A circuit for fast turn-off MOS

Abstract

The application relates to a circuit capable of quickly turning off a MOS, which comprises a driving chip, a diode D1, a MOS Q2, a resistor R2 and a triode Q1, the positive electrode of the diode D1 is connected with the driving chip, the negative electrode of the diode D1 is connected with the G electrode of the MOS Q2, the B electrode of the triode Q1 is connected with the driving chip, the E electrode of the triode Q1 is connected with the G electrode of the MOS Q2, the C electrode of the triode Q1 is connected with one end of the resistor R2, the other end of the resistor R2 is connected with the S electrode of the MOS Q2, one end of the resistor R1 is connected with the driving chip, the other end of the resistor R1 is connected with the G electrode of the MOS Q2, one end of the resistor R3 is connected with the S electrode of the MOS Q2, and the other end of the resistor R3 is connected with the driving chip; the voltage of the G electrode of the MOS Q2 is discharged through the resistor R1, the voltage of the S electrode of the MOS Q2 is discharged through the resistor R3, the voltage of the G electrode of the MOS Q2 can make the C and E electrodes of the triode Q1 conduct, the voltage between the G electrode and the S electrode is pulled to be consistent and reduced to 0 through the resistor R2, and the quick turn-off function is realized.

Description

Technical Field

[0001] This invention relates to the field of circuit protection, and in particular to a circuit that can quickly turn off a MOS transistor. Background Technology

[0002] To increase overcurrent protection, existing circuits, such as lithium battery BMS or protection boards, typically use multiple MOSFETs connected in parallel. This parallel connection increases the junction capacitance across the gate-source (GS) terminals of the entire MOSFET. When the BMS or protection board needs to perform circuit breaker protection, it must quickly turn off the MOSFETs to protect the lithium battery. Because the junction capacitance increases with multiple parallel connections, the MOSFET turn-off time is prolonged, effectively leaving the MOSFET in a semi-conductive state with high internal resistance. Furthermore, a large current flows through the MOSFET during a short circuit, potentially causing overload and damage, resulting in the MOSFET failing to shut off the discharge circuit in the event of a battery pack short circuit.

[0003] To solve the above problems, the voltage across the gate and source terminals of the MOS is usually discharged through a discharge circuit via a discharge resistor at the source terminal of the MOS. However, this results in a slow turn-off time for the MOS, a slow decrease in the VGS voltage of the MOS, and a prolonged period of time in the semi-conducting region. The large current passing through the MOS during a short circuit causes the MOS to overheat and be damaged. Therefore, it is necessary to design a method that can turn off the MOS faster. Summary of the Invention

[0004] Therefore, it is necessary to provide a circuit that can quickly turn off the MOS to address the problem of slow MOS turn-off speed.

[0005] A circuit capable of quickly turning off a MOSFET includes a driver chip, a diode D1, a MOSFET Q2, a resistor R2, and a transistor Q1. The positive terminal of the diode D1 is connected to the driver chip, the negative terminal of the diode D1 is connected to the gate (G) terminal of the MOSFET Q2, the base (B) terminal of the transistor Q1 is connected to the driver chip, the emitter (E) terminal of the transistor Q1 is connected to the gate (G) terminal of the MOSFET Q2, the collector (C) terminal of the transistor Q1 is connected to one end of the resistor R2, and the other end of the resistor R2 is connected to the source (S) terminal of the MOSFET Q2. One end of resistor R1 is connected to the driver chip, and the other end of resistor R1 is connected to the gate (G) terminal of MOSFET Q2. One end of resistor R3 is connected to the source (S) terminal of MOSFET Q2, and the other end of resistor R3 is connected to the driver chip. The voltage at the gate (G) terminal of MOSFET Q2 is discharged through resistor R1, and the voltage at the source (S) terminal of MOSFET Q2 is discharged through resistor R3. The voltage at the gate (G) terminal of MOSFET Q2 will cause the collector (C) and emitter (E) terminals of transistor Q1 to conduct. Through resistor R2, the voltage across the gate (G) and source terminals will be pulled down to 0, thus quickly turning off the transistor.

[0006] In one embodiment, a diode Z1 is further included, the positive terminal of which is connected to the source terminal (S) of the MOSFET Q2, and the negative terminal of which is connected to the drain terminal (D) of the MOSFET Q2.

[0007] In one embodiment, the drain terminal of the MOS transistor Q2 can be used as an input terminal.

[0008] In one embodiment, the source terminal of the MOS transistor Q2 can form an output terminal.

[0009] This invention incorporates a resistor R2 and a transistor Q1. The positive terminal of diode D1 is connected to the driver chip, the negative terminal of diode D1 is connected to the gate (G) terminal of MOSFET Q2, the base (B) terminal of transistor Q1 is connected to the driver chip, the emitter (E) terminal of transistor Q1 is connected to the gate (G) terminal of MOSFET Q2, the collector (C) terminal of transistor Q1 is connected to one end of resistor R2, and the other end of resistor R2 is connected to the source (S) terminal of MOSFET Q2. One end of resistor R1 is connected to the driver chip, and the other end of resistor R1 is connected to the gate (G) terminal of MOSFET Q2. One end of resistor R3 is connected to the source (S) terminal of MOSFET Q2, and the other end of resistor R3 is connected to the driver chip. The voltage at the gate (G) terminal of the MOSFET is released through resistor R1, and the voltage at the source (S) terminal is released through resistor R3. Furthermore, the gate (G) voltage of the MOSFET causes the collector (C) and emitter (E) terminals of transistor Q1 to conduct. Then, through resistor R2, the voltages VGS are pulled together and finally dropped to 0, thereby achieving a rapid turn-off effect. Attached Figure Description

[0010] Figure 1 This is the circuit diagram of the present invention. Detailed Implementation

[0011] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0012] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0013] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

[0014] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0015] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0016] Please see Figure 1 This invention relates to a circuit that can quickly turn off a MOS transistor. Its main function is to quickly turn off the MOS transistor when circuit protection is required, thereby increasing the turn-off time and thus providing circuit protection.

[0017] In this embodiment, the device includes a driver chip 10, a diode D1, a MOSFET Q2, a resistor R2, and a transistor Q1. The positive terminal of the diode D1 is connected to the driver chip, the negative terminal of the diode D1 is connected to the gate (G) terminal of the MOSFET Q2, the base (B) terminal of the transistor Q1 is connected to the driver chip, the emitter (E) terminal of the transistor Q1 is connected to the gate (G) terminal of the MOSFET Q2, the collector (C) terminal of the transistor Q1 is connected to one end of the resistor R2, and the other end of the resistor R2 is connected to the source (S) terminal of the MOSFET Q2. The voltage at the gate (G) terminal of the MOSFET Q2 will cause the collector (C) and emitter (E) terminals of the transistor Q1 to conduct, and the voltage across the gate (G) and source (S) terminals will be brought together by the resistor R2.

[0018] Additionally, it includes resistors R1 and R3. One end of resistor R1 is connected to the driver chip, and the other end of resistor R1 is connected to the gate (G) terminal of the MOSFET Q2. One end of resistor R3 is connected to the source (S) terminal of the MOSFET Q2, and the other end of resistor R3 is connected to the driver chip.

[0019] When a rapid turn-off of MOSFET Q2 is required, the main function of resistor R1 is to simultaneously discharge the voltage at the gate (G) terminal of MOSFET Q2 through resistor R1. This discharges and dissipates the electrical charge stored in the junction capacitance of MOSFET Q2 until the voltage at the gate terminal of MOSFET Q2 is completely discharged. Therefore, when resistor R1 is connected, the voltage at the gate terminal of MOSFET Q2 can be further released, reducing the voltage at the gate terminal of MOSFET Q2 to 0. By adjusting resistor R1, the discharge rate at the gate terminal of MOSFET Q2 can be adjusted.

[0020] Furthermore, a resistor R3 is included. One end of resistor R3 is connected to the source (S) terminal of MOSFET Q2, and the other end is connected to the driver chip 10. When MOSFET Q2 is turned off, the voltage at the source terminal of MOSFET Q2 is discharged through resistor R3, causing the voltage at the source terminal of MOSFET Q2 to be released quickly. Furthermore, the discharge time of the voltage at the source terminal of MOSFET Q2 can be adjusted by changing the value of resistor R3 to meet the circuit requirements.

[0021] The driver chip 10 can output a drive signal, and the two ends of diode D1 are connected to the driver chip 10 and the gate (G) terminal of MOSFET Q2, respectively. Thus, the drive signal can be output to the gate (G) terminal of MOSFET Q2 through diode D1, causing the VGS voltage of MOSFET Q2 to exceed the turn-on threshold, thereby turning on MOSFET Q2 and enabling it to operate. When MOSFET Q2 is closed, the output signal through diode D1 is a high signal.

[0022] By connecting transistor Q1 and resistor R2, the function of resistor R2 is that when the driver chip 10 shuts down its output control signal (i.e., the control signal of the driver chip 10 is low, i.e., low voltage), the voltage at the base (B) terminal of transistor Q1 is 0. The voltage at the gate (G) terminal of MOSFET Q2 causes the collector (C) and emitter (E) terminals of transistor Q1 to conduct, and through resistor R2, quickly pulls the voltage across the gate (GS) terminals to be the same. It can be understood that when the collector (C) and emitter (E) terminals of transistor Q1 are conducting, the collector (CE) terminals of transistor Q1, resistor R2, and the GS terminals of MOSFET Q2 form a circuit, which consumes the GS voltage of MOSFET Q2, pulling the GS voltage across MOSFET Q2 to be the same. This pulls the VGS voltage to be the same because the turn-off mechanism of MOSFET Q2 is that it turns off when the VGS voltage is less than the turn-on threshold voltage. Simultaneously, by closing transistor Q1, the GS terminals of MOSFET Q2 can be directly turned on, pulling the VGS voltage to be the same and eventually reducing it to 0, thus achieving a rapid turn-off effect.

[0023] In this embodiment, the drain (D) terminal of the MOSFET Q2 can be used as the input terminal. The source (S) terminal of the MOSFET Q2 can be used as the output terminal. The input and output terminals of the MOSFET Q2 can be connected to other circuits or electronic components.

[0024] In this embodiment, a diode Z1 is also included. The positive terminal of diode Z1 is connected to the source (S) terminal of the MOSFET Q2, and the negative terminal of diode Z1 is connected to the drain (D) terminal of the MOSFET Q2. The main function of diode Z1 is that when the MOSFET Q2 needs to be turned off quickly, the voltage at the output terminal of the MOSFET Q2 drops rapidly due to discharge, while the voltage at the input terminal remains unchanged or drops slowly, which can cause VDS overvoltage of the MOSFET Q2. Diode Z1 can be used to absorb and clamp the surge voltage across the DS terminals of the MOSFET Q2, thereby preventing damage to the MOSFET Q2 due to overvoltage and forming a protection mechanism for the MOSFET Q2.

[0025] It should be noted that the driver chip 10 is the chip that outputs the drive signal of MOSFET Q2. Resistor R1 is the discharge resistor of the gate terminal of MOSFET Q2 when MOSFET Q2 is turned off. Transistor Q1 is the discharge switch when turned off. Resistor R2 is the discharge current limiting resistor. MOSFET Q2 is the MOSFET that needs to be controlled to turn off. Resistor R3 is the discharge resistor of the source terminal of MOSFET Q2. Diode Z1 is the clamping diode of the MOSFET's drain and source terminals.

[0026] It should be noted that the MOSFET Q2 turns off when the VGS voltage is less than the turn-on threshold voltage. At the same time, by closing the transistor Q1, the gate and source terminals of the MOSFET Q2 can be directly turned on, which quickly reduces the VGS voltage and thus turns it off quickly.

[0027] This invention incorporates a resistor R2 and a transistor Q1. The positive terminal of diode D1 is connected to the driver chip 10, the negative terminal of diode D1 is connected to the gate (G) terminal of MOSFET Q2, the base (B) terminal of transistor Q1 is connected to the driver chip, the emitter (E) terminal of transistor Q1 is connected to the gate (G) terminal of MOSFET Q2, the collector (C) terminal of transistor Q1 is connected to one end of resistor R2, and the other end of resistor R2 is connected to the source (S) terminal of MOSFET Q2. One end of resistor R1 is connected to the driver chip, and the other end of resistor R1 is connected to the gate (G) terminal of MOSFET Q2. One end of resistor R3 is connected to the source (S) terminal of MOSFET Q2, and the other end of resistor R3 is connected to the driver chip. Resistor R1 releases the voltage at the gate (G) terminal, and resistor R3 releases the voltage at the source (S) terminal. Furthermore, the gate (G) voltage of the MOSFET causes the collector (C) and emitter (E) terminals of transistor Q1 to conduct. Resistor R2 then pulls the VGS voltage together, eventually reducing it to 0, thus achieving a rapid turn-off effect.

[0028] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A circuit capable of rapidly turning off a MOS transistor, characterized in that, The system includes a driver chip, diode D1, MOSFET Q2, resistors R1, R2, and R3, and transistor Q1. The positive terminal of diode D1 is connected to the driver chip, the negative terminal of diode D1 is connected to the gate (G) of MOSFET Q2, the base (B) terminal of transistor Q1 is connected to the driver chip, the emitter (E) terminal of transistor Q1 is connected to the gate (G) of MOSFET Q2, the collector (C) terminal of transistor Q1 is connected to one end of resistor R2, and the other end of resistor R2 is connected to the source (S) terminal of MOSFET Q2. Resistor R1... One end of the resistor R1 is connected to the driver chip, and the other end of the resistor R3 is connected to the gate (G) terminal of the MOSFET Q2. One end of the resistor R3 is connected to the source (S) terminal of the MOSFET Q2, and the other end of the resistor R3 is connected to the driver chip. The voltage at the gate (G) terminal of the MOSFET Q2 is discharged through the resistor R1, and the voltage at the source (S) terminal of the MOSFET Q2 is discharged through the resistor R3. The voltage at the gate (G) terminal of the MOSFET Q2 will cause the collector (C) and emitter (E) terminals of the transistor Q1 to conduct. Through the resistor R2, the voltage across the gate (G) and source terminals will be pulled down to 0, thus quickly turning off the transistor. It also includes diode Z1, the positive terminal of which is connected to the source terminal of MOSFET Q2, and the negative terminal of diode Z1 is connected to the drain terminal of MOSFET Q2; The input terminal is formed at the drain terminal of the MOS transistor Q2.

2. The circuit capable of rapidly turning off the MOS according to claim 1, characterized in that, The S terminal of the MOS transistor Q2 forms the output terminal.

Images