WO2022027919A1

WO2022027919A1 - Over voltage protection circuit and electronic device

Info

Publication number: WO2022027919A1
Application number: PCT/CN2020/141823
Authority: WO
Inventors: 刘利书
Original assignee: 广东美的白色家电技术创新中心有限公司; 美的集团股份有限公司
Priority date: 2020-08-05
Filing date: 2020-12-30
Publication date: 2022-02-10
Also published as: CN112086945B; CN112086945A

Abstract

Disclosed are an over voltage protection circuit and an electronic device. The over voltage protection circuit comprises: a measurement circuit, used for measuring an output voltage; a first protection circuit, connected to the measurement circuit, and used for outputting a corresponding control signal in response to the change amplitude of the output voltage being greater than a first set threshold; a second protection circuit, connected to the measurement circuit, and used for outputting a corresponding control signal in response to the output voltage being greater than a second set threshold and a set time elapsing; and a control circuit, connected to the first protection circuit and the second protection circuit, and used for performing over voltage protection adjustment on the output voltage in response to the control signal output by the first protection circuit or the second protection circuit. In this way, the present application is applicable to different over voltage cases, and then transistors and chips are better protected.

Description

An overvoltage protection circuit and electronic equipment

This application claims the priority of the Chinese patent application with the application number 2020107799561 filed on August 5, 2020, and the invention title is "An Overvoltage Protection Circuit and Electronic Equipment", which is fully incorporated into this application by reference.

【Technical field】

The present application relates to the technical field of circuits, and in particular, to an overvoltage protection circuit and an electronic device.

【Background technique】

Over Voltage Protection (OVP) refers to a protection method that disconnects the power supply or reduces the voltage of the controlled equipment when the voltage of the protected line exceeds a predetermined maximum value.

For semiconductor devices and chips, designers need to pay special attention to the design of overvoltage protection, especially the OVP design of amplifier modules that require overvoltage protection and low distortion, low noise, and high bandwidth. The overvoltage can be caused by human error, such as short circuiting the input of the chip to the high voltage power supply, or it can be an error in the application, such as the output voltage of the transmitter is usually higher than the power supply voltage of the chip. Overvoltage may cause device or chip failure, and in severe cases, device or chip burnout.

[Content of the invention]

In order to solve the above problems, the present application provides an overvoltage protection circuit and an electronic device, which can be applied to different overvoltage modes and have better protection for transistors and chips.

A technical solution adopted in the present application is: to provide an overvoltage protection circuit, the overvoltage protection circuit includes: a detection circuit for detecting the output voltage; a first protection circuit, connected to the detection circuit, in response to the change of the output voltage The amplitude is greater than the first set threshold, and a corresponding control signal is output; the second protection circuit, connected to the detection circuit, outputs a corresponding control signal in response to the output voltage being greater than the second set threshold and exceeding the set time; the control circuit, connected to the first A protection circuit and a second protection circuit perform overvoltage protection regulation on the output voltage in response to the control signal output by the first protection circuit or the second protection circuit.

Wherein, the detection circuit includes: a voltage divider circuit for dividing the output voltage; a first comparison circuit, connected to the voltage divider circuit, for comparing the divided output voltage with the first reference voltage.

The voltage divider circuit includes: a first resistor, the output voltage is input from the first end of the first resistor, and the second end of the first resistor is used as a voltage divider output; a second resistor, the first end of the second resistor is connected to the first resistor The second terminal of the second resistor is grounded.

The first comparison circuit includes: an error amplifier, the first input end of the error amplifier is input with the first reference voltage, the second input end of the error amplifier is connected to the second end of the first resistor; a capacitor, the first end of the capacitor is connected to the error The second input end of the amplifier and the second end of the capacitor are connected to the output end of the error amplifier.

Wherein, the first protection circuit includes: a second comparator, the first input terminal of the second comparator is connected to the output terminal of the detection circuit for inputting the detection current, and the second input terminal of the second comparator inputs the reference current.

The reference current includes a first reference current and a second reference current, and the first reference current is smaller than the second reference current; the control circuit reduces the voltage value of the output voltage in response to the detection current output by the detection circuit being greater than the first reference current; or controls The circuit stops the output of the output voltage in response to the detection current output by the detection circuit being greater than the second reference current.

The control circuit restores the output of the output voltage in response to the detection current output by the detection circuit being smaller than the third reference current, wherein the third reference current is smaller than the first reference current.

Wherein, the second protection circuit includes: a third comparator, the first end of the third comparator is connected to the output end of the detection circuit, and the second input end of the third comparator inputs the second reference voltage.

The control circuit stops outputting the output voltage in response to the detection voltage output by the detection circuit being greater than the second reference voltage.

The control circuit includes: a logic OR circuit, the first input end of the logic OR circuit is connected to the output end of the first protection circuit, and the second input end of the logic OR circuit is connected to the output end of the second protection circuit; The input end is connected to the output end of the logic OR circuit; the drive circuit is connected to the output end of the multiplication circuit and the output end of the logic OR circuit, and is used for overvoltage protection and regulation of the output voltage according to the control signal output by the multiplication circuit and the logic OR circuit.

The driving circuit is an IGBT driving circuit, which is used for turning off according to the control signal output by the multiplying circuit and the logic OR circuit, and performing overvoltage protection and regulation on the output voltage.

Another technical solution adopted in the present application is to provide an electronic device including the above-mentioned overvoltage protection circuit.

The overvoltage protection circuit provided by the present application includes: a detection circuit for detecting the output voltage; a first protection circuit, which is connected to the detection circuit, and outputs a corresponding control signal in response to the variation range of the output voltage being greater than the first set threshold; The second protection circuit, connected to the detection circuit, outputs a corresponding control signal in response to the output voltage being greater than the second set threshold and exceeding the set time; the control circuit, connected to the first protection circuit and the second protection circuit, responds to the first protection The control signal output by the circuit or the second protection circuit performs overvoltage protection regulation on the output voltage. In the above manner, by setting the first protection circuit to detect the dynamic voltage change, and setting the second protection circuit to detect the static voltage change, it is suitable for more overvoltage situations. In addition, by setting the control circuit, the voltage can be adjusted It has high withstand voltage and large discharge capacity, which has played a good role in protecting electronic components such as transistors and chips.

【Description of drawings】

In order to illustrate the technical solutions in the embodiments of the present application more clearly, the following briefly introduces the drawings that are used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort. in:

1 is a schematic structural diagram of an embodiment of an overvoltage protection circuit provided by the present application;

2 is a schematic circuit diagram of a detection circuit provided by the present application;

3 is a schematic circuit diagram of a first protection circuit of the present application;

4 is a schematic circuit diagram of a second protection circuit of the present application;

5 is a schematic circuit diagram of a control circuit provided by the present application;

6 is a schematic circuit diagram of an embodiment of an overvoltage protection circuit provided by the present application;

FIG. 7 is a schematic structural diagram of an electronic device provided by the present application.

【detailed description】

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. It should be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application. In addition, it should be noted that, for the convenience of description, the drawings only show some but not all the structures related to the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

The terms "first", "second", etc. in this application are used to distinguish different objects, rather than to describe a specific order. Furthermore, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but optionally also includes unlisted steps or units, or optionally also includes For other steps or units inherent to these processes, methods, products or devices.

Reference herein to an "embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor a separate or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

Referring to FIG. 1 , FIG. 1 is a schematic structural diagram of an embodiment of an overvoltage protection circuit provided by the present application. The overvoltage protection circuit 100 includes a detection circuit 10 , a first protection circuit 21 , a second protection circuit 22 and a control circuit 30 .

The first protection circuit 21 is connected to the detection circuit 10 , the second protection circuit 22 is connected to the detection circuit 10 , and the control circuit 30 is connected to the first protection circuit 21 and the second protection circuit 22 .

The detection circuit 10 is used to detect the output voltage Vout; the first protection circuit 21 outputs a corresponding control signal in response to the change of the output voltage Vout being greater than the first set threshold; the second protection circuit 22 responds to the output voltage greater than The second set threshold value exceeds the set time, and outputs the corresponding control signal; the control circuit 30 performs overvoltage protection regulation on the output voltage Vout in response to the control signal output by the first protection circuit 21 or the second protection circuit 22, and finally outputs Adjust the voltage V0 or stop the voltage output.

It can be understood that the overvoltage protection circuit in this embodiment needs to detect the instantaneous change of the voltage, that is, the huge change of the voltage in a short period of time. Therefore, a comparison circuit can be used to determine whether the output voltage is greater than the preset first reference voltage. .

Specifically, as shown in FIG. 2 , which is a schematic circuit diagram of a detection circuit provided by the present application, the detection circuit 10 may include a voltage divider circuit and a first comparison circuit. The voltage divider circuit includes a first resistor R1 and a second resistor R2, the output voltage Vout is input from the first end of the first resistor R1, and the second end of the first resistor R2 is used as a voltage divider output; the first end of the second resistor R2 The terminal is connected to the second terminal of the first resistor R1, and the second terminal of the second resistor R2 is grounded. The first comparison circuit includes an error amplifier C1 and a capacitor CC, the first input terminal of the error amplifier C1 inputs the first reference voltage V1, and the second input terminal of the error amplifier C1 is connected to the second terminal of the first resistor R1; The first end is connected to the second input end of the error amplifier C1, and the second end of the capacitor CC is connected to the output end of the error amplifier C1.

In the above circuit, a change of ΔV will be detected from the resistor R1, the output of the comparator is connected to an input through the capacitor CC, and feedback is established. The change is fed back through the INV pin and amplified by EA. The generated detection voltage ΔV and the corresponding detection current ΔI.

Next, the first protection circuit 21 and the second protection circuit 22 will be introduced.

Referring to FIG. 3 , FIG. 3 is a schematic circuit diagram of the first protection circuit of the present application. The first protection circuit 21 includes a second comparator C2 , and the first input end of the second comparator C2 is connected to the output end of the detection circuit 21 for The detection current is input, and the reference current is input to the second input terminal of the second comparator C2.

Wherein, in an embodiment, the reference current includes a first reference current I1 and a second reference current I2, and the first reference current I1 is smaller than the second reference current I2.

In one embodiment, in response to the detection current ΔI output by the detection circuit 10 being greater than the first reference current I1 , the control circuit 30 reduces the voltage value of the output voltage Vout, that is, V0 is smaller than Vout.

In another embodiment, the control circuit 30 stops the output of the output voltage Vout in response to the detection current ΔI output by the detection circuit 10 being greater than the second reference current I2.

In one embodiment, we need to detect the detection current ΔI up to about 21μA. Therefore, for the setting of the first reference current I1, it can be slightly less than 21μA, for example, 20μA, and the second reference current I2 can be set to 27μA. Specifically, when the detection current ΔI reaches about 21 μA, or reaches 20 μA, the output voltage Vout is lowered. If the detection current ΔI continues to increase to 27 μA, it will directly turn off the output voltage Vout and stop working.

In addition, the control circuit 30 restores the output of the output voltage in response to the detection current ΔI output by the detection circuit 10 being smaller than the third reference I3 current, wherein the third reference current is smaller than the first reference current. For example, until the third reference current I3 can be set to 7 μA, when the detection current ΔI is less than 7 μA, the overvoltage protection is released and the system returns to normal.

The settings of the above reference currents need to be set according to the voltage value of the output voltage Vout and the parameters of each component in the overvoltage protection circuit.

Referring to FIG. 4, FIG. 4 is a schematic circuit diagram of the second protection circuit of the present application, the second protection circuit 21 includes a third comparator C3, the first end of the third comparator C3 is connected to the output end of the detection circuit 10, and the third comparator C3 A second reference voltage V2 is input to the second input terminal of the device C3.

Optionally, with reference to the above embodiment of FIG. 2 , in an embodiment, the first reference voltage V1 is set to 2.5V, and the second reference voltage V2 is set to 2.25V.

In this embodiment, the control circuit 30 stops the output of the output voltage Vout in response to the detection voltage ΔV output by the detection circuit 10 being greater than the second reference voltage V2.

Understandably, when the output voltage Vout is higher than the normal output range for a long time (for example, the load is small), at this time, the voltage feedback value detected by the INV pin of the first comparator C1 is very large, and the first comparator C1 The output terminal COMP will output a low level, and the first comparator C1 will enter the saturation region. When the third comparator C3 detects that the voltage at the COMP terminal is less than 2.25V, the third comparator C3 is triggered to output a control signal, and the control signal will The control circuit 30 stops the voltage output operation. Further, after the output voltage returns to the normal range, the output of the first comparator C1 returns to the linear region again, and the system resumes normal operation.

Referring to FIG. 5 , FIG. 5 is a schematic circuit diagram of the control circuit provided by the present application. The control circuit 30 includes a logic OR circuit 31 , a multiplying circuit 32 and a driving circuit 33 .

The first input terminal of the logical OR circuit 31 is connected to the output terminal of the first protection circuit 21, the second input terminal of the logical OR circuit 31 is connected to the output terminal of the second protection circuit 22, and the input terminal of the multiplication circuit 32 is connected to the logical OR circuit. The output terminal of 31; the driving circuit 33 is connected to the output terminal of the multiplication circuit 32 and the output terminal of the logical OR circuit 31, and is used to perform overvoltage protection regulation on the output voltage Vout according to the control signal output by the multiplication circuit 32 and the logical OR circuit 31.

The outputs of the first protection circuit 21 and the second protection circuit 22 can affect the output of the multiplication circuit 32, and the output of the multiplication circuit 32, the outputs of the first protection circuit 21 and the second protection circuit 22 further control the driving circuit 33.

Optionally, the drive circuit 33 is an IGBT (Insulated Gate Bipolar Transistor, insulated gate bipolar transistor) drive circuit, which is used for turning off according to the control signal of the multiplying circuit 32 and the logic OR circuit output 31, and performing a pass-through on the output voltage Vout. Voltage protection adjustment.

It can be understood that the transistors in the driving circuit 33 can be made of CMOS (Complementary Metal Oxide Semiconductor) process, BJT (Bipolar Junction Transistor, bipolar junction transistor) process, BCD (Bioolar-CMOS-DMOS,) process, One or more of SOI (Silicon-On-Insulator, silicon on insulating substrate) processes.

Referring to FIG. 6 below, FIG. 6 is a schematic circuit diagram of an embodiment of an overvoltage protection circuit provided by the present application, and is described by a specific circuit in conjunction with the above-mentioned FIGS. 1 to 5 .

The circuit mainly includes a dynamic OVP part (corresponding to the first protection circuit) and a static OVP part (corresponding to the second protection circuit).

First, a change of ΔV will be detected from the resistor R1, and the change will be fed back through the INV pin of the first comparator C1, and the ΔV generated by the amplification of the first comparator C1 and the corresponding detection current ΔI, the detection current ΔI will flow into the dynamic OVP part and be compared with the preset reference value (I1/I2). When the detection current ΔI reaches about 21μA, it will affect the output value of the multiplier (MULTIPILER) and force the IGBT in the driver circuit (DRIVER). The on-time is reduced, thereby reducing the output voltage Vout. If the current ΔI continues to increase to 27μA, it will directly force the IGBT to turn off, and the entire voltage output system will stop working. Until ΔI is less than 7μA, the dynamic overvoltage protection is released and the system returns to normal.

When the output voltage Vout of the whole system is higher than the normal output range for a long time (for example, the load is small), the static overvoltage protection part needs to be used. At this time, the voltage feedback value detected by the INV pin of the first comparator C1 is very large, the output terminal COMP of the first comparator C1 will output a low level, and the first comparator C1 will enter the saturation region. When the protection module detects that the voltage at the COMP terminal is less than 2.25V, the static overvoltage protection is triggered, and the control signal will force the IGBT in the drive circuit to turn off, and the entire voltage output system will stop working. After the output voltage of the system returns to the normal range, the output of the first comparator C1 returns to the linear region, and the system resumes normal operation.

Different from the prior art, the overvoltage protection circuit provided in this embodiment includes: a detection circuit for detecting the output voltage; a first protection circuit, connected to the detection circuit, in response to the change of the output voltage being greater than the first set threshold , output the corresponding control signal; the second protection circuit, connected to the detection circuit, outputs the corresponding control signal in response to the output voltage being greater than the second set threshold and exceeding the set time; the control circuit, connected to the first protection circuit and the second protection circuit The circuit performs overvoltage protection regulation on the output voltage in response to the control signal output by the first protection circuit or the second protection circuit. In the above manner, by setting the first protection circuit to detect the dynamic voltage change, and setting the second protection circuit to detect the static voltage change, it is suitable for more overvoltage situations. In addition, by setting the control circuit, the voltage can be adjusted It has high withstand voltage and large discharge capacity, which has played a good role in protecting electronic components such as transistors and chips.

Referring to FIG. 7 , FIG. 7 is a schematic structural diagram of an electronic device provided by the present application. The electronic device 70 is provided with an overvoltage protection circuit 100 , and the overvoltage protection circuit 100 is the overvoltage protection circuit in the above-mentioned embodiments.

In this embodiment, the electronic device 70 can be a power supply device, such as a switching power supply applied to alternating current, or other electronic devices with a power supply, such as a cooking device, such as an induction cooker, a rice cooker, an electric pressure cooker, a water heater, a microwave oven, etc. .

In the several embodiments provided in this application, it should be understood that the disclosed method and device may be implemented in other manners. For example, the device implementations described above are only illustrative. For example, the division of the modules or units is only a logical function division. In actual implementation, there may be other divisions. For example, multiple units or components may be Incorporation may either be integrated into another system, or some features may be omitted, or not implemented.

The units described as separate components may or may not be physically separated, and components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution in this implementation manner.

In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit. The above-mentioned integrated units may be implemented in the form of hardware, or may be implemented in the form of software functional units.

The above description is only an embodiment of the present application, and is not intended to limit the scope of the patent of the present application. Any equivalent structure or equivalent process transformation made according to the contents of the description and drawings of the present application, or directly or indirectly applied to other related technologies Fields are similarly included within the scope of patent protection of this application.

Claims

An overvoltage protection circuit, characterized in that the overvoltage protection circuit comprises:

A detection circuit is used to detect the output voltage;

a first protection circuit, connected to the detection circuit, and outputting a corresponding control signal in response to the variation range of the output voltage being greater than a first set threshold;

A second protection circuit, connected to the detection circuit, outputs a corresponding control signal in response to the output voltage being greater than a second set threshold and exceeding a set time;

A control circuit is connected to the first protection circuit and the second protection circuit, and in response to a control signal output by the first protection circuit or the second protection circuit, performs overvoltage protection regulation on the output voltage.
The overvoltage protection circuit according to claim 1, wherein,

The detection circuit includes:

a voltage divider circuit for dividing the output voltage;

The first comparison circuit is connected to the voltage dividing circuit, and is used for comparing the divided output voltage with a first reference voltage.
The overvoltage protection circuit according to claim 2, wherein,

The voltage divider circuit includes:

a first resistor, the output voltage is input from the first end of the first resistor, and the second end of the first resistor is output as a voltage divider;

A second resistor, the first end of the second resistor is connected to the second end of the first resistor, and the second end of the second resistor is grounded.
The overvoltage protection circuit according to claim 3, wherein,

The first comparison circuit includes:

an error amplifier, the first input end of the error amplifier is input with a first reference voltage, and the second input end of the error amplifier is connected to the second end of the first resistor;

A capacitor, the first end of the capacitor is connected to the second input end of the error amplifier, and the second end of the capacitor is connected to the output end of the error amplifier.
The overvoltage protection circuit according to claim 1, wherein,

The first protection circuit includes:

The second comparator, the first input terminal of the second comparator is connected to the output terminal of the detection circuit for inputting the detection current, and the second input terminal of the second comparator inputs the reference current.
The overvoltage protection circuit according to claim 5, wherein,

the reference current includes a first reference current and a second reference current, the first reference current is smaller than the second reference current;

The control circuit reduces the voltage value of the output voltage in response to the detection current output by the detection circuit being greater than the first reference current; or

The control circuit stops the output of the output voltage in response to the detection current output by the detection circuit being greater than the second reference current.
The overvoltage protection circuit according to claim 6, wherein,

The control circuit restores the output of the output voltage in response to the detection current output by the detection circuit being smaller than a third reference current, wherein the third reference current is smaller than the first reference current.
The overvoltage protection circuit according to claim 1, wherein,

The second protection circuit includes:

The third comparator, the first end of the third comparator is connected to the output end of the detection circuit, and the second input end of the third comparator inputs the second reference voltage.
The overvoltage protection circuit according to claim 8, wherein,

The control circuit stops the output of the output voltage in response to the detection voltage output by the detection circuit being greater than the second reference voltage.
The overvoltage protection circuit according to claim 1, wherein,

The control circuit includes:

a logic OR circuit, the first input end of the logic OR circuit is connected to the output end of the first protection circuit, and the second input end of the logic OR circuit is connected to the output end of the second protection circuit;

a multiplying circuit, the input end of the multiplying circuit is connected to the output end of the logic OR circuit;

The driving circuit is connected to the output terminal of the multiplication circuit and the output terminal of the logic OR circuit, and is used for performing overvoltage protection regulation on the output voltage according to the control signal output by the multiplication circuit and the logic OR circuit.
The overvoltage protection circuit according to claim 10, wherein,

The driving circuit is an IGBT driving circuit, and is used for turning off according to the control signal output by the multiplying circuit and the logic OR circuit, and performing overvoltage protection regulation on the output voltage.
An electronic device, characterized in that, the electronic device comprises the overvoltage protection circuit according to any one of claims 1-11.