A short-circuit protection circuit and a charger

Abstract

An embodiment of the present invention discloses a short-circuit protection circuit and a charger. The short-circuit protection circuit is applied to the charger, and the charger includes a power input interface, a power output interface, and a first power ground. The short-circuit protection circuit includes a sampling module, a signal generating module, and a switch module. The sampling module is respectively connected to the first power ground and the second power ground of the short-circuit protection circuit. The sampling module is used to output a sampling signal based on the current between the first power ground and the second power ground. The signal generating module is respectively connected to the sampling module and the power output interface. The signal generating module is used to output a control signal based on the sampling signal and the voltage of the power output interface. The switch module is respectively connected to the signal generating module, the input power supply, and the power input interface. The switch module is used to switch the switch state based on the control signal. Through the above method, when a short-circuit fault occurs in the charger, the short-circuit current can be reduced to zero.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic circuits, and in particular to a short-circuit protection circuit and a charger. Background Art

[0002] Many MP3 players and mobile phones now come equipped with USB chargers, which use the data cable as the power cord and automatically start charging when plugged into a computer. Furthermore, with economic development, users are increasingly prioritizing the personal experience of using electronic products. When using digital electronic devices such as mobile phones and tablets, users often seek faster charging speeds. As a result, USB-PD fast charging technology has gradually matured and become popular, and the corresponding use of USB-PD chargers has also become increasingly widespread.

[0003] For existing USB chargers on the market, especially USB-PD chargers, when a short-circuit fault occurs on their output, their internal protection strategy is usually to limit the output current to a set maximum operating current threshold. However, this protection strategy still poses the risk of damaging the charger. Summary of the Invention

[0004] The embodiment of the present invention aims to provide a short-circuit protection circuit, which can reduce the short-circuit current to zero when a short-circuit fault occurs in a charger.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a short-circuit protection circuit for use in a charger, the charger comprising a power input interface, a power output interface, and a first power ground, the short-circuit protection circuit comprising:

[0006] a sampling module, the sampling module being connected to the first power ground and the second power ground of the short-circuit protection circuit respectively, and the sampling module being configured to output a sampling signal based on a current between the first power ground and the second power ground;

[0007] a signal generating module, the signal generating module being connected to the sampling module and the power output interface respectively, and the signal generating module being configured to output a control signal based on the sampling signal and the voltage of the power output interface;

[0008] A switch module, wherein the switch module is respectively connected to the signal generating module, the input power supply and the power input interface, and the switch module is used to switch the switch state based on the control signal to control the connection state between the input power supply and the power input interface.

[0009] In an optional manner, the sampling module includes a sampling resistor and a first operational amplifier;

[0010] The first end of the sampling resistor is respectively connected to the inverting input terminal of the first operational amplifier and the second power ground, the second end of the sampling resistor is respectively connected to the non-inverting input terminal of the first operational amplifier and the first power ground, and the output terminal of the first operational amplifier is connected to the signal generating module.

[0011] In an optional manner, the signal generating module includes a first switching unit and a comparing unit;

[0012] The first switch unit is connected to the power output interface, and the first switch unit is used to switch the switch state based on the voltage of the power output interface;

[0013] The comparison unit is connected to the sampling module and the first switch unit, and is configured to output a control signal based on the sampling signal and the switch state of the first switch unit.

[0014] In an optional manner, the first switch unit includes a first switch tube and a first resistor;

[0015] The control end of the first switch tube is connected to the power output interface through the first resistor, the first end of the first switch tube is connected to the second power ground, and the second end of the first switch tube is connected to the comparison unit.

[0016] In an optional manner, the comparison unit includes a second operational amplifier, a second resistor, a third resistor, a fourth resistor and a fifth resistor;

[0017] The non-inverting input terminal of the second operational amplifier is connected to the sampling module through the second resistor, the inverting input terminal of the second operational amplifier is respectively connected to one end of the third resistor and one end of the fourth resistor, the other end of the third resistor is connected to the second power supply ground, the other end of the fourth resistor is connected to the first power supply, the output terminal of the second operational amplifier is respectively connected to one end of the fifth resistor and the first switching unit, and the other end of the fifth resistor is connected to the first power supply.

[0018] In an optional manner, the switch module includes a second switch unit, a third switch unit and a fourth switch unit;

[0019] The second switch unit is connected to the signal generating module, and the second switch unit is used to switch the switch state based on the control signal;

[0020] The third switch unit is connected to the second switch unit, and the third switch unit is used to switch the switch state based on the switch state of the second switch unit;

[0021] The fourth switch unit is connected to the third switch unit, the input power supply and the power input interface respectively, and the fourth switch unit is used to switch its switch state based on the switch state of the third switch unit to control the connection state between the input power supply and the power input interface.

[0022] In an optional manner, the second switch unit includes a second switch tube, a sixth resistor and a seventh resistor connected in series;

[0023] The non-series end of the sixth resistor is connected to the signal generating module, the connection point between the sixth resistor and the seventh resistor is connected to the control end of the second switching tube, the first end of the second switching tube and the non-series end of the seventh resistor are both connected to the second power supply ground, and the second end of the second switching tube is connected to the third switching unit.

[0024] In an optional manner, the third switch unit includes a third switch tube, an eighth resistor, and a ninth resistor and a tenth resistor connected in series;

[0025] The non-series end of the ninth resistor is connected to the input power supply and the fourth switch unit respectively, the connection point between the ninth resistor and the tenth resistor is connected to the control end of the third switch tube through the eighth resistor, the non-series end of the tenth resistor and the second end of the third switch tube are both connected to the second power supply ground, and the second end of the third switch tube is connected to the fourth switch unit.

[0026] In an optional manner, the fourth switch unit includes a fourth switch tube, an eleventh resistor, a twelfth resistor and a thirteenth resistor;

[0027] One end of the eleventh resistor is connected to the third switch unit, the other end of the eleventh resistor is respectively connected to one end of the twelfth resistor and one end of the thirteenth resistor, the other end of the twelfth resistor is connected to the control end of the fourth switch tube, the other end of the thirteenth resistor is respectively connected to the input power supply and the first end of the fourth switch tube, and the second end of the fourth switch tube is connected to the power input interface.

[0028] In a second aspect, the present invention further provides a charger, comprising a power input interface, a power output interface, a first power ground, and the short-circuit protection circuit as described above;

[0029] The short-circuit protection circuit is connected to the power input interface, the power output interface and the first power ground respectively.

[0030] The beneficial effects of the embodiments of the present invention are as follows: the short-circuit protection circuit provided by the present invention is applied to a charger, and the charger includes a power input interface, a power output interface, and a first power ground. The short-circuit protection circuit includes a sampling module, a signal generating module, and a switch module, wherein the sampling module is connected to the first power ground and the second power ground of the short-circuit protection circuit, the signal generating module is respectively connected to the sampling module and the power output interface, and the switch module is respectively connected to the signal generating module, the input power supply, and the power input interface. Therefore, when a short-circuit fault occurs in the charger, the sampling module can output a sampling signal based on the current (i.e., the short-circuit current) flowing between the first power ground and the second power ground. The sampling signal is received by the signal generating module. At the same time, the voltage on the power output interface of the charger is zero. At this time, the control signal output by the signal sending module can switch the switch state of the switch module to the off state. Then, the connection between the input power supply and the power input interface is disconnected, and no power is input to the power input interface of the charger, thereby reducing the short-circuit current to zero. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings. These exemplifications do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements. Unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0032] Figure 1 A schematic diagram of the structure of a charger provided in an embodiment of the present invention;

[0033] Figure 2 A schematic structural diagram of a short-circuit protection circuit provided in an embodiment of the present invention;

[0034] Figure 3 A schematic diagram of the circuit structure of a sampling module and a signal generating module provided in an embodiment of the present invention;

[0035] Figure 4 A schematic structural diagram of a short-circuit protection circuit provided in another embodiment of the present invention;

[0036] Figure 5 A schematic diagram of the circuit structure of a switch module provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0037] To make the purpose, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of the charger provided by the embodiment of the present invention. Figure 1 As shown, the charger includes a short-circuit protection circuit 100, a first power ground 201, a power input interface 202 and a power input interface 203, wherein the first power ground 201 refers to the ground corresponding to the positive pole of the working power supply of the charger.

[0039] It is understood that in the embodiments of the present invention, a charger refers to a device that uses a charging port to connect to a computer or a charging head to charge electronic products. Chargers include but are not limited to: fast charging chargers (for example, USB-PD chargers) and ordinary chargers.

[0040] Specifically, the short-circuit protection circuit 100 is respectively connected to the first power ground 201, the power output interface 202 and the power input interface 203. At the same time, the short-circuit protection circuit 100 is also used to connect to the external input power supply 300, that is, the charger is connected to the input power supply 300 through the short-circuit protection circuit 100.

[0041] The short-circuit protection circuit 10 is designed to promptly disconnect the input power source 300 from the power input interface 203 when a short circuit occurs at the charger's output, thereby reducing the short-circuit current to zero and protecting the charger from damage. When a short circuit occurs at the charger's output, the voltage at the power output interface 202 is zero, and a short-circuit current exists between the first power ground 201 and the second power ground of the short-circuit protection circuit 100. Based on this short-circuit current and the voltage at the power output interface 202, the short-circuit protection circuit 100 is controlled to disconnect the input power source 300 from the power input interface 203, thereby reducing the short-circuit current to zero.

[0042] It should be understood that Figure 1 What is shown is a charger including the short-circuit protection circuit 100 , that is, the short-circuit protection circuit 100 is arranged on the charger.

[0043] In another embodiment, the short-circuit protection circuit 100 can be used solely as a circuit structure connected to an existing charger, as existing chargers do not have such a short-circuit protection circuit. By connecting the short-circuit protection circuit 100 to an existing charger, the short-circuit current of the charger can be reduced to zero in the event of a short-circuit fault.

[0044] All the following embodiments are described by taking the short circuit protection circuit 100 connected to a charger as an example, wherein the charger includes a first power ground 201 , a power output interface 202 , and a power input interface 203 .

[0045] Among them, such as Figure 2 As shown, the short circuit protection circuit 100 includes a sampling module 101, a signal generating module 102, a switch module 103 and a second power ground 104. The second power ground 104 refers to the ground corresponding to the positive pole of the working power supply of the short circuit protection circuit 100.

[0046] Specifically, the sampling module 101 is connected to the first power ground 201 and the second power ground 104 of the short-circuit protection circuit 100. The sampling module 101 can output a sampling signal based on the current between the first power ground 201 and the second power ground 104. In other words, when the current between the first power ground 201 and the second power ground 104 changes, the sampling module 101 can output a corresponding sampling signal based on the different currents, thereby determining whether a short circuit anomaly has occurred in the charger.

[0047] In one embodiment, the sampling module 101 includes a sampling resistor and a first operational amplifier. Figure 3 The circuit structure of the sampling module 101 shown in FIG. Figure 3 As shown, the sampling resistor corresponds to the resistor R1 , the first operational amplifier corresponds to the operational amplifier U1 , the second power ground 104 corresponds to the power ground PGND, and the sampling module 101 is connected to the first power ground 201 through the power ground interface AGND.

[0048] Optionally, the sampling module 101 further includes a resistor R2 , a resistor R3 , a resistor R4 , a resistor R5 , a capacitor C1 , and a capacitor C2 .

[0049] Among them, both ends of the resistor R1 are respectively connected to the power ground interface AGND and the power ground PGND, one end of the resistor R2 is connected to the power ground interface AGND, the other end of the resistor R2 is respectively connected to the inverting input terminal of the operational amplifier U1, one end of the capacitor C2 and one end of the resistor R5, the other end of the capacitor C2 and the other end of the resistor R5 are both connected to the output terminal of the operational amplifier U1, the other end of the resistor R3 is respectively connected to the non-inverting input terminal of the operational amplifier U1, one end of the resistor R4 and one end of the capacitor C1, the other end of the resistor R4 and the other end of the capacitor C1 are connected to the power ground PGND.

[0050] If current flows between the power ground interface AGND and the power ground PGND, that is, current flows between the first power ground 201 and the power ground PGND, the current will cause a voltage difference to exist across the resistor R1. The voltage difference is input to the inverting input and the non-inverting input of the operational amplifier U1, respectively, so that the output of the operational amplifier U1 outputs a corresponding sampling voltage (i.e., a sampling signal).

[0051] If there is no current between the power ground interface AGND and the power ground PGND, the output of the op amp U1 is 0, which means that the charger is not connected to the electronic product.

[0052] Please refer again Figure 2 The signal generating module 102 is connected to the sampling module 101 and the power output interface 202, respectively. The signal generating module 102 can output a control signal based on the sampling signal and the voltage of the power output interface 202. In other words, the sampling signal and the voltage of the power output interface 202 are combined as the judgment conditions for outputting different control signals. In other words, the control signal output by the signal generating module 102 varies with the sampling signal or the voltage of the power output interface 202.

[0053] In one embodiment, please refer to Figure 4 The signal generating module 102 includes a first switch unit 1021 and a comparison unit 1022 , wherein the first switch unit 1021 is connected to the power output interface 202 , and the comparison unit 1022 is connected to the sampling module 101 and the first switch unit.

[0054] Specifically, the first switch unit 1021 can switch between on and off states based on the voltage of the power output interface. The on and off states of the first switch unit 1021 include an on state and a off state. The on and off states of the first switch unit 1021 vary depending on the voltage of the power output interface 202. Furthermore, when the charger output is short-circuited, the voltage of the power output interface 202 changes, causing the first switch unit 1021 to switch between on and off states.

[0055] The comparison unit 1022 further outputs a control signal based on the switching state of the first switch unit 1021 and the sampling signal output by the sampling module 101. Specifically, the switching state of the first switch unit 1021 combined with the sampling signal serves as a criterion for outputting different control signals. In other words, the control signal output by the signal generation module 102 varies with the sampling signal or the switching state of the first switch unit 1021.

[0056] Optionally, the first switching unit includes a first switching tube and a first resistor.

[0057] Optionally, the comparison unit includes a second operational amplifier, a second resistor, a third resistor, a fourth resistor, and a fifth resistor.

[0058] by Figure 3 The circuit structure of the first switch unit 1021 and the comparison unit 1022 shown in FIG. Figure 3As shown, the first switch tube corresponds to transistor Q1, the first resistor corresponds to resistor R10, and the first switch unit 1021 is also connected to the power output interface 202 via the power interface VOUT. The second operational amplifier, the second resistor, the third resistor, the fourth resistor, and the fifth resistor correspond to the operational amplifier U2, the resistor R7, the resistor R8, the resistor R6, and the resistor R9, respectively.

[0059] Optionally, the first switch unit 1021 further includes a resistor R11 and a capacitor C5, and the comparison unit 1022 further includes a capacitor C3, a capacitor C4 and a diode D1.

[0060] Specifically, the base of the transistor Q1 is connected to one end of the resistor R10, the other end of the resistor R10 is respectively connected to one end of the resistor R11 and the power interface VOUT, the emitter of the transistor Q1 and the other end of the resistor R11 are both connected to the power ground PGND, the capacitor C5 is connected in parallel with the resistor R11, the collector of the transistor Q1 is respectively connected to the anode of the diode D1, the output end of the operational amplifier U2 and one end of the resistor R9, the other end of the resistor R9 is connected to the first power supply V1, the cathode of the diode D1 is connected to the switch module 103 through the connection point S1, the non-inverting input end of the operational amplifier U2 is connected to one end of the resistor R7, the other end of the resistor R7 is connected to the output end of the operational amplifier U1 in the sampling module 101, the inverting input end of the operational amplifier U2 is respectively connected to one end of the resistor R8 and one end of the resistor R6, the other end of the resistor R6 is connected to the first power supply V1, and the other end of the resistor R8 is connected to the power ground PGND.

[0061] In practical applications, the sampling signal output by the output terminal of op amp U1 of sampling module 101 is input to the non-inverting input terminal of op amp U2 through resistor R7. The input voltage of op amp U2's inverting input terminal is the voltage divided by the first power supply V1 across resistor R6 and resistor R8, resulting in the divided voltage across resistor R8. Therefore, when the voltage of the sampling signal is greater than the divided voltage of the first power supply V1 across resistor R8, op amp U2 outputs a high-level signal; when the voltage of the sampling signal is less than the divided voltage of the first power supply V1 across resistor R8, op amp U2 outputs a low-level signal.

[0062] The voltage at the power output interface 202 is input to the base of the transistor Q1 via the power interface VOUT. Therefore, when the voltage at the power output interface 202 is high, the transistor Q1 is turned on, and the collector of the transistor Q1 is connected to the power ground PGND via the emitter, forcing the collector of the transistor Q1 to be pulled low. When the voltage at the power output interface 202 is low, the transistor Q1 is turned off, and the collector of the transistor Q1 is connected to the first power source V1 via the resistor R9, forcing the collector of the transistor Q1 to be pulled high.

[0063] In summary, the collector of the transistor Q1 is connected to the output end of the operational amplifier U2, that is, the signal at the connection point between the collector of the transistor Q1 and the output end of the operational amplifier U2 is the control signal. The control signal is transmitted to the connection point S1 through the diode D1, and is transmitted to the switch module 103 through the connection point S1.

[0064] Then, when the operational amplifier U2 outputs a high-level signal and the collector of the transistor Q1 is a high-level signal, the control signal outputted from the connection point between the collector of the transistor Q1 and the output terminal of the operational amplifier U2 is a high-level signal, that is, the signal generating module 102 outputs a high-level signal.

[0065] When the op amp U2 outputs a low-level signal or the collector of the transistor Q1 is a low-level signal, or the op amp U2 outputs a low-level signal and the collector of the transistor Q1 is a low-level signal, the connection point between the collector of the transistor Q1 and the output end of the op amp U2 will be forced to be pulled low, that is, a low-level signal is output. At this time, the signal generating module 102 outputs a low-level signal.

[0066] It should be understood that the first power source V1 can be a power source on the charger, for example, the power output by the voltage stabilizing module on the charger. Of course, the first power source V1 can also be a separate external power source, which is not limited here.

[0067] Please refer again Figure 2 The switch module 103 is connected to the signal generating module 102 and the power input interface 203. The switch module 103 can switch the switch state according to the control signal to control the connection state between the input power 300 and the power input interface 203.

[0068] In one embodiment, please refer to Figure 4 The switch module 103 includes a second switch unit 1031, a third switch unit 1032 and a fourth switch unit 1033, wherein the second switch unit 1031 is connected to the signal generating module 102, the third switch unit 1032 is connected to the second switch unit 1031, and the fourth switch unit 1033 is respectively connected to the third switch unit 1032, the input power supply 300 and the power input interface 203.

[0069] Specifically, the second switch unit 1031 is configured to switch between on and off states based on a control signal. The on and off states of the second switch unit 1031 include an on state and an off state. Depending on whether the control signal is a high-level signal or a low-level signal, the second switch unit 1031 can be controlled to be in different on and off states. For example, when the control signal is a high-level signal, the second switch unit 1031 is in the on state. Conversely, when the control signal is a low-level signal, the second switch unit 1031 is in the off state.

[0070] Optionally, the second switch unit includes a second switch tube, a sixth resistor and a seventh resistor connected in series.

[0071] Optionally, the third switch unit includes a third switch tube, an eighth resistor, and a ninth resistor and a tenth resistor connected in series.

[0072] Optionally, the fourth switch unit includes a fourth switch tube, an eleventh resistor, a twelfth resistor, and a thirteenth resistor.

[0073] by Figure 5 The circuit structures of the second switch unit 1031, the third switch unit 1032 and the fourth switch unit 1033 are used as an example for explanation. Figure 5 As shown, the second switch, the sixth resistor connected in series, and the seventh resistor correspond to the transistor Q2, the resistor R13, and the resistor R12, respectively. The third switch, the eighth resistor, and the ninth and tenth resistors connected in series correspond to the transistor Q3, the resistor R16, the resistor R14, and the resistor R15, respectively. The fourth switch, the eleventh resistor, the twelfth resistor, and the thirteenth resistor correspond to the MOS transistor Q4, the resistor R18, the resistor R19, and the resistor R17, respectively.

[0074] Meanwhile, the input power source V0 corresponds to the input power source 300 in the above embodiment, the second switch unit 1031 is connected to the connection point S1 in the signal generating module 102 via the connection point S11, and the fourth switch unit 1033 is connected to the power input interface 203 via the power interface VIN.

[0075] Optionally, the second switch unit 1031 further includes a capacitor C6. The short circuit protection circuit 100 further includes a fuse F1.

[0076] Specifically, the input power supply V0 is connected to one end of the fuse F1, the other end of the fuse F1 is respectively connected to one end of the resistor R14, one end of the resistor R17 and the source of the MOS transistor Q4, the drain of the MOS transistor Q4 is connected to the power input interface 203 through the power interface VIN, the gate of the MOS transistor Q4 is connected to one end of the resistor R19, the other end of the resistor R19 is respectively connected to the other end of the resistor R17 and one end of the resistor R18, the other end of the resistor R18 is connected to the collector of the transistor Q3, and the base of the transistor Q3 is connected to the collector of the transistor Q3. The base of the transistor Q2 is connected to one end of the resistor R12 and one end of the resistor R13, respectively. The other end of the resistor R12 is connected to the connection point S11. The other end of the resistor R13, the emitter of the transistor Q2, the other end of the capacitor C6, the other end of the resistor R15, and the emitter of the transistor Q3 are all connected to the power ground PGND.

[0077] From the above content, we can see that Figure 3 The control signal at the connection point S1 in can be a high level signal or a low level signal. Figure 5 The connection point S11 is used to connect Figure 3 The connection point S1 in is connected, so the connection point S11 is also at a low level or a high level.

[0078] When the voltage at connection point S11 is low, the base of transistor Q2 is also low, turning off transistor Q2. The divided voltage of input power supply V0 across resistor R15 is input to the base of transistor Q3, turning on transistor Q3. Input power supply V0, resistor R17, resistor R18, the collector and emitter of transistor Q3, and power ground PGND form a loop. This creates a voltage difference across resistor R17, and thus a voltage difference between the gate and source of MOS transistor Q4. MOS transistor Q4 then turns on, and input power supply V0 is connected to the power interface VIN through the source and drain of MOS transistor Q4, providing operating voltage to the charger through the power interface VIN.

[0079] When the voltage at connection point S11 is high, the base of transistor Q2 is also high, turning on transistor Q2. The base of transistor Q3 is connected to the power ground PGND through resistor R16, forcing the base of transistor Q3 low and turning off transistor Q3. The input power supply V0, resistors R17, and resistor R18 form no loop. There is almost no voltage difference between the gate and source of MOS transistor Q4, causing MOS transistor Q4 to turn off, disconnecting the input power supply V0 from the power interface VIN. This means the charger loses its operating voltage.

[0080] It should be noted that the first, second, third, and fourth switching transistors can be selected from any of triodes, MOS transistors, and IGBT switching transistors. Furthermore, the first, second, third, and fourth switching transistors can be the same or different. For example, the first, second, and third switching transistors can all be triodes, while the fourth switching transistor can be a MOS transistor.

[0081] Taking the first switch tube as an example, if the first switch tube is a transistor, the base of the transistor is the control end of the first switch tube, the emitter of the transistor is the first end of the first switch tube, and the collector of the transistor is the second end of the first switch tube.

[0082] If the first switch tube is a MOS tube or an IGBT switch tube, the gate of the MOS tube or the IGBT switch tube is the control end of the first switch tube, the source of the MOS tube or the IGBT switch tube is the first end of the first switch tube, and the drain of the MOS tube or the IGBT switch tube is the second end of the first switch tube.

[0083] In summary, please also refer to Figure 3 and Figure 5 In actual applications, when the charger is not connected to an electronic product, the default output voltage and current of the charger are both 0. That is, the current between the power ground interface AGND and the power ground PGND is 0, the voltage across resistor R1 is 0, and the output voltage of op amp U1 is 0. The voltage at the inverting input of op amp U2 is greater than the voltage at the non-inverting input, and op amp U2 outputs a low-level signal, which is transmitted to connection point S11 through connection point S1. Transistor Q2 is turned off, transistor Q3 is turned on, and MOS transistor Q4 is turned on. The entire short-circuit protection circuit 100 is in normal operation, that is, it maintains the default output state.

[0084] When the charger is connected to an electronic product, it communicates with the product through a handshake. The charger adjusts the output voltage and current according to the communication protocol (at this point, the charger obtains the operating voltage from the input power supply V0 through the power interface VIN) to charge the electronic product. At this time, the voltage output by the power interface VOUT can turn on transistor Q1, thereby lowering the voltage at the output of op amp U2. That is, the voltage at connection point S1 is pulled low, and connection point S1 outputs a low-level signal, which is transmitted to connection point S11 through connection point S1. At this time, transistor Q2 is turned off, transistor Q3 is turned on, and MOS tube Q4 is turned on. The charger can operate normally and keep charging the electronic product.

[0085] When the charger output short-circuits, the charger's output voltage drops to zero, meaning the voltage at the power interface VOUT is zero, and transistor Q1 turns off. Furthermore, the current between the power ground interface AGND and the power ground PGND becomes a short-circuit current. This circuit generates a voltage difference across resistor R1, causing op amp U1 to output the corresponding sampling voltage (i.e., the sampling signal). By adjusting the voltage divider of the first power supply V1 at resistor R8 (i.e., the voltage at the inverting input of op amp U2) to be lower than the current sampling voltage, the voltage at the non-inverting input of op amp U2 becomes greater than the voltage at the inverting input, causing op amp U2 to output a high level. At this point, connection point S1 transmits the high level to connection point S11, causing the base voltage of transistor Q2 to become a high-level signal, turning on transistor Q2, while transistor Q3 turns off and MOS transistor Q4 also turns off. The connection between input power supply V0 and power interface VIN is disconnected, effectively cutting off the charger's input power. The charger shuts off its output, reducing the short-circuit current to zero, completing the short-circuit protection function.

[0086] Furthermore, when the short-circuit current decreases to zero, the voltage on resistor R1 is 0, and the sampling voltage output by op amp U1 is 0. The voltage at the non-inverting input of op amp U2 is less than the voltage at the inverting input, and op amp U2 outputs a low level. Connection point S1 outputs a low-level signal, and the low-level signal is transmitted to connection point S11 through connection point S1. At this time, transistor Q2 is turned off, transistor Q3 is turned on, and MOS tube Q4 is turned on again. The charger resumes output, completing the self-recovery function after the output short circuit. It can be understood that at this time, if the charger output is still in a short-circuit state, the short-circuit protection function of the short-circuit protection circuit 100 will be triggered again.

[0087] At the same time, due to the charge and discharge characteristics of capacitor C6, the voltage across capacitor C6 changes between high and low levels over a certain period of time, which depends on the capacitance value of capacitor C6. Furthermore, this period of time controls the switching time between the on and off state of transistor Q3, thereby controlling the switching time between the on and off state of MOS transistor Q4. Therefore, by adjusting the capacitance value of capacitor C6, the time it takes for the charger to resume output after the short-circuit protection function is triggered can be controlled, thereby controlling the triggering frequency of the short-circuit protection function, thereby enhancing the charger's ability to cope with impact loads. Furthermore, the short-circuit protection circuit 100 is relatively simple, low-cost, highly sensitive, and highly resistant to interference, making it easy to promote and apply.

[0088] The short-circuit protection circuit 100 provided by the present invention is applied to a charger, and the charger includes a power input interface 203, a power output interface 202 and a first power ground 201. The short-circuit protection circuit 100 includes a sampling module 101, a signal generating module 102 and a switch module 103, wherein the sampling module 102 is connected to the first power ground 201 and the second power ground 104 of the short-circuit protection circuit 100, the signal generating module 102 is respectively connected to the sampling module 101 and the power output interface 202, and the switch module 103 is respectively connected to the signal generating module 102, the input power 300 and the power input interface 203. Therefore, when a short circuit fault occurs in the charger, the sampling module 101 can output a sampling signal based on the current (i.e., the short-circuit current) flowing between the first power ground 201 and the second power ground 104. The sampling signal is received by the signal generating module 102. At the same time, the voltage on the power output interface 203 of the charger is zero. At this time, the control signal output by the signal sending module 102 can switch the switch state of the switch module 103 to the disconnected state. Then, the connection between the input power supply 300 and the power input interface 203 is disconnected, and the power input interface of the charger has no power input, thereby reducing the short-circuit current to zero.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Under the idea of the present invention, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the present invention as described above. For the sake of simplicity, they are not provided in detail. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of this application.

Claims

1. A short circuit protection circuit, characterized in that: Applied to a charger, the charger includes a power input interface, a power output interface and a first power ground, and the short-circuit protection circuit includes: a sampling module, the sampling module being connected to the first power ground and the second power ground of the short-circuit protection circuit respectively, and the sampling module being configured to output a sampling signal based on a current between the first power ground and the second power ground; a signal generating module, the signal generating module being connected to the sampling module and the power output interface respectively, and the signal generating module being configured to output a control signal based on the sampling signal and the voltage of the power output interface; a switch module, the switch module being connected to the signal generating module, the input power supply, and the power input interface, respectively, and the switch module being configured to switch a switch state based on the control signal to control a connection state between the input power supply and the power input interface; The sampling module includes a sampling resistor and a first operational amplifier; One end of the sampling resistor is connected to the inverting input terminal of the first operational amplifier and the first power ground respectively, the other end of the sampling resistor is connected to the non-inverting input terminal of the first operational amplifier and the second power ground respectively, and the output terminal of the first operational amplifier is connected to the signal generating module; The signal generating module includes a first switching unit and a comparing unit; The first switch unit is connected to the power output interface, and the first switch unit is used to switch the switch state based on the voltage of the power output interface; The comparison unit is connected to the sampling module and the first switch unit, and the comparison unit is configured to output a control signal based on the sampling signal and the switch state of the first switch unit; The first switch unit includes a first switch tube and a first resistor; The control end of the first switch tube is connected to the power output interface through the first resistor, the first end of the first switch tube is connected to the second power ground, and the second end of the first switch tube is connected to the comparison unit; The comparison unit includes a second operational amplifier, a second resistor, a third resistor, a fourth resistor and a fifth resistor; The non-inverting input terminal of the second operational amplifier is connected to the output terminal of the first operational amplifier through the second resistor, the inverting input terminal of the second operational amplifier is connected to one end of the third resistor and one end of the fourth resistor respectively, the other end of the third resistor is connected to the second power supply ground, the other end of the fourth resistor is connected to the first power supply, the output terminal of the second operational amplifier is connected to one end of the fifth resistor and the second end of the first switching tube respectively, and the other end of the fifth resistor is connected to the first power supply; The switch module includes a second switch unit, a third switch unit and a fourth switch unit; The second switch unit is connected to the signal generating module, and the second switch unit is used to switch the switch state based on the control signal; The third switch unit is connected to the second switch unit, and the third switch unit is used to switch the switch state based on the switch state of the second switch unit; The fourth switch unit is connected to the third switch unit, the input power supply, and the power input interface respectively, and the fourth switch unit is used to switch its switch state based on the switch state of the third switch unit to control the connection state between the input power supply and the power input interface; The second switch unit includes a second switch tube, a sixth resistor and a seventh resistor connected in series; The non-series end of the sixth resistor is connected to the output end of the second operational amplifier, the connection point between the sixth resistor and the seventh resistor is connected to the control end of the second switching transistor, the first end of the second switching transistor and the non-series end of the seventh resistor are both connected to the second power supply ground, and the second end of the second switching transistor is connected to the third switch unit; The third switch unit includes a third switch tube, an eighth resistor, and a ninth resistor and a tenth resistor connected in series; The non-series end of the ninth resistor is connected to the input power supply and the fourth switch unit respectively; the connection point between the ninth resistor and the tenth resistor is connected to the control end of the third switch tube through the eighth resistor; the connection point between the ninth resistor and the tenth resistor is connected to the second end of the second switch tube; the non-series end of the tenth resistor and the first end of the third switch tube are both connected to the second power supply ground; and the second end of the third switch tube is connected to the fourth switch unit; The fourth switch unit includes a fourth switch tube, an eleventh resistor, a twelfth resistor and a thirteenth resistor; One end of the eleventh resistor is connected to the second end of the third switching tube, the other end of the eleventh resistor is respectively connected to one end of the twelfth resistor and one end of the thirteenth resistor, the other end of the twelfth resistor is connected to the control end of the fourth switching tube, the other end of the thirteenth resistor is respectively connected to the input power supply, the non-series end of the ninth resistor and the first end of the fourth switching tube, and the second end of the fourth switching tube is connected to the power input interface.

2. A charger, characterized in that: The charger comprises a power input interface, a power output interface, a first power ground, and the short-circuit protection circuit according to claim 1; The short-circuit protection circuit is connected to the power input interface, the power output interface and the first power ground respectively.

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