MOS tube voltage switch protection circuit

Abstract

The utility model provides an MOS tube voltage switch protection circuit. The MOS tube voltage switch protection circuit comprises a voltage division circuit, a voltage-regulator tube U1, a comparator U2, a triode Q2 and an MOS tube Q3. A voltage division circuit is used for dividing a high-voltage electric signal of the input end of a high-voltage power supply to be low enough and then connecting the high-voltage electric signal to the input end of a voltage-regulator tube U1, and a low enough voltage VCC1 is formed at the output end of the voltage-regulator tube; the voltage VCC1 and the low voltage VCC are connected with the input end of the comparator U2 at the same time, and the output end of the comparator U2 is connected with the grid electrode of the MOS tube Q3. The second voltage division circuit divides the high voltage to the ground into about 2.7 VDC to be connected with the drain electrode of the MOS tube Q3, and the source electrode of the MOS tube Q3 is grounded; a base electrode of the triode Q2 is connected with a drain electrode of the MOS tube Q3, a collector electrode is connected with high voltage through a collector electrode resistor R2, and an emitter electrode is grounded; the collector electrode of the triode Q2 forms a protection signal and is connected with the grid electrode of the MOS tube Q1. When the protection circuit is applied to a high-voltage part of an electronic product, electronic components can be effectively protected, and the reliability of the product is improved.

Description

Technical Field

[0001] The utility model relates to the field of voltage switch protection circuits, in particular to a MOS transistor voltage switch protection circuit. Background Art

[0002] When high-voltage current is applied, a switch is generally required to control whether it is applied. Currently, when DC high voltage is applied, an electronic switch is generally used. For example, a MOS transistor is used as a voltage switch. The source-drain electrodes of the MOS transistor are respectively connected to a high-voltage power supply and an electrical device. When an effective control signal is applied to the gate of the MOS transistor, the source-drain electrodes of the MOS transistor are turned on, and power supply from the high-voltage power supply to the electrical device is realized. When the control signal applied to the gate of the MOS transistor fails, the source-drain electrodes of the MOS transistor are not turned on, cutting off the connection between the high-voltage power supply and the electrical device and disconnecting the power supply of the electrical device.

[0003] Currently, in the actual application of such a MOS transistor voltage switch in an electronic product, when the electronic product operates at both a low voltage (Vcc) and a high voltage (100V) simultaneously, if the high voltage continues to operate when the low voltage VCC is turned off, the electronic product may be burned out due to a large current. Summary of the Utility Model

[0004] The purpose of the utility model is to provide a MOS transistor voltage switch protection circuit to ensure that when there is an input of low voltage, the high voltage can always be in the output state; when the low voltage is turned off, the high voltage can be in the off state, avoiding the product from being burned out by overcurrent of the high voltage due to a large current during application.

[0005] The technical solution adopted by the utility model to achieve its technical purpose is: a MOS transistor voltage switch protection circuit, in an electronic product that operates at both a low voltage VCC and a high voltage simultaneously, protects a MOS transistor Q1 whose source-drain electrodes are respectively connected to a high-voltage power supply input terminal and a high-voltage output terminal, including a voltage-dividing circuit, a voltage-stabilizing diode U1, a comparator U2, a triode Q2, and a MOS transistor Q3;

[0006] The voltage-dividing circuit divides the high-voltage electrical signal at the high-voltage power supply input terminal to a sufficiently low level and then connects it to the input terminal of the voltage-stabilizing diode U1, and a sufficiently low voltage VCC1 is formed at the output terminal of the voltage-stabilizing diode;

[0007] The voltage VCC1 and the low voltage VCC are simultaneously connected to the input terminal of the comparator U2, and the output terminal of the comparator U2 is connected to the gate of the MOS transistor Q3;

[0008] It further includes a second voltage-dividing circuit, and the second voltage-dividing circuit divides the high voltage with respect to the ground to about 2.7VDC and connects it to the drain of the MOS transistor Q3, and the source of the MOS transistor Q3 is grounded;

[0009] The base of the triode Q2 is connected to the drain of the MOS transistor Q3. The collector is connected to a high voltage through the collector resistor R2, and the emitter is grounded.

[0010] The collector of the triode Q2 forms a protection signal and is connected to the gate of the MOS transistor Q1.

[0011] Furthermore, in the above MOS transistor voltage switch protection circuit: A capacitor C2 is also provided between the high voltage output terminal and the ground. A diode D1 is also provided between the gate of the MOS transistor Q1 and the high voltage output terminal, and the anode of the diode D1 is connected to the high voltage output terminal.

[0012] Furthermore, in the above MOS transistor voltage switch protection circuit: The high voltage power supply is a DC power supply that outputs 100VDC.

[0013] Furthermore, in the above MOS transistor voltage switch protection circuit: The voltage dividing circuit includes a resistor R1 with a resistance value of 560K and a resistor R4 with a resistance value of 22K. The resistor R1 and the resistor R4 are connected in series between the output terminal of the high voltage power supply 100VDC and the ground. The other end of the resistor R4 is grounded, and the common terminal where the resistor R1 and the resistor R4 are connected is connected to the input terminal of the voltage stabilizing diode U1.

[0014] Furthermore, in the above MOS transistor voltage switch protection circuit: The second voltage dividing circuit includes a resistor R3 with a resistance value of 560K and a resistor R6 with a resistance value of 15K. The resistor R3 and the resistor R6 are connected in series between the output terminal of the high voltage power supply 100VDC and the ground. The other end of the resistor R6 is grounded, and the common terminal where the resistor R3 and the resistor R6 are connected is connected to the drain of the MOS transistor Q3.

[0015] Furthermore, in the above MOS transistor voltage switch protection circuit: The resistance value of the collector resistor R2 is 560K.

[0016] Furthermore, in the above MOS transistor voltage switch protection circuit: A current limiting resistor R5 with a resistance value of 1K is also provided between the collector of the triode Q2 and the gate of the MOS transistor Q1.

[0017] In the present utility model, the protection circuit ensures that when there is a low voltage input, the high voltage can always be in the output state; when the low voltage is turned off, the high voltage can be in the off state, avoiding the product from being burned out by overcurrent due to a large current during application. It is a voltage protection circuit.

[0018] In addition, when the protection circuit of the present utility model is applied to the high voltage part of electronic products, it can effectively protect electronic components and improve the reliability of the product.

[0019] The following further describes the present utility model in conjunction with the accompanying drawings and specific embodiments. Description of the Drawings

[0020] Attached Figure 1 is the schematic diagram of the MOS transistor voltage switch protection circuit in Embodiment 1 of the present utility model;

[0021] Attached Figure 2 is the principle block diagram of the MOS transistor voltage switch voltage protection in Embodiment 1 of the present utility model;

[0022] Attached Figure 3 is the test diagram of the Vcc on state in Embodiment 1 of the present utility model;

[0023] Attached Figure 4 is the test diagram of the Vcc off state in Embodiment 1 of the present utility model. Specific implementation manner

[0024] In this embodiment, in an electronic product that works simultaneously at a low voltage (Vcc) and a high voltage (100V), when there is an input at the low voltage, the high voltage can always be in the output state; when the low voltage is turned off, the high voltage can be in the off state, avoiding the product from being burned by overcurrent of the high voltage due to a large current during application. This is a voltage protection circuit.

[0025] As Figure 1 shown: This embodiment is a MOS transistor voltage switch protection circuit. In an electronic product that works simultaneously at a low voltage VCC and a high voltage of 100VDC, it protects the MOS transistor Q1 whose source-drain electrodes are respectively connected to the high-voltage power input terminal and the high-voltage output terminal.

[0026] As Figure 1 shown, the protection circuit of this embodiment includes a voltage division circuit, a second voltage division circuit, a voltage stabilizing diode U1, a comparator U2, a triode Q2, and a MOS transistor Q3.

[0027] In this embodiment, the voltage division circuit divides the 100VDC voltage to form a voltage VCC1 that is lower than the low voltage VCC in this electronic product. In this embodiment, the voltage division circuit includes a resistor R1 with a resistance value of 560K and a resistor R4 with a resistance value of 22K. The resistor R1 and the resistor R4 are connected in series between the output terminal of the high-voltage power supply 100VDC and the ground. The other end of the resistor R4 is grounded, and the common end where the resistor R1 and the resistor R4 are connected is connected to the input terminal of the voltage stabilizing diode U1.

[0028] The second voltage dividing circuit, like the voltage dividing circuit, also divides the high voltage of 100VDC to form a threshold voltage used in the integrated circuit, such as 2.7VDC, etc., to supply power for the conduction of MOS transistor Q3. In this embodiment, the second voltage dividing circuit includes a resistor R3 with a resistance value of 560K and a resistor R6 with a resistance value of 15K. Resistor R3 and resistor R6 are connected in series between the output terminal of the high voltage power supply 100VDC and the ground. The other end of resistor R6 is grounded, and the common terminal where resistor R3 and resistor R6 are connected is connected to the drain of the MOS transistor Q3.

[0029] In practice, since VCC1 is close to the threshold voltage used in the integrated circuit, such as 2.7VDC, the second voltage dividing circuit can also be omitted, and the output of the voltage dividing circuit composed of resistor R1 and resistor R2 can be directly connected to the drain of MOS transistor Q3.

[0030] As Figure 1 shown: The high voltage signal at the input terminal of the high voltage power supply is divided by the voltage dividing circuit to a sufficiently low level and then connected to the input terminal of the voltage stabilizing diode U1. The output terminal of the voltage stabilizing diode forms a sufficiently low voltage VCC1; The voltage VCC1 and the low voltage VCC are simultaneously connected to the input terminal of the comparator U2. The output terminal of the comparator U2 is connected to the gate of the MOS transistor Q3; The second voltage dividing circuit divides the high voltage with respect to the ground into about 2.7VDC and connects it to the drain of the MOS transistor Q3. The source of the MOS transistor Q3 is grounded; The base of the triode Q2 is connected to the drain of the MOS transistor Q3, the collector is connected to the high voltage through the collector resistor R2, and the emitter is grounded; The collector of the triode Q2 forms a protection signal and is connected to the gate of the MOS transistor Q1. A capacitor C2 is also provided between the high voltage output terminal and the ground. A diode D1 is also provided between the gate of the MOS transistor Q1 and the high voltage output terminal. The anode of the diode D1 is connected to the high voltage output terminal. A current limiting resistor R5 with a resistance value of 1K is also provided between the collector of the triode Q2 and the gate of the MOS transistor Q1.

[0031] In summary, in this embodiment, the circuit is composed of a voltage stabilizing diode U1, a comparator U2, a triode Q2, an N-channel MOS transistor Q1, an N-channel MOS transistor Q3, a filtering capacitor C1, a filtering capacitor C2, a switching diode D1, and resistors R1, R2, R3, R4, R5, and R6. The circuit structure is very simple.

[0032] The voltage protection principle block diagram of this embodiment is as Figure 1 shown, and it is composed of three parts: a main control voltage circuit, a voltage stabilizing diode, and a comparator.

[0033] The purpose of this embodiment can achieve two states:

[0034] The first: When +Vcc and +100V IN are input simultaneously, +100V OUT is in the output state; As Figure 3 shown.

[0035] The second type: when there is no input of +Vcc and there is an input of +100V IN, the +100V OUT is in a no-output state; as Figure 4 shown.

[0036] The first working state is when there are inputs of +Vcc and +100V IN. After the +100V IN is stepped down by resistor R1 and resistor R4, it is regulated by voltage regulator diode U1 to output +Vcc1, which is compared with the voltage at the 5th pin of comparator U2. At this time, +Vcc is greater than +Vcc1, and the comparator U2 outputs an equivalent voltage of +Vcc at its 1st pin to MOS transistor Q3. At this time, MOS transistor Q3 conducts, transistor Q2 cuts off, and the protected MOS transistor Q1 conducts. The 2nd pin (source D) of MOS transistor Q1 has a +100V OUT output state.

[0037] The second working state is when there is no input of +Vcc and there is an input of +100V IN. After the +100V IN is stepped down by resistor R1 and resistor R4, it is regulated by voltage regulator diode U1 to output +Vcc1, which is compared with the voltage at the 5th pin of comparator U2. At this time, +Vcc is less than +Vcc1, so there is no voltage output at the 1st pin of comparator U2, MOS transistor Q3 does not conduct, transistor Q2 conducts, the protected MOS transistor Q1 cuts off, and the 2nd pin of MOS transistor Q1 has a +100V OUT no-output state.

Claims

1. A MOS tube voltage switch protection circuit, in an electronic product with low voltage VCC and high voltage working at the same time, protects the MOS tube Q1 whose source and drain are respectively connected to the high voltage power input terminal and the high voltage output terminal, characterized in that: It includes a voltage divider circuit, a voltage regulator U1, a comparator U2, a transistor Q2, and a MOS tube Q3; The voltage divider circuit is used to divide the high voltage signal at the input end of the high voltage power supply to a sufficiently low voltage and then connected to the input end of the voltage regulator U1. The output end of the voltage regulator forms a sufficiently low voltage VCC1. The voltage VCC1 and the low voltage VCC are simultaneously connected to the input end of the comparator U2, and the output end of the comparator U2 is connected to the gate of the MOS tube Q3; It also includes a second voltage divider circuit, which divides the high voltage to ground into about 2.7VDC and connects the drain of the MOS tube Q3, and the source of the MOS tube Q3 is grounded; The base of transistor Q2 is connected to the drain of MOS tube Q3, the collector is connected to a high voltage through collector resistor R2, and the emitter is grounded; The collector of the transistor Q2 forms a protection signal and is connected to the gate of the MOS tube Q1.

2. The MOS tube voltage switch protection circuit according to claim 1, characterized in that: A capacitor C2 is further provided between the high voltage output terminal and the ground, and a diode D1 is further provided between the gate of the MOS tube Q1 and the high voltage output terminal, with the anode of the diode D1 being connected to the high voltage output terminal.

3. The MOS tube voltage switch protection circuit according to claim 1 or 2, characterized in that: The high voltage power supply is a direct current power supply that outputs 100VDC.

4. The MOS tube voltage switch protection circuit according to claim 3, characterized in that: The voltage divider circuit includes a resistor R1 with a resistance of 560K and a resistor R4 with a resistance of 22K. The resistor R1 and the resistor R4 are connected in series between the 100VDC output end of the high-voltage power supply and the ground. The other end of the resistor R4 is grounded. The common end connected to the resistor R1 and the resistor R4 is connected to the input end of the voltage regulator U1.

5. The MOS tube voltage switch protection circuit according to claim 4, characterized in that: The second voltage divider circuit includes a resistor R3 with a resistance of 560K and a resistor R6 with a resistance of 15K. The resistor R3 and the resistor R6 are connected in series between the 100VDC output end of the high-voltage power supply and the ground. The other end of the resistor R6 is grounded. The common end connected to the resistor R3 and the resistor R6 is connected to the drain of the MOS tube Q3.

6. The MOS tube voltage switch protection circuit according to claim 5, characterized in that: The resistance of the collector resistor R2 is 560K.

7. The MOS tube voltage switch protection circuit according to claim 6, characterized in that: A current limiting resistor R5 with a resistance of 1K is also provided between the collector of the transistor Q2 and the gate of the MOS transistor Q1.

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