Protection circuit and protection circuit system

Abstract

The embodiment of the utility model provides a protection circuit and a protection circuit system, comprising a first resistor, the first end of which is connected with the power supply input end of the protection circuit; the first end of the first control circuit is connected with the power supply input end, and the second end of the first control circuit is connected with the second end of the first resistor; the first end of the first control switch is connected with the third end of the first control circuit, the second end of the first control switch is connected with the second end of the first resistor, and the third end of the first control switch is connected with the power output end of the protection circuit; the first end of the second control circuit is connected with the power input end, the second end of the second control circuit is connected with the first end of the first control switch, and the third end, the fourth end and the fifth end of the second control circuit are grounded. The problem of equipment damage caused by long response time of the protection circuit can be solved, and the effect of reducing the response time of the protection circuit and further protecting the equipment is achieved.

Description

Technical Field

[0001] This utility model relates to the field of circuits, and more specifically, to a protection circuit and a protection circuit system. Background Technology

[0002] In related technologies, excessive current in a circuit can severely affect the normal operation of equipment. Currently, current detection chips are mainly used to monitor the current in the circuit. When the detected current is too high, it is limited to protect the circuit. However, the protection circuit requires a process involving the current detection chip detecting the excessive current, issuing a current-limiting command, and the current in the circuit decreasing in response to the current-limiting command. This results in a long response time for the protection circuit, which can easily lead to equipment damage.

[0003] This indicates that there is a technical problem in the relevant technology where the long response time of the protection circuit leads to equipment damage.

[0004] There is currently no effective solution to the aforementioned problems in the relevant technologies. Utility Model Content

[0005] This utility model provides a protection circuit and protection circuit system to at least solve the technical problem of equipment damage caused by long response time of protection circuits in related technologies.

[0006] According to one embodiment of the present invention, a protection circuit is provided, comprising: a first resistor, a first terminal of which is connected to a power input terminal of the protection circuit, wherein the power input terminal is configured to be connected to a power supply; a first control circuit, a first terminal of which is connected to the power input terminal, and a second terminal of which is connected to a second terminal of the first resistor; and a first control switch, a first terminal of which is connected to a third terminal of the first control circuit, a second terminal of which is connected to a second terminal of the first resistor, and a third terminal of which is connected to a power output terminal of the protection circuit, wherein the power output terminal is configured to be connected to a power supply. The system is configured to connect to the load and supply power to it; a second control circuit is configured such that its first terminal is connected to the power input terminal, its second terminal is connected to the first terminal of the first control switch, and its third, fourth, and fifth terminals are grounded; wherein, when the current in the first resistor is greater than a preset current, the first control circuit is turned on and the second control circuit is turned off to control the first control switch to turn off and stop supplying power to the load; when the current in the first resistor is less than or equal to the preset current, the first control switch is turned off and the second control circuit is turned on to control the first control switch to turn on and supply power to the load.

[0007] In an exemplary embodiment, the first control circuit includes: a first transistor, a first terminal of which is connected to a second terminal of the first resistor, a second terminal of which is connected to the power input terminal, and a third terminal of which is connected to a third terminal of the second control circuit; and a second transistor, a first terminal of which is connected to a second terminal of the first resistor, a second terminal of which is connected to a second terminal of the first transistor, and a third terminal of which is connected to a first terminal of the first control switch.

[0008] In one exemplary embodiment, the first control circuit includes: a second resistor, wherein a first terminal of the first transistor is connected to a second terminal of the first resistor via the second resistor; and a third resistor, wherein a first terminal of the second transistor is connected to a second terminal of the first resistor via the third resistor.

[0009] In an exemplary embodiment, the second control circuit includes: a second control switch, a first terminal of which is connected to a fourth terminal of the first control circuit, and a second terminal of which is grounded; and a third transistor, a first terminal of which is connected to a third terminal of the second control switch, a second terminal of which is grounded, and a third terminal of which is connected to a first terminal of the first control switch.

[0010] In an exemplary embodiment, the second control circuit further includes a delay circuit, wherein a first terminal of the delay circuit is connected to a fourth terminal of the first control circuit, a second terminal of the delay circuit is connected to a first terminal of the second control switch, and a third terminal of the delay circuit is grounded.

[0011] In one exemplary embodiment, the delay circuit includes: a fourth resistor, the first end of which is connected to a fourth terminal of the first control circuit; a fifth resistor, the first end of which is connected to a second terminal of the fourth resistor, the first end of which is also connected to a first terminal of the second control switch, and the second terminal of the fifth resistor is grounded; and a first capacitor, which is connected in parallel with the fifth resistor.

[0012] In an exemplary embodiment, the second control circuit includes: a first transient suppression diode, a first terminal of the first transient suppression diode being connected to a first terminal of the second control switch, and a second terminal of the first transient suppression diode being connected to a second terminal of the second control switch.

[0013] In an exemplary embodiment, the second control circuit includes: a second transient suppression diode, the first terminal of the second transient suppression diode being connected to the first terminal of the third transistor, and the second terminal of the second transient suppression diode being connected to the second terminal of the third transistor.

[0014] In one exemplary embodiment, the second control circuit includes: a sixth resistor, the first end of which is connected to the third end of the second control switch, and the second end of which is connected to the first end of the third transistor; a seventh resistor, the first end of which is connected to the power input terminal, and the second end of which is connected to the first end of the sixth resistor; and an eighth resistor, the first end of which is connected to the second end of the seventh resistor, and the second end of which is grounded.

[0015] In one exemplary embodiment, the second control circuit includes: a second capacitor, a first terminal of the second capacitor being connected to a third terminal of the second control switch, the first terminal of the second capacitor also being connected to the power input terminal, and a second terminal of the second capacitor being grounded.

[0016] In one exemplary embodiment, the protection circuit further includes a ninth resistor, the first end of which is connected to the power input terminal, and the second end of which is connected to the first end of the second capacitor.

[0017] In an exemplary embodiment, the first resistor includes: a tenth resistor, the first end of which is connected to the power input terminal; and a thermistor, the first end of which is connected to the second end of the tenth resistor, and the second end of which is connected to the second terminal of the first control switch.

[0018] In one exemplary embodiment, the protection circuit further includes: an eleventh resistor, the first end of which is connected to the first end of the first resistor, and the second end of which is connected to the first end of the first control switch; and a twelfth resistor, the third end of the first control circuit being connected to the second end of the second control circuit through the twelfth resistor.

[0019] According to another embodiment of the present invention, a protection circuit system is provided, including a power supply, a load device, and the protection circuit described in any of the above embodiments. The power supply is connected to the power input terminal of the protection circuit, and the power output terminal of the protection circuit is connected to the load device.

[0020] The protection circuit provided by this utility model allows the first control circuit to conduct and the second control circuit to turn off when the current flowing through the first resistor exceeds a preset current. When the second control circuit is off, it can also turn off the first control switch, stopping power supply to the load connected to the first control switch. When the current flowing through the first resistor is less than or equal to the preset current, the first control switch turns off and the second control circuit conducts. When the second control circuit is on, the first control switch turns on, supplying power to the load. By comparing the current flowing through the first resistor with the preset current, the first control switch connected to the load can be disconnected and power supply to the load can be stopped when the current exceeds the preset current. Therefore, this solves the problem of long response time in protection circuits leading to equipment damage, achieving the effect of reducing protection circuit response time and thus protecting the equipment. Attached Figure Description

[0021] Figure 1 This is a structural block diagram of the protection circuit according to an embodiment of the present utility model;

[0022] Figure 2 This is a protection circuit block diagram according to a specific embodiment of the present utility model. Detailed Implementation

[0023] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples.

[0024] It should be noted that the terms "first," "second," etc., in the specification, claims, and drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0025] This embodiment provides a protection circuit. Figure 1 This is a structural block diagram of the protection circuit according to an embodiment of the present utility model, as shown below. Figure 1 As shown, the protection circuit includes:

[0026] A first resistor 102, the first end of the first resistor is connected to the power input terminal of the protection circuit, wherein the power input terminal is configured to be connected to a power supply.

[0027] A first control circuit 104, wherein a first terminal of the first control circuit is connected to the power input terminal, and a second terminal of the control circuit is connected to the second terminal of the first resistor;

[0028] A first control switch 106, the first end of the first control switch is connected to the third end of the first control circuit, the second end of the first control switch is connected to the second end of the first resistor, and the third end of the first control switch is connected to the power output terminal of the protection circuit, wherein the power output terminal is configured to be connected to the load to supply power to the load;

[0029] The second control circuit 108 has a first terminal connected to the power input terminal, a second terminal connected to the first terminal of the first control switch, and a third, fourth, and fifth terminal grounded.

[0030] Specifically, when the current in the first resistor is greater than a preset current, the first control circuit is turned on and the second control circuit is turned off, thereby controlling the first control switch to turn off and stop supplying power to the load; when the current in the first resistor is less than or equal to the preset current, the first control switch is turned off and the second control circuit is turned on, thereby controlling the first control switch to turn on and supply power to the load.

[0031] In the above embodiments, the overall architecture diagram of the protection circuit can be found here. Figure 2 , Figure 2 This is a protection circuit block diagram according to a specific embodiment of the present utility model, such as... Figure 2 As shown, the protection circuit may include a first resistor, a first control circuit 202, a first control switch M1, and a second control circuit 204. The first terminal of the first resistor is connected to the power input terminal VCC_IN of the protection circuit, and the second terminal is connected to the second terminal of the first control switch M1. The first terminal of the first control circuit 202 is connected to the power input terminal VCC_IN, and the second terminal is connected to the second terminal of the first resistor. The first terminal of the first control switch M1 is connected to the third terminal of the first control circuit 202, the second terminal is connected to the second terminal of the first resistor, and the third terminal is connected to the power output terminal VCC_OUT of the protection circuit. The power output terminal VCC_OUT can be connected to the load to be monitored, which can be a capacitive load, an inductive load, or a motor, etc. The first terminal of the second control circuit 204 is connected to the power input terminal VCC_IN, the second terminal is connected to the first terminal of the first control switch M1, and the third, fourth, and fifth terminals are grounded.

[0032] In the above embodiment, when the current flowing through the first resistor exceeds the preset current Imax, the first control circuit 202 will conduct. The preset current Imax can be understood as the maximum current limit, which can be set according to the voltage in the first control circuit and the resistance value of the first resistor. The conduction of the first control circuit 202 clamps the gate (G) of the first control switch M1 to approximately 21V, with a voltage drop of approximately -3V between it and the source (S). At this time, the first control switch M1 is in the variable resistance region. When VGS rises to approximately 2V, the second control circuit 204 can be completely turned off. Turning off the second control circuit 204 completely turns off the first control switch M1, meaning that the power output terminal VCC_OUT does not output voltage, stopping power supply to the load. The first control switch M1 can be a MOSFET (Metal Oxide Semiconductor). Being in the variable resistance region means that changes in the gate voltage of the first control switch M1 significantly affect the current magnitude. In other words, the first control switch M1 in the variable resistance region can be equivalent to a variable resistor, with the current magnitude controlled by the gate. In this embodiment, the second control circuit will only be turned on and the first control switch M1 will only be turned on when the current flowing through the first resistor is less than or equal to the preset current Imax. Only then can the entire protection circuit work normally and continue to supply power to the load.

[0033] The protection circuit provided by this utility model allows the first control circuit to conduct and the second control circuit to turn off when the current flowing through the first resistor exceeds a preset current. When the second control circuit is off, it can also turn off the first control switch, stopping power supply to the load connected to the first control switch. When the current flowing through the first resistor is less than or equal to the preset current, the first control switch turns off and the second control circuit conducts. When the second control circuit is on, the first control switch turns on, supplying power to the load. By comparing the current flowing through the first resistor with the preset current, the first control switch connected to the load can be disconnected and power supply to the load can be stopped when the current exceeds the preset current. Therefore, this solves the problem of long response time in protection circuits leading to equipment damage, achieving the effect of reducing protection circuit response time and thus protecting the equipment.

[0034] In an exemplary embodiment, the first control circuit includes: a first transistor, a first terminal of which is connected to a second terminal of the first resistor, a second terminal of which is connected to the power input terminal, and a third terminal of which is connected to a third terminal of the second control circuit; and a second transistor, a first terminal of which is connected to a second terminal of the first resistor, a second terminal of which is connected to a second terminal of the first transistor, and a third terminal of which is connected to a first terminal of the first control switch.

[0035] In the above embodiments, see again Figure 2 The first control circuit 202 may include a first transistor Q1 and a second transistor Q2. The second terminal of the first transistor Q1 is connected to the power input terminal VCC_IN, and the third terminal is connected to the third terminal of the second control circuit 204. The third terminal of the first transistor Q1 can be directly connected to the third terminal of the second control circuit 204, or indirectly connected via a resistor. The first terminal of the second transistor Q2 is connected to the second terminal of a first resistor, the second terminal of the first transistor Q1, and the third terminal of the first control switch M1. The first transistor Q1 and the second transistor Q2 can automatically conduct when the current flowing through the first resistor exceeds a preset current Imax, thereby turning off the second control circuit 204 for protection. Once the overcurrent or overheating situation is eliminated, Q1 and Q2 in the first control circuit can automatically return to normal operating conditions without external intervention or restart, ensuring continuous operation of the load device. Furthermore, the preset current Imax can be controlled based on the voltage between the second and third terminals of the second transistor Q2. That is, the design of the first control circuit can adaptively adjust the current limit point Imax according to the actual working state (current and temperature) of the load device, so that the protection circuit can provide effective protection when facing different loads and working conditions without the need for manual adjustment of circuit parameters.

[0036] In one exemplary embodiment, the first control circuit includes: a second resistor, wherein a first terminal of the first transistor is connected to a second terminal of the first resistor via the second resistor; and a third resistor, wherein a first terminal of the second transistor is connected to a second terminal of the first resistor via the third resistor.

[0037] In the above embodiments, see again Figure 2 The first control circuit 202 also includes a second resistor R2 and a third resistor R3. The first terminal of the first transistor Q1 is connected to the second terminal of the first resistor via the second resistor R2, and the first terminal of the second transistor Q2 is connected to the second terminal of the first resistor via the third resistor R3. The second resistor R2 is connected in series with the first transistor Q1, and the third resistor R3 is connected in series with the second transistor Q2. This reduces the input voltage to a suitable range, which can be used to adjust the feedback signal to suit the input range of the control circuit.

[0038] In an exemplary embodiment, the second control circuit includes: a second control switch, a first terminal of which is connected to a fourth terminal of the first control circuit, and a second terminal of which is grounded; and a third transistor, a first terminal of which is connected to a third terminal of the second control switch, a second terminal of which is grounded, and a third terminal of which is connected to a first terminal of the first control switch.

[0039] In the above embodiments, see again Figure 2 The second control circuit 204 may include a second control switch M2 and a third transistor Q3. The first terminal of the second control switch M2 is connected to the fourth terminal of the first control circuit, and the second terminal is grounded. The first terminal of the third transistor Q3 is connected to the third terminal of the second control switch M2, the second terminal is grounded, and the third terminal is connected to the first terminal of the first control switch M1. The second terminal of the second control switch M2 is the fifth terminal of the second control circuit, and the second terminal of the third transistor is the fourth terminal of the second control circuit. When the first control circuit 202 is on, the first transistor Q1 gradually pulls up the VGS voltage of the second control switch M2, meaning the second control switch M2 is grounded, which turns off the third transistor Q3, thus turning off the entire second control circuit 204. When the load current is lower than the preset current Imax, the first transistor Q1 in the first control circuit 202 turns off. At this time, the VGS voltage of the second control switch M2 drops below 0.5V, which can control the third transistor Q3 to turn on, thus turning on the entire second control circuit 204.

[0040] In an exemplary embodiment, the second control circuit further includes a delay circuit, wherein a first terminal of the delay circuit is connected to a fourth terminal of the first control circuit, a second terminal of the delay circuit is connected to a first terminal of the second control switch, and a third terminal of the delay circuit is grounded.

[0041] In the above embodiments, see again Figure 2 The second control circuit 204 may further include a delay circuit 206. The first terminal of the delay circuit 202 is connected to the fourth terminal of the first control circuit, the second terminal of the delay circuit 206 is connected to the first terminal of the second control switch M2, and the third terminal is grounded. The third terminal of the delay circuit 206 is the same as the third terminal of the second control circuit 204. In overcurrent or overheat protection circuits, the delay circuit can prevent false protection triggering caused by instantaneous current or temperature fluctuations. For example, when a load starts, a high current may momentarily appear, but it will quickly drop to a normal level. If the protection circuit responds immediately, it may cause unnecessary protection action. With the delay circuit, the protection mechanism is only activated after the abnormality has lasted for a certain period, avoiding the impact of instantaneous interference on the system.

[0042] In one exemplary embodiment, the delay circuit includes: a fourth resistor, the first end of which is connected to a fourth terminal of the first control circuit; a fifth resistor, the first end of which is connected to a second terminal of the fourth resistor, the first end of which is also connected to a first terminal of the second control switch, and the second terminal of the fifth resistor is grounded; and a first capacitor, which is connected in parallel with the fifth resistor.

[0043] In the above embodiments, see again Figure 2 The delay circuit 206 may include a fourth resistor R4, a fifth resistor R5, and a first capacitor C1. The first terminal of the fourth resistor R4 is connected to the fourth terminal of the first control circuit 202. The first terminal of the fifth resistor R5 is connected to the second terminal of the fourth resistor R4, and the first terminal is also connected to the first terminal of the second control switch M2, while the second terminal is grounded. The second terminal of the fifth resistor is the third terminal of the delay circuit 206. The first terminal of the fifth resistor R5 can be directly connected to the second control switch M2, or it can be connected to the second control switch M2 through a thirteenth resistor R13. The first capacitor C1 is connected in parallel with the fifth resistor R5. When the first control circuit 202 is turned on, the first transistor Q1 can charge the first capacitor C1. The soft-start time of the protection circuit can be adjusted by adjusting the parameters of the first capacitor C1 and the fourth resistor R4, ensuring that the system restarts after a certain delay under stable voltage, avoiding frequent restarts caused by voltage fluctuations.

[0044] In an exemplary embodiment, the second control circuit includes: a first transient suppression diode, a first terminal of the first transient suppression diode being connected to a first terminal of the second control switch, and a second terminal of the first transient suppression diode being connected to a second terminal of the second control switch.

[0045] In the above embodiments, see again Figure 2 The second control circuit 204 may further include a first transient suppression diode D1, wherein a first terminal of the first transient suppression diode D1 is connected to a first terminal of the second control switch M2, and a second terminal is connected to a second terminal of the second control switch M2. The first transient suppression diode D1 can provide transient voltage protection. When the transient voltage exceeds the clamping voltage of the first transient suppression diode D1, the diode will quickly conduct, clamping the voltage at a preset level, thereby preventing the voltage from rising further and protecting other components in the circuit from damage by high voltage.

[0046] In an exemplary embodiment, the second control circuit includes: a second transient suppression diode, the first terminal of the second transient suppression diode being connected to the first terminal of the third transistor, and the second terminal of the second transient suppression diode being connected to the second terminal of the third transistor.

[0047] In the above embodiments, see again Figure 2The second control circuit 204 may also include a second transient suppression diode D2, wherein the first end of the second transient suppression diode D2 is connected to the first end of the third transistor Q3, and the second end is connected to the second end of the third transistor Q3. The second transient suppression diode D2 can also provide transient voltage protection, which can prevent voltage spikes caused by sudden changes in current of inductive load during switching from damaging the circuit.

[0048] In one exemplary embodiment, the second control circuit includes: a sixth resistor, the first end of which is connected to the third end of the second control switch, and the second end of which is connected to the first end of the third transistor; a seventh resistor, the first end of which is connected to the power input terminal, and the second end of which is connected to the first end of the sixth resistor; and an eighth resistor, the first end of which is connected to the second end of the seventh resistor, and the second end of which is grounded.

[0049] In the above embodiments, see again Figure 2 The second control circuit 204 may further include a sixth resistor R6, a seventh resistor R7, and an eighth resistor R8. The first terminal of the sixth resistor R6 is connected to the third terminal of the second control switch M2, and the second terminal is connected to the first terminal of the third transistor Q3. The first terminal of the seventh resistor R7 is connected to the power input terminal VCC_IN, and the second terminal is connected to the first terminal of the sixth resistor R6. The first terminal of the eighth resistor R8 is connected to the second terminal of the seventh resistor R7, and the second terminal is grounded. The series connection of the seventh resistor R7 and the eighth resistor R8 can be used for voltage division to prevent excessive current flowing through the second control switch M2 from damaging components. Furthermore, the series connection of the sixth resistor R6 and the third transistor Q3 can set the bias voltage of the third transistor Q3, ensuring it operates at the correct point. The first terminal of the seventh resistor is the first terminal of the second control circuit.

[0050] In one exemplary embodiment, the second control circuit includes: a second capacitor, a first terminal of the second capacitor being connected to a third terminal of the second control switch, the first terminal of the second capacitor also being connected to the power input terminal, and a second terminal of the second capacitor being grounded.

[0051] In the above embodiments, see again Figure 2The second control circuit 204 may further include a second capacitor C2. The first terminal of the second capacitor C2 is connected to the third terminal of the second control switch M2, and the first terminal is also connected to the power input terminal VCC_IN. The second terminal is grounded. Placing the second capacitor C2 at the power input terminal VCC_IN filters out high-frequency noise and transient voltage fluctuations in the power supply line, ensuring the stability of the power supply voltage and thus improving the stability and reliability of the entire circuit system. Furthermore, the second capacitor C2 can provide a soft-start function for the circuit. When the circuit is turned on (the current flowing through the first resistor is less than or equal to a preset current), it can delay the response time of the protection circuit, ensuring that the circuit will not falsely trigger the protection mechanism due to brief current or temperature fluctuations, thus improving the accuracy of the protection.

[0052] In one exemplary embodiment, the protection circuit further includes a ninth resistor, the first end of which is connected to the power input terminal, and the second end of which is connected to the first end of the second capacitor.

[0053] In the above embodiments, see again Figure 2 The protection circuit may also include a ninth resistor R9, wherein the first end of the ninth resistor R9 is connected to the power input terminal VCC_IN, and the second end is connected to the first end of the second capacitor C2. When the current flowing through the first resistor exceeds the preset circuit, the current flowing through the first transistor Q1 can be adjusted through the ninth resistor R9, limiting the current flowing into the base, which can prevent the transistor from oversaturating or entering the cutoff state, thereby better controlling the transistor's conduction and turn-off.

[0054] In an exemplary embodiment, the first resistor includes: a tenth resistor, the first end of which is connected to the power input terminal; and a thermistor, the first end of which is connected to the second end of the tenth resistor, and the second end of which is connected to the second terminal of the first control switch.

[0055] In the above embodiments, see again Figure 2The first resistor may include a tenth resistor R10 and a thermistor RT1. The first terminal of the tenth resistor R10 is connected to the power input terminal VCC_IN, and the first terminal of the thermistor RT1 is connected to the second terminal of the tenth resistor R10. The second terminal of the thermistor RT1 is connected to the second terminal of the first control switch M1. The thermistor RT1 can be understood as a thermal sensor. At room temperature, the resistance of the thermistor RT1 is 0. As the temperature increases, the resistance increases. The preset current Imax can be calculated using the following formula: Imax = Vbe / Rsense, where Rsense can be understood as the sum of the resistances of the tenth resistor R10 and the thermistor RT1, increasing with temperature, thus Imax decreases with increasing temperature. Vbe can be understood as the voltage between terminals 1 and 2 of the second transistor Q2. After confirming the preset current Imax, the resistance of the tenth resistor R10 can be set to Vbe / Imax. That is, when Vbe≈0.5V, the resistance of the tenth resistor R10 can be 0.51Ω, and the preset current Imax at this time is 0.5V / 0.51Ω=980mA.

[0056] In the above embodiment, the thermistor monitors the temperature at the load end. For example, in a motor system, motor stall or overload is often accompanied by heat generation. In this case, the output current decreases, protecting the motor from over-power burnout of the motor windings. The tenth resistor R10 can be understood as a sampling resistor, detecting the current flowing through the thermistor. The tenth resistor R10 and the thermistor RT1 can simultaneously monitor the load from both current and temperature perspectives, resulting in low cost and enabling constant current control. Furthermore, the entire protection circuit system is simple, without complex sampling and main control acquisition. Through dual feedback of current and temperature, it has a fast response speed, achieving dual protection for the load.

[0057] In one exemplary embodiment, the protection circuit further includes: an eleventh resistor, the first end of which is connected to the first end of the first resistor, and the second end of which is connected to the first end of the first control switch; and a twelfth resistor, the third end of the first control circuit being connected to the second end of the second control circuit through the twelfth resistor.

[0058] In the above embodiments, see again Figure 2The protection circuit may further include an eleventh resistor R11 and a twelfth resistor R12. The first end of the eleventh resistor R11 is connected to the first end of the first resistor, and the second end is connected to the first end of the first control switch M1. The third end of the first control circuit 202 is connected to the second end of the second control circuit 204 through the twelfth resistor R12. The eleventh resistor R11 is connected in parallel with the first resistor and is located at the input terminal of the protection circuit. It can be used to limit the current flowing through the circuit during circuit startup or sudden load changes, preventing overcurrent. The twelfth resistor R12 is connected in series with the third transistor Q3, forming the load portion of the circuit. It can be used to convert voltage signals into current signals to set the gain and stability of the circuit. The first end of the twelfth resistor is the second end of the second control circuit.

[0059] In one exemplary embodiment, the second control circuit includes a fourteenth resistor, a first end of which is connected to a first end of the second control switch, and a second end of which is grounded.

[0060] In the above embodiments, the second control circuit may further include a fourteenth resistor R14, wherein the fourteenth resistor R14 may have its first end connected to the first end of the second control switch M2, and its second end grounded. The fourteenth resistor R14 can be selectively connected or not connected in the protection circuit. This ensures that, when the second control switch M2 is in a saturated state, the voltage between the third and second ends of the second control switch M2 will not exceed a certain threshold, thereby protecting the circuit from overvoltage.

[0061] This embodiment also provides a protection circuit system, including a power supply, a load device, and the protection circuit described in any of the above embodiments. The power supply is connected to the power input terminal of the protection circuit, and the power output terminal of the protection circuit is connected to the load device.

[0062] In the above embodiments, the overall architecture diagram of the protection circuit can be found here. Figure 2 , Figure 2 This is a protection circuit block diagram according to a specific embodiment of the present utility model, such as... Figure 2As shown, the protection circuit may include a first resistor, a first control circuit 202, a first control switch M1, and a second control circuit 204. The first terminal of the first resistor is connected to the power input terminal VCC_IN of the protection circuit, and the second terminal is connected to the second terminal of the first control switch M1. The first terminal of the first control circuit 202 is connected to the power input terminal VCC_IN, and the second terminal is connected to the second terminal of the first resistor. The first terminal of the first control switch M1 is connected to the third terminal of the first control circuit 202, the second terminal is connected to the second terminal of the first resistor, and the third terminal is connected to the power output terminal VCC_OUT of the protection circuit. The power output terminal VCC_OUT can be connected to the load to be monitored, which can be a capacitive load, an inductive load, or a motor, etc. The first terminal of the second control circuit 204 is connected to the power input terminal VCC_IN, the second terminal is connected to the first terminal of the first control switch M1, and the third, fourth, and fifth terminals are grounded.

[0063] In the above embodiment, when the current flowing through the first resistor exceeds the preset current Imax, the first control circuit 202 will conduct. The preset current Imax can be understood as the maximum current limit, which can be set according to the voltage in the first control circuit and the resistance value of the first resistor. The conduction of the first control circuit 202 clamps the gate (G) of the first control switch M1 to approximately 21V, with a voltage drop of approximately -3V between it and the source (S). At this time, the first control switch M1 is in the variable resistance region. When VGS rises to approximately 2V, the second control circuit 204 can be completely turned off. Turning off the second control circuit 204 completely turns off the first control switch M1, meaning that the power output terminal VCC_OUT does not output voltage, stopping power supply to the load. The first control switch M1 can be a MOSFET (Metal Oxide Semiconductor). Being in the variable resistance region means that changes in the gate voltage of the first control switch M1 significantly affect the current magnitude. In other words, the first control switch M1 in the variable resistance region can be equivalent to a variable resistor, with the current magnitude controlled by the gate. In this embodiment, the second control circuit will only be turned on and the first control switch M1 will only be turned on when the current flowing through the first resistor is less than or equal to the preset current Imax. Only then can the entire protection circuit work normally and continue to supply power to the load.

[0064] In the above embodiments, see again Figure 2The first control circuit 202 may include a first transistor Q1 and a second transistor Q2. The second terminal of the first transistor Q1 is connected to the power input terminal VCC_IN, and the third terminal is connected to the third terminal of the second control circuit 204. The third terminal of the first transistor Q1 can be directly connected to the third terminal of the second control circuit 204, or indirectly connected via a resistor. The first terminal of the second transistor Q2 is connected to the second terminal of a first resistor, the second terminal of the first transistor Q1, and the third terminal of the first control switch M1. The first transistor Q1 and the second transistor Q2 can automatically conduct when the current flowing through the first resistor exceeds a preset current Imax, thereby turning off the second control circuit 204 for protection. Once the overcurrent or overheating situation is eliminated, Q1 and Q2 in the first control circuit can automatically return to normal operating conditions without external intervention or restart, ensuring continuous operation of the load device. Furthermore, the preset current Imax can be controlled based on the voltage between the second and third terminals of the second transistor Q2. That is, the design of the first control circuit can adaptively adjust the current limit point Imax according to the actual working state (current and temperature) of the load device, so that the protection circuit can provide effective protection when facing different loads and working conditions without the need for manual adjustment of circuit parameters.

[0065] In the above embodiments, see again Figure 2 The first control circuit 202 also includes a second resistor R2 and a third resistor R3. The first terminal of the first transistor Q1 is connected to the second terminal of the first resistor via the second resistor R2, and the first terminal of the second transistor Q2 is connected to the second terminal of the first resistor via the third resistor R3. The second resistor R2 is connected in series with the first transistor Q1, and the third resistor R3 is connected in series with the second transistor Q2. This reduces the input voltage to a suitable range, which can be used to adjust the feedback signal to suit the input range of the control circuit.

[0066] In the above embodiments, see again Figure 2The second control circuit 204 may include a second control switch M2 and a third transistor Q3. The first terminal of the second control switch M2 is connected to the fourth terminal of the first control circuit, and the second terminal is grounded. The first terminal of the third transistor Q3 is connected to the third terminal of the second control switch M2, the second terminal is grounded, and the third terminal is connected to the first terminal of the first control switch M1. The second terminal of the second control switch M2 is the fifth terminal of the second control circuit, and the second terminal of the third transistor is the fourth terminal of the second control circuit. When the first control circuit 202 is on, the first transistor Q1 gradually pulls up the VGS voltage of the second control switch M2, meaning the second control switch M2 is grounded, which turns off the third transistor Q3, thus turning off the entire second control circuit 204. When the load current is lower than the preset current Imax, the first transistor Q1 in the first control circuit 202 turns off. At this time, the VGS voltage of the second control switch M2 drops below 0.5V, which can control the third transistor Q3 to turn on, thus turning on the entire second control circuit 204.

[0067] In the above embodiments, see again Figure 2 The second control circuit 204 may further include a delay circuit 206. The first terminal of the delay circuit 202 is connected to the fourth terminal of the first control circuit, the second terminal of the delay circuit 206 is connected to the first terminal of the second control switch M2, and the third terminal is grounded. The third terminal of the delay circuit 206 is the same as the third terminal of the second control circuit 204. In overcurrent or overheat protection circuits, the delay circuit can prevent false protection triggering caused by instantaneous current or temperature fluctuations. For example, when a load starts, a high current may momentarily appear, but it will quickly drop to a normal level. If the protection circuit responds immediately, it may cause unnecessary protection action. With the delay circuit, the protection mechanism is only activated after the abnormality has lasted for a certain period, avoiding the impact of instantaneous interference on the system.

[0068] In the above embodiments, see again Figure 2The delay circuit 206 may include a fourth resistor R4, a fifth resistor R5, and a first capacitor C1. The first terminal of the fourth resistor R4 is connected to the fourth terminal of the first control circuit 202. The first terminal of the fifth resistor R5 is connected to the second terminal of the fourth resistor R4, and the first terminal is also connected to the first terminal of the second control switch M2, while the second terminal is grounded. The second terminal of the fifth resistor is the third terminal of the delay circuit 206. The first terminal of the fifth resistor R5 can be directly connected to the second control switch M2, or it can be connected to the second control switch M2 through a thirteenth resistor R13. The first capacitor C1 is connected in parallel with the fifth resistor R5. When the first control circuit 202 is turned on, the first transistor Q1 can charge the first capacitor C1. The soft-start time of the protection circuit can be adjusted by adjusting the parameters of the first capacitor C1 and the fourth resistor R4, ensuring that the system restarts after a certain delay under stable voltage, avoiding frequent restarts caused by voltage fluctuations.

[0069] In the above embodiments, see again Figure 2 The second control circuit 204 may further include a first transient suppression diode D1, wherein a first terminal of the first transient suppression diode D1 is connected to a first terminal of the second control switch M2, and a second terminal is connected to a second terminal of the second control switch M2. The first transient suppression diode D1 can provide transient voltage protection. When the transient voltage exceeds the clamping voltage of the first transient suppression diode D1, the diode will quickly conduct, clamping the voltage at a preset level, thereby preventing the voltage from rising further and protecting other components in the circuit from damage by high voltage.

[0070] In the above embodiments, see again Figure 2 The second control circuit 204 may also include a second transient suppression diode D2, wherein the first end of the second transient suppression diode D2 is connected to the first end of the third transistor Q3, and the second end is connected to the second end of the third transistor Q3. The second transient suppression diode D2 can also provide transient voltage protection, which can prevent voltage spikes caused by sudden changes in current of inductive load during switching from damaging the circuit.

[0071] In the above embodiments, see again Figure 2The second control circuit 204 may further include a sixth resistor R6, a seventh resistor R7, and an eighth resistor R8. The first terminal of the sixth resistor R6 is connected to the third terminal of the second control switch M2, and the second terminal is connected to the first terminal of the third transistor Q3. The first terminal of the seventh resistor R7 is connected to the power input terminal VCC_IN, and the second terminal is connected to the first terminal of the sixth resistor R6. The first terminal of the eighth resistor R8 is connected to the second terminal of the seventh resistor R7, and the second terminal is grounded. The series connection of the seventh resistor R7 and the eighth resistor R8 can be used for voltage division to prevent excessive current flowing through the second control switch M2 from damaging components. Furthermore, the series connection of the sixth resistor R6 and the third transistor Q3 can set the bias voltage of the third transistor Q3, ensuring it operates at the correct point. The first terminal of the seventh resistor is the first terminal of the second control circuit.

[0072] In the above embodiments, see again Figure 2 The second control circuit 204 may further include a second capacitor C2. The first terminal of the second capacitor C2 is connected to the third terminal of the second control switch M2, and the first terminal is also connected to the power input terminal VCC_IN. The second terminal is grounded. Placing the second capacitor C2 at the power input terminal VCC_IN filters out high-frequency noise and transient voltage fluctuations in the power supply line, ensuring the stability of the power supply voltage and thus improving the stability and reliability of the entire circuit system. Furthermore, the second capacitor C2 can provide a soft-start function for the circuit. When the circuit is turned on (the current flowing through the first resistor is less than or equal to a preset current), it can delay the response time of the protection circuit, ensuring that the circuit will not falsely trigger the protection mechanism due to brief current or temperature fluctuations, thus improving the accuracy of the protection.

[0073] In the above embodiments, see again Figure 2 The protection circuit may also include a ninth resistor R9, wherein the first end of the ninth resistor R9 is connected to the power input terminal VCC_IN, and the second end is connected to the first end of the second capacitor C2. When the current flowing through the first resistor exceeds the preset circuit, the current flowing through the first transistor Q1 can be adjusted through the ninth resistor R9, limiting the current flowing into the base, which can prevent the transistor from oversaturating or entering the cutoff state, thereby better controlling the transistor's conduction and turn-off.

[0074] In the above embodiments, see again Figure 2The first resistor may include a tenth resistor R10 and a thermistor RT1. The first terminal of the tenth resistor R10 is connected to the power input terminal VCC_IN, and the first terminal of the thermistor RT1 is connected to the second terminal of the tenth resistor R10. The second terminal of the thermistor RT1 is connected to the second terminal of the first control switch M1. The thermistor RT1 can be understood as a thermal sensor. At room temperature, the resistance of the thermistor RT1 is 0. As the temperature increases, the resistance increases. The preset current Imax can be calculated using the following formula: Imax = Vbe / Rsense, where Rsense can be understood as the sum of the resistances of the tenth resistor R10 and the thermistor RT1, increasing with temperature, thus Imax decreases with increasing temperature. Vbe can be understood as the voltage between terminals 1 and 2 of the second transistor Q2. After confirming the preset current Imax, the resistance of the tenth resistor R10 can be set to Vbe / Imax. That is, when Vbe≈0.5V, the resistance of the tenth resistor R10 can be 0.51Ω, and the preset current Imax at this time is 0.5V / 0.51Ω=980mA.

[0075] In the above embodiment, the thermistor monitors the temperature at the load end. For example, in a motor system, motor stall or overload is often accompanied by heat generation. In this case, the output current decreases, protecting the motor from over-power burnout of the motor windings. The tenth resistor R10 can be understood as a sampling resistor, detecting the current flowing through the thermistor. The tenth resistor R10 and the thermistor RT1 can simultaneously monitor the load from both current and temperature perspectives, resulting in low cost and enabling constant current control. Furthermore, the entire protection circuit system is simple, without complex sampling and main control acquisition. Through dual feedback of current and temperature, it has a fast response speed, achieving dual protection for the load.

[0076] In the above embodiments, see again Figure 2 The protection circuit may further include an eleventh resistor R11 and a twelfth resistor R12. The first end of the eleventh resistor R11 is connected to the first end of the first resistor, and the second end is connected to the first end of the first control switch M1. The third end of the first control circuit 202 is connected to the second end of the second control circuit 204 through the twelfth resistor R12. The eleventh resistor R11 is connected in parallel with the first resistor and is located at the input terminal of the protection circuit. It can be used to limit the current flowing through the circuit during circuit startup or sudden load changes, preventing overcurrent. The twelfth resistor R12 is connected in series with the third transistor Q3, forming the load portion of the circuit. It can be used to convert voltage signals into current signals to set the gain and stability of the circuit. The first end of the twelfth resistor is the second end of the second control circuit.

[0077] In the above embodiments, the second control circuit may further include a fourteenth resistor R14, wherein the fourteenth resistor R14 may have its first end connected to the first end of the second control switch M2, and its second end grounded. The fourteenth resistor R14 can be selectively connected or not connected in the protection circuit. This ensures that, when the second control switch M2 is in a saturated state, the voltage between the third and second ends of the second control switch M2 will not exceed a certain threshold, thereby protecting the circuit from overvoltage.

[0078] Obviously, those skilled in the art will understand that the modules or steps of the present invention described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. They can be implemented using computer-executable program code, and thus can be stored in a storage device for execution by a computing device. In some cases, the steps shown or described can be performed in a different order than those presented here, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, the present invention is not limited to any particular combination of hardware and software.

[0079] The above description is merely a preferred embodiment of this utility model and is not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A protection circuit, characterized by, The application relates to a protection circuit, which comprises: a first resistor, a first end of the first resistor being connected with a power input end of the protection circuit, wherein the power input end is configured to be connected with a power supply; a first control circuit, a first end of the first control circuit being connected with the power input end, and a second end of the control circuit being connected with a second end of the first resistor; a first control switch, a first end of the first control switch being connected with a third end of the first control circuit, a second end of the first control switch being connected with the second end of the first resistor, and a third end of the first control switch being connected with a power output end of the protection circuit, wherein the power output end is configured to be connected with a load to supply power to the load; a second control circuit, a first end of the second control circuit being connected with the power input end, a second end of the second control circuit being connected with a first end of the first control switch, and a third end, a fourth end and a fifth end of the second control circuit being grounded; wherein, when the current of the first resistor is greater than a preset current, the first control circuit is turned on, the second control circuit is turned off, the first control switch is turned off to stop supplying power to the load; when the current of the first resistor is less than or equal to the preset current, the first control switch is turned off, the second control circuit is turned on to control the first control switch to be turned on to supply power to the load.

2. The protection circuit of claim 1, wherein The first control circuit comprises: a first triode, a first end of the first triode being connected with the second end of the first resistor, a second end of the first triode being connected with the power input end, and a third end of the first triode being connected with the third end of the second control circuit; a second triode, a first end of the second triode being connected with the second end of the first resistor, a second end of the second triode being connected with the second end of the first triode, and a third end of the second triode being connected with the first end of the first control switch.

3. The protection circuit of claim 2, wherein, The first control circuit comprises: a second resistor, the first end of the first triode being connected with the second end of the first resistor through the second resistor; a third resistor, the first end of the second triode being connected with the second end of the first resistor through the third resistor.

4. The protection circuit of claim 1, wherein, The second control circuit comprises: a second control switch, a first end of the second control switch being connected with the fourth end of the first control circuit, and a second end of the second control switch being grounded; a third triode, a first end of the third triode being connected with a third end of the second control switch, a second end of the third triode being grounded, and a third end of the third triode being connected with the first end of the first control switch.

5. The protection circuit of claim 4, wherein, The second control circuit further comprises a delay circuit, a first end of the delay circuit being connected with the fourth end of the first control circuit, a second end of the delay circuit being connected with the first end of the second control switch, and a third end of the delay circuit being grounded.

6. The protection circuit of claim 5, wherein, The delay circuit comprises: a fourth resistor, a first end of the fourth resistor being connected with the fourth end of the first control circuit; a fifth resistor, a first end of the fifth resistor is connected with the second end of the fourth resistor, and the first end of the fifth resistor is also connected with the first end of the second control switch, and a second end of the fifth resistor is grounded; a first capacitor, the first capacitor is connected with the fifth resistor in parallel.

7. The protection circuit of claim 4, wherein, The second control circuit comprises: a first transient suppression diode, a first end of the first transient suppression diode is connected with the first end of the second control switch, and a second end of the first transient suppression diode is connected with the second end of the second control switch.

8. The protection circuit of claim 4, wherein, The second control circuit comprises: a second transient suppression diode, a first end of the second transient suppression diode is connected with the first end of the third transistor, and a second end of the second transient suppression diode is connected with the second end of the third transistor.

9. The protection circuit of claim 4, wherein, The second control circuit comprises: a sixth resistor, a first end of the sixth resistor is connected with the third end of the second control switch, and a second end of the sixth resistor is connected with the first end of the third transistor; a seventh resistor, a first end of the seventh resistor is connected with the power input end, and a second end of the seventh resistor is connected with the first end of the sixth resistor; an eighth resistor, a first end of the eighth resistor is connected with the second end of the seventh resistor, and a second end of the eighth resistor is grounded.

10. The protection circuit of claim 4, wherein, The second control circuit comprises: a second capacitor, a first end of the second capacitor is connected with the third end of the second control switch, and the first end of the second capacitor is also connected with the power input end, and a second end of the second capacitor is grounded.

11. The protection circuit according to claim 10, characterized in that The protection circuit further comprises: a ninth resistor, a first end of the ninth resistor is connected with the power input end, and a second end of the ninth resistor is connected with the first end of the second capacitor.

12. The protection circuit of claim 1, wherein, The first resistor comprises: a tenth resistor, a first end of the tenth resistor is connected with the power input end; a thermistor, a first end of the thermistor is connected with a second end of the tenth resistor, and a second end of the thermistor is connected with the second end of the first control switch.

13. The protection circuit of claim 1, wherein, The protection circuit further comprises: an eleventh resistor, a first end of the eleventh resistor is connected with the first end of the first resistor, and a second end of the eleventh resistor is connected with the first end of the first control switch; a twelfth resistor, a third end of the first control circuit is connected with a second end of the second control circuit through the twelfth resistor.

14. A protection circuit system, characterized by comprise a power supply, a load device, and the protection circuit according to any one of claims 1 to 13, the power supply is connected with the power input end of the protection circuit, and the power output end of the protection circuit is connected with the load device.

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