Short-circuit protection circuit

Abstract

The utility model relates to the technical field of power supplies, in particular to a short-circuit protection circuit, which comprises a lightning protection module, a switch tube Q3, a voltage division module, a cathode current detection module, a short-circuit protection module and a controller U1, an external power supply is connected with the voltage division module after passing through the lightning protection module, the voltage division module is used for providing break-over voltage for the control end of the switch tube Q3, and the cathode current detection module is connected with the short-circuit protection module through the controller U1. One switch end of the switch tube Q3 is connected with the negative electrode of the power supply through the negative electrode current detection module, the other switch end of the switch tube Q3 is grounded, the negative electrode current detection module is in signal connection with the controller U1, and the controller U1 controls the short circuit protection module to work according to a received current signal. And the short-circuit protection module controls the closing of the switch tube Q3 according to a control signal of the controller U1. According to the utility model, the situation that the rear-end switch is damaged by large current due to short circuit of the power supply can be prevented, the reliability and stability of the switch are greatly improved, the principle is simple, and the cost is low.

Description

Technical Field

[0001] The utility model relates to the technical field of power supply, in particular to a short-circuit protection circuit. Background Art

[0002] With the advancement of network communications technology, Power over Ethernet (PoE) has gained widespread adoption in various applications due to its convenience and flexibility. PoE allows both power and data signals to be transmitted over the same Ethernet cable, simplifying installation and reducing cabling costs. PoE switches are particularly popular in the Internet of Things (IoT), security surveillance, wireless access points, and other fields.

[0003] Most PoE switches currently on the market use direct current (DC) power supplies. While this method is convenient and fast, it also carries potential safety risks. In particular, if a DC power supply fails, such as a short circuit, it can generate a significant short-circuit current. This can damage not only the power supply itself but also the connected PoE switch. This situation is common in real-world applications, and the risk is particularly significant for PoE switches operating in harsh environments.

[0004] To prevent equipment damage caused by power short circuits, existing solutions typically rely on overcurrent protection devices such as fuses or thermistors. However, these devices often fail to provide adequate protection, especially in high-power PoE applications. Furthermore, these traditional protection measures often require regular maintenance or replacement, increasing costs and maintenance difficulties. Summary of the Invention

[0005] The utility model provides a short-circuit protection circuit to solve the problems of the prior art, which can prevent the large current from damaging the back-end switch due to a power short circuit, thereby greatly improving the reliability and stability of the switch, and has a simple principle and low cost.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions: a short-circuit protection circuit, including a lightning protection module, a switch tube Q3, a voltage divider module, a negative current detection module, a short-circuit protection module and a controller U1. The external power supply is connected to the voltage divider module after passing through the lightning protection module. The voltage divider module is used to provide a conduction voltage for the control end of the switch tube Q3. One switch end of the switch tube Q3 is connected to the negative pole of the power supply through the negative current detection module, and the other switch end of the switch tube Q3 is grounded. The negative current detection module is connected to the controller U1 signal. The controller U1 controls the operation of the short-circuit protection module according to the received current signal, and the short-circuit protection module controls the shutdown of the switch tube Q3 according to the control signal of the controller U1.

[0007] Preferably, the voltage divider module includes a resistor R1, a resistor R3 and a voltage regulator diode D3, the external power supply is connected to one end of the resistor R3 through the resistor R1, the other end of the resistor R3 is connected to the other switch end of the switch tube Q3, and the voltage regulator diode D3 is connected in parallel with the resistor R3.

[0008] Preferably, the negative electrode current detection module includes a resistor R7, a resistor R6, a resistor R5 and a switch tube Q2, the switch tube Q3 is connected to the negative electrode of the external power supply through the resistor R7, one end of the resistor R6 is connected to the controller U1, and the other end of the resistor R6 is connected to the control end of the switch tube Q2 through the resistor R5, one switch end of the switch tube Q2 is grounded, and the other switch end of the switch tube Q2 is connected to the control end of the switch tube Q3.

[0009] Preferably, the short-circuit protection module includes a resistor R2, a resistor R4 and a switch tube Q1, one end of the resistor R4 is connected to the controller U1, the other end of the resistor R4 is connected to the control end of the switch tube Q1, one end of the resistor R2 is connected to the positive pole of the external power supply, the other end of the resistor R2 is connected to one end of the resistor R4, one switch end of the switch tube Q1 is grounded, and the other switch end of the switch tube Q1 is connected to the control end of the switch tube Q3.

[0010] Preferably, the lightning protection module includes a Zener diode D2 and a capacitor C1, the cathode of the Zener diode D2 is connected to the positive electrode of the external power supply, the anode of the Zener diode D2 is grounded, and the capacitor C1 is connected in parallel with the Zener diode D2.

[0011] Beneficial effects of the utility model:

[0012] 1. It can prevent the situation where a large current caused by a power short circuit damages the back-end switch, thus greatly improving the reliability and stability of the switch;

[0013] 2. The design is simple and reliable, the faults are easy to eliminate and the maintenance cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is the circuit schematic diagram of the utility model;

[0015] Figure 2 This is a circuit diagram of the controller of the present utility model.

[0016] exist Figures 1 to 2 Reference numerals in the figures include:

[0017] 1-Lightning protection module, 2-voltage divider module, 3-negative current detection module, 4-short circuit protection module. DETAILED DESCRIPTION

[0018] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with the embodiments and drawings. The contents mentioned in the embodiments are not intended to limit the present invention. The present invention is described in detail below in conjunction with the drawings.

[0019] This embodiment provides a short circuit protection circuit, such as Figure 1 and Figure 2 , including a lightning protection module 1, a switch tube Q3, a voltage divider module 2, a negative current detection module 3, a short-circuit protection module 4 and a controller U1. The external power supply is connected to the voltage divider module 2 after passing through the lightning protection module. The voltage divider module 2 is used to provide a conduction voltage for the control end of the switch tube Q3. One switch end of the switch tube Q3 is connected to the negative pole of the power supply through the negative current detection module 3, and the other switch end of the switch tube Q3 is grounded. The negative current detection module 3 is signal-connected to the controller U1. The controller U1 controls the operation of the short-circuit protection module 4 according to the received current signal, and the short-circuit protection module 4 controls the shutdown of the switch tube Q3 according to the control signal of the controller U1.

[0020] Among them, the controller U1 is a conventional controller U1 such as a single chip microcomputer. Figure 2 As shown, a signal can be received and a signal for control adjustment can be issued according to the received signal.

[0021] The switch tube Q3 of the embodiment is a MOS tube, and the switch tube Q1 and the switch tube Q2 are triodes. Specifically, the voltage division module 2 of the embodiment includes the resistor R1, the resistor R3, and the voltage stabilizing diode D3. The external power supply is connected to one end of the resistor R1 and the resistor R3, the other end of the resistor R3 is connected to the other switch end of the switch tube Q3, and the voltage stabilizing diode D3 is connected in parallel with the resistor R3. The negative current detection module 3 includes the resistor R7, the resistor R6, the resistor R5, and the switch tube Q2. The switch tube Q3 is connected to the negative pole of the external power supply through the resistor R7, one end of the resistor R6 is connected to the controller U1, the other end of the resistor R6 is connected to the control end of the switch tube Q2 through the resistor R5, one switch end of the switch tube Q2 is grounded, and the other switch end of the switch tube Q2 is connected to the control end of the switch tube Q3. The short circuit protection module 4 includes the resistor R2, the resistor R4, and the switch tube Q1. One end of the resistor R4 is connected to the controller U1, the other end of the resistor R4 is connected to the control end of the switch tube Q1, one end of the resistor R2 is connected to the positive pole of the external power supply, the other end of the resistor R2 is connected to one end of the resistor R4, one switch end of the switch tube Q1 is grounded, and the other switch end of the switch tube Q1 is connected to the control end of the switch tube Q3. The lightning protection module includes the voltage stabilizing diode D2 and the capacitor C1. The cathode of the voltage stabilizing diode D2 is connected to the positive pole of the external power supply, the anode of the voltage stabilizing diode D2 is grounded, and the capacitor C1 is connected in parallel with the voltage stabilizing diode D2. The specific connection mode is shown in Figure 1 .

[0022] As Figure 1 , the specific working principle of the embodiment is as follows:

[0023] 1. When the DC power supply is input, it first passes through the TVS tube, i.e., the voltage stabilizing diode D2 and the filter capacitor C1. The voltage stabilizing diode D2 is mainly used for lightning protection, providing a discharge channel for the incoming lightning energy to protect the rear-end circuit. Then it passes through the resistor R1 and the resistor R3 connected in parallel with the positive and negative poles. The resistor R1 and the resistor R3 are mainly used for voltage division of the gate of the switch tube Q3 and limiting the current of the gate of the switch tube Q3. At the same time, after voltage division of the resistor R1 and the resistor R3, the voltage stabilizing diode D3 connected in parallel with the resistor R3 will stabilize the voltage of the gate of the switch tube Q3 at 12V, protecting the gate of the switch tube Q3. At this time, the switch tube Q3 is turned on, and the circuit starts to work normally.

[0024] 2. When the positive and negative poles start to short circuit, the current of the negative pole will increase sharply when passing through the resistor R7, which will cause the voltage at both ends of the resistor R7 to rise. Then, through the resistor R5, the current of the base and emitter of the switch tube Q2 is increased, and the collector and emitter are turned on. The switch tube Q2 is in an amplification state, i.e., the low voltage of the gate of the switch tube Q3 is pulled down by the switch tube Q2, but it is not pulled down to 0V. At this time, the switch tube Q3 is still in a half-conductive state, which can reduce the current size from full conduction to half conduction.

[0025] 3. At the same time, after the voltage across resistor R7 increases, it can be detected by the ADC pin of the MCU, i.e., the controller U1, through resistor R6. When the controller U1 finds that the voltage of the ADC pin detecting the negative electrode has increased and exceeded the limit value, the controller U1 will give the base of the switch tube Q1 a high level (3.3V) through resistor R4, so that current flows between the base and emitter of the switch tube Q1, thereby turning on the switch tube Q1, and then lowering the gate voltage of the switch tube Q3, turning off the switch tube Q3, thereby protecting the back-end circuit from damaging the switch due to large currents generated by faults such as short circuits.

[0026] Therefore, the circuit breaker protection circuit of this embodiment can prevent the situation where a large current caused by a power short circuit damages the back-end switch, thereby greatly improving the reliability and stability of the switch. In addition, the circuit is simple and reliable, faults are easy to troubleshoot, maintenance costs are low, service life is long, and it is more practical.

[0027] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention is disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of the above-disclosed technical contents without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technology of the present invention, which do not depart from the content of the technical solution of the present invention, are within the scope of the technical solution of the present invention.

Claims

1. A short-circuit protection circuit, characterized in that: It includes a lightning protection module, a switch tube Q3, a voltage divider module, a negative current detection module, a short-circuit protection module and a controller U1. The external power supply is connected to the voltage divider module after passing through the lightning protection module. The voltage divider module is used to provide a conduction voltage for the control end of the switch tube Q3. One switch end of the switch tube Q3 is connected to the negative pole of the power supply through the negative current detection module, and the other switch end of the switch tube Q3 is grounded. The negative current detection module is connected to the controller U1 signal. The controller U1 controls the operation of the short-circuit protection module according to the received current signal, and the short-circuit protection module controls the shutdown of the switch tube Q3 according to the control signal of the controller U1.

2. The short-circuit protection circuit according to claim 1, characterized in that: The voltage divider module includes a resistor R1, a resistor R3 and a voltage regulator diode D3. The external power supply is connected to one end of the resistor R3 through the resistor R1, and the other end of the resistor R3 is connected to the other switch end of the switch tube Q3. The voltage regulator diode D3 is connected in parallel with the resistor R3.

3. The short-circuit protection circuit according to claim 1, characterized in that: The negative electrode current detection module includes a resistor R7, a resistor R6, a resistor R5 and a switch tube Q2. The switch tube Q3 is connected to the negative electrode of the external power supply through the resistor R7. One end of the resistor R6 is connected to the controller U1. The other end of the resistor R6 is connected to the control end of the switch tube Q2 through the resistor R5. One switch end of the switch tube Q2 is grounded, and the other switch end of the switch tube Q2 is connected to the control end of the switch tube Q3.

4. The short-circuit protection circuit according to claim 1, characterized in that: The short-circuit protection module includes a resistor R2, a resistor R4, and a switch tube Q1. One end of the resistor R4 is connected to the controller U1, and the other end of the resistor R4 is connected to the control end of the switch tube Q1. One end of the resistor R2 is connected to the positive electrode of the external power supply, and the other end of the resistor R2 is connected to one end of the resistor R4. One switch end of the switch tube Q1 is grounded, and the other switch end of the switch tube Q1 is connected to the control end of the switch tube Q3.

5. The short-circuit protection circuit according to claim 1, characterized in that: The lightning protection module includes a voltage-stabilizing diode D2 and a capacitor C1 . The cathode of the voltage-stabilizing diode D2 is connected to the positive electrode of the external power supply, the anode of the voltage-stabilizing diode D2 is grounded, and the capacitor C1 is connected in parallel with the voltage-stabilizing diode D2 .

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