical fault signal by detecting the electrical signal of the power bus; it can also obtain an over-temperature signal by using a temperature sensor to detect the temperature signal of the soft-start switch circuit. The following explanation uses the example of obtaining an electrical fault signal by detecting the electrical signal of the power bus as an example.

[0038] In a first aspect, embodiments of this application provide a protection circuit for a power supply. The protection circuit can be a standalone circuit module or a sub-module integrated into the power supply circuit.

[0039] Example 1A

[0040] Reference Figure 4 The power supply protection circuit in this example includes:

[0041] The detection module includes a detection input terminal and a detection output terminal, wherein the detection input terminal is electrically connected to the power bus.

[0042] The response module includes at least one first switching device for controlling the turn-off of the soft-start switch transistor, wherein the control terminal of the first switching device is connected to the detection output terminal.

[0043] In some examples, the power supply includes a power bus and a soft-start switch. The detection module can be used to detect electrical signals on the power bus. These electrical signals can be voltage signals or current signals, etc.; this embodiment uses a voltage signal as an example for illustration.

[0044] In some examples, refer to Figure 5The detection module of the protection circuit and the slow-start switch drive circuit (such as the slow-start MOS drive unit) of the slow-start switch transistors Q1 to Qn share a common ground (i.e., the protection circuit and the slow-start switch drive circuit have the same reference ground). The output terminal of the first switching device in the response module can be connected to the control terminal of the slow-start switch transistors Q1 to Qn to directly drive the slow-start switch transistors Q1 to Qn, so as to control the slow-start switch transistors Q1 to Qn to turn off when a fault occurs.

[0045] The following is an application example.

[0046] Application Example 1A-1

[0047] Reference Figure 6 In this application example, the detection module includes a first voltage divider resistor R6 and a second voltage divider resistor R7 for voltage signal sampling. The first voltage divider resistor R6 and the second voltage divider resistor R7 are connected in series. One end of the first voltage divider resistor R6 serves as the detection input terminal connected to the positive line of the power supply bus, and one end of the second voltage divider resistor R7 is connected to the negative line of the power supply bus as the reference ground of the protection circuit. The reference ground of the protection circuit is located at the left end of the soft-start resistor R1 (i.e., the network before the soft-start circuit). The connection node of the first voltage divider resistor R6 and the second voltage divider resistor R7 serves as the detection output terminal of the detection module and is connected to the input terminal of the response module.

[0048] In this application example, the detection output terminal of the detection module is connected to the input terminal of the response module. The response module includes at least one first switching device VT1, which receives the electrical signal and outputs an action signal according to the electrical signal to control the turn-off of the power supply's soft-start switching transistors Q1 to Q4. The first switching device VT1 is a hardware-based device for judgment and switching action (not a software-controlled device), such as a transistor, MOSFET, or other devices with switching functions. The number of first switching devices VT1 can be one or more, such as using multiple first switching transistors cascaded together. In this example, the first switching device VT1 is a PMOS transistor, and the gate of the PMOS transistor is connected as the control terminal of the response module to the detection output terminal of the detection module (the connection node of the first voltage divider resistor R6 and the second voltage divider resistor R7). In some examples, the response module also includes a first protection diode D1 and a second protection diode D2. The anode of the first protection diode D1 is connected to the gate of the PMOS transistor, and the cathode is connected to the source of the PMOS transistor. The anode of the second protection diode D2 is connected to the base of the PMOS transistor, and the cathode is connected to the detection output terminal of the detection module (the connection node of the first voltage divider resistor R6 and the second voltage divider resistor R7). That is, the base of the PMOS transistor is connected to the detection output terminal of the detection module through the second protection diode D2. The drain of the PMOS transistor is connected to the negative line of the power supply bus as the reference ground of the protection circuit, and the reference ground of the protection circuit is located at the left end of the soft-start resistor R1 (i.e., the network before the soft-start circuit). The source of the PMOS transistor is used to output an action signal to the control terminal of the soft-start switches Q1 to Q4 of the power supply to control the soft-start switches Q1 to Q4 of the power supply to turn off.

[0049] In this application example, when the power supply is operating normally, the voltage signal of the power bus is high when divided by the first voltage divider resistor R6 and the second voltage divider resistor R7. At this time, the voltage difference Vgs between the gate and source of the PMOS transistor is higher than the turn-on threshold voltage, which will cause PMOS transistor VT1 to be turned off. The action signal output by PMOS transistor VT1 is high, and the soft-start switches Q1 to Q4 remain on, and the power supply operates normally. However, after the soft start, if a fault occurs on the power bus (such as a short circuit between the positive and negative lines of the power bus), the voltage value obtained by the first voltage divider resistor R6 and the second voltage divider resistor R7 drops rapidly to a low level. At this time, the voltage difference Vgs between the gate and source of the PMOS transistor is lower than the turn-on threshold voltage, and PMOS transistor VT1 quickly turns on, pulling the voltage at the control terminal of the soft-start switches Q1 to Q4 to a low level, thereby turning off the soft-start switches Q1 to Q4 in a short time. The large current during a fault will cause the resistance of the positive temperature coefficient thermistor R1 to rise rapidly, which will cause the current in the circuit to drop rapidly. The power supply will then enter the hiccup protection mode according to the characteristics of the thermistor.

[0050] Because the soft-start switch turns off quickly, the peak current in the power bus input circuit is limited, and the duration of the high current is extremely short, thus reducing heat generation and effectively controlling the risk of power supply damage, smoke, and fire. Furthermore, the extremely short duration of the high current significantly reduces the electrical and thermal stress requirements on circuit components, allowing for a lower specification requirement for the soft-start switch Q1. This enables the selection of more economical components, reducing costs while simultaneously improving power supply performance.

[0051] In some embodiments, such as Embodiment 1A above, the response module can directly output a control command to drive the soft-start switch to turn off. In other embodiments, such as Embodiment 1B below, the first switching device controls the soft-start switch of the power supply to turn off sequentially through an isolation module and a secondary response module.

[0052] Example 1B

[0053] Reference Figure 7 The protection circuit in this example includes:

[0054] A detection module is used to detect electrical signals of the power bus; the detection module includes a detection input terminal and a detection output terminal, and the detection input terminal is electrically connected to the power bus.

[0055] The response module includes at least one first switching device, the control terminal of which is connected to the detection output terminal; the first switching device is used to receive the electrical signal and output an action signal according to the electrical signal.

[0056] An isolation module is connected between the response module and the secondary response module to achieve signal isolation;

[0057] The secondary response module has its input terminal connected to the output terminal of the response module. The secondary response module is used to control the power supply's soft-start switch Q1 to turn off according to the action signal.

[0058] Reference Figure 8 In some examples, because there is a difference between the reference ground of the detection signal and the reference ground of the drive signal of the soft-start switches Q1 to Qn, that is, when the detection module of the protection circuit and the soft-start switch drive circuit of the soft-start switches Q1 to Qn do not share a common ground, isolation is required. An isolation module can be used to achieve signal isolation between the response module and the secondary response module. The isolation module can be implemented using electronic devices with isolation functions, such as optocoupler U1 or isolation chip U1. The response module controls the soft-start switches of the power supply to turn off sequentially through the isolation module and the secondary response module.

[0059] For details regarding the detection module, please refer to the corresponding description in Example 1A, which will not be repeated here.

[0060] The response module includes at least one first switching device VT1. The first switching device VT1 receives the electrical signal and outputs an action signal based on the electrical signal to control the turn-off of the power supply's soft-start switch Q1. The first switching device VT1 is a hardware-based device for judgment and switching action (not a software-controlled device), such as a transistor, MOSFET, or other devices with switching functions. The number of first switching devices VT1 can be one or more, such as by cascading multiple first switching transistors.

[0061] The secondary response module includes at least one second switching device VT2. The second switching device VT2 is a hardware-based device that implements the judgment and switching action (not a software-controlled device), such as a transistor, MOSFET, or other device with switching functionality. There can be one or more second switching devices VT2, such as multiple second switching transistors cascaded together.

[0062] The following are two application examples.

[0063] Application Example 1B-1

[0064] Reference Figure 9 The protection circuit in this application example can be used in high-power (e.g., 2500W) low-voltage DC power supplies. The soft-start circuit uses a positive temperature coefficient thermistor (soft-start resistor R1) and six soft-start MOSFETs (soft-start switches) connected in parallel. The six MOSFETs are designated as Q1 to Q6, and all are NMOS transistors. In some examples, to quickly turn off the drive of the soft-start MOSFETs, it is generally necessary to extract the gate-source charge of the soft-start MOSFETs with a capacity of several amperes and maintain a low level for a period of time.

[0065] In this application example, the detection module includes a first voltage divider resistor R6 and a second voltage divider resistor R7 for voltage signal sampling. The first voltage divider resistor R6 and the second voltage divider resistor R7 are connected in series. One end of the first voltage divider resistor R6 is connected to the positive line of the power bus, and one end of the second voltage divider resistor R7 is connected to the negative line of the power bus. The connection node of the first voltage divider resistor R6 and the second voltage divider resistor R7 serves as the output terminal of the detection module and is connected to the input terminal of the response module.

[0066] The isolation module is implemented using an optocoupler U1. The optocoupler U1 includes a first input terminal, a second input terminal, a first output terminal, and a second output terminal.

[0067] The response module includes a PNP transistor, the emitter of which is connected to the second input terminal of optocoupler U1. The first input terminal of optocoupler U1 is connected to the first power supply terminal VCC1 via the fifth resistor R5. The collector of the PNP transistor is connected to the reference ground of the detection signal (i.e., the right end of the soft-start resistor R1, hereinafter referred to as the primary reference ground of the protection circuit), and the base is connected to the output terminal of the detection module (the connection node of the first voltage divider resistor R6 and the second voltage divider resistor R7). In some examples, the response module also includes a first protection diode D1 and a second protection diode D2. The anode of the first protection diode D1 is connected to the base of the PNP transistor, and the cathode is connected to the emitter of the PNP transistor. The anode of the second protection diode D2 is connected to the base of the PNP transistor, and the cathode is connected to the output terminal of the detection module. That is, the base of the PNP transistor is connected to the output terminal of the detection module through the second protection diode D2. The collector of the PNP transistor is connected to the negative line of the power supply bus as the primary reference ground of the protection circuit, and the primary reference ground of the protection circuit is located at the right end of the soft-start resistor R1 (i.e., in the network after the soft-start circuit). The emitter of the PNP transistor is used to output the action signal, which is transmitted to the secondary response module through the isolation module.

[0068] The secondary response module employs a second MOSFET as the second switch. This second MOSFET can be a small-signal MOSFET (in this application example, a small-signal NMOS transistor is chosen) to reduce cost. The secondary response module also includes a second power supply terminal VCC2, a third resistor R3, a fourth resistor R4, and a second capacitor C2. The second power supply terminal VCC2 is connected to the first output terminal of optocoupler U1 via the fourth resistor R4, and the second output terminal of optocoupler U1 is connected to the gate of the second MOSFET. The gate of the second MOSFET is connected to the drive signal reference ground of the soft-start switch Q1 (i.e., the left end of the soft-start resistor R1) via a parallel circuit formed by the third resistor R3 and the second capacitor C2. The source of the second MOSFET is connected to the drive signal reference ground of the soft-start switch Q1, and the drain of the second MOSFET is connected to the gates of soft-start MOSFETs Q1 to Q6.

[0069] In this example, when the power supply is operating normally, the voltage signal from the power bus is divided by the first voltage divider resistor R6 and the second voltage divider resistor R7 to obtain a high-level voltage (e.g., higher than the voltage at the first power supply terminal VCC1). This will turn off the PNP transistor VT1, and the action signal output by the PNP transistor VT1 will be high. This will cause the optocoupler U1 to stop working, the second MOSFET VT2 to be in the off state, and the slowly turned-on MOSFETs Q1 to Q6 to maintain the conducting state, allowing the power supply to operate normally. When a fault occurs on the power bus after the soft start-up (such as a short circuit between the positive and negative lines of the power bus), the voltage obtained by the first voltage divider resistor R6 and the second voltage divider resistor R7 quickly drops to a low level (e.g., below the voltage of the first power supply terminal VCC1). The PNP transistor VT1 quickly turns on, followed by the optocoupler U1, and then the second MOSFET VT2 also quickly turns on. This pulls the voltage at the control terminals of the six parallel soft-start MOSFETs Q1 to Q6 to a low level within 1-2 microseconds, thus turning off the six soft-start MOSFETs Q1 to Q6. The large current during the fault will cause the resistance of the positive temperature coefficient thermistor R1 to rise rapidly, resulting in a rapid decrease in the current in the circuit. The power supply will then enter a hiccup protection mode based on the characteristics of the thermistor.

[0070] Because the soft-start switch turns off quickly, the peak current in the power bus input circuit is limited, and the duration of the high current is extremely short, thus reducing heat generation and effectively controlling the risk of power supply damage, smoke, and fire. Furthermore, the extremely short duration of the high current significantly reduces the electrical and thermal stress requirements on circuit components, allowing for a lower specification requirement for the soft-start switch Q1. This enables the selection of more economical components, reducing costs while simultaneously improving power supply performance.

[0071] Application Example 1B-2

[0072] Reference Figure 10 The protection circuit in this application example can be used in medium to high power (e.g., 1500W) low-voltage DC power supplies. The soft-start circuit uses a positive temperature coefficient thermistor (soft-start resistor R1) and four soft-start MOSFETs (soft-start switches) connected in parallel. The four MOSFETs are designated as the first soft-start MOSFET Q1 to the fourth soft-start MOSFET Q4, and all four MOSFETs are NMOS transistors. In some examples, to quickly turn off the drive of the soft-start MOSFETs, it is generally necessary to extract the gate-source charge of the soft-start MOSFETs with a capacity of several amperes and maintain a low level for a period of time.

[0073] Compared to Application Example 1B-1, this application example is applied to a lower-power, low-voltage DC power supply, therefore fewer parallel slow-start MOSFETs are used. The first switching device VT1 is a PMOS transistor, the isolation module uses isolation chip U1, and the second switching device VT2 is an NPN transistor. The parameters of the external third resistor R3 and second capacitor C2 can be adjusted according to the actual situation. The remaining circuit structure of Application Example 1B-2 is similar to that of Application Example 1B-1, see details below. Figure 9 This will not be elaborated upon here. The protection circuit in Application Example 1B-2 can also achieve the purpose of quickly shutting down the slow-start MOSFET when a power bus fault occurs, thereby protecting the power supply.

[0074] Reference Figure 12 This illustrates the input circuit current I before and after the power supply adopts the embodiment of the present invention, during a fault. in Size and duration of action. Before adding the protection circuit (without the protection circuit), during a fault, the slow-start MOS drive unit was used to detect and the slow-start MOS transistor was turned off using software. The peak current of the input loop current curve L1 reached 800A, the peak current was high, and the current action time T1 was relatively long, making the power supply prone to damage. After adding the protection circuit (with the protection circuit), this embodiment of the invention uses hardware to detect the electrical signal of the power bus after the slow-start position and then directly drives the slow-start MOS transistor to turn off. The peak current of the input loop current curve L2 is about 300A, the peak current is significantly reduced, and the current action time T2 is shortened, improving the reliability of the power supply. Therefore, by using this embodiment of the invention, it is possible to quickly turn off the slow-start switch Q1 when a fault occurs and effectively reduce the stress requirements on the slow-start switch Q1.

[0075] Secondly, embodiments of this application provide a power supply including the protection circuit described in the first aspect. The power supply can be a switching power supply or other types of power supplies (such as a linear power supply); it can be a DC power supply or an AC power supply. The following description uses a DC power supply as an example only.

[0076] Example 2

[0077] Reference Figure 5 or Figure 8 or Figure 11 The power supply in this example includes:

[0078] Power input terminal;

[0079] A power bus, which is connected to the power input terminal;

[0080] Power output terminal;

[0081] A soft-start circuit is provided at the power bus for soft-starting the power supply; the soft-start circuit includes a soft-start resistor and a soft-start switch connected in parallel.

[0082] As in Example 1A or Example 1B, there is a protection circuit for a power supply.

[0083] In some examples, the power input terminal is used to connect to an external power supply; the power bus includes a positive line and a negative line, with an input bus capacitor C1 placed between the positive and negative lines. The detection module of the protection circuit can monitor the power supply's operating status by detecting the voltage signal (electrical signal) across the input bus capacitor C1. Obviously, the electrical signal can also be a current signal, a power signal, impedance, etc.

[0084] In some examples, the power supply is a switching power supply, which also includes a power conversion module connected between the power supply input and output terminals. The power conversion module can be implemented using common power conversion circuits, generally including a circuit that converts DC voltage to pulse voltage, or a circuit that converts DC voltage to pulse voltage and then to DC output voltage.

[0085] In some examples, the soft-start circuit includes a soft-start MOS driver unit, a soft-start resistor R1, and a soft-start switch Q1. The soft-start MOS driver unit detects the power supply's operating state by sensing the voltage signal of the power bus and outputs control commands to drive the soft-start switch Q1, thereby controlling the switching state of Q1. The soft-start MOS driver unit can be implemented using a microcontroller or other processor through software processing, or it can be implemented purely in hardware using discrete components. The soft-start resistor R1 and the soft-start switch Q1 can be located on the positive line (positive input line) of the power bus, or on the negative line (negative input line), or simultaneously on both lines (with the soft-start resistor R1 and the soft-start switch Q1 on both lines). Figure 5 or Figure 8 or Figure 11 This diagram illustrates a power circuit structure where the slow-start resistor R1 and the slow-start switch Q1 are located on the negative line of the power bus. Figure 5 This illustrates a power circuit structure in which the protection circuit is placed before the soft-start circuit, and the detection module of the protection circuit and the soft-start switch drive circuit of the soft-start switch transistor share a common ground (i.e., the detection module of the protection circuit and the soft-start switch drive circuit have the same reference ground). Figure 8 or Figure 11This diagram illustrates a power supply circuit structure where the protection circuit is positioned after the soft-start circuit, and the detection module of the protection circuit and the soft-start switch drive circuit of the soft-start switch transistor are not grounded. The soft-start resistor R1 can be any type of resistor, such as a constant resistor or a thermistor; the soft-start switch transistor Q1 can be any type of switching transistor, such as a transistor or a MOSFET. The number of soft-start resistors R1 and soft-start switch transistors Q1 can be arbitrarily set according to actual needs. Figure 11 The diagram illustrates the circuit structure of a soft-start circuit, which includes a soft-start resistor R1 and a soft-start switch Q1. The soft-start resistor R1 and the soft-start switch Q1 are connected in parallel. This circuit structure is generally suitable for power supplies with lower power. Figure 8 The diagram illustrates a soft-start circuit consisting of a soft-start resistor R1 and multiple soft-start switches Q1 to Qn. The soft-start resistor R1 and the multiple soft-start switches Q1 are connected in parallel. This circuit structure is generally suitable for power supplies with higher power.

[0086] The power supply using this embodiment can achieve the goal of turning off the slow-start switch Q1 in microseconds when a fault (such as a short circuit) occurs, thereby limiting the magnitude and duration of the current in the input circuit after the fault occurs, and effectively controlling the risk of power supply damage, smoke, and fire. In addition, it can effectively reduce the electrical and thermal stress requirements on the slow-start switch Q1, allowing for the selection of a more economical slow-start switch Q1, reducing costs while improving power supply performance.

[0087] Reference Figure 12 This illustrates the input circuit current I before and after the power supply adopts the embodiment of the present invention, during a fault. in Size and duration of action. Before adding the protection circuit (without the protection circuit), during a fault, the slow-start MOS drive unit was used to detect and the slow-start MOS transistor was turned off using software. The peak current of the input loop current curve L1 reached 800A, the peak current was high, and the current action time T1 was relatively long, making the power supply prone to damage. After adding the protection circuit (with the protection circuit), this embodiment of the invention uses hardware to detect the electrical signal of the power bus after the slow-start position and then directly drives the slow-start MOS transistor to turn off. The peak current of the input loop current curve L2 is about 300A, the peak current is significantly reduced, and the current action time T2 is shortened, improving the reliability of the power supply. Therefore, by using this embodiment of the invention, it is possible to quickly turn off the slow-start switch Q1 when a fault occurs and effectively reduce the stress requirements on the slow-start switch Q1.

[0088] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0089] It will be understood by those skilled in the art that all or some of the steps and systems in the methods disclosed above can be implemented as software, firmware, hardware, and suitable combinations thereof. Some or all of the physical components can be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible to a computer. Furthermore, as is known to those skilled in the art, communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

[0090] The above is a detailed description of the preferred embodiments of this application. However, this application is not limited to the above embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of this application. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A protection circuit for a power supply, the power supply including a soft-start switching transistor, characterized in that, The protection circuit includes: The detection module includes a detection input terminal and a detection output terminal, wherein the detection input terminal is used to acquire the fault signal of the power supply; The response module includes at least one first switching device for controlling the turn-off of the soft-start switch transistor, wherein the control terminal of the first switching device is connected to the detection output terminal; The detection module includes a first voltage divider resistor R6 and a second voltage divider resistor R7 for voltage signal sampling. The first voltage divider resistor R6 and the second voltage divider resistor R7 are connected in series. One end of the first voltage divider resistor R6 serves as the detection input terminal connected to the positive line of the power bus, and one end of the second voltage divider resistor R7 is connected to the negative line of the power bus as a protection circuit reference ground. The connection node of the first voltage divider resistor R6 and the second voltage divider resistor R7 serves as the detection output terminal of the detection module. The response module further includes a first protection diode D1 and a second protection diode D2. The anode of the first protection diode D1 is connected to the control terminal of the first switching device, and the cathode of the first protection diode D1 is connected to the input terminal of the first switching device. The anode of the second protection diode D2 is connected to the control terminal of the first switching device, and the cathode of the second protection diode D2 is connected to the detection output terminal. The output terminal of the first switching device is connected to the reference ground of the protection circuit.

2. The circuit according to claim 1, characterized in that, The fault signal is an electrical fault signal or an over-temperature signal.

3. The circuit according to claim 1, characterized in that, The output terminal of the first switching device is connected to the control terminal of the soft-start switching transistor.

4. The circuit according to claim 1, characterized in that, It also includes an isolation module and a secondary response module, wherein the first switching device controls the power supply's soft-start switching transistor to turn off in sequence through the isolation module and the secondary response module.

5. The circuit according to claim 4, characterized in that, The secondary response module includes at least one second switching device. The control terminal of the second switching device is connected to the output terminal of the isolation module, and the input terminal of the isolation module is connected to the output terminal of the first switching device. The output terminal of the second switching device is used to control the soft-start switch to turn off.

6. The circuit according to any one of claims 1 to 5, characterized in that, The first switching device is a transistor or a MOSFET.

7. A power supply, comprising: Power input terminal; A power bus, which is connected to the power input terminal; Power output terminal; A soft-start circuit is provided at the power bus for soft-starting the power supply; the soft-start circuit includes a soft-start resistor and a soft-start switch connected in parallel. A protection circuit for a power supply as described in any one of claims 1 to 6.

8. The power supply according to claim 7, characterized in that, The power supply is a switching power supply, and the switching power supply further includes a power conversion module, which is connected between the power input terminal and the power output terminal.

9. The power supply according to claim 7 or 8, characterized in that, It also includes an input bus capacitor, which is connected between the power supply buses, and the detection input terminal is used to acquire the electrical signal of the input bus capacitor.

10. The power supply according to claim 7 or 8, characterized in that, The soft-start circuit includes: A soft-start resistor and a soft-start switch, wherein the soft-start resistor and the soft-start switch are connected in parallel; or, A soft-start resistor and multiple soft-start switching transistors, wherein the soft-start resistor and multiple soft-start switching transistors are connected in parallel; or, Multiple soft-start resistors and one soft-start switch transistor, wherein the multiple soft-start resistors and one soft-start switch transistor are connected in parallel; or, Multiple soft-start resistors and multiple soft-start switches are connected in parallel.

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