Self-clamping protection circuit

Abstract

The utility model provides a self-clamping protection circuit. A power supply end VS is connected with a drain electrode of a power transistor M0 and a voltage sampling module VS-sns; the voltage sampling module VS-sns is connected with the control end of the voltage-controlled current source I0; on one hand, the voltage sampling module Gate-sns is connected with the grid electrode of the power transistor M0, and on the other hand, the voltage sampling module Gate-sns is connected with the control end of the voltage-controlled current source I1; a grid electrode of the power transistor M0 is connected with the driving module on one hand, and is grounded through the voltage-controlled current source I0 and the voltage-controlled current source I1 on the other hand; the enabling module is connected with the control end of the voltage sampling module VS-sns and the control end of the voltage sampling module Gate-sns through the switching circuit. According to the utility model, the voltage-controlled current source I0 and the voltage-controlled current source I1 complement each other so as to achieve the self-pull-down function that the channel of the power transistor M0 is opened due to different power-on speeds of the power supply end VS, so that the power transistor M0 can be protected when the power supply is rapidly powered on.

Description

A self-clamping protection circuit Technical Field

[0001] This utility model relates to the field of electronic circuit technology, and more specifically, to a self-clamping protection circuit applied to automotive-grade power supply chips. Background Technology

[0002] Because power transistors (MOSFETs) have large parasitic capacitance, when the power supply is rapidly powered on, the power transistor channel is opened by the parasitic capacitance. At this time, automotive-grade power chips are not enabled, and the power transistor has no over-temperature or over-current protection, thus causing damage. Summary of the Invention

[0003] The present invention aims to provide a self-clamping protection circuit to protect power transistors when the power supply is rapidly powered on.

[0004] The present invention provides a self-clamping protection circuit, comprising a first voltage sampling module VS-sns, a second voltage sampling module Gate-sns, a first voltage-controlled current source I0, a second voltage-controlled current source I1, and a switching circuit;

[0005] The power supply terminal VS is connected to the drain of the power transistor M0 and the first voltage sampling module VS-sns, respectively. The first voltage sampling module VS-sns is connected to the control terminal of the first voltage-controlled current source I0. A parasitic capacitance Cgd is connected between the gate and drain of the power transistor M0, and the source of the power transistor M0 is connected to the output terminal VOUT. The second voltage sampling module Gate-sns is connected to the gate of the power transistor M0 on one side and to the control terminal of the second voltage-controlled current source I1 on the other side. The gate of the power transistor M0 is connected to the driver module Driver on one side and grounded through the first voltage-controlled current source I0 and the second voltage-controlled current source I1 on the other side. The enable module EN is connected to the control terminals of the first voltage sampling module VS-sns and the second voltage sampling module Gate-sns through a switching circuit.

[0006] In some embodiments, the switching circuit uses a switching transistor M1; the gate of the switching transistor M1 is connected to the enable module EN, the source of the switching transistor M1 is grounded, and the drain of the switching transistor M1 is connected to the control terminals of the first voltage sampling module VS-sns and the second voltage sampling module Gate-sns, respectively.

[0007] In some embodiments, the self-clamping protection circuit further includes a current limiting circuit, through which the gate of the power transistor M0 is connected to the drive module Driver, the first voltage-controlled current source I0, and the second voltage-controlled current source I1, respectively.

[0008] In some embodiments, the current limiting circuit employs a current limiting resistor R0.

[0009] In some embodiments, the self-clamping protection circuit further includes a differential pressure protection circuit connected between the gate and source of the power transistor MOS.

[0010] In some embodiments, the differential pressure protection circuit employs a Zener diode D0.

[0011] In some embodiments, the self-clamping protection circuit is applied to automotive-grade power supply chips.

[0012] In summary, due to the adoption of the above technical solution, the beneficial effects of this utility model are:

[0013] In this invention, the first voltage-controlled current source I0 and the second voltage-controlled current source I1 complement each other to achieve the function of opening the channel of the power transistor M0 due to different power-on speeds VS at the power supply end, thereby protecting the power transistor M0 when the power supply is rapidly powered on. Attached Figure Description

[0014] Figure 1 is a structural diagram of a self-clamping protection circuit provided by this utility model. Detailed Implementation

[0015] 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, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0016] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0017] Example

[0018] As shown in Figure 1, this embodiment proposes a self-clamping protection circuit, including a first voltage sampling module VS-sns, a second voltage sampling module Gate-sns, a first voltage-controlled current source I0, a second voltage-controlled current source I1, and a switching circuit. The switching circuit is used to control the start and stop of the first voltage sampling module VS-sns and the second voltage sampling module Gate-sns according to the enable signal of the enable module. Any device that can realize the switching function can be used. In this embodiment, the switching transistor M1 is selected.

[0019] The power supply terminal VS is connected to the drain of power transistor M0 and the first voltage sampling module VS-sns. The first voltage sampling module VS-sns is connected to the drain of switching transistor M1 and the control terminal of the first voltage-controlled current source I0. The parasitic capacitance Cgd is connected between the gate and drain of power transistor M0, and the source of power transistor M0 is connected to the output terminal VOUT. The second voltage sampling module Gate-sns is connected to the gate of power transistor M0 and the drain of switching transistor M1 on one side, and to the control terminal of the second voltage-controlled current source I1 on the other side. The gate of power transistor M0 is connected to the driver module Driver on one side, and grounded through the first voltage-controlled current source I0 and the second voltage-controlled current source I1 on the other side. The gate of switching transistor M1 is connected to the enable terminal EN, and the source of switching transistor M1 is grounded.

[0020] The working principle of the above self-clamping protection circuit is as follows:

[0021] 1. When the power supply terminal VS is quickly powered on and the enable module EN has no enable signal, the parasitic capacitance Cgd of the power transistor M0 will pull up the gate of the power transistor M0, thus opening the channel of the power transistor M0. If there is any load connected to the output terminal VOUT, the power transistor M0 will automatically turn on without any protection. At this time, the power transistor M0 is easily damaged.

[0022] (1) At this time, the output voltage of the first voltage sampling module VS-sns increases as the power supply terminal VS is powered on faster, and the leakage current of the first voltage-controlled current source I0 increases as the output of the first voltage sampling module VS-sns increases. Therefore, the parasitic capacitance Cgd of the power transistor M0 is discharged by the first voltage-controlled current source I0, and then the power transistor M0 is turned off.

[0023] (2) If the power supply terminal VS is powered on relatively slowly, the first voltage-controlled current source I0 is too small, the gate voltage of the power transistor M0 rises, the second voltage sampling module Gate-sns works, and the output voltage of the second voltage sampling module Gate-sns increases only according to the increase of the gate voltage of the power transistor M0. The second voltage-controlled current source I1 also serves as the leakage current of the gate of the power transistor M0.

[0024] (3) The first voltage-controlled current source I0 and the second voltage-controlled current source I1 complement each other to achieve the function of opening the channel of the power transistor M0 when the power supply terminal VS has different power-on speeds, thereby protecting the power transistor M0 when the power supply is powered on quickly.

[0025] In some embodiments, the self-clamping protection circuit further includes a current-limiting circuit implemented with a current-limiting resistor R0, wherein the gate of the power transistor M0 is connected to the drive module Driver, the first voltage-controlled current source I0 and the second voltage-controlled current source I1 via the current-limiting resistor R0, for limiting the gate current of the power transistor M0.

[0026] In some embodiments, the self-clamping protection circuit further includes a differential voltage protection circuit implemented with a Zener diode D0, which is connected between the gate and source of the power transistor M0 to protect the voltage difference between the gate and source of the power transistor M0.

[0027] 2. When the power supply terminal VS is powered on normally and the enable signal of the enable module EN is high, the switching transistor M1 will shut down the first voltage sampling module VS-sns and the second voltage sampling module Gate-sns.

[0028] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A self-clamping protection circuit, characterized in that, The system includes a first voltage sampling module VS-sns, a second voltage sampling module Gate-sns, a first voltage-controlled current source I0, a second voltage-controlled current source I1, and a switching circuit. The power supply terminal VS is connected to the drain of the power transistor M0 and the first voltage sampling module VS-sns. The first voltage sampling module VS-sns is connected to the control terminal of the first voltage-controlled current source I0. A parasitic capacitance Cgd is connected between the gate and drain of the power transistor M0, and the source of the power transistor M0 is connected to the output terminal VOUT. The second voltage sampling module Gate-sns is connected to the gate of the power transistor M0 on one side and to the control terminal of the second voltage-controlled current source I1 on the other side. The gate of the power transistor M0 is connected to the driver module Driver on one side and grounded through the first voltage-controlled current source I0 and the second voltage-controlled current source I1 on the other side. The enable module EN is connected to the control terminals of the first voltage sampling module VS-sns and the second voltage sampling module Gate-sns through the switching circuit.

2. The self-clamping protection circuit according to claim 1, characterized in that, The switching circuit uses a switching transistor M1; the gate of the switching transistor M1 is connected to the enable module EN, the source of the switching transistor M1 is grounded, and the drain of the switching transistor M1 is connected to the control terminals of the first voltage sampling module VS-sns and the second voltage sampling module Gate-sns, respectively.

3. The self-clamping protection circuit according to claim 1, characterized in that, It also includes a current limiting circuit, through which the gate of the power transistor M0 is connected to the drive module Driver, the first voltage-controlled current source I0, and the second voltage-controlled current source I1, respectively.

4. The self-clamping protection circuit according to claim 3, characterized in that, The current limiting circuit uses a current limiting resistor R0.

5. The self-clamping protection circuit according to claim 1, characterized in that, It also includes a differential pressure protection circuit, which is connected between the gate and source of the power transistor M0.

6. The self-clamping protection circuit according to claim 5, characterized in that, It also includes a differential pressure protection circuit, which uses a Zener diode D0.

7. The self-clamping protection circuit according to any one of claims 1-6, characterized in that, The self-clamping protection circuit is used in automotive-grade power supply chips.

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