CN111934304A - A protection circuit and protection method for preventing hot-swap voltage surge - Google Patents

Abstract

The invention discloses a protection circuit and a protection method for preventing hot-plug voltage surges, and relates to the technical field of circuit design. The circuit includes a power MOS field effect transistor, an optocoupler D2 and an impedance resistor; the power MOS field effect transistor includes an N-channel power MOS transistor Q3 and a P-channel power MOS transistor Q2; The cathode is connected to the G pole of the power MOS transistor Q3, and the collector output end is connected to the G pole of the power MOS transistor Q2; the impedance resistor includes a low impedance resistor R2 and high impedance resistors R3 and R4. In this embodiment, the above protection circuit is used to replace the surge protection component TVS on the traditional hot-swap line, which effectively improves the response speed of the surge protection at the input end, and increases the alarm function for small surges, avoiding the need for surge protection devices. An issue where the response is too slow to cause damage to the backend components.

Description

A protection circuit and protection method for preventing hot-swap voltage surge

technical field

Embodiments of the present invention relate to the technical field of circuit design, and in particular, to a protection circuit and a protection method for preventing hot-swap voltage surges.

Background technique

Hot-swap controllers are a preferred method for providing highly desirable system protection and electrical management in distributed power systems, especially for the stringent requirements of the server market. Features of hot-swap controllers typically include safe control of live circuit board insertion and removal, fault monitoring, diagnosis and protection, and control of high-precision electrical environments. In practice, if a fault occurs in one line card of a server rack, the fault should remain isolated from that particular line card and neither affect the system backplane nor other line cards powered by that live backplane. Therefore, to ensure reliability, server system designers must consider the parasitics and associated transient behavior of hot-swap circuits.

In existing designs, as shown in Figure 1, to prevent surge voltages from damaging vulnerable downstream components, a fast-responding unidirectional TVS silicon diode is typically connected from VIN to GND in a shunt protection configuration. TVS diodes are similar to Zener diodes with optimized die area and bonding capabilities for high inrush current and peak power dissipation during avalanche breakdown. Therefore, it is theoretically simple and easy to use this protection mechanism. Under normal working conditions, the TVS diode presents a high impedance to the protected circuit, but when the safe working voltage of the protected circuit exceeds the safe working voltage of the protected circuit, the TVS diode works in the avalanche mode, which is The transient current provides a low impedance path to ground. The maximum voltage of the protected circuit is usually small and limited by the clamping voltage of the TVS diode. The TVS device returns to a high impedance state after the transient current is reduced. However, in actual use, the above protection mechanism still has shortcomings: First, the allowable deviation of the reverse working voltage of the TVS diode is very large. According to the TVS data sheet, the higher the reverse working voltage required by the TVS, the greater the deviation. , the required TVS diode cannot be selected more accurately; secondly, when the input voltage is slightly higher, but the overvoltage protection of the hot-swap controller is not reached, there is no way to notify the control system in time.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a protection circuit and a protection method for preventing hot-swap voltage surges, effectively improving the response speed of voltage surge protection, and at the same time increasing the alarm function for small surges, so as to avoid the slow response of the surge protection device. Problems with broken backend components.

To achieve the above object, the present invention discloses the following technical solutions:

One aspect of the present invention provides a protection circuit for preventing hot-swap voltage surges, comprising a power MOS field effect transistor, a photocoupler D2 and an impedance resistor;

The power MOS field effect transistor includes an N-channel power MOS transistor Q3 and a P-channel power MOS transistor Q2;

The cathode of the input end of the optocoupler D2 is connected to the G pole of the power MOS transistor Q3, and the collector output end is connected to the G pole of the power MOS transistor Q2;

The impedance resistors include a low impedance resistor R2 and high impedance resistors R3 and R4.

Based on the above circuit, further, one end of the impedance resistors R2, R3 and R4 is connected to the input voltage Vin, and the other end is connected to the S pole of the MOS transistor Q2, the anode of the input end of the photocoupler D2 and the S pole of the MOS transistor Q3, respectively. The D pole of the tube Q2 and the emitter of the photocoupler D2 are both grounded.

Further, the protection circuit also includes a current-limiting resistor R5 and a current-limiting resistor R7; one end of the resistor R5 is connected to the D pole of the MOS tube Q3, and the other end is connected to the circuit system; one end of the resistor R7 is connected to the input end of the optocoupler D2. The cathode is connected and the other end is grounded.

Further, the protection circuit also includes a current detection resistor R1, an N-channel power MOS transistor Q1 and an output capacitor C1; one end of the current detection resistor R1 is connected to the input voltage Vin, and the other end is connected to the S pole of the MOS transistor Q1; The G pole of Q1 is connected to the hot-swap controller, and the other end is connected to the output voltage Vout; one end of the output capacitor C1 is connected to the output voltage Vout, and the other end is grounded.

The protection circuit for preventing hot-swap voltage surges as described above, when there is a large surge voltage at the input end, the input end of the photocoupler D2 drives the photodiode to emit light, and generates a photocurrent after being received by the photodetector , and then output after further amplification, and then drive the gate of MOS transistor Q2 to make the gate become low level and grounded, and the drain and source of Q2 are connected, which is equal to the conduction between the input terminal and the ground, thus effectively protecting the circuit. At the same time, the photodiode at the input end of the photocoupler D2 drives the gate of the MOS transistor Q3, so that the gate sends a high-level signal to the circuit system. The response speed of the optocoupler is relatively fast, and the high-impedance resistor R3 can be used to control the voltage value of the protection more accurately.

When the surge voltage at the input terminal does not reach the set value, the photodiode of the optocoupler D2 will also drive the gate of the MOS transistor Q3, but the driving potential is relatively low, so that the gate sends a high-level signal to the circuit system. Make the system notice that there is a surge at the input.

Another aspect of the present invention provides a protection method for preventing hot-swap voltage surges, the protection method comprising the following steps:

An N-channel power MOS transistor Q3, an optocoupler D2 and a P-channel power MOS transistor Q2 are arranged between the voltage input terminal Vin and the circuit system;

Connect the cathode of the input end of the optocoupler D2 to the G pole of the power MOS transistor Q3, and the collector output end to the G pole of the power MOS transistor Q2;

Connect the D pole of the MOS tube Q3 to the circuit system through the current limiting resistor R5, the S pole of the MOS tube Q2, the anode of the input end of the photocoupler D2 and the S pole of the MOS tube Q3 are connected to the voltage input through the impedance resistors R2, R3 and R4 respectively. terminal Vin connection.

Further, the above-mentioned protection method for preventing hot-swap voltage surges further includes the following steps:

A current limiting resistor R7 is set between the cathode of the input end of the optocoupler D2 and the G electrode of the power MOS transistor Q3, and the other end of the current limiting resistor R7 is grounded;

The D pole of the MOS transistor Q2 and the emitter pole of the photocoupler D2 are grounded.

Further, based on the above-mentioned protection method, also comprise the following steps:

Set current detection resistor R1, N-channel power MOS transistor Q1 and output capacitor C1;

Connect one end of the current detection resistor R1 to the input voltage Vin, and the other end to the S pole of the MOS transistor Q1;

Connect the G pole of the MOS transistor Q1 to the hot-swap controller, and the other end to the output voltage Vout;

One end of the output capacitor C1 is connected to the output voltage Vout, and the other end is grounded.

The effects provided in the summary of the invention are only the effects of the embodiments, rather than all the effects of the invention. One of the above technical solutions has the following advantages or beneficial effects:

A protection circuit and a protection method for preventing hot-swap voltage surge provided by the embodiment of the present application, an N-channel power MOS transistor Q3, a photocoupler D2 and a P-channel power MOS are arranged between the voltage input terminal and the circuit system tube Q2; the cathode of the input terminal of the photocoupler D2 is connected to the G pole of the MOS tube Q3, and the collector output terminal is connected to the G pole of the MOS tube Q2; the D pole of the MOS tube Q3 is connected to the circuit system through the current limiting resistor R5, and the MOS tube The S pole of Q2, the anode of the input end of the photocoupler D2 and the S pole of the MOS transistor Q3 are respectively connected to the voltage input end through impedance resistors R2, R3 and R4. This embodiment adopts the above-mentioned protection circuit and method to replace the surge protection component TVS on the traditional hot-swappable line, effectively improving the response speed of the surge protection at the input end, and increasing the alarm function for small surges, avoiding sudden surges. The wave protector reacts too slowly, causing damage to the rear components. The technical solution of this embodiment can be applied to different hot-swap controllers, and surge voltage protection is performed by changing the resistance.

Description of drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description serve to explain the principles of the application.

Figure 1 is a schematic structural diagram of a traditional hot-swap voltage surge protection circuit;

2 is a schematic structural diagram of a protection circuit for preventing hot-swap voltage surges according to an embodiment of the present application;

FIG. 3 is a schematic flowchart of a protection method for preventing a hot-plug voltage surge according to an embodiment of the present application.

Detailed ways

In order to make those skilled in the art better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described The embodiments are only some of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

In order to facilitate the understanding of the embodiments, the abbreviations and key terms involved in the embodiments are explained and described below.

TVS diode: Transient-voltage-suppression diode, transient voltage suppression diode;

Hotswap Controller: hot swap controller;

System: circuit system.

FIG. 2 shows a schematic structural diagram of a protection circuit for preventing hot-plug voltage surge provided by an embodiment of the present application.

Referring to FIG. 2 , the protection circuit for preventing hot-swap voltage surges in this embodiment includes a power MOS field effect transistor, an optocoupler D2 and an impedance resistor;

The power MOS field effect transistor includes an N-channel power MOS transistor Q3 and a P-channel power MOS transistor Q2;

The cathode of the input terminal of the optocoupler D2 is connected to the G pole of the power MOS transistor Q3, and the collector output terminal is connected to the G pole of the power MOS transistor Q2;

The impedance resistors include low impedance resistor R2 and high impedance resistors R3 and R4.

Specifically, as shown in FIG. 2 , one end of the impedance resistors R2, R3 and R4 is connected to the input voltage Vin, and the other end is connected to the S pole of the MOS transistor Q2, the anode of the input end of the photocoupler D2 and the S pole of the MOS transistor Q3 respectively. pole, the D pole of the MOS transistor Q2 and the emitter of the photocoupler D2 are both grounded.

Further, the protection circuit also includes a current-limiting resistor R5 and a current-limiting resistor R7; one end of the resistor R5 is connected to the D pole of the MOS tube Q3, and the other end is connected to the circuit system; one end of the resistor R7 is connected to the input end of the optocoupler D2. The cathode is connected and the other end is grounded.

More specifically, the protection circuit further includes a current detection resistor R1, an N-channel power MOS transistor Q1 and an output capacitor C1; one end of the current detection resistor R1 is connected to the input voltage Vin, and the other end is connected to the S pole of the MOS transistor Q1; The G pole of the MOS transistor Q1 is connected to the hot-swap controller, and the other end is connected to the output voltage Vout; one end of the output capacitor C1 is connected to the output voltage Vout, and the other end is grounded.

The protection circuit for preventing hot-swap voltage surges as described above, when there is a large surge voltage at the input end, the input end of the photocoupler D2 drives the photodiode to emit light, and generates a photocurrent after being received by the photodetector , and then output after further amplification, and then drive the gate of MOS transistor Q2 to make the gate become low level and grounded, the drain and source of Q2 are connected, which is equal to the conduction between the input terminal and the ground, thus effectively protecting the circuit, The conducting current will be determined according to the surge voltage. If the current is too large, the power supply end will be protected against overcurrent. At the same time, the photodiode at the input end of the photocoupler D2 drives the gate of the MOS transistor Q3, so that the gate sends a high-level signal to the circuit system. The response speed of the optocoupler is relatively fast, and the high-impedance resistor R3 can be used to control the voltage value of the protection more accurately.

When the surge voltage at the input terminal does not reach the set value, the photodiode of the optocoupler D2 will also drive the gate of the MOS transistor Q3, but the driving potential is relatively low, so that the gate sends a high-level signal to the circuit system. Make the system notice that there is a surge at the input.

FIG. 3 shows a schematic flowchart of a protection method for preventing a hot-plug voltage surge provided by an embodiment of the present application.

Referring to FIG. 3 , the protection method for preventing hot-swap voltage surges in this embodiment includes the following steps:

S1. An N-channel power MOS transistor Q3, an optocoupler D2 and a P-channel power MOS transistor Q2 are arranged between the voltage input terminal Vin and the circuit system;

S2. Connect the cathode of the input end of the photocoupler D2 to the G pole of the power MOS transistor Q3, and the collector output end to the G pole of the power MOS transistor Q2;

S3. Connect the D pole of the MOS transistor Q3 to the circuit system through the current limiting resistor R5. The S pole of the MOS transistor Q2, the anode of the input end of the photocoupler D2 and the S pole of the MOS transistor Q3 pass through the impedance resistors R2, R3 and R4 respectively. The voltage input terminal Vin is connected.

Further, the above-mentioned protection method for preventing hot-swap voltage surges further includes the following steps:

A current limiting resistor R7 is set between the cathode of the input end of the optocoupler D2 and the G electrode of the power MOS transistor Q3, and the other end of the current limiting resistor R7 is grounded;

The D pole of the MOS transistor Q2 and the emitter pole of the photocoupler D2 are grounded.

Further, above-mentioned protection method, also comprises the following steps:

Set current detection resistor R1, N-channel power MOS transistor Q1 and output capacitor C1;

Connect one end of the current detection resistor R1 to the input voltage Vin, and the other end to the S pole of the MOS transistor Q1;

Connect the G pole of the MOS transistor Q1 to the hot-swap controller, and the other end to the output voltage Vout;

One end of the output capacitor C1 is connected to the output voltage Vout, and the other end is grounded.

For the content not described in detail in the protection method for preventing hot-plug voltage surge provided in the embodiment of the present application, reference may be made to the protection circuit for preventing hot-plug voltage surge provided in the above embodiment, and details are not described herein again.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, any modifications, improvements and equivalent replacements made without departing from the principles of the present invention, etc. , are included in the protection scope of the present invention.

Claims (8)

1. A protection circuit for preventing hot plug voltage surge is characterized by comprising a power MOS field effect transistor, a photoelectric coupler D2 and an impedance resistor;

the power MOS field effect transistor comprises an N-channel power MOS transistor Q3 and a P-channel power MOS transistor Q2;

the cathode of the input end of the photoelectric coupler D2 is connected with the G pole of the power MOS tube Q3, and the output end of the collector is connected with the G pole of the power MOS tube Q2;

the impedance resistor comprises a low impedance resistor R2 and high impedance resistors R3 and R4.

2. The protection circuit of claim 1, wherein one end of the resistance resistors R2, R3 and R4 is connected to the input voltage Vin, the other end is connected to the S-pole of the MOS transistor Q2, the anode of the input terminal of the photocoupler D2 and the S-pole of the MOS transistor Q3, and the D-pole of the MOS transistor Q2 and the emitter of the photocoupler D2 are all grounded.

3. The protection circuit for preventing hot swap voltage surge according to claim 1, wherein the protection circuit further comprises a current limiting resistor R5 and a current limiting resistor R7; one end of the resistor R5 is connected with the D pole of the MOS transistor Q3, and the other end is connected with the circuit system; one end of the resistor R7 is connected with the cathode of the input end of the photoelectric coupler D2, and the other end is grounded.

4. The protection circuit for preventing hot swap voltage surge according to claim 1, wherein the protection circuit further comprises a current detection resistor R1, an N-channel power MOS transistor Q1 and an output capacitor C1; one end of the current detection resistor R1 is connected with the input voltage Vin, and the other end is connected with the S pole of the MOS transistor Q1; the G pole of the MOS tube Q1 is connected with a hot plug controller, and the other end of the MOS tube Q1 is connected with an output voltage Vout; one end of the output capacitor C1 is connected to the output voltage Vout, and the other end is connected to ground.

5. The protection circuit for preventing hot plug voltage surge according to claim 1, wherein when the surge voltage at the input terminal exceeds the predetermined value, the input terminal of the photocoupler D2 drives the photodiode to emit light, which is received by the photodetector to generate a photocurrent which is further amplified and output, and further drives the MOS transistor Q2 to turn on the drain and the source of the Q2, and the photodiode at the input terminal of the photocoupler D2 drives the gate of the MOS transistor Q3 to send a high level signal to the circuit system.

6. The protection circuit of claim 1, wherein when the input surge voltage does not reach the predetermined value, the photodiode of the optocoupler D2 drives the gate of the MOS transistor Q3, so that the gate sends a high signal to the circuitry.

7. A protection method for preventing hot plug voltage surge is characterized by comprising the following steps:

an N-channel power MOS tube Q3, a photoelectric coupler D2 and a P-channel power MOS tube Q2 are arranged between the voltage input end and the circuit system;

the cathode of the input end of the photoelectric coupler D2 is connected with the G pole of a power MOS tube Q3, and the output end of the collector is connected with the G pole of a power MOS tube Q2;

the D pole of the MOS transistor Q3 is connected to a circuit system through a current-limiting resistor R5, and the S pole of the MOS transistor Q2, the anode of the input end of the photoelectric coupler D2 and the S pole of the MOS transistor Q3 are respectively connected with a voltage input end through impedance resistors R2, R3 and R4.

8. The method according to claim 7, further comprising the steps of:

a current-limiting resistor R7 is arranged between the cathode of the input end of the photoelectric coupler D2 and the G pole of the power MOS transistor Q3, and the other end of the resistor R7 is grounded;

the D pole of the MOS transistor Q2 and the emitter of the photocoupler D2 are grounded.

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