A hot plug protection circuit

Abstract

The utility model discloses a kind of hot plug protection circuits, mainly including by thyristor and voltage divider resistance component input voltage overshoot detection circuit, by triode component MOS pipe control circuit, and hot plug controller and main power MOS pipe. Through the voltage division and delay network of resistance and capacitor composition, input surge voltage is detected in real time, and pass through flip-flop device drive transistor control enable path, to judge whether main power MOS pipe is cut off;While combining current detection resistance monitoring power supply loop current state, realize the double protection of overvoltage and overcurrent.Hot plug controller is judged according to input signal synthesis, pass through grid control main power MOS pipe on-off, ensure that power supply path is rapidly disconnected under abnormal state, prevent damage to electrical load.The utility model circuit structure is compact, response is fast, and anti-interference ability is strong, applicable to the power supply and distribution system needing to support hot plug operation.

Description

Technical Field

[0001] This utility model relates to the field of circuit protection technology, and in particular to a hot-swap protection circuit, especially a protection circuit design technology for detecting and quickly responding to hot-swap surge voltage and current. Background Technology

[0002] In modern electronic systems, especially in fields such as communications, computing, industrial control, and high-performance computing devices, the insertion and removal of power modules and load modules are frequent and often require hot-swapping functionality—that is, directly inserting or removing modules while the device is powered on without cutting off the power to the entire system. While hot-swapping improves the convenience of system maintenance and component replacement, it also raises a series of potential electrical safety and equipment reliability issues.

[0003] During hot-swapping, the power supply and load circuit are in direct contact under unsteady conditions, and the establishment of the instantaneous current path is often accompanied by drastic changes in surge voltage and surge current. This sudden change may be caused by a combination of factors, including nonlinear fluctuations in contact resistance, transient changes in power supply output impedance, and the coupling effects of system parasitic parameters (such as parasitic capacitance and inductance). On the one hand, the high-amplitude surge voltage generated during hot-swapping may break down the input protection devices of the electrical load; on the other hand, the sudden large current is also very likely to cause the power devices to overheat or even burn out, and in severe cases, it may even cause the entire power supply system to fail.

[0004] To address these issues, traditional systems typically employ protection methods such as delayed power-on, NTC thermistors, and capacitor soft-start. However, these methods have significant limitations in terms of response speed, circuit integration, and load adaptability, failing to meet the demands of high-density power architectures or applications requiring increasingly rapid switching. For example, traditional capacitor buffer structures struggle to achieve effective voltage suppression in a very short time, while thermistor devices suffer from thermal saturation and are prone to failure after repeated hot-swapping operations.

[0005] Therefore, designing a hot-swap control circuit with fast response, high reliability, compact structure, and dual overvoltage and overcurrent protection has become a significant technical challenge in the power supply system field. Especially in systems with large capacitance on the load side or the risk of short-term reverse current, there is an urgent need to construct an intelligent protection mechanism that can dynamically monitor the power supply status and control the on / off state in real time to ensure the stability of the system and the safety of the electrical equipment during hot-swapping. Utility Model Content

[0006] To solve the above-mentioned technical problems, this utility model provides a hot-swap protection circuit.

[0007] Specifically, the technical solution provided by this utility model is as follows: A hot-swap protection circuit includes a power input terminal and a load connection terminal. The positive terminal VIN+ of the power input terminal is connected to the positive terminal VOUT+ of the load connection terminal through a MOSFET Q1, and the negative terminal VIN- of the power input terminal is connected to the negative terminal VOUT- of the load connection terminal and grounded. The positive terminal VIN+ is connected to a voltage divider branch, which includes resistors R4 and R10 connected in series, with resistor R10 grounded. The connection between resistors R4 and R10 is connected to the R terminal of thyristor U3. The K terminal of thyristor U3 is connected to the positive terminal VIN+ through resistor R3, and the K terminal is also connected to transistor Q3 to drive transistor Q3. Transistor Q3 is used to drive MOSFET Q4. Resistors R5 and R6 are connected between the positive terminal VIN+ and the negative terminal VIN-. The connection between resistors R5 and R6 is connected to MOSFET Q4 and simultaneously to the EN terminal of the hot-swap controller. The GATE terminal of the hot-swap controller is connected to MOSFET Q1 and is used to drive MOSFET Q1.

[0008] Furthermore, a current sensing resistor RCS is provided between the positive electrode VIN+ and the MOSFET Q1, and this resistor is connected to the SENSE terminal of the hot-swap controller.

[0009] Furthermore, resistor R10 is connected in parallel with capacitor C1, and resistor R10 and capacitor C1 together form an RC buffer network.

[0010] Furthermore, resistor R6 is connected in parallel with capacitor C3, and resistor R6 and capacitor C3 together form an RC buffer network.

[0011] Furthermore, the K terminal of the thyristor U3 is connected to the base of the transistor Q3 through the Zener diode ZD1, the emitter of the transistor Q3 is connected to the positive terminal VIN+ through the resistor R9, and the collector of the transistor Q3 is connected to the gate of the MOSFET Q4; the source of the MOSFET Q4 is grounded, and its drain is connected to the EN terminal of the hot-swap controller.

[0012] Furthermore, a decoupling component consisting of a resistor R8 and a capacitor C2 connected in parallel is provided between the gate and source of the MOS transistor Q4.

[0013] This invention introduces a multi-level collaborative control mechanism, utilizes a voltage divider network and thyristors to achieve real-time monitoring of input surge voltage, and improves anti-interference capability while ensuring response speed through the parallel structure of delay capacitor C1 and resistor R10. Furthermore, by combining the cascaded control method of transistors and field-effect transistors, it achieves dual-channel judgment and independent blocking of voltage and current in the protection logic, significantly improving the accuracy and reliability of protection actions.

[0014] Furthermore, the hot-swap controller U1 not only integrates current detection, enable control, and MOS gate drive functions, but also possesses rapid response and external fault condition identification capabilities, enabling the entire system to achieve high integration and high reliability while maintaining a compact structure. Especially in the event of surge voltage or current anomalies, the system can complete the judgment and power-off operation within microseconds, effectively preventing damage to downstream electrical equipment from overvoltage, overcurrent, or short circuits, significantly improving safety and fault tolerance during the hot-swap process. Attached Figure Description

[0015] The accompanying drawings are provided to further understand the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation thereof.

[0016] Figure 1 This is a hot-swap protection circuit diagram provided in an embodiment of the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are all within the protection scope of this utility model.

[0018] This embodiment provides a hot-swap protection circuit, the core objective of which is to monitor and quickly cut off the risks that may be caused by abnormal conditions such as surge voltage, inrush current, and load short circuit during the hot-swap of electronic devices, thereby effectively protecting the stability and safety of downstream load circuits.

[0019] like Figure 1 As shown, the circuit design provided in this embodiment mainly includes: an input voltage overshoot detection circuit composed of thyristor U3, resistors R3, R4, and R10; a gate control circuit of MOSFET Q4 composed of Zener diode ZD1, resistor R9, and transistor Q3; an enable circuit composed of MOSFET Q4, resistors R5 and R6; and a hot-swap controller U1 (such as LTC4211) and MOSFET Q1.

[0020] After power is connected to the input terminal VIN+, the power supply voltage first enters the voltage overshoot detection circuit. When the input voltage is within the normal range, the voltage is divided by R4 and R10 (the voltage division value is less than 2.5V) and sent to thyristor U3, which is not turned on. At this time, transistor Q3 connected to the output terminal (K terminal) of U3 remains off, and its base is connected to U3 by Zener diode ZD1, ensuring that it only conducts under high voltage excitation. When Q3 is off, the gate of MOSFET Q4 is at a low level, and Q4 is off. In this state, the enable voltage EN of hot-swap controller U1 is determined by the voltage division of R5 and R6 and is kept within the normal operating voltage range, so that the GATE pin of U1 outputs a high level, driving MOSFET Q1 to conduct, and the power supply voltage is successfully transferred to the output terminal VOUT+, completing the normal power supply to the load.

[0021] If an input voltage overshoot occurs during hot-plugging, such as due to capacitor imbalance or sudden changes in power supply impedance leading to excessively high surge voltage, the voltage division value of R4 and R10 increases, exceeding the trigger threshold of U3 (e.g., 2.5V). At this point, U3 turns on, driving Q3 to turn on rapidly. After Q3 turns on, it pulls up the gate voltage of MOSFET Q4, causing Q4 to turn on. After Q4 turns on, the EN terminal voltage of the hot-plug controller U1 is pulled low. U1 detects that the EN terminal voltage is lower than the set value and immediately pulls the GATE terminal output low, turning off Q1. This quickly disconnects the power supply path to the load, preventing overvoltage damage to the load devices.

[0022] In addition to voltage anomaly monitoring, this embodiment also introduces an overcurrent protection mechanism. A current sensing resistor RCS is connected in series in the power output path and is connected to the SENSE pin of U1. When the current through Q1 exceeds a preset threshold, the voltage drop across RCS increases. After U1 detects that the SENSE voltage is higher than the limit, it will also lower the level of the GATE pin, causing Q1 to quickly turn off and cut off the power supply path. This mechanism is particularly suitable for suppressing large current surges, such as load-side short circuits or sudden starting currents.

[0023] In addition, to ensure the stability of the control response and the filtering effect, multiple sets of capacitors are introduced into the circuit. C1 and the voltage divider resistor R10 are connected in parallel to form an RC snubber network, which not only participates in the voltage division process, but also has key functions such as transient filtering, anti-interference and trigger delay control; C2 and R8 are connected in parallel between the gate of Q4 and ground, as a decoupling component of the Q4 gate; C3 and R6 are connected to form an RC snubber network for the Q4 enable path to prevent false triggering caused by excessively fast fluctuations at the EN terminal.

[0024] In summary, this circuit achieves overvoltage detection through input voltage division and comparison triggering, and overcurrent detection through a current sensing resistor. With U1 as the core control unit, it controls the on / off state of the power MOSFET Q1. By introducing filtering and protection components at multiple nodes, it forms a hot-swap protection system integrating voltage detection, current detection, logic judgment, signal transmission, and MOSFET driving. This system is widely applicable to DC power supply applications with high reliability requirements, ensuring safe isolation and timely protection between the power system and the load system during device hot-swapping.

[0025] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it; although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A hot-swap protection circuit, characterized in that, It includes a power input terminal and a load connection terminal. The positive terminal VIN+ of the power input terminal is connected to the positive terminal VOUT+ of the load connection terminal through the MOSFET Q1, and the negative terminal VIN- of the power input terminal is connected to the negative terminal VOUT- of the load connection terminal and grounded. The positive terminal VIN+ is connected to a voltage divider branch, which includes resistors R4 and R10 connected in series, with resistor R10 grounded. The connection between resistors R4 and R10 is connected to the R terminal of thyristor U3. The K terminal of thyristor U3 is connected to the positive terminal VIN+ through resistor R3, and the K terminal is also connected to transistor Q3 to drive transistor Q3. Transistor Q3 is used to drive MOSFET Q4. Resistors R5 and R6 are connected between the positive terminal VIN+ and the negative terminal VIN-. The connection between resistors R5 and R6 is connected to MOSFET Q4 and simultaneously to the EN terminal of the hot-swap controller. The GATE terminal of the hot-swap controller is connected to MOSFET Q1 and is used to drive MOSFET Q1.

2. The hot-swap protection circuit as described in claim 1, characterized in that, A current sensing resistor RCS is also provided between the positive electrode VIN+ and the MOSFET Q1, and this resistor is connected to the SENSE terminal of the hot-swap controller.

3. The hot-swap protection circuit as described in claim 1, characterized in that, The resistor R10 is connected in parallel with the capacitor C1, and the resistor R10 and the capacitor C1 together form an RC buffer network.

4. The hot-swap protection circuit as described in claim 1, characterized in that, The resistor R6 is connected in parallel with the capacitor C3, and the resistor R6 and the capacitor C3 together form an RC buffer network.

5. The hot-swap protection circuit as described in claim 1, characterized in that, The K terminal of the thyristor U3 is connected to the base of the transistor Q3 through the Zener diode ZD1. The emitter of the transistor Q3 is connected to the positive terminal VIN+ through the resistor R9. The collector of the transistor Q3 is connected to the gate of the MOSFET Q4. The source of the MOSFET Q4 is grounded, and its drain is connected to the EN terminal of the hot-swap controller.

6. The hot-swap protection circuit as described in claim 5, characterized in that, A decoupling component consisting of a resistor R8 and a capacitor C2 connected in parallel is also provided between the gate and source of the MOS transistor Q4.

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