An overvoltage protection circuit and system for low current chips

Abstract

The utility model relates to circuit technical field especially is related to a kind of overvoltage protection circuit and system for small current chip, the utility model under the condition of given input voltage, the voltage generation module generates first voltage and second voltage, the voltage selection module selects the voltage of greater voltage in first voltage and second voltage as third voltage transmission to voltage switching module;Third voltage is compared with input voltage, when the third voltage and input voltage difference is less than or equal to threshold voltage, the output voltage of voltage switching module is the input voltage;When the third voltage and input voltage difference is greater than threshold voltage, the chip to be protected and voltage switching module share input voltage at this moment, to realize the purpose of protecting small current chip, compared with the overvoltage protection circuit of traditional discharge current mode, reduce the requirement to chip power supply top layer metal routing, reduce the pin number required for packaging.

Description

Technical Field

[0001] This utility model relates to the field of circuit technology, and in particular to an overvoltage protection circuit and system for low-current chips. Background Technology

[0002] Traditional on-chip overvoltage protection circuits ensure that the internal power supply voltage remains unaffected as the external input voltage increases. This method places strict requirements on the chip's external packaging and internal wiring, necessitating sufficient metal width and a large number of package leads to meet the high current discharge capability. However, current technologies cannot meet these packaging or wiring requirements for low-current, small-area chips.

[0003] Therefore, overcoming the shortcomings of the existing technology is an urgent problem to be solved in this technical field. Utility Model Content

[0004] The technical problem this invention aims to solve is how to provide overvoltage protection for chips with low current and small area.

[0005] The present invention adopts the following technical solution:

[0006] In a first aspect, an overvoltage protection circuit for a low-current chip is provided, comprising a voltage generation module, a voltage selection module, and a voltage switching module. The voltage generation module is connected to an input voltage and the voltage selection module, respectively. The voltage selection module is also connected to the voltage switching module, and the voltage switching module is also used to connect to the chip to be protected.

[0007] The voltage generation module is used to divide the input voltage to output a first voltage and a second voltage, and the voltage selection module is used to output a third voltage, wherein the third voltage is equal to the larger of the first voltage and the second voltage;

[0008] When the difference between the third voltage and the input voltage is less than or equal to the threshold voltage, the output voltage of the voltage switching module is the input voltage; when the difference between the third voltage and the input voltage is greater than the threshold voltage, the voltage switching module is used to divide the input voltage and transmit it to the chip to be protected.

[0009] Preferably, the voltage generation module includes a first voltage divider unit, which includes a resistor R1 and a resistor R2. One end of the resistor R1 is connected to the input voltage, and the other end of the resistor R1 is connected to one end of the resistor R2. The other end of the resistor R2 is grounded. The first voltage is the voltage at the first voltage divider point between the other end of the resistor R1 and one end of the resistor R2.

[0010] Preferably, the voltage generation module further includes a second voltage divider unit, which includes a resistor R3 and a transistor M1. One end of the resistor R3 is connected to the input voltage, and the other end of the resistor R3 is connected to the gate and drain of the transistor M1, respectively. The source of the transistor M1 is grounded. The second voltage is the voltage at the second voltage divider point between the other end of the resistor R3 and the gate and drain of the transistor M1.

[0011] Preferably, the voltage selection module includes transistor M2 and transistor M3. The source of transistor M2 is connected to the first voltage divider point corresponding to the first voltage, and the gate of transistor M2 is connected to the second voltage divider point corresponding to the second voltage. The source of transistor M3 is connected to the second voltage divider point, and the gate of transistor M3 is connected to the first voltage divider point.

[0012] The drains of transistors M2 and M3 are connected and output the third voltage.

[0013] Preferably, the voltage switching module includes a third voltage divider unit, a switching unit, and a fourth voltage divider unit. The third voltage divider unit is connected to the voltage selection module, the fourth voltage divider unit is connected to the input voltage, and the third and fourth voltage divider units are respectively connected to the switching unit. The switching unit is also used to connect to the chip to be protected.

[0014] Preferably, the third voltage divider unit includes a transistor M4 and a resistor R4. The source of the transistor M4 is connected to the input voltage, and the gate of the transistor M4 is connected to the voltage point corresponding to the third voltage. The drain of the transistor M4 is connected to one end of the resistor R4, and the other end of the resistor R4 is grounded.

[0015] Preferably, the switching unit includes a transistor M5, the gate of the transistor M5 is connected to the third voltage divider point between the drain of the transistor M4 and one end of the resistor R4; the source of the transistor M5 is connected to the output voltage, and the drain of the transistor M5 is used to connect to the chip to be protected.

[0016] Preferably, the fourth voltage divider unit includes resistor R5, resistor R6, transistor M6, and transistor M7. One end of resistor R5 is connected to the input voltage, the other end of resistor R5 is connected to the drain of transistor M6, the source of transistor M6 is connected to one end of resistor R6, and the other end of resistor R6 is grounded. The gates of transistor M6 and transistor M7 are respectively connected to the third voltage divider point.

[0017] The drain of transistor M7 is connected to the fourth voltage divider point between the source of transistor M6 and resistor R6, and the source of transistor M7 is used to connect to the chip to be protected.

[0018] Preferably, the threshold voltage ranges from 0.6V to 1V.

[0019] In a second aspect, an overvoltage protection system is provided, comprising an overvoltage protection circuit for a low-current chip as described in the first aspect and a chip to be protected, wherein the voltage output terminal of the voltage switching module is connected to the chip to be protected.

[0020] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0021] In this invention, given an input voltage, the voltage generation module generates a first voltage and a second voltage. The voltage selection module selects the larger of the first and second voltages as a third voltage and transmits it to the voltage switching module. The third voltage is compared with the input voltage. When the difference between the third voltage and the input voltage is less than or equal to a threshold voltage, the output voltage of the voltage switching module is the input voltage. When the difference between the third voltage and the input voltage is greater than the threshold voltage, the chip to be protected and the voltage switching module share the input voltage, thereby achieving the purpose of protecting low-current chips. Compared with traditional overvoltage protection circuits that discharge current, this invention reduces the requirements for the top metal traces of the chip power supply and reduces the number of pins required for the package. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of an overvoltage protection circuit for a low-current chip provided by an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the specific structure of an overvoltage protection circuit for a low-current chip provided in an embodiment of this utility model;

[0025] Figure 3 This is a schematic diagram of an overvoltage protection system for low-current chips provided by an embodiment of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0027] Unless the context otherwise requires, throughout the specification and claims, the term "comprising" is interpreted as openly inclusive, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiment," "example," "specific example," or "some examples" are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this disclosure. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics mentioned may be included in any suitable manner in any one or more embodiments or examples; that is, although they may be incorporated into embodiments or examples using the above terms for reasons such as order and position, it does not limit them to be incorporated in combination by a single embodiment or example.

[0028] In the description of this utility model, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this disclosure, unless otherwise stated, "a plurality of" means two or more. Furthermore, for example, the description may use the prefix "A" or "B" to describe the same type of nouns as two independent entities. In this case, the features defined with "A" and "B" are used only to distinguish between similar entities and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features.

[0029] In describing some embodiments, the terms "coupled," "coupled," and "connected," and their derivative expressions, may be used. For example, the term "connected" may be used in describing some embodiments to indicate that two or more components have direct physical or electrical contact with each other. Similarly, the term "coupled" may be used in describing some embodiments to indicate that two or more components have direct physical or electrical contact. However, the terms "connected" or "coupled" may also refer to two or more components that do not have direct contact with each other but still cooperate or interact with each other, such as "optical coupling" or "wireless connection." The embodiments disclosed herein are not necessarily limited to the scope of this invention.

[0030] Furthermore, the technical features involved in the various embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0031] To address the problems of existing technologies, this embodiment proposes an overvoltage protection circuit for low-current chips, such as... Figure 1 As shown, the system includes a voltage generation module, a voltage selection module, and a voltage switching module. The voltage generation module is connected to both the input voltage and the voltage selection module. The voltage selection module is also connected to the voltage switching module, which is further connected to the chip to be protected. The voltage generation module divides the input voltage to output a first voltage and a second voltage. The voltage selection module outputs a third voltage, where the third voltage is equal to the larger of the first and second voltages. When the first voltage is greater than the second voltage, the voltage selection module outputs the third voltage corresponding to the first voltage. When the difference between the third voltage and the input voltage is less than or equal to a threshold voltage, the output voltage of the voltage switching module is the input voltage. When the difference between the third voltage and the input voltage is greater than the threshold voltage, the voltage switching module divides the input voltage and transmits it to the chip to be protected.

[0032] The voltage generation module receives an external input voltage and generates a first voltage and a second voltage based on the input voltage. The voltage selection module compares the magnitudes of the first voltage and the second voltage. The first voltage and the second voltage are related to the structure of the voltage generation module, as detailed in the following embodiments.

[0033] In one embodiment, the magnitude of the third voltage is not fixed. If the first voltage is less than or equal to the second voltage, the third voltage is equal to the second voltage; conversely, if the first voltage is greater than the second voltage, the third voltage is equal to the first voltage.

[0034] The third voltage and the original input voltage are sent together to the voltage switching module. The voltage switching module checks the difference between the third voltage and the input voltage at various times. If the difference is less than or equal to a predetermined threshold voltage, the input voltage is directly allowed to be output as the chip to be protected for normal operation. If the difference between the third voltage and the input voltage is greater than the threshold voltage, it indicates abnormal fluctuations in the input voltage, and the large voltage may damage the chip to be protected. In this case, the voltage switching module divides the input voltage and then sends the divided voltage to the chip to be protected, thus preventing the chip from malfunctioning or being damaged due to excessively high voltage. In one embodiment, the threshold voltage ranges from 0.6V to 1V. That is, the threshold voltage can be 0.6V, 1V, or any voltage value between 0.6V and 1V; a more specific value needs to be determined based on the normal operating parameters of the chip to be protected, which will not be elaborated upon in this embodiment.

[0035] The specific structure of each module in the overvoltage protection circuit will be described in detail below.

[0036] In one embodiment, such as Figure 2 As shown, the voltage generation module includes a first voltage divider unit, which includes resistors R1 and R2. One end of resistor R1 is connected to the input voltage, and the other end of resistor R1 is connected to one end of resistor R2. The other end of resistor R2 is grounded. The first voltage is the voltage at the first voltage divider point (i.e., point A) between the other end of resistor R1 and one end of resistor R2.

[0037] When the input voltage is applied, the current flows from the input voltage terminal through resistor R1, then through resistor R2, and finally to ground. According to the voltage divider principle of a series circuit, the first voltage is generated at the first voltage divider point between resistors R1 and R2. The formula for calculating the first voltage V1 is:

[0038]

[0039] in, The input voltage is... The resistance value of resistor R1 is... Let R2 be the resistance value.

[0040] In one embodiment, refer to Figure 2The voltage generation module further includes a second voltage divider unit, which includes a resistor R3 and a transistor M1. One end of the resistor R3 is connected to the input voltage, and the other end of the resistor R3 is connected to the gate and drain of the transistor M1, respectively. The source of the transistor M1 is grounded. The second voltage is the voltage at the second voltage divider point (i.e., point B) between the other end of the resistor R3 and the gate and drain of the transistor M1.

[0041] In this embodiment, all transistors can be MOS (Metal-Oxide-Semiconductor) transistors, which will not be repeated in the following embodiments.

[0042] In one embodiment, when the input voltage is applied to the circuit, current flows from the input voltage terminal through resistor R3 and then to the gate-drain connection point of transistor M1. The magnitude of the second voltage generated at the second voltage divider point is related to the characteristics of transistor M1 and resistor R3; transistor M1 and resistor R3 work together to divide the voltage. Assuming the equivalent resistance of transistor M1 is RM1 (this equivalent resistance changes with the transistor's operating state), according to the voltage divider principle, the formula for calculating the second voltage V2 is:

[0043]

[0044] in, Let R3 be the resistance value. It should be noted that, due to... Since it is not a fixed value, the variation of the second voltage is more complex than that of the first voltage generated by the first voltage divider unit, specifically in the following ways:

[0045] In the voltage generation module, the first voltage is obtained by dividing the input voltage using resistors R1 and R2, and the second voltage is obtained by dividing the input voltage using resistor R3 and transistor M1. Before the input voltage rises to a certain level, both the first and second voltages follow the input voltage, with the second voltage being greater than the first voltage. After the input voltage rises linearly to a certain level, the first voltage continues to rise linearly according to the voltage division ratio, while the second voltage output tends to a stable value. At this point, the first voltage is greater than the second voltage, and the difference between the two voltages gradually increases as the input voltage continues to increase.

[0046] Specifically, for the first voltage, as long as the resistance values ​​of resistors R1 and R2 are fixed, the first voltage will have a linear relationship with the input voltage. When the input voltage increases linearly, the first voltage will rise linearly according to a fixed voltage division ratio.

[0047] For the second voltage, during the lower input voltage phase, transistor M1 operates in the variable resistance region or near-linear operation. At this time, since resistor R3 and transistor M1 (which can be considered as an equivalent resistor) jointly divide the input voltage, and the equivalent resistance changes with Vin, the second voltage can rise along with the input voltage.

[0048] When the input voltage rises to a certain level, transistor M1 may enter the saturation region. Taking a MOS transistor as an example, when the gate-source voltage exceeds its turn-on voltage and the drain-source voltage reaches a certain value, the drain current of transistor M1 essentially no longer changes with the input voltage. At this point, transistor M1 approximates a fixed voltage drop. The second voltage is then mainly determined by the relatively stable operating state of transistor M1, no longer increasing significantly with the increase of the input voltage, but rather tending towards a stable value. For example, assuming that the equivalent resistance of transistor M1 remains almost constant in the saturation state, the second voltage will fluctuate around a stable value determined by the equivalent resistance and the voltage division of resistor R3, no longer increasing linearly with the linear increase of the input voltage.

[0049] In one embodiment, refer to Figure 2 The voltage selection module includes transistor M2 and transistor M3. The source of transistor M2 is connected to the first voltage divider point, and the gate of transistor M2 is connected to the second voltage divider point. The source of transistor M3 is connected to the second voltage divider point, and the gate of transistor M3 is connected to the first voltage divider point. The drains of transistors M2 and M3 are connected and output the third voltage.

[0050] In one embodiment, both transistor M2 and transistor M3 are P-type MOS transistors. When the first voltage V1 <= the second voltage V2, transistor M3 is turned on, and the third voltage V3 is equal to the second voltage V2; when the first voltage V1 > the second voltage V2, transistor M2 is turned on, and the third voltage V3 is equal to the first voltage V1.

[0051] In one embodiment, refer to Figure 2 The voltage switching module includes a third voltage divider unit, a switching unit, and a fourth voltage divider unit. The third voltage divider unit is connected to the voltage selection module, the fourth voltage divider unit is connected to the input voltage, and the third and fourth voltage divider units are respectively connected to the switching unit. The switching unit is also used to connect to the chip to be protected.

[0052] Specifically, when the difference between the third voltage and the input voltage is less than or equal to a threshold voltage, the output voltage of the switching unit is the input voltage; when the difference between the third voltage and the input voltage is greater than the threshold voltage, the fourth voltage divider unit is used to divide the input voltage and transmit it to the chip to be protected.

[0053] In one embodiment, refer to Figure 2 The third voltage divider unit includes a transistor M4 and a resistor R4. The source of the transistor M4 is connected to the input voltage, and the gate of the transistor M4 is connected to the drain of the transistors M2 and M3. The drain of the transistor M4 is connected to one end of the resistor R4, and the other end of the resistor R4 is grounded.

[0054] The source of transistor M4 is connected to the input voltage, enabling it to acquire the input voltage. The gate of transistor M4 is connected to the drains of transistors M2 and M3. Therefore, the conduction of transistor M4 is controlled by a third voltage output from the voltage selection module. Specifically, the difference between the third voltage and the input voltage is compared to a threshold voltage. If the third voltage minus the input voltage is greater than the threshold voltage, transistor M4 is turned on; if the third voltage minus the input voltage is less than or equal to the threshold voltage, transistor M4 is turned off.

[0055] In one embodiment, refer to Figure 2 The switching unit includes transistor M5. The gate of transistor M5 is connected to the third voltage divider point (i.e., point C) between the drain of transistor M4 and one end of resistor R4. The source of transistor M5 is connected to the output voltage, and the drain of transistor M5 is used to connect to the chip to be protected. (Refer to...) Figure 2 The fourth voltage divider unit includes resistors R5 and R6, transistor M6 and transistor M7. One end of resistor R5 is connected to the input voltage, and the other end of resistor R5 is connected to the drain of transistor M6. The source of transistor M6 is connected to one end of resistor R6, and the other end of resistor R6 is grounded. The gates of transistor M6 and M7 are respectively connected to the third voltage divider point. The drain of transistor M7 is connected to the fourth voltage divider point (i.e., point D) between the source of transistor M6 and resistor R6. The source of transistor M7 is used to connect to the chip to be protected.

[0056] Specifically, when the difference between the third voltage V3 and the input voltage Vin is less than or equal to the threshold voltage Vth: Since the difference between the third voltage V3 and the input voltage Vin is small, transistor M4 is turned off. At this time, the drain voltage V4 of transistor M4 is connected to ground GND through resistor R4, and V4 is approximately 0V (because R4 pulls V4 to ground potential). For transistor M5, its gate voltage V4 is approximately 0V, and its source is connected to the input voltage Vin, so the gate voltage - source voltage of transistor M5 = Vin - 0 = Vin. Assuming the threshold voltage of transistor M5 is Vth5, and Vin > Vth5, then transistor M5 is turned on. For transistors M6 and M7, their gate voltage V4 is approximately 0V, so the gate voltage - source voltage of transistors M6 and M7 is less than their threshold voltage, therefore transistors M6 and M7 are turned off.

[0057] Because transistor M5 is turned on, transistors M6 and M7 are turned off. The input voltage Vin is directly output to Vout through the turned-on transistor M5, so the output voltage Vout is equal to the input voltage Vin.

[0058] When the difference between the third voltage V3 and the input voltage Vin is greater than the threshold voltage Vth:

[0059] At this time, transistor M4 is turned on. Because transistor M4 is turned on, its drain voltage V4 will rise to near the input voltage Vin (because after transistor M4 is turned on, the resistance between its drain and source is relatively small, approximately a short circuit). For transistor M5, its gate voltage V4 is close to Vin, and its source is connected to the input voltage Vin. Therefore, the gate voltage minus the source voltage of transistor M5 is approximately 0V, which is less than its threshold voltage Vth5, so transistor M5 is turned off. For transistors M6 and M7, their gate voltage V4 is close to Vin. For transistor M7, its source is connected to Vout, and its drain is grounded through resistor R6. Assuming the threshold voltage of transistor M7 is Vth7, and Vin - Vout > Vth7, then transistor M7 is turned on. For transistor M6, its source is grounded, and its gate voltage V4 is close to Vin. Assuming the threshold voltage of transistor M6 is Vth6, and Vin > Vth6, then transistor M6 is turned on.

[0060] Because transistor M5 is off, transistors M6 and M7 are on. At this time, the output voltage Vout is determined by the voltage divider formed by resistors R5 and R6. According to the voltage divider formula:

[0061]

[0062] in, Let R5 be the resistance value. The resistance value of resistor R6 is... This is the output voltage.

[0063] In summary, under a given input voltage, the voltage generation module generates a first voltage and a second voltage. The voltage selection module selects the larger of the first and second voltages as the third voltage and transmits it to the voltage switching module. The third voltage is compared with the input voltage. When the difference between the third voltage and the input voltage is less than or equal to a threshold voltage, the output voltage of the voltage switching module is the input voltage. When the difference between the third voltage and the input voltage is greater than the threshold voltage, the chip to be protected and the voltage switching module share the input voltage, thereby achieving the purpose of protecting the low-current chip. Compared with the traditional overvoltage protection circuit using current discharge, this reduces the requirements for the top metal traces of the chip power supply and reduces the number of pins required for the package.

[0064] The foregoing embodiments presented an overvoltage protection circuit for low-current chips. The following embodiments will present an overvoltage protection system, such as... Figure 3 As shown, it includes the overvoltage protection circuit for low-current chips and the chip to be protected, with the voltage output terminal of the voltage switching module connected to the chip to be protected.

[0065] The overvoltage protection circuit for low-current chips described above is consistent with the embodiments described above and will not be repeated here.

[0066] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An overvoltage protection circuit for low-current chips, characterized in that, It includes a voltage generation module, a voltage selection module, and a voltage switching module. The voltage generation module is connected to the input voltage and the voltage selection module, the voltage selection module is also connected to the voltage switching module, and the voltage switching module is also used to connect to the chip to be protected. The voltage generation module is used to divide the input voltage to output a first voltage and a second voltage, and the voltage selection module is used to output a third voltage, wherein the third voltage is equal to the larger of the first voltage and the second voltage; When the difference between the third voltage and the input voltage is less than or equal to the threshold voltage, the output voltage of the voltage switching module is the input voltage; when the difference between the third voltage and the input voltage is greater than the threshold voltage, the voltage switching module is used to divide the input voltage and transmit it to the chip to be protected.

2. The overvoltage protection circuit for low-current chips according to claim 1, characterized in that, The voltage generation module includes a first voltage divider unit, which includes a resistor R1 and a resistor R2. One end of the resistor R1 is connected to the input voltage, and the other end of the resistor R1 is connected to one end of the resistor R2. The other end of the resistor R2 is grounded. The first voltage is the voltage at the first voltage divider point between the other end of the resistor R1 and one end of the resistor R2.

3. The overvoltage protection circuit for low-current chips according to claim 1, characterized in that, The voltage generation module further includes a second voltage divider unit, which includes a resistor R3 and a transistor M1. One end of the resistor R3 is connected to the input voltage, and the other end of the resistor R3 is connected to the gate and drain of the transistor M1, respectively. The source of the transistor M1 is grounded. The second voltage is the voltage at the second voltage divider point between the other end of the resistor R3 and the gate and drain of the transistor M1.

4. The overvoltage protection circuit for low-current chips according to claim 1, characterized in that, The voltage selection module includes transistor M2 and transistor M3. The source of transistor M2 is connected to the first voltage divider point corresponding to the first voltage, and the gate of transistor M2 is connected to the second voltage divider point corresponding to the second voltage. The source of transistor M3 is connected to the second voltage divider point, and the gate of transistor M3 is connected to the first voltage divider point. The drains of transistors M2 and M3 are connected and output the third voltage.

5. The overvoltage protection circuit for low-current chips according to claim 1, characterized in that, The voltage switching module includes a third voltage divider unit, a switching unit, and a fourth voltage divider unit. The third voltage divider unit is connected to the voltage selection module, the fourth voltage divider unit is connected to the input voltage, and the third and fourth voltage divider units are respectively connected to the switching unit. The switching unit is also used to connect to the chip to be protected.

6. The overvoltage protection circuit for low-current chips according to claim 5, characterized in that, The third voltage divider unit includes a transistor M4 and a resistor R4. The source of the transistor M4 is connected to the input voltage, and the gate of the transistor M4 is connected to the voltage point corresponding to the third voltage. The drain of the transistor M4 is connected to one end of the resistor R4, and the other end of the resistor R4 is grounded.

7. The overvoltage protection circuit for low-current chips according to claim 6, characterized in that, The switching unit includes a transistor M5, the gate of which is connected to the third voltage divider point between the drain of the transistor M4 and one end of the resistor R4; the source of the transistor M5 is connected to the output voltage, and the drain of the transistor M5 is used to connect to the chip to be protected.

8. The overvoltage protection circuit for low-current chips according to claim 7, characterized in that, The fourth voltage divider unit includes resistors R5 and R6, transistor M6 and transistor M7. One end of resistor R5 is connected to the input voltage, and the other end of resistor R5 is connected to the drain of transistor M6. The source of transistor M6 is connected to one end of resistor R6, and the other end of resistor R6 is grounded. The gates of transistor M6 and transistor M7 are respectively connected to the third voltage divider point. The drain of transistor M7 is connected to the fourth voltage divider point between the source of transistor M6 and resistor R6, and the source of transistor M7 is used to connect to the chip to be protected.

9. The overvoltage protection circuit for a low-current chip according to any one of claims 1 to 8, characterized in that, The threshold voltage ranges from 0.6V to 1V.

10. An overvoltage protection system, characterized in that, The circuit includes an overvoltage protection circuit for a low-current chip as described in any one of claims 1 to 9, and the chip to be protected, wherein the voltage output terminal of the voltage switching module is connected to the chip to be protected.

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