Overvoltage detection circuit and electronic equipment

Abstract

The invention provides an overvoltage detection circuit and electronic equipment, the overvoltage detection circuit comprises an external resistor and an integrated chip, the external resistor is connected between a power supply voltage and a power supply input port of the integrated chip; the external resistor is used for detecting power supply voltage, and the integrated chip is used for carrying out overvoltage detection on the power supply voltage and outputting a detection result. According to the overvoltage detection circuit and the electronic equipment provided by the invention, the problem that the existing overvoltage detection circuit detects the power supply voltage through two external resistors, so that the circuit area is relatively large is solved.

Description

Technical Field

[0001] This invention relates to the field of electronic circuit design technology, and in particular to an overvoltage detection circuit and electronic device. Background Technology

[0002] Electronic products and electrical appliances all need to be connected to a power source or power grid. However, the voltage on the power source and power grid is not constant, and voltage fluctuations can easily damage electronic products and electrical appliances. In existing technology, an overvoltage detection circuit is usually added to the power input port. When the detected power supply voltage exceeds the detection threshold, an overvoltage protection mechanism is activated.

[0003] Figure 1 An overvoltage detection circuit is shown, including a first resistor R1, a second resistor R2, a reference voltage source VREF, and a hysteresis comparator CMP. The first resistor R1 and the second resistor R2 are connected in series between the power supply voltage VPP and the reference ground, and the series node of the two is connected to the non-inverting input terminal of the hysteresis comparator CMP. The inverting input terminal of the hysteresis comparator CMP is connected to the output terminal of the reference voltage source VREF. The output terminal of the hysteresis comparator CMP outputs the detection result OUT.

[0004] The detection result OUT is output by detecting the power supply voltage VPP and comparing it with the detection threshold VOV, so as to perform overvoltage protection based on the detection result OUT. When the power supply voltage VPP is less than the detection threshold VOV, the detection result OUT output by the hysteresis comparator CMP is low level; when the power supply voltage VPP is greater than the detection threshold VOV, the detection result OUT output by the hysteresis comparator CMP is high level. The detection threshold satisfies VOV=VREF*(R1+R2) / R2, where VOV is the detection threshold, VREF is the reference voltage output by the reference voltage source, R1 is the resistance value of the first resistor, and R2 is the resistance value of the second resistor.

[0005] In the above overvoltage detection circuit, the reference voltage source VREF and the hysteresis comparator CMP are integrated inside the chip, while the first resistor R1 and the second resistor R2 are located outside the chip and interconnected with the hysteresis comparator CMP through the power input port IN. The detection threshold VOV is set by changing the resistance values ​​of the first resistor R1 and the second resistor R2. In practical applications, the built-in resistors of the chip generally have very low accuracy, and their resistance values ​​change with temperature and voltage. Therefore, the two resistors used to detect the power supply voltage VPP cannot be integrated inside the chip and must be external resistors. The use of external resistors inevitably leads to an increase in circuit area.

[0006] It should be noted that the above description of the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of the present invention and facilitating understanding by those skilled in the art. It should not be assumed that the above technical solutions are known to those skilled in the art simply because they have been described in the background section of this invention. Summary of the Invention

[0007] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide an overvoltage detection circuit and electronic device to solve the problem that the existing overvoltage detection circuits have a large circuit area due to the use of two external resistors for power supply voltage detection.

[0008] To achieve the above and other related objectives, the present invention provides an overvoltage detection circuit, comprising:

[0009] An external resistor and an integrated chip, wherein the external resistor is connected between a power supply voltage and a power input port of the integrated chip;

[0010] The external resistor is used to detect the power supply voltage, and the integrated chip is used to perform overvoltage detection on the power supply voltage and output the detection result.

[0011] Optionally, the integrated chip includes:

[0012] A conversion module is set up and connected to the power input port. Based on the negative feedback mechanism, the port voltage of the power input port is set as a reference voltage, and the power supply voltage is converted into a detection current based on the reference voltage.

[0013] The current comparison module, connected to the setting conversion module, compares the detected current with the reference current and outputs the detection result.

[0014] Optionally, the setting conversion module includes an operational amplifier, a reference voltage source, and a first transistor, wherein the non-inverting input of the operational amplifier is connected to the output of the reference voltage source, the inverting input of the operational amplifier is connected to the first terminal of the first transistor, the output of the operational amplifier is connected to the control terminal of the first transistor, the first terminal of the first transistor is also connected to the power input port, and the second terminal of the first transistor serves as the output of the setting conversion module.

[0015] Optionally, the current comparison module includes:

[0016] A current mirroring unit, connected to the setting conversion module, mirrors the detected current based on the mirroring ratio and outputs a mirrored current.

[0017] A reference providing unit is used to provide a reference current;

[0018] The current comparison unit is connected to the current mirror unit and the reference providing unit respectively, and compares the mirrored current with the reference current to output the detection result.

[0019] Optionally, the current mirror unit includes a second transistor and a third transistor, wherein the control terminal of the second transistor is connected to the control terminal of the third transistor, the first terminal of the second transistor is connected to a reference ground, the second terminal of the second transistor is connected to its control terminal and the output terminal of the setting conversion module, the first terminal of the third transistor is connected to the reference ground, and the second terminal of the third transistor serves as the output terminal of the current mirror unit.

[0020] Optionally, the reference providing unit is implemented using a reference current source.

[0021] Optionally, the current comparison unit includes a Schmitt trigger, wherein the input terminal of the Schmitt trigger is connected to the output terminal of the current mirror unit and the output terminal of the reference providing unit, and the output terminal of the Schmitt trigger serves as the output terminal of the overvoltage detection circuit.

[0022] The present invention also provides an electronic device, comprising: an overvoltage detection circuit as described in any of the above claims.

[0023] Optionally, it further includes: an overvoltage protection circuit connected to the overvoltage detection circuit, which provides overvoltage protection to the electronic device based on the detection result.

[0024] Optionally, the overvoltage protection circuit is integrated into the integrated chip.

[0025] As described above, the overvoltage detection circuit and electronic device of the present invention only require one external resistor around the integrated chip to achieve overvoltage detection, and can also set the detection threshold. Compared with the existing circuit structure, it saves one external resistor, which is beneficial to reduce area and cost in system design. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of an existing overvoltage detection circuit.

[0027] Figure 2 The diagram shown is a structural schematic of an overvoltage detection circuit in an embodiment of the present invention.

[0028] Figure 3 The diagram shown is a structural schematic of an electronic device according to an embodiment of the present invention.

[0029] Component designation explanation

[0030] 1. Electronic equipment

[0031] 10 Overvoltage detection circuit

[0032] 100 integrated chips

[0033] 110 Setting Conversion Module

[0034] 120 Current Comparison Module

[0035] 121 Current Mirror Unit

[0036] 122 Reference Providing Unit

[0037] 123 Current Comparison Unit

[0038] 20 Overvoltage Protection Circuit Detailed Implementation

[0039] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0040] Please see Figure 2 and Figure 3 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the shape, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0041] Example 1

[0042] like Figure 2 As shown, this embodiment provides an overvoltage detection circuit 10, including an external resistor R and an integrated chip 100. Wherein:

[0043] An external resistor R is connected between the power supply voltage VPP and the power input port IN of the integrated chip 100 to detect the power supply voltage VPP. In this embodiment, the detection threshold can be set by adjusting the resistance value of the external resistor R; in practical applications, the resistance value of the external resistor R should be designed according to specific requirements, and no further restrictions are imposed on it.

[0044] An integrated chip 100 is used to perform overvoltage detection on the power supply voltage VPP and output the detection result OUT. In one embodiment, the integrated chip 100 includes a setting conversion module 110 and a current comparison module 120.

[0045] The conversion module 110 is connected to the power input port IN. Based on the negative feedback mechanism, the port voltage of the power input port IN is set to the reference voltage VREF, and the power supply voltage VPP is converted into the detection current IDET based on the reference voltage VREF.

[0046] In a specific example, the setting conversion module 110 includes an operational amplifier OP, a reference voltage source VREF, and a first transistor M1. Specifically: the non-inverting input of the operational amplifier OP is connected to the output of the reference voltage source VREF to receive a reference voltage; the inverting input of the operational amplifier OP is connected to the first terminal of the first transistor M1; the output of the operational amplifier OP is connected to the control terminal of the first transistor M1; the first terminal of the first transistor M1 is also connected to the power input port IN; and the second terminal of the first transistor M1 serves as the output of the setting conversion module 110 to output the detection current IDET. In practical applications, the positive terminal of the reference voltage source VREF is used as the output terminal, and the negative terminal is connected to ground. As an optional configuration, the first transistor M1 is a PMOS transistor; correspondingly, the control terminal is the gate terminal, the first terminal is the source terminal, and the second terminal is the drain terminal.

[0047] In this example, the operational amplifier OP, the reference voltage source VREF, and the first transistor M1 constitute a negative feedback structure. Due to the negative feedback mechanism, the port voltage of the power input port IN is equal to the reference voltage output by the reference voltage source VREF. Let the port voltage of the power input port IN be denoted as VIN, and the reference voltage be denoted as VREF, then VIN = VREF. Furthermore, the input current of the non-inverting and inverting input terminals of the operational amplifier OP is zero. Therefore, the current flowing through the external resistor R and into the power input port IN is equal to the drain current of the first transistor M1. This current is the detection current IDET, which satisfies the formula IDET = (VPP - VREF) / R, where VPP is the power supply voltage, VREF is the reference voltage, and R is the resistance value of the external resistor.

[0048] The current comparison module 120, connected to the setting conversion module 110, compares the detected current IDET with the reference current IREF and outputs the detection result OUT. As an example, the current comparison module 120 includes a current mirror unit 121, a reference providing unit 122, and a current comparison unit 123.

[0049] The current mirror unit 121 is connected to the setting conversion module 110. Based on the mirror ratio, it performs mirror processing on the detected current IDET and outputs the mirror current IMIR.

[0050] In a specific example, the current mirror unit 121 includes a second transistor M2 and a third transistor M3. Specifically: the control terminal of the second transistor M2 is connected to the control terminal of the third transistor M3; the first terminal of the second transistor M2 is connected to reference ground; the second terminal of the second transistor M2 is connected to its control terminal; and the second terminal of the second transistor M2 is also connected to the output terminal of the setting conversion module 110 to access the detection current IDET; the first terminal of the third transistor M3 is connected to reference ground; and the second terminal of the third transistor M3 serves as the output terminal of the current mirror unit 121 to output the mirrored current IMIR. Alternatively, both the second transistor M2 and the third transistor M3 can be NMOS transistors; correspondingly, the control terminal is the gate terminal, the first terminal is the source terminal, and the second terminal is the drain terminal.

[0051] In this example, the second transistor M2 and the third transistor M3 form a current mirror structure. The ratio of the width-to-length ratio of the second transistor M2 to that of the third transistor M3 is M:1. Therefore, the mirror ratio of this current mirror structure is M:1, that is, the ratio of the drain current of the second transistor M2 to the drain current of the third transistor M3 is M:1, which also means that the ratio of the detection current IDET to the mirror current IMIR is M:1, where M is a natural number greater than 1. By converting the detection current IDET to the mirror current IMIR through the current mirror structure, the value of the detection current IDET can be reduced, which is beneficial to the implementation of the subsequent current comparison.

[0052] Reference providing unit 122 is used to provide reference current IREF.

[0053] In a specific example, the reference providing unit 122 includes a reference current source IREF. The input terminal of the reference current source IREF is connected to the operating voltage, and the output terminal of the reference current source IREF outputs a reference current. In practical applications, the reference current source IREF can be implemented using any existing known circuit structure capable of providing a reference current; no further restrictions are imposed on this.

[0054] The current comparison unit 123 is connected to the current mirror unit 121 and the reference providing unit 122 respectively, and compares the mirror current IMIR with the reference current IREF to output the detection result OUT.

[0055] In a specific example, the current comparison unit 123 includes a Schmitt trigger SMIT. The input of the Schmitt trigger SMIT is connected to the output of the current mirror unit 121 to receive the mirrored current IMIR. The input of the Schmitt trigger SMIT is also connected to the output of the reference providing unit 122 to receive the reference current IREF. The output of the Schmitt trigger SMIT serves as the output of the overvoltage detection circuit 10 to output the detection result OUT.

[0056] In this example, the mirror current IMIR and the reference current IREF are compared using a Schmitt trigger SMIT. When the mirror current IMIR is less than the reference current IREF, the input of the Schmitt trigger SMIT is at a high level, and correspondingly, the output of the Schmitt trigger SMIT is at a low level, that is, the detection result OUT is low. When the mirror current IMIR is greater than the reference current IREF, the input of the Schmitt trigger SMIT is at a low level, and correspondingly, the output of the Schmitt trigger SMIT is at a high level, that is, the detection result OUT is high.

[0057] It is important to note that the Schmitt trigger (SMIT) does not directly compare the mirror current IMIR and the reference current IREF like a comparator. Instead, it uses the difference between the mirror current IMIR and the reference current IREF to create different voltage levels at the input of the Schmitt trigger (SMIT), thereby outputting the corresponding detection result and achieving indirect current comparison.

[0058] The overvoltage detection circuit 10 in this embodiment compares the mirror current IMIR and the reference current IREF. Essentially, it compares the power supply voltage VPP and the detection threshold VOV. That is, when the power supply voltage VPP is less than the detection threshold VOV, the detection result OUT is low; when the power supply voltage VPP is greater than the detection threshold VOV, the detection result OUT is high. The detection threshold satisfies VOV = M * IREF * R + VREF, where VOV is the detection threshold, M is the mirror ratio, IREF is the reference current, R is the external resistor, and VREF is the reference voltage. In practical applications, the detection threshold VOV can be set by changing the value of the external resistor R to meet different application requirements.

[0059] Example 2

[0060] like Figure 3 As shown, this embodiment provides an electronic device 1, including an overvoltage detection circuit 10, and further including an overvoltage protection circuit 20. In practical applications, the electronic device 1 can be an electronic product or an electrical appliance; of course, other power supply devices with electronic circuits are also feasible and are not limited thereto.

[0061] The overvoltage detection circuit 10 is used to detect overvoltage of the power supply voltage VPP and output the detection result OUT. Specifically, when the power supply voltage VPP is less than the detection threshold VOV, the detection result OUT is low; when the power supply voltage VPP is greater than the detection threshold VOV, the detection result OUT is high. The overvoltage detection circuit 10 is implemented using the circuit structure described in Embodiment 1, the relevant details of which can be found above and will not be repeated here.

[0062] The overvoltage protection circuit 20, connected to the overvoltage detection circuit 10, provides overvoltage protection for the electronic device 1 based on the detection result OUT. For example, overvoltage protection can be achieved by clamping the power supply voltage VPP. Of course, other techniques that can achieve overvoltage protection are also feasible and are not limited to this. Specifically, when the detection result OUT is low, the electronic device 1 is powered through the power supply voltage VPP; when the detection result OUT is high, the power supply voltage VPP is clamped before powering on the electronic device 1. In practical applications, the overvoltage protection circuit 20 is usually integrated into the integrated chip 100 to reduce the area of ​​the electronic device 1.

[0063] In summary, the overvoltage detection circuit and electronic device of the present invention require only one external resistor around the integrated chip to achieve overvoltage detection, and also allows for setting the detection threshold. Compared with existing circuit structures, it saves one external resistor, which is beneficial for reducing area and cost during system design. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0064] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. An overvoltage detection circuit, characterized in that, include: An external resistor and an integrated chip, wherein the external resistor is connected between a power supply voltage and a power input port of the integrated chip; The external resistor is used to detect the power supply voltage, and the integrated chip is used to perform overvoltage detection on the power supply voltage and output the detection result.

2. The overvoltage detection circuit according to claim 1, characterized in that, The integrated chip includes: A conversion module is set up and connected to the power input port. Based on the negative feedback mechanism, the port voltage of the power input port is set as a reference voltage, and the power supply voltage is converted into a detection current based on the reference voltage. The current comparison module, connected to the setting conversion module, compares the detected current with the reference current and outputs the detection result.

3. The overvoltage detection circuit according to claim 2, characterized in that, The setting conversion module includes an operational amplifier, a reference voltage source, and a first transistor. The non-inverting input of the operational amplifier is connected to the output of the reference voltage source, the inverting input of the operational amplifier is connected to the first terminal of the first transistor, the output of the operational amplifier is connected to the control terminal of the first transistor, the first terminal of the first transistor is also connected to the power input port, and the second terminal of the first transistor serves as the output of the setting conversion module.

4. The overvoltage detection circuit according to claim 2, characterized in that, The current comparison module includes: A current mirroring unit, connected to the setting conversion module, mirrors the detected current based on the mirroring ratio and outputs a mirrored current. A reference providing unit is used to provide a reference current; The current comparison unit is connected to the current mirror unit and the reference providing unit respectively, and compares the mirrored current with the reference current to output the detection result.

5. The overvoltage detection circuit according to claim 4, characterized in that, The current mirror unit includes a second transistor and a third transistor, wherein the control terminal of the second transistor is connected to the control terminal of the third transistor, the first terminal of the second transistor is connected to a reference ground, the second terminal of the second transistor is connected to its control terminal and the output terminal of the setting conversion module, the first terminal of the third transistor is connected to the reference ground, and the second terminal of the third transistor serves as the output terminal of the current mirror unit.

6. The overvoltage detection circuit according to claim 4, characterized in that, The reference providing unit is implemented using a reference current source.

7. The overvoltage detection circuit according to claim 4, characterized in that, The current comparison unit includes a Schmitt trigger, wherein the input terminal of the Schmitt trigger is connected to the output terminal of the current mirror unit and the output terminal of the reference providing unit, and the output terminal of the Schmitt trigger serves as the output terminal of the overvoltage detection circuit.

8. An electronic device, characterized in that, include: The overvoltage detection circuit as described in any one of claims 1 to 7.

9. The electronic device according to claim 8, characterized in that, Also includes: An overvoltage protection circuit is connected to the overvoltage detection circuit and provides overvoltage protection for the electronic device based on the detection results.

10. The electronic device according to claim 9, characterized in that, The overvoltage protection circuit is integrated into the integrated chip.

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