Quick turn-off circuit of MOS (Metal Oxide Semiconductor) tube

Abstract

The utility model is suitable for the technical field of analog electronics, and provides a quick turn-off circuit of an MOS (Metal Oxide Semiconductor) tube. The circuit comprises a control module, an electrifying module and a negative pressure module, the control module is used for sending a first voltage signal to the power-on module; the power-on module is used for receiving a first voltage signal of the control module and receiving a second voltage signal of the negative voltage module; the negative voltage module comprises a capacitor C2, a resistor R5 and a triode Q5 and is used for sending a second voltage signal to the power-on module; the end a of the capacitor C2 is connected with the output end of the control module and the controlled end of the electrifying module, and the end b of the capacitor C2 is connected with a ground wire and is connected with the pole b of the triode Q5 through the resistor R5; the c pole of the triode Q5 is connected with the a end of the capacitor C2, and the e pole of the triode Q5 is connected with the power-on module. According to the utility model, the problem that the service life of the MOS tube is prolonged by reducing the turn-off loss of the MOS tube by quickly turning off the MOS tube is solved.

Description

Technical Field

[0001] The utility model belongs to the field of analog electronic technology, and particularly relates to a fast turn-off circuit for a MOS transistor. Background Art

[0002] MOS transistors (MOSFETs, metal-oxide-semiconductor field-effect transistors) have a series of characteristics that make them an ideal choice for controlling power switches. Using MOS transistors as switches to control the on and off of a power circuit is a common means.

[0003] Currently, in a switching circuit using a MOS transistor, a discharge resistor is usually provided between the S pole and the G pole of the MOS transistor to discharge the voltage at the GS terminal of the MOS transistor.

[0004] Doing so mainly relies on the self-discharge of the voltage at the GS terminal of the MOS transistor, which requires a relatively long turn-off time. During the turn-off time, there is a relatively large turn-off loss in the MOS transistor. As the number of switchings increases, the probability of MOS transistor damage due to the turn-off loss of the MOS transistor will increase significantly. Therefore, it is necessary to quickly turn off the MOS transistor to reduce the turn-off loss of the MOS transistor and thus extend the service life of the MOS transistor. Summary of the Utility Model

[0005] The purpose of the embodiment of the utility model is to provide a fast turn-off circuit for a MOS transistor, aiming to solve the problem that it is necessary to quickly turn off the MOS transistor to reduce the turn-off loss of the MOS transistor and thus extend the service life of the MOS transistor.

[0006] The embodiment of the utility model is implemented as follows. A fast turn-off circuit for a MOS transistor, the fast turn-off circuit for the MOS transistor includes: a control module, a power-on module, and a negative voltage module;

[0007] The output end of the control module is connected to the controlled end of the power-on module and the power supply end of the negative voltage module, and is used to send a first voltage signal to the power-on module to control the conduction of the power-on module and provide a charging voltage for the negative voltage module;

[0008] The controlled end of the power-on module is connected to the power supply end of the negative voltage module, and is used to receive the first voltage signal of the control module to realize the conduction of the power-on module, and receive the second voltage signal of the negative voltage module to realize the fast turn-off of the power-on module;

[0009] The negative voltage module includes a capacitor C2, a resistor R5, and a triode Q5, and is used to send a second voltage signal to the power-on module to control the fast turn-off of the power-on module;

[0010] The a terminal of the capacitor C2 is connected to the output terminal of the control module and the controlled terminal of the energization module, and the b terminal is connected to the ground wire and, through the resistor R5, to the base of the triode Q5;

[0011] The collector of the triode Q5 is connected to the a terminal of the capacitor C2, and the emitter is connected to the energization module.

[0012] Preferably, the control module includes a resistor R6, a triode Q7, a triode Q6, a resistor R1, a resistor R2, a resistor R3, and a resistor R7;

[0013] One end of the resistor R6 is connected to the main control module, and the other end is connected to the base of the triode Q7;

[0014] The emitter of the triode Q7 is connected to the ground wire, and the collector is connected to the base of the triode Q6;

[0015] The emitter of the triode Q6 is connected to the ground wire, and the base is connected to the positive pole of the DC bus power module through the resistor R1;

[0016] The a terminal of the resistor R3 is connected to the collector of the triode Q6 and, through the resistor R2, to the positive pole of the DC bus power module, and the b terminal is connected to the controlled terminal of the energization module and the a terminal of the capacitor C2;

[0017] One end of the resistor R7 is connected to the base of the triode Q7, and the other end is connected to the emitter of the triode Q7.

[0018] Preferably, the energization module includes MOS transistors Q1, Q2, Q3, and Q4;

[0019] The gate of the MOS transistor Q1 is connected to the gates of the MOS transistors Q2, Q3, and Q4, the b terminal of the resistor R3, and the a terminal of the capacitor C2, the drain is connected to the positive pole of the charging power module, and the source is connected to the source of the MOS transistor Q2;

[0020] The drain of the MOS transistor Q2 is connected to the positive pole of the battery module and the emitter of the triode Q5;

[0021] The drain of the MOS transistor Q3 is connected to the positive pole of the charging power module, and the source is connected to the source of the MOS transistor Q4;

[0022] The drain of the MOS transistor Q4 is connected to the positive pole of the battery module and the emitter of the triode Q5.

[0023] Preferably, a plurality of fuses are connected between the drain of the MOS transistor Q2 and the positive pole of the battery module.

[0024] Preferably, the fast turn-off circuit of the MOS transistor further includes a resistor R4 and a light-emitting diode D1;

[0025] One end of the resistor R4 is connected to the b terminal of the resistor R3, and the other end is connected to the positive electrode of the light-emitting diode D1;

[0026] The negative electrode of the light-emitting diode D1 is connected to the ground wire.

[0027] A beneficial effect brought by the fast turn-off circuit of the MOS transistor provided by the embodiment of the present invention is that:

[0028] When the control module sends a first voltage signal to the power-on module to control the conduction of the power-on module, the capacitor C2 of the negative voltage module is charged; when the control module does not send the first voltage signal to the power-on module, the capacitor C2 discharges through the resistor R5 to make the triode Q5 conduct, thereby forming a negative voltage circuit to send a second voltage signal to the power-on module to control the fast turn-off of the power-on module. This solves the problem that the MOS transistor needs to be quickly turned off to reduce the turn-off loss of the MOS transistor and thus extend the service life of the MOS transistor. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural diagram of a fast turn-off circuit of a MOS transistor provided by an embodiment of the present invention;

[0030] Figure 2 It is a circuit diagram of a fast turn-off circuit of a MOS transistor provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] The following describes in detail the specific implementation of the present invention with reference to specific embodiments.

[0033] As Figure 1 、 Figure 2 shown, it is a structural diagram and a circuit diagram of a fast turn-off circuit of a MOS transistor provided by an embodiment of the present invention, including: a control module, a power-on module and a negative voltage module;

[0034] The output terminal of the control module is connected to the controlled terminal of the power-on module and the power supply terminal of the negative voltage module, and is used to send a first voltage signal to the power-on module to control the conduction of the power-on module and provide a charging voltage for the negative voltage module;

[0035] The controlled terminal of the power-on module is connected to the power supply terminal of the negative voltage module, and is used to receive the first voltage signal of the control module to achieve the conduction of the power-on module, and receive the second voltage signal of the negative voltage module to achieve the rapid turn-off of the power-on module;

[0036] The negative voltage module includes a capacitor C2, a resistor R5, and a triode Q5, and is used to send a second voltage signal to the power-on module to control the rapid turn-off of the power-on module;

[0037] The a terminal of the capacitor C2 is connected to the output terminal of the control module and the controlled terminal of the power-on module, and the b terminal is connected to the ground wire and, through the resistor R5, to the b electrode of the triode Q5;

[0038] The c electrode of the triode Q5 is connected to the a terminal of the capacitor C2, and the e electrode is connected to the power-on module.

[0039] In the embodiment of the present invention, the power supply terminal of the negative voltage module is the a terminal of the capacitor C2.

[0040] In the embodiment of the present invention, the first voltage signal is a positive voltage. The power-on module conducts after receiving the first voltage signal and turns off when not receiving the first voltage signal.

[0041] In the embodiment of the present invention, the second voltage signal is a negative voltage. The power-on module will accelerate the turn-off speed after receiving the second voltage signal to reduce the turn-off loss.

[0042] In the embodiment of the present invention, when the control module sends the first voltage signal to the power-on module, the first voltage signal also flows to the a terminal of the capacitor C2 to charge the capacitor C2. After the control module stops sending the first voltage signal to the power-on module, the b terminal of the capacitor C2 starts to discharge, and the current flows through the resistor R5 to the b electrode of the triode Q5 to make the triode Q5 conduct, thus forming a negative voltage circuit. The controlled terminal of the power-on module is connected to the a terminal of the capacitor C2. At this time, the potential of the a terminal of the capacitor C2 is lower than that of the b terminal, and the b terminal is connected to the ground wire, that is, the potential of the b terminal is 0V. Therefore, the potential of the a terminal of the capacitor C2 is negative, that is, the capacitor C2 provides a negative voltage to the controlled terminal of the power-on module, so as to achieve the effect of quickly turning off the power-on module.

[0043] In the embodiment of the present invention, essentially the power-on module can be regarded as a MOS transistor. The MOS transistor has parasitic capacitance. When the MOS transistor conducts, the parasitic capacitance will be charged. When the MOS transistor turns off, the parasitic capacitance discharges, thus prolonging the turn-off speed of the MOS transistor. The current method generally uses additional dissipating components such as a discharge resistor and a diode to consume the voltage of the parasitic capacitance. And the fast turn-off circuit of the MOS transistor applies a negative voltage to the MOS transistor to quickly reduce the voltage of the parasitic capacitance, so as to achieve the effect of quickly turning off the MOS transistor.

[0044] In the embodiment of the present utility model, when the power-on module is turned on, the capacitor C2 is in a charging state, which can filter the first voltage signal entering the power-on module and at the same time reduce the increase of the Miller effect.

[0045] A fast turn-off circuit for a MOS transistor provided by the embodiment of the present utility model charges the capacitor C2 of the negative voltage module when the control module sends a first voltage signal to the power-on module to control the conduction of the power-on module; when the control module does not send the first voltage signal to the power-on module, the capacitor C2 discharges through the resistor R5 to make the triode Q5 conduct, thereby forming a negative voltage circuit to send a second voltage signal to the power-on module to control the fast turn-off of the power-on module. This solves the problem that the MOS transistor needs to be quickly turned off to reduce the turn-off loss of the MOS transistor and thus extend the service life of the MOS transistor.

[0046] As Figure 2 shown, as a preferred embodiment of the present utility model, the control module includes a resistor R6, a triode Q7, a triode Q6, a resistor R1, a resistor R2, a resistor R3 and a resistor R7;

[0047] One end of the resistor R6 is connected to the main control module, and the other end is connected to the b-pole of the triode Q7;

[0048] The e-pole of the triode Q7 is connected to the ground wire, and the c-pole is connected to the b-pole of the triode Q6;

[0049] The e-pole of the triode Q6 is connected to the ground wire, and the b-pole is connected to the positive pole of the DC bus power module through the resistor R1;

[0050] The a-end of the resistor R3 is connected to the c-pole of the triode Q6 and to the positive pole of the DC bus power module through the resistor R2, and the b-end is connected to the controlled end of the power-on module and the a-end of the capacitor C2;

[0051] One end of the resistor R7 is connected to the b-pole of the triode Q7, and the other end is connected to the e-pole of the triode Q7.

[0052] In the embodiment of the present utility model, the output end of the control module is the b-end of the resistor R3.

[0053] In the embodiment of the present utility model, the main control module can be an MCU chip, and one end of the resistor R6 is connected to the IO pin of the MCU chip. As Figure 2As shown, the resistor R6 is connected to the CTRL pin of the MCU chip. When the CTRL pin outputs a high level, the triode Q7 conducts. At this time, the b - pole of the triode Q6 receives a low level, and the triode Q6 cuts off. The positive pole of the DC bus power module outputs a high level, that is, the first voltage signal, to the power - on module through the resistor R2 and the resistor R3, and at the same time charges the capacitor C2. When the CTRL pin outputs a low level, the triode Q7 turns off. The positive pole of the DC bus power module makes the b - pole of the triode Q6 in a high - level state through the resistor R1, and the triode Q6 conducts. At this time, the positive pole of the DC bus power module is connected to the ground wire through the resistor R2 and does not flow through the resistor R3. The power - on module does not receive the first voltage signal, that is, the controlled end of the power - on module is in a low - level state, and the power - on module turns off.

[0054] In the embodiment of the present invention, a fuse F4 and a fuse F6 are further arranged between the positive pole of the DC bus power module and the resistor R2. The fuse F4 is connected in series between the positive pole of the DC bus power module and the resistor R2, and the fuse F6 is connected in parallel at both ends of the fuse F4. Both the fuse F4 and the fuse F6 are used to cut off the fuse when the current is too large to protect the subsequent circuit.

[0055] As Figure 2 shown, as a preferred embodiment of the present invention, the power - on module includes a MOS transistor Q1, a MOS transistor Q2, a MOS transistor Q3, and a MOS transistor Q4;

[0056] The G - pole of the MOS transistor Q1 is connected to the G - pole of the MOS transistor Q2, the G - pole of the MOS transistor Q3, the G - pole of the MOS transistor Q4, the b - end of the resistor R3, and the a - end of the capacitor C2. The D - pole is connected to the positive pole of the charging power module, and the S - pole is connected to the S - pole of the MOS transistor Q2;

[0057] The D - pole of the MOS transistor Q2 is connected to the positive pole of the battery module and the e - pole of the triode Q5;

[0058] The D - pole of the MOS transistor Q3 is connected to the positive pole of the charging power module, and the S - pole is connected to the S - pole of the MOS transistor Q4;

[0059] The D - pole of the MOS transistor Q4 is connected to the positive pole of the battery module and the e - pole of the triode Q5.

[0060] In the embodiment of the present invention, the controlled end of the power - on module is the G - poles of the MOS transistors Q1, Q2, Q3, and Q4.

[0061] In the embodiment of the present utility model, essentially the power-on module is a MOS transistor. The power input terminal of the power-on module is connected to the positive pole of the charging power module, and the power output terminal is connected to the positive pole of the battery. When the power-on module is turned on, the charging power module charges the battery; when the power-on module is turned on, the charging power module stops charging the battery. Of course, a load can also be connected to the power output terminal of the power-on module to serve as a switch for controlling the load.

[0062] In the embodiment of the present utility model, MOS transistor Q1 and MOS transistor Q2 form an anti-backflow circuit to prevent the backflow of the current from the charging power module or the battery when the power-on module is turned off.

[0063] In the embodiment of the present utility model, when the capacitor C2 discharges, it is equivalent to applying a negative voltage, i.e., the second voltage signal, to the G poles of MOS transistors Q1, Q2, Q3, and Q4. At this time, the discharge of the G poles of MOS transistors Q1, Q2, Q3, and Q4 is added, thereby accelerating the turn-off of the MOS transistors and reducing the loss of MOS turn-off.

[0064] As Figure 2 shown, as a preferred embodiment of the present utility model, a plurality of fuses are connected between the D pole of the MOS transistor Q2 and the positive pole of the battery module.

[0065] In the embodiment of the present utility model, the fuse is used to cut off the fuse when the current is too large to protect the subsequent circuit.

[0066] As Figure 2 shown, as a preferred embodiment of the present utility model, the fast turn-off circuit of the MOS transistor further includes a resistor R4 and a light-emitting diode D1;

[0067] One end of the resistor R4 is connected to the b terminal of the resistor R3, and the other end is connected to the positive pole of the light-emitting diode D1;

[0068] The negative pole of the light-emitting diode D1 is connected to the ground wire.

[0069] In the embodiment of the present utility model, the resistor R4 is used to divide the input voltage of the DC bus power module.

[0070] In the embodiment of the present utility model, when the power-on module is in the on state, the light-emitting diode D1 emits light. When the power-on module is in the off state, the light-emitting diode D1 goes out.

[0071] The above are only the preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present utility model shall be included in the protection scope of the present utility model.

Claims

1. A fast shutdown circuit for a MOS tube, characterized in that: The fast shutdown circuit of the MOS tube comprises: a control module, a power-on module and a negative pressure module; The output end of the control module is connected to the controlled end of the power-on module and the power supply end of the negative pressure module, and is used to send a first voltage signal to the power-on module to control the conduction of the power-on module and provide a charging voltage for the negative pressure module; The controlled end of the power-on module is connected to the power supply end of the negative pressure module, and is used to receive the first voltage signal of the control module to realize the conduction of the power-on module, and receive the second voltage signal of the negative pressure module to realize the rapid shutdown of the power-on module; The negative pressure module includes a capacitor C2, a resistor R5 and a transistor Q5, which are used to send a second voltage signal to the power-on module to control the rapid shutdown of the power-on module; The a end of the capacitor C2 is connected to the output end of the control module and the controlled end of the power-on module, and the b end is connected to the ground wire and to the b pole of the transistor Q5 through the resistor R5; The c-pole of the transistor Q5 is connected to the a-end of the capacitor C2, and the e-pole is connected to the power-on module.

2. The fast shutdown circuit of the MOS tube according to claim 1, characterized in that: The control module includes a resistor R6, a transistor Q7, a transistor Q6, a resistor R1, a resistor R2, a resistor R3 and a resistor R7; One end of the resistor R6 is connected to the main control module, and the other end is connected to the b pole of the transistor Q7; The e-pole of the transistor Q7 is connected to the ground wire, and the c-pole is connected to the b-pole of the transistor Q6; The e-pole of the transistor Q6 is connected to the ground wire, and the b-pole is connected to the positive electrode of the DC bus power supply module through the resistor R1; The a end of the resistor R3 is connected to the c pole of the transistor Q6 and to the positive pole of the DC bus power supply module through the resistor R2, and the b end is connected to the controlled end of the power-on module and the a end of the capacitor C2; One end of the resistor R7 is connected to the b-pole of the transistor Q7, and the other end is connected to the e-pole of the transistor Q7.

3. The fast shutdown circuit of the MOS tube according to claim 2, characterized in that: The power-on module includes MOS transistor Q1, MOS transistor Q2, MOS transistor Q3 and MOS transistor Q4; The G pole of the MOS tube Q1 is connected to the G pole of the MOS tube Q2, the G pole of the MOS tube Q3, the G pole of the MOS tube Q4, the b end of the resistor R3, and the a end of the capacitor C2, the D pole is connected to the positive pole of the charging power module, and the S pole is connected to the S pole of the MOS tube Q2; The D pole of the MOS tube Q2 is connected to the positive pole of the battery module and the e pole of the transistor Q5; The D pole of the MOS tube Q3 is connected to the positive pole of the charging power module, and the S pole is connected to the S pole of the MOS tube Q4; The D pole of the MOS tube Q4 is connected to the positive pole of the battery module and the E pole of the transistor Q5.

4. The fast shutdown circuit of the MOS tube according to claim 3, characterized in that: A plurality of fuses are connected between the D pole of the MOS tube Q2 and the positive pole of the battery module.

5. The fast shutdown circuit of the MOS tube according to claim 3, characterized in that: The fast shutdown circuit of the MOS tube also includes a resistor R4 and a light emitting diode D1; One end of the resistor R4 is connected to the end b of the resistor R3, and the other end is connected to the positive electrode of the light emitting diode D1; The cathode of the light emitting diode D1 is connected to the ground wire.

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