A protection control circuit and switching power supply

Abstract

This invention discloses a protection control circuit and a switching power supply. The protection control circuit includes: first and second switching transistors, a sampling module, and first and second comparison control modules. The first and second switching transistors are connected in series in a first power line. The sampling module is connected in a second power line to acquire first and second voltage signals characterizing the current magnitude in the second power line. The first and second comparison control modules compare the first and second voltage signals with first and second reference voltages, respectively, and then control the first and second switching transistors to turn on and off. The sampling module includes resistors R110 and R111, and a bypass module. Resistors R110 and R111 are connected in series in the second power line, and the bypass module is connected in parallel with resistor R111 to ensure that resistor R111 is only connected to the second power line when the switching power supply is short-circuited. This invention can add dual control functions of overcurrent and short-circuit protection to the switching power supply, limiting the current magnitude during overcurrent and short-circuit protection according to actual application conditions.

Description

Technical Field

[0001] This invention relates to switching power supply technology, and particularly to protection and control under overcurrent and short-circuit conditions when a switching power supply supplies power to a load. Background Technology

[0002] Overcurrent and short-circuit protection are key performance indicators of switching power supplies. Overcurrent protection protects against power supply output current exceeding a set current specification. Short-circuit protection protects against short-circuit faults caused by electrical short circuits within the power supply. Most switching power supplies have both overcurrent and short-circuit protection functions, with different protection methods configured depending on the specific situation. When the switching power supply itself lacks overcurrent protection or the overcurrent protection specification is too high, additional circuitry can be added for overcurrent protection control. Similarly, in the event of a short circuit at the output, if power current limiting is ineffective, additional circuitry can be added for short-circuit protection. Existing technologies have the following main characteristics:

[0003] Currently, commonly used protection circuits employ controllers to limit current for protection. This control method works in conjunction with the current-limiting resistor of the primary MOSFET to control the maximum output power and achieve protection. Traditional protection cannot control the current during protection, especially in cases where very small currents need to be limited. In switching power supply protection, it cannot meet the requirement of limiting small short-circuit currents. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to provide a protection control circuit and a switching power supply that can realize the external overcurrent protection function of the switching power supply while limiting the magnitude of the short-circuit current.

[0005] To achieve the above objectives, as a first aspect of the present invention, the technical solution of the provided protection control circuit embodiment is as follows:

[0006] A protection control circuit is applied to a system where a switching power supply powers a load. The line electrically connecting the output terminal of the switching power supply and the input terminal of the load is a first power line, and the line electrically connecting the output ground of the switching power supply and the input ground of the load is a second power line. The protection control circuit includes:

[0007] The system comprises a first switching transistor, a second switching transistor, a sampling module, a first comparison control module, and a second comparison control module. The first and second switching transistors are connected in series in the first power line. The sampling module is connected in the second power line to acquire a first voltage signal and a second voltage signal representing the magnitude of the current in the second power line. The first comparison control module compares the first voltage signal with a first reference voltage and controls the first switching transistor to turn on when the first voltage signal is less than or equal to the first reference voltage, and controls the first switching transistor to turn off when the first voltage signal is greater than or equal to the first reference voltage. The second comparison control module compares the second voltage signal with a second reference voltage and controls the second switching transistor to turn on when the second voltage signal is less than or equal to the second reference voltage, and controls the second switching transistor to turn off when the second voltage signal is greater than or equal to the second reference voltage.

[0008] The sampling module includes resistor R110, resistor R111, and a bypass module. One end of resistor R110 is connected to the output ground of the switching power supply. The other end of resistor R110 and one end of resistor R111 are connected together as the output terminal of the first voltage signal. The other end of resistor R111 serves as the output terminal of the second voltage signal and is connected to the input ground of the load. The bypass module is connected in parallel with resistor R111 to ensure that resistor R111 is only connected to the second power line when the switching power supply is short-circuited.

[0009] Furthermore, the resistance value of resistor R110 is less than the resistance value of resistor R111.

[0010] Furthermore, the resistors R110 and R111 are adjustable resistors.

[0011] Preferably, the bypass module includes a switching transistor Q501, a resistor R109, and a capacitor C104. One end of the capacitor C104 is connected to the output terminal of the switching power supply, and the other end of the capacitor C104 is connected to both one end of the resistor R109 and the gate of the switching transistor Q501. The other end of the resistor R109 is connected to the input terminal of the load. The source of the switching transistor Q501 is connected to one end of the resistor R111, and the drain of the switching transistor Q501 is connected to the other end of the resistor R111.

[0012] Preferably, the switching transistor Q501 is a MOSFET.

[0013] Preferably, the first switch is a MOSFET Q101.

[0014] Preferably, the first comparison control module includes operational amplifier U1A, operational amplifier U1B, resistors R103 and R104, and switching transistor Q301. The negative input terminal of operational amplifier U1A and the non-inverting input terminal of operational amplifier U1B are connected together to input the first reference voltage. The non-inverting input terminal of operational amplifier U1A and the negative input terminal of operational amplifier U1B are connected together to input the first voltage signal. The output terminal of operational amplifier U1A is connected to one end of resistor R103, the output terminal of operational amplifier U1B is connected to one end of resistor R104, the other end of resistor R104 is connected to the gate of switching transistor Q301, the other end of resistor R103 and the drain of switching transistor Q301 are simultaneously connected to the gate of the first switching transistor, and the source of switching transistor Q301 is used to connect to the output terminal of the switching power supply.

[0015] Preferably, the switching transistor Q301 is a MOSFET.

[0016] Preferably, the second switch is a MOSFET Q201.

[0017] Preferably, the second comparison control module includes operational amplifier U2A, operational amplifier U2B, resistors R106 and R107, and switching transistor Q401. The negative input terminal of operational amplifier U2A and the non-inverting input terminal of operational amplifier U2B are connected together to input the second reference voltage. The non-inverting input terminal of operational amplifier U2A and the negative input terminal of operational amplifier U2B are connected together to input the second voltage signal. The output terminal of operational amplifier U2A is connected to one end of resistor R106, the output terminal of operational amplifier U2B is connected to one end of resistor R107, the other end of resistor R107 is connected to the gate of switching transistor Q401, the other end of resistor R106 and the drain of switching transistor Q401 are simultaneously connected to the gate of the second switching transistor, and the source of switching transistor Q401 is used to connect to the output terminal of the switching power supply.

[0018] Preferably, the switching transistor Q401 is a MOSFET.

[0019] To achieve the above objectives, as a second aspect of the present invention, the technical solution of the provided switching power supply embodiment is as follows:

[0020] A switching power supply, including the protection control circuitry described in any of the first aspects above.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The protection control circuit and switching power supply of the present invention realize overcurrent protection function by sampling the output current of the switching power supply, and the resistance value of the resistor R110 can be designed to limit the size of the overcurrent protection current. It can be used in switching power supplies without overcurrent protection or with a large overcurrent protection point to limit the size of the overcurrent point.

[0023] 2. The protection control circuit and switching power supply of the present invention sample the output current of the switching power supply and simultaneously realize the short circuit protection function. The magnitude of the short circuit current can be adjusted by designing the resistance value of resistor R111, thereby realizing the function of limiting a small short circuit current. It can be used in most constant voltage output switching power supply products.

[0024] 3. The protection control circuit and switching power supply of the present invention can not only provide short-circuit protection for the switching power supply and limit the short-circuit current to a smaller value than the normal load, but also, since the resistor R111 is only connected to the second power line when the system is short-circuited, when the switching power supply has a small short-circuit current design value, the second voltage signal is equal to the first voltage signal because the resistor R111 is bypassed, and the conditions for triggering short-circuit protection are not met, so the startup process is not affected by the false triggering of the short-circuit protection function.

[0025] 4. The protection control circuit of this invention does not use a digital control chip, which reduces the complexity of the circuit and the development cost of the switching power supply, and has advantages in terms of space and cost;

[0026] 5. The protection control circuit and switching power supply of the present invention can protect not only the customer application load end, but also the switching power supply end, without causing stress damage or thermal damage to the components. Attached Figure Description

[0027] Figure 1 This is an application framework diagram of the protection control circuit of the present invention;

[0028] Figure 2 This is a specific circuit diagram of the protection control circuit of the present invention. Detailed Implementation

[0029] To make the technical solution of the present invention clearer, the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention. Those skilled in the art can make other modifications, substitutions, or changes to the present invention without creative effort, and these modifications, substitutions, or changes still fall within the protection scope of the present invention.

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0031] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be used interchangeably where appropriate for the purposes of describing embodiments of this application herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0032] It should be understood that in the specification, claims, and drawings, when a step is described as continuing into another step, the step may directly continue into that other step or be continued into that other step through a third step; when an element / unit is described as "continuing" into another element / unit, the element / unit may be "directly connected" to that other element / unit or "connected" to that other element / unit through a third element / unit.

[0033] Furthermore, the accompanying drawings are merely illustrative of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions thereof will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0034] This invention can add dual control functions of overcurrent and short-circuit protection to a switching power supply, limiting the current magnitude during overcurrent and short-circuit protection according to actual application conditions. Figure 1 This is an application framework diagram of the protection control circuit of the present invention. Figure 2 This is a specific circuit diagram of the protection control circuit of the present invention.

[0035] Please see Figure 1 The protection control circuit of this invention is applied to a system where a switching power supply powers a load. The line electrically connecting the output terminal of the switching power supply and the input terminal of the load is a first power line, and the line electrically connecting the output ground of the switching power supply and the input ground of the load is a second power line. The protection control circuit includes:

[0036] The system comprises a first switching transistor, a second switching transistor, a sampling module, a first comparison control module, and a second comparison control module. The first and second switching transistors are connected in series in a first power line. The sampling module is connected in the second power line to acquire a first voltage signal and a second voltage signal representing the magnitude of the current in the second power line. The first comparison control module compares the first voltage signal with a first reference voltage, and controls the first switching transistor to turn on when the first voltage signal is less than or equal to the first reference voltage, and controls it to turn off when the first voltage signal is greater than or equal to the first reference voltage. The second comparison control module compares the second voltage signal with a second reference voltage, and controls the second switching transistor to turn on when the second voltage signal is less than or equal to the second reference voltage, and controls it to turn off when the second voltage signal is greater than or equal to the second reference voltage. Wherein:

[0037] The sampling module includes resistor R110, resistor R111, and a bypass module. One end of resistor R110 is used to connect to the output ground of the switching power supply. The other end of resistor R110 and one end of resistor R111 are connected together as the output terminal of the first voltage signal. The other end of resistor R111 is used as the output terminal of the second voltage signal and is connected to the input ground of the load. The bypass module is connected in parallel with resistor R111 to ensure that resistor R111 is only connected to the second power line when the switching power supply is short-circuited.

[0038] The formula for calculating the first voltage signal V1 is V1 = Io * R110, where Io is the output current of the switching power supply and R110 is the resistance of the sampling resistor R110. When resistor R111 is connected to the second power line, the formula for calculating the second voltage signal V2 is V2 = Io * (R110 + R111), where R111 is the resistance of the sampling resistor R110. When resistor R111 is not connected to the second power line, the voltage drop across the bypass circuit is ignored, and the second voltage signal V2 is equal to the first voltage signal V1.

[0039] In this configuration, the first and second switching transistors are connected in series. Figure 1 The positions of the transistors can be interchanged. When the first transistor is turned off, it provides overcurrent protection for the switching power supply. At this time, it is not required whether the second transistor is turned off. Similarly, when the second transistor is turned off, it provides short-circuit protection for the switching power supply. At this time, it is not required whether the first transistor is turned off.

[0040] The bypass module is used to ensure that resistor R111 is connected to the second power line only when the switching power supply is short-circuited, that is, resistor R111 is not connected to the second power line when the switching power supply is working normally or during overcurrent.

[0041] The first reference voltage and the resistance value of resistor R110 are related to the desired overcurrent protection point, while the second reference voltage, the resistance values ​​of resistor R110 and resistor R111 are related to the desired short-circuit protection point. The first reference voltage and the first reference can be the same or different. Those skilled in the art can make reasonable configurations by combining the resistance values ​​of resistor R110 and resistor R111, the first reference voltage and the second reference voltage.

[0042] The overcurrent protection point means that when the output current of the switching power supply reaches a multiple of the rated current setting (e.g., 1.5 times), the first switching transistor is controlled to turn off; the short circuit protection point means that when the output current of the switching power supply reaches a multiple of the rated current setting (e.g., 3 times), the second switching transistor is controlled to turn off.

[0043] Figure 1 The protection control circuit samples the output current of the switching power supply, thus achieving both overcurrent and short-circuit protection. Resistor R111 is only connected to the second power line when the system supplying the load is short-circuited. This ensures that even when the switching power supply is designed with a small short-circuit current (when the output current reaches this value, the second switch is turned off, triggering short-circuit protection), the startup process is unaffected by false triggering of the short-circuit protection function. This is because when the switching power supply starts up, resistor R111 is bypassed and not connected to the second power line; the second voltage signal equals the first voltage signal, failing to meet the conditions for triggering short-circuit protection.

[0044] Preferably, the resistance of resistor R110 is less than that of resistor R111, thereby reducing the power consumption of the sampling module when the switching power supply is working normally, and better limiting the current flowing through the switching power supply when short-circuited.

[0045] Furthermore, resistors R110 and R111 are adjustable resistors, allowing the overcurrent protection current and short-circuit protection current to be adjusted as needed. In this embodiment of the invention, the protection control circuit controls the two protection functions independently, allowing for the setting of a larger overcurrent current while limiting a smaller short-circuit current. For example, if the switching power supply normally carries a 10A load, the overcurrent protection current can be set to 12A, while the short-circuit current can be limited to a smaller 1A.

[0046] Please see Figure 2 Preferably, the bypass module includes a switching transistor Q501, a resistor R109, and a capacitor C104. One end of the capacitor C104 is used to connect to the output terminal of the switching power supply, and the other end of the capacitor C104 is connected to both one end of the resistor R109 and the gate of the switching transistor Q501. The other end of the resistor R109 is used to connect to the input terminal of the load. The source of the switching transistor Q501 is connected to one end of the resistor R111, and the drain of the switching transistor Q501 is connected to the other end of the resistor R111.

[0047] Please see Figure 2 Preferably, the switching transistor Q501 is a MOSFET.

[0048] Please see Figure 2 Preferably, the first switching transistor is a MOSFET Q101.

[0049] Please see Figure 2 Preferably, the first comparison control module includes operational amplifier U1A, operational amplifier U1B, resistors R103 and R104, and switching transistor Q301. The negative input terminal of operational amplifier U1A and the non-inverting input terminal of operational amplifier U1B are connected together to input a first reference voltage. The non-inverting input terminal of operational amplifier U1A and the negative input terminal of operational amplifier U1B are connected together to input a first voltage signal. The output terminal of operational amplifier U1A is connected to one end of resistor R103, the output terminal of operational amplifier U1B is connected to one end of resistor R104, the other end of resistor R104 is connected to the gate of switching transistor Q301, the other end of resistor R103 and the drain of switching transistor Q301 are simultaneously connected to the gate of the first switching transistor Q101, and the source of switching transistor Q301 is used to connect to the output terminal of the switching power supply.

[0050] Please see Figure 2 Preferably, the switching transistor Q301 is a MOSFET.

[0051] Please see Figure 2 Preferably, the second switch is a MOSFET Q201.

[0052] Please see Figure 2 Preferably, the second comparison control module includes operational amplifier U2A, operational amplifier U2B, resistors R106 and R107, and switching transistor Q401. The negative input terminal of operational amplifier U2A and the non-inverting input terminal of operational amplifier U2B are connected together to input a second reference voltage. The non-inverting input terminal of operational amplifier U2A and the negative input terminal of operational amplifier U2B are connected together to input a second voltage signal. The output terminal of operational amplifier U2A is connected to one end of resistor R106, the output terminal of operational amplifier U2B is connected to one end of resistor R107, the other end of resistor R107 is connected to the gate of switching transistor Q401, the other end of resistor R106 and the drain of switching transistor Q401 are simultaneously connected to the gate of a second switching transistor Q201, and the source of switching transistor Q401 is used to connect to the output terminal of the switching power supply.

[0053] Please see Figure 2 Preferably, the switching transistor Q401 is a MOSFET.

[0054] It should be noted that operational amplifiers U1A, U1B, U2A, and U2B are active devices and require a power supply voltage. The circuit for obtaining the power supply voltage is a conventional circuit, and those skilled in the art can also choose how to design it. Since these conventional unit circuits are not the innovation of this invention, and those skilled in the art can derive them without creative effort, the lack of a specific implementation circuit does not affect the implementation of this invention.

[0055] Figure 2 The turn-on conditions for switching transistors Q101 and Q201 are: VGS (gate-source voltage) is negative, meaning VS (source voltage) is higher than VG (gate voltage), and VSD (source-gate voltage) is forward-biased. The turn-on condition for switching transistor Q501 is: VGS (gate-source voltage) is positive, meaning VG (gate voltage) is higher than VS (source voltage), and VDS (gate-source voltage) is forward-biased. The following section compares... Figure 2 The working principle is analyzed as follows, including the following four working conditions:

[0056] (1) Starting the switching power supply

[0057] When the switching power supply starts up, switching transistors Q101 and Q201 are not yet turned on. The output terminal VIN+ of the switching power supply charges capacitor C104, providing the operating voltage between the gate and source of switching transistor Q501. Switch Q501 turns on, and resistor R111 is bypassed and not connected to the second power line. Therefore, the first voltage signal generated at the other end of resistor R110 is equal to the second voltage signal generated at the other end of resistor R111. During this stage, even if the short-circuit current design value of the switching power supply is small, the short-circuit protection function will not be falsely triggered during startup. For example, if the short-circuit current design value of the switching power supply is 0.5A, the actual output current of the switching power supply may rise to 10A. Figure 2 When the circuit is powered on, resistor R111 is not bypassed. When the output current of the switching power supply reaches 0.5A, the voltage across the other end of resistor R111 changes from the voltage drop across resistor R110 to the sum of the voltage drops across resistor R110 and resistor R111. The switching power supply will then trigger its short-circuit protection function. (This is the implementation details.) Figure 2 When the circuit is started, after resistor R111 is bypassed, the voltage at the other end of resistor R111 is only the voltage drop across resistor R110, which does not meet the conditions for the switching power supply to trigger the short circuit protection function. Therefore, even if the switching power supply is designed to have a small short circuit current design value, the short circuit protection function will not be falsely triggered when the switching power supply is started. The principle of short circuit protection triggering will be explained in detail in the fourth working condition below.

[0058] (2) The system in which the switching power supply powers the load is operating normally.

[0059] After the switching power supply starts up and enters the normal working state, the switching transistor Q501 remains on and the resistor R111 continues to be bypassed, so the first voltage signal generated at the other end of the resistor R110 is equal to the second voltage signal generated at the other end of the resistor R111.

[0060] By setting the first reference voltage and the value of resistor R110, the first voltage signal at the non-inverting input of operational amplifier U1A can be made less than or equal to the first reference voltage at the inverting input. The output of operational amplifier U1A is low, and this low level is output to the gate of switching transistor Q101 through resistor R103. The source of switching transistor Q101 is connected to the output of the switching power supply and is always high. At this time, the source level of switching transistor Q101 is higher than the gate level, VGS (gate-source voltage) is negative, and switching transistor Q101 is turned on. Simultaneously, the first voltage signal at the inverting input of operational amplifier U1B is less than or equal to the reference voltage at the non-inverting input, and the output of operational amplifier U1B is high. This high level is output to the gate of switching transistor Q301 through resistor R104. At this time, both the gate and source of switching transistor Q301 are high, and the turn-on voltage cannot be reached; therefore, switching transistor Q301 is in the off state and does not conduct.

[0061] Similarly, switch Q201 is turned on, while switch Q401 is not turned on;

[0062] In summary, under this operating condition, the first comparison control module controls the first switching transistor to turn on, the second comparison control module controls the second power transistor to turn on, and the first power line to turn on.

[0063] (3) An overcurrent abnormality occurs in the system where the switching power supply powers the load.

[0064] Switch Q501 remains on, and resistor R111 is bypassed. Therefore, the first voltage signal generated at the other end of resistor R110 and the second voltage signal generated at the other end of resistor R111 are equal. However, according to the formula V1 = Io * R110, the first and second voltage signals will increase. Consequently, the first voltage signal at the non-inverting input of operational amplifier U1A is greater than the reference voltage at the inverting input, resulting in a high output level for operational amplifier U1A. This high level is then output to the gate of switch Q101 through resistor R103. The voltage at the inverting input of operational amplifier U1B is greater than the voltage at the non-inverting input. The voltage at the terminal of the operational amplifier U1B is low, and the low level is output to the gate of the switching transistor Q301 through the resistor R104. The source of the switching transistor Q301 is connected to the output of the switching power supply and is always high. The source level of the switching transistor Q301 is higher than the gate level, and VGS (gate-source voltage) is negative, so the switching transistor Q301 is turned on. The voltage at the source of the switching transistor Q301 is equal to the voltage at the gate of the switching transistor Q101, both of which are high. The switching transistor Q101 cannot meet the turn-on condition. At this time, the switching transistor Q101 is turned off, realizing the overcurrent protection function.

[0065] Under this operating condition, it is not required whether the switching transistor Q201 is designed to be on.

[0066] (4) A short circuit abnormality occurs in the system where the switching power supply powers the load.

[0067] When the customer's back-end load experiences an abnormal short circuit, the voltage at the load's input terminal VO+ is pulled to zero by the load's input ground. The gate voltage of the switching transistor Q501 is instantly pulled down to zero, and the switching transistor Q501 is turned off. Resistor R111 is connected to the second power line, and the output current Io of the switching power supply flows from the load's input terminal to the load's input ground, then to resistor R111, and finally to resistor R110. At this time, the second voltage signal V2 = Io * (R110 + R111), so the first voltage signal generated at the other end of resistor R110 is less than the second voltage signal generated at the other end of resistor R111.

[0068] By setting the values ​​of the reference voltage, resistor R110, and resistor R111, the second voltage signal at the non-inverting input of operational amplifier U2A can be made greater than the reference voltage at the inverting input, resulting in a high-level output from operational amplifier U2A. This high-level signal is then output to the gate of switching transistor Q201 via resistor R106. Conversely, the second voltage signal at the inverting input of operational amplifier U2B can be made greater than the reference voltage at the non-inverting input, resulting in a low-level output from operational amplifier U2B via resistor R107. When the voltage is high at the gate of switch Q401 and the source of switch Q401 is connected to the input terminal VIN+, the voltage level at the source of switch Q401 is higher than the voltage level at the gate, and VGS (gate-source voltage) is negative, switch Q401 is turned on. The voltage at the source of switch Q401 is equal to the voltage at the gate of switch Q201, both of which are high. Switch Q201 cannot meet the turn-on condition, so switch Q201 is turned off, the first power line is turned off, and the short-circuit protection function is realized.

[0069] Under this operating condition, it is not required whether the switching transistor Q101 is designed to be on.

[0070] This invention also provides a switching power supply, including any specific implementation of the above-described protection and control circuit. Those skilled in the art will readily understand that, in this case, the output terminal of the switching power supply is directly connected to the input terminal of the load, i.e. Figure 1 At the port where the intermediate node VO+ is located, the output ground of the switching power supply becomes directly connected to the input ground of the load, i.e. Figure 1 The port where the middle node VO is located.

[0071] The above description is only for illustrating the technical solution of the present invention and is not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art can make modifications or substitutions to the specific embodiments of the present invention. Any modifications or substitutions that do not depart from the spirit and scope of the present invention are within the protection scope of the claims of the present invention.

Claims

1. A protection control circuit applied to a system where a switching power supply powers a load, wherein the line electrically connecting the output terminal of the switching power supply and the input terminal of the load is a first power line, and the line electrically connecting the output ground of the switching power supply and the input ground of the load is a second power line, characterized in that, The protection control circuit includes: The system comprises a first switching transistor, a second switching transistor, a sampling module, a first comparison control module, and a second comparison control module. The first and second switching transistors are connected in series in the first power line. The sampling module is connected in the second power line to acquire a first voltage signal and a second voltage signal representing the magnitude of the current in the second power line. The first comparison control module compares the first voltage signal with a first reference voltage and controls the first switching transistor to turn on when the first voltage signal is less than or equal to the first reference voltage, and controls the first switching transistor to turn off when the first voltage signal is greater than or equal to the first reference voltage. The second comparison control module compares the second voltage signal with a second reference voltage and controls the second switching transistor to turn on when the second voltage signal is less than or equal to the second reference voltage, and controls the second switching transistor to turn off when the second voltage signal is greater than or equal to the second reference voltage. The sampling module includes resistor R110, resistor R111, and a bypass module. One end of resistor R110 is connected to the output ground of the switching power supply. The other end of resistor R110 and one end of resistor R111 are connected together as the output terminal of the first voltage signal. The other end of resistor R111 serves as the output terminal of the second voltage signal and is connected to the input ground of the load. The bypass module is connected in parallel with resistor R111 to ensure that resistor R111 is only connected to the second power line when the switching power supply is short-circuited.

2. The protection control circuit according to claim 1, characterized in that: The resistance value of resistor R110 is less than the resistance value of resistor R111.

3. The protection control circuit according to claim 1, characterized in that: The resistors R110 and R111 are adjustable resistors.

4. The protection control circuit according to claim 1, characterized in that: The bypass module includes a switching transistor Q501, a resistor R109, and a capacitor C104. One end of the capacitor C104 is connected to the output terminal of the switching power supply, and the other end of the capacitor C104 is connected to both one end of the resistor R109 and the gate of the switching transistor Q501. The other end of the resistor R109 is connected to the input terminal of the load. The source of the switching transistor Q501 is connected to one end of the resistor R111, and the drain of the switching transistor Q501 is connected to the other end of the resistor R111.

5. The protection control circuit according to claim 4, characterized in that: The switching transistor Q501 is a MOSFET.

6. The protection control circuit according to any one of claims 1 to 5, characterized in that: The first switch is a MOSFET Q101.

7. The protection control circuit according to claim 6, characterized in that: The first comparison control module includes operational amplifier U1A, operational amplifier U1B, resistors R103 and R104, and switching transistor Q301. The negative input terminal of operational amplifier U1A and the non-inverting input terminal of operational amplifier U1B are connected together to input the first reference voltage. The non-inverting input terminal of operational amplifier U1A and the negative input terminal of operational amplifier U1B are connected together to input the first voltage signal. The output terminal of operational amplifier U1A is connected to one end of resistor R103, and the output terminal of operational amplifier U1B is connected to one end of resistor R104. The other end of resistor R104 is connected to the gate of switching transistor Q301. The other end of resistor R103 and the drain of switching transistor Q301 are both connected to the gate of the first switching transistor. The source of switching transistor Q301 is used to connect to the output terminal of the switching power supply.

8. The protection control circuit according to claim 7, characterized in that: The switching transistor Q301 is a MOSFET.

9. The protection control circuit according to any one of claims 1 to 5, characterized in that: The second switch is a MOSFET Q201.

10. The protection control circuit according to claim 9, characterized in that: The second comparison control module includes operational amplifiers U2A and U2B, resistors R106 and R107, and a switching transistor Q401. The negative input terminal of operational amplifier U2A and the non-inverting input terminal of operational amplifier U2B are connected together to input the second reference voltage. The non-inverting input terminal of operational amplifier U2A and the negative input terminal of operational amplifier U2B are connected together to input the second voltage signal. The output terminal of operational amplifier U2A is connected to one end of resistor R106, and the output terminal of operational amplifier U2B is connected to one end of resistor R107. The other end of resistor R107 is connected to the gate of switching transistor Q401. The other end of resistor R106 and the drain of switching transistor Q401 are both connected to the gate of the second switching transistor. The source of switching transistor Q401 is used to connect to the output terminal of the switching power supply.

11. The protection control circuit according to claim 10, characterized in that: The switching transistor Q401 is a MOSFET.

12. A switching power supply, characterized in that: This includes the protection control circuit described in any one of claims 1 to 11.

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