Voltage change protection circuit for multi-voltage system and multi-voltage system

Abstract

The invention discloses a voltage change protection circuit for a multi-voltage system and the multi-voltage system, and relates to the field of circuit protection. The voltage change protection circuit comprises a voltage division circuit, a comparator U1, an MOS tube Q1 and a resistor R2. Wherein one end of the voltage division circuit is connected with a variable voltage V2, and the other end of the voltage division circuit is grounded; the voltage division output end of the voltage division circuit is connected with the positive input end of the comparator U1; the negative input end of the comparator U1 is connected with a reference voltage V1; the output end of the comparator U1 is connected with the grid electrode of the MOS tube Q1 and one end of the resistor R2. The source electrode of the MOS tube Q1 and the other end of the resistor R2 are connected with a controlled power supply voltage Vin. And the drain electrode of the MOS tube Q1 is connected with a functional module of which the power supply is controlled to be on and off. The voltage change protection circuit can automatically control the on-off of the functional module power supply circuit when a certain path of voltage changes, so as to protect the safety of the powered functional module.

Description

Technical Field

[0001] The present application relates to the technical field of circuit protection, and in particular to a voltage variation protection circuit for a multi-voltage system and a multi-voltage system. Background Art

[0002] For more complex electronic products, there will be multiple different voltages in the system to supply functional modules with different needs. In order to facilitate users to connect different functional modules, it is sometimes necessary to adjust a certain voltage, which may cause some functional modules in the system to be damaged due to excessive voltage. In order to prevent individual functional modules from being damaged due to voltage changes, it is necessary to disconnect the power supply of the corresponding functional module before adjusting the voltage. This operation of disconnecting the power supply is generally performed using a switch. However, traditional devices are prone to voltage changes due to ignoring or forgetting to operate the switch and directly adjusting the voltage, thereby causing damage to some functional modules. . Summary of the invention

[0003] In view of the problems existing in the above-mentioned prior art, the purpose of this application is to provide a voltage change protection circuit and a multi-voltage system for a multi-voltage system, which can automatically control the on and off of the power supply circuit when a certain voltage changes to protect the safety of the powered functional modules.

[0004] To achieve the above objectives, this application provides the following solutions.

[0005] On the one hand, the present application provides a voltage variation protection circuit for a multi-voltage system, including: a voltage divider circuit, a comparator U1, a MOS tube Q1 and a resistor R2;

[0006] One end of the voltage divider circuit is connected to a variable voltage V2, and the other end of the voltage divider circuit is grounded; the voltage divider output end of the voltage divider circuit is connected to the positive input end of the comparator U1; the negative input end of the comparator U1 is connected to a reference voltage V1; the power supply voltage of the comparator U1 is V3; the output end of the comparator U1 is respectively connected to the gate of the MOS tube Q1 and one end of the resistor R2; the source of the MOS tube Q1 and the other end of the resistor R2 are both connected to a controlled power supply voltage Vin; the drain of the MOS tube Q1 is connected to a functional module controlled to turn on and off the power supply.

[0007] Optionally, the voltage divider circuit includes a resistor R1 and a resistor R3 connected in series; one end of the resistor R1 is connected to a variable voltage V2; the other end of the resistor R1 is connected to one end of the resistor R3, and the connection point is the voltage divider output end of the voltage divider circuit; the other end of the resistor R3 is grounded.

[0008] Optionally, the voltage at the voltage divider output terminal of the voltage divider circuit Vo=V2*R 3 / (R 1 +R 3 );where R 1 is the resistance value of the resistor R1; R 3 is the resistance value of the resistor R3.

[0009] Optionally, when the variable voltage V2 is in a normal voltage variation range, the voltage Vo at the voltage divider output terminal of the voltage divider circuit is less than the reference voltage V1, the comparator U1 outputs a low level, the MOS tube Q1 is in an on state, and the controlled power supply voltage Vin normally supplies power to the functional module.

[0010] Optionally, when the variable voltage V2 exceeds the normal voltage variation range, the voltage Vo at the voltage divider output terminal of the voltage divider circuit is greater than the reference voltage V1, the comparator U1 outputs a high level, the MOS tube Q1 is in an off state, and the controlled supply voltage Vin stops supplying power to the functional module.

[0011] Optionally, the variable voltage V2 and the controlled supply voltage Vin are the same voltage.

[0012] On the other hand, the present application also provides a multi-voltage system, including: a power module, a microcontroller, an in-vehicle Ethernet and the voltage change protection circuit; the input voltage of the power module is 12V, and it outputs two voltages of 3.3V and 5V; the 3.3V and 5V voltage output ends of the power module are connected to the VDDB pin of the microcontroller through a switch S7; the VDDB pin voltage is respectively used as a variable voltage V2, a power supply voltage V3 of a comparator U1 and a controlled power supply voltage Vin; the reference voltage V1 is 3.3V; and the in-vehicle Ethernet is a functional module for controlling the on-off of power supply.

[0013] Optionally, the resistance value of the resistor R1 is 1 KΩ; the resistance value of the resistor R3 is 9.1 KΩ.

[0014] Optionally, the resistance of the resistor R2 is 4.7KΩ.

[0015] Optionally, the multi-voltage system also includes: a CAN transceiver, a LIN transceiver and a sensor; the on-board Ethernet, CAN transceiver, LIN transceiver and the sensor are all communicatively connected to the microcontroller; the CAN transceiver is powered by a 5V voltage; the LIN transceiver is powered by a 5V and 12V voltage; the VCC pin of the sensor is connected to the VDDB pin voltage.

[0016] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0017] The voltage change protection circuit provided in the present application is constructed using commonly used simple components, takes the variable voltage V2 as input, and automatically controls the on and off of the functional module power supply voltage Vin according to the voltage change of V2, effectively avoiding overvoltage damage to the functional module and strictly protecting the safety of the powered functional modules in the multi-voltage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A schematic diagram of a voltage variation protection circuit for a multi-voltage system;

[0020] Figure 2 It is a structural schematic diagram of a multi-voltage system embodiment. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0022] The purpose of this application is to propose a voltage change protection circuit and a multi-voltage system for a multi-voltage system. When a certain voltage changes, the power supply circuit can be automatically controlled according to the changed voltage to effectively protect the safety of the powered functional modules.

[0023] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0024] In an exemplary embodiment, the present application provides a voltage variation protection circuit for a multi-voltage system. Figure 1 As shown, the voltage change protection circuit includes: a voltage divider circuit, a comparator U1, a MOS transistor Q1 and a resistor R2. In an exemplary embodiment, the voltage divider circuit includes a resistor R1 and a resistor R3 connected in series. The MOS transistor Q1 is a P-channel MOS transistor.

[0025] See also Figure 1, one end of the voltage divider circuit, i.e. one end of the resistor R1, is connected to a variable voltage V2. The other end of the resistor R1 is connected to one end of the resistor R3, and the connection point is the voltage divider output end of the voltage divider circuit, and the voltage at the voltage divider output end is Vo. The other end of the voltage divider circuit, i.e. the other end of the resistor R3, is grounded. Specifically, the voltage at the voltage divider output end of the voltage divider circuit is Vo = V2*R 3 / (R 1 +R 3 );where R 1 is the resistance value of the resistor R1; R 3 is the resistance value of the resistor R3.

[0026] The voltage divider output end of the voltage divider circuit is connected to the positive input end of the comparator U1. The negative input end of the comparator U1 is connected to the reference voltage V1. The power supply voltage of the comparator U1 is V3. The output end of the comparator U1 is respectively connected to the gate of the MOS tube Q1 and one end of the resistor R2. The source of the MOS tube Q1 and the other end of the resistor R2 are both connected to the controlled power supply voltage Vin. The drain of the MOS tube Q1 is connected to the functional module of the controlled power supply on and off.

[0027] The input voltages of the voltage variation protection circuit of the present application are V1, V2, V3 and Vin. Among them, V3 is used to power the comparator chip U1. V1 is connected to the negative input terminal of the comparator chip U1 as a reference voltage. V2 is a voltage with a variable voltage. Vin is a power supply voltage that is controlled to be on and off. In an exemplary embodiment, the variable voltage V2, the power supply voltage V3 of the comparator U1 and the controlled power supply voltage Vin can be the same voltage.

[0028] The function of the entire voltage change protection circuit is roughly as follows. First, the gate of the MOS tube Q1 is connected to the controlled power supply voltage Vin through the resistor R2. Then, before the output of the comparator U1, only when Vin supplies power, the gate and source voltages of the MOS tube Q1 are consistent, and the MOS tube Q1 is in the off state. Then look at the output of the comparator U1. The positive input terminal of the comparator U1 is the voltage after the variable voltage V2 is divided by the resistors R1 and R3, that is, the voltage Vo at the voltage divider output terminal; the negative input terminal is V1. If the voltage Vo at the positive input terminal of the comparator U1 is greater than the voltage V1 at the negative input terminal, the comparator U1 will output a high level, and the MOS tube Q1 will remain in the off state. If the voltage Vo at the positive input terminal of the comparator U1 is less than the voltage V1 at the negative input terminal, the comparator U1 will output a low level, pulling the gate voltage of the MOS tube Q1 down to 0V, at which time the MOS tube Q1 will enter the on state, and Vin will supply power to the corresponding functional module.

[0029] Therefore, when the voltage change protection circuit of the present application is applied to a multi-voltage system, the normal voltage change range of the variable voltage V2 can be confirmed first, and then the ratio of resistors R1 and R3 can be adjusted so that when the V2 voltage is normal, the voltage Vo after the resistor division is smaller than V1, and when V2 is adjusted to a relatively large voltage, the voltage Vo after the resistor division is larger than V1.

[0030] That is to say, when the voltage variation protection circuit of the present application is applied to a multi-voltage system, it is necessary to ensure that when the variable voltage V2 is within the normal voltage variation range, the voltage Vo at the voltage divider output terminal of the voltage divider circuit is less than the reference voltage V1, at which time the comparator U1 outputs a low level, the MOS tube Q1 is in the on state, and the controlled power supply voltage Vin supplies power to the functional module normally. When the variable voltage V2 exceeds the normal voltage variation range, the voltage Vo at the voltage divider output terminal of the voltage divider circuit is greater than the reference voltage V1, at which time the comparator U1 outputs a high level, the MOS tube Q1 is in the off state, and the controlled power supply voltage Vin automatically stops supplying power to the functional module.

[0031] Traditional devices generally use switches to disconnect the power supply of functional modules. It is easy to ignore or forget to operate the switch and directly adjust the voltage, resulting in voltage changes that cause damage to the functional modules; and the switch device is large in size and cumbersome to operate. The voltage change protection circuit of the present application uses commonly used simple components to build a simple and effective circuit. It takes the variable voltage V2 as input and automatically controls the on and off of the functional module power supply voltage Vin according to the voltage change of V2, effectively avoiding the overvoltage damage of the functional module and strictly protecting the safety of the powered functional module.

[0032] Furthermore, in an exemplary embodiment, the present application also provides a multi-voltage system, which is usually mounted on a vehicle. Figure 2As shown, the multi-voltage system includes: a power module, a microcontroller, an in-vehicle Ethernet, a CAN transceiver, a LIN transceiver, a sensor and the voltage change protection circuit. The in-vehicle Ethernet, the CAN transceiver, the LIN transceiver and the sensor are all connected to the microcontroller in communication. Among them, the input voltage of the power module is 12V, and it outputs two voltages of 3.3V and 5V. The 3.3V and 5V voltage output ends of the power module are connected to the VDDB pin of the microcontroller through the switch S7. The VDDB power domain of the microcontroller can be selected by the switch S7 to be powered by 3.3V or 5V. The CAN transceiver is powered by 5V voltage. The LIN transceiver is powered by 5V and 12V voltage. The VCC pin of the sensor is connected to the VDDB pin voltage. In this exemplary embodiment, the VDDB pin voltage is used as the variable voltage V2, the power supply voltage V3 of the comparator U1 and the controlled power supply voltage Vin respectively. The reference voltage V1 is 3.3V. The in-vehicle Ethernet is a functional module for controlling the power supply on and off. The power supply voltage range of the automotive Ethernet chip only supports 3.1~3.5V, so when the VDDB voltage needs to be changed to 5V, the power supply of the Ethernet chip must be turned off to avoid damage to the chip due to overvoltage.

[0033] In order to prevent the chip from being damaged due to overvoltage, the voltage change protection circuit of the present application is applied in the multi-voltage system, which consists of three resistors R305, R306, and R307 (corresponding to Figure 1 The resistors R1, R2, R3 in the circuit), a comparator chip U22 (corresponding to Figure 1 The comparator U1 in the circuit), a P-channel MOS tube Q5 (corresponding to Figure 1 The two ends of resistor R305 are connected to the VDDB pin voltage of the microcontroller and the positive input end of the comparator U22 respectively. The two ends of resistor R307 are connected to the positive input end of the comparator U22 and the ground respectively. Resistors R307 and R305 together form a voltage divider circuit of VDDB. The resistance value of the resistor R305 is 1KΩ; the resistance value of the resistor R307 is 9.1KΩ. The comparator U22 can use the LMV331TP-TR chip. The negative input end of the comparator U22 is connected to V1, and V1=3.3V in this exemplary embodiment. The output end of the comparator U22 is connected to the gate of the MOS tube Q5. One end of the resistor R306 is connected to the gate of the MOS tube Q5, and the other end is connected to the source of the MOS tube and the VDDB pin voltage. The resistance value of the resistor R306 is 4.7KΩ. In this way, when the VDDB pin voltage changes (for example, from 3.3V to 5V), the voltage change protection circuit can control the on and off of the Vin (VDDB) power supply circuit according to the change of V2 voltage (i.e., VDDB pin voltage), effectively protecting the safety of the on-board Ethernet chip.

[0034] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0035] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A voltage variation protection circuit for a multi-voltage system, characterized in that: include: Voltage divider circuit, comparator U1, MOS tube Q1 and resistor R2; One end of the voltage divider circuit is connected to a variable voltage V2, and the other end of the voltage divider circuit is grounded; the voltage divider output end of the voltage divider circuit is connected to the positive input end of the comparator U1; the negative input end of the comparator U1 is connected to a reference voltage V1; the power supply voltage of the comparator U1 is V3; the output end of the comparator U1 is respectively connected to the gate of the MOS tube Q1 and one end of the resistor R2; the source of the MOS tube Q1 and the other end of the resistor R2 are both connected to a controlled power supply voltage Vin; the drain of the MOS tube Q1 is connected to a functional module controlled to turn on and off the power supply.

2. The voltage variation protection circuit according to claim 1, characterized in that: The voltage divider circuit includes a resistor R1 and a resistor R3 connected in series; one end of the resistor R1 is connected to a variable voltage V2; the other end of the resistor R1 is connected to one end of the resistor R3, and the connection point is the voltage divider output end of the voltage divider circuit; the other end of the resistor R3 is grounded.

3. The voltage variation protection circuit according to claim 2, characterized in that: The voltage at the voltage divider output terminal of the voltage divider circuit is Vo=V2*R3 / (R1+R3); wherein R1 is the resistance value of the resistor R1; and R3 is the resistance value of the resistor R3.

4. The voltage variation protection circuit according to claim 3, characterized in that: When the variable voltage V2 is in the normal voltage variation range, the voltage Vo at the voltage divider output terminal of the voltage divider circuit is less than the reference voltage V1, the comparator U1 outputs a low level, the MOS tube Q1 is in the on state, and the controlled power supply voltage Vin normally supplies power to the functional module.

5. The voltage variation protection circuit according to claim 3, characterized in that: When the variable voltage V2 exceeds the normal voltage variation range, the voltage Vo at the voltage divider output terminal of the voltage divider circuit is greater than the reference voltage V1, the comparator U1 outputs a high level, the MOS tube Q1 is in the off state, and the controlled power supply voltage Vin stops supplying power to the functional module.

6. The voltage variation protection circuit according to claim 1, characterized in that: The variable voltage V2 and the controlled power supply voltage Vin are the same voltage.

7. A multi-voltage system, characterized in that: include: A power module, a microcontroller, an in-vehicle Ethernet and a voltage change protection circuit as claimed in claim 1; the input voltage of the power module is 12V, and it outputs two voltages of 3.3V and 5V; the 3.3V and 5V voltage output terminals of the power module are connected to the VDDB pin of the microcontroller through a switch S7; the VDDB pin voltage is used as a variable voltage V2, a power supply voltage V3 of a comparator U1 and a controlled power supply voltage Vin respectively; the reference voltage V1 is 3.3V; the in-vehicle Ethernet is a functional module for controlling the on-off of power supply.

8. The multi-voltage system according to claim 7, characterized in that: The resistance value of the resistor R1 is 1KΩ; the resistance value of the resistor R3 is 9.1KΩ.

9. The multi-voltage system according to claim 7, characterized in that: The resistance value of the resistor R2 is 4.7KΩ.

10. The multi-voltage system according to claim 7, characterized in that: Also includes: CAN transceiver, LIN transceiver and sensor; the vehicle Ethernet, CAN transceiver, LIN transceiver and sensor are all connected to the microcontroller for communication; the CAN transceiver is powered by 5V voltage; the LIN transceiver is powered by 5V and 12V voltage; the VCC pin of the sensor is connected to the VDDB pin voltage.

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