A micro-power low voltage detection circuit for mcu

Abstract

The application discloses a micro-power low-voltage detection circuit for MCU, and relates to the technical field of detection circuits, comprising a reference current module for transmitting reference current; an electric energy detection module and a detection control module for detecting the port voltage and working voltage of an MCU module respectively; a switch control module for signal transmission; an MCU module for receiving signals and controlling work; a sample-and-hold module for signal holding; a state judgment module for overvoltage and undervoltage judgment; and a timing control module for periodically controlling the work of the reference current module. The micro-power low-voltage detection circuit for MCU detects the port voltage and working voltage of the MCU module respectively, and carries out holding processing on the detected signals; after the holding is completed, the detection on the working voltage is disconnected, overvoltage and undervoltage judgment is carried out on the held signals and the port voltage, and the periodic detection of voltage is realized by periodically providing reference current.

Description

Technical Field

[0001] This invention relates to the field of detection circuit technology, specifically a low-power, low-voltage detection circuit for MCUs. Background Technology

[0002] With the development of data control technology, MCUs have been widely used. An MCU is a complex system capable of providing different control effects for different occasions. To ensure the stable and reliable operation of the MCU system, its power supply voltage and port voltage must be maintained within a certain voltage range. If the voltage is too low, the MCU system will not work properly; if the voltage is too high, the MCU system is easily damaged. Most existing MCU systems use a resistor divider circuit to detect the power supply voltage and port voltage of the MCU system, and a comparator circuit performs voltage analysis. After the voltage detection is completed, the low voltage detection circuit will be shut down to reduce the loss of the detection circuit. However, this method cannot provide timely protection when the MCU system experiences a power supply abnormality, which poses a certain safety hazard and therefore needs to be improved. Summary of the Invention

[0003] This invention provides a low-power, low-voltage detection circuit for an MCU to solve the problems mentioned in the background art.

[0004] According to an embodiment of the present invention, a low-power low-voltage detection circuit for an MCU is provided. The low-power low-voltage detection circuit for an MCU includes: a power supply module, a reference current module, an energy detection module, a switch control module, a detection control module, an MCU module, a sample and hold module, a state judgment module, and a timing control module.

[0005] The power supply module is used to provide the operating voltage and reference current required by the MCU module;

[0006] The reference current module is connected to the power supply module, the power detection module, the detection control module, and the MCU module. It is used to copy the reference current through the current mirror circuit and transmit it to the power detection module and the detection control module. It is also used to control the working state of the current mirror circuit through the power transistor circuit.

[0007] The power detection module is connected to the power supply module and is used to receive the reference current and perform voltage detection on the port voltage of the MCU module, and to output a first voltage signal.

[0008] The switch control module is connected to the power detection module and the power supply module, and is used to receive the working voltage and transmit the first voltage signal to the intelligent control module and the status judgment module.

[0009] The detection and control module is connected to the power module and the MCU module. It is used to control the connection with the power module through a switch control circuit, to receive the reference current and to perform voltage detection on the operating voltage of the input MCU module, and to output a second voltage signal.

[0010] The MCU module is used to receive signals output by the power detection module, detection control module and status judgment module through the MCU circuit, to control the operation of the reference current module, sampling protection module and detection control module through the MCU circuit output control signals, and to output timing signals and control the periodic operation of the timing control module.

[0011] The sample-and-hold module is connected to the detection control module and the MCU module, and is used to control the sample-and-hold operation of the sample-and-hold circuit through the control signal, and to sample and hold the second voltage signal and output the third voltage signal through the sample-and-hold circuit.

[0012] The state judgment module is connected to the sample and hold module, the switch control module and the MCU module, and is used to perform overvoltage and undervoltage judgment on the third voltage signal and the first voltage signal through the comparison circuit and transmit the judgment to the MCU module in the form of a level signal.

[0013] The timing control module is connected to the MCU module and the reference current module, and is used to receive the timing signal and control the reference current module to work periodically.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: The low-power low-voltage detection circuit for MCUs of the present invention uses a power detection module and a detection control module to detect the port voltage of the MCU module and the operating voltage input to the MCU module, respectively. The switch control module is triggered by the power supply module and controls the MCU module to receive the port voltage detection result. The sample-and-hold module holds the voltage signal detected by the detection control module and disconnects the detection of the operating voltage after the sample-and-hold module has completed the sampling and holding process, thereby reducing circuit loss. At the same time, the held signal is compared with the signal detected by the power detection module through the state judgment module for overvoltage and undervoltage judgment. Furthermore, the MCU circuit outputs a timing signal to control the reference current module to periodically provide a reference current, controlling the periodic voltage detection of the power detection module and the detection control module, thereby further reducing circuit loss without affecting voltage detection. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic block diagram of a low-power, low-voltage detection circuit for an MCU, provided as an example of the present invention.

[0017] Figure 2 This is a circuit diagram of a low-power, low-voltage detection circuit for an MCU, provided as an example of the present invention.

[0018] Figure 3 The connection circuit diagram of the state determination module provided for an example of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1, please refer to Figure 1 A low-power, low-voltage detection circuit for an MCU includes: a power supply module 1, a reference current module 2, an energy detection module 3, a switch control module 4, a detection control module 5, an MCU module 6, a sample and hold module 7, a status judgment module 8, and a timing control module 9.

[0021] Specifically, the power supply module 1 is used to provide the operating voltage and reference current required by the MCU module 6;

[0022] The reference current module 2 is connected to the power supply module 1, the power detection module 3, the detection control module 5, and the MCU module 6. It is used to copy the reference current through the current mirror circuit and transmit it to the power detection module 3 and the detection control module 5. It is also used to control the working state of the current mirror circuit through the power transistor circuit.

[0023] The power detection module 3 is connected to the power module 1 and is used to receive the reference current and perform voltage detection on the port voltage of the MCU module 6, and to output a first voltage signal.

[0024] The switch control module 4 is connected to the power detection module 3 and the power supply module 1, and is used to receive the working voltage and transmit the first voltage signal to the intelligent control module and the status judgment module 8.

[0025] The detection control module 5 is connected to the power module 1 and the MCU module 6. It is used to control the connection with the power module 1 through the switch control circuit, to receive the reference current and to perform voltage detection on the working voltage of the input MCU module 6, and to output a second voltage signal.

[0026] MCU module 6 is used to receive signals output by the power detection module 3, the detection control module 5 and the status judgment module 8 through the MCU circuit, to control the operation of the reference current module 2, the sampling protection module and the detection control module 5 through the MCU circuit, and to output timing signals and control the periodic operation of the timing control module 9.

[0027] The sample-and-hold module 7 is connected to the detection and control module 5 and the MCU module 6. It is used to control the sample-and-hold operation of the sample-and-hold circuit through the control signal, and to sample and hold the second voltage signal and output the third voltage signal through the sample-and-hold circuit.

[0028] The status judgment module 8 is connected to the sample and hold module 7, the switch control module 4 and the MCU module 6. It is used to perform overvoltage and undervoltage judgment on the third voltage signal and the first voltage signal through the comparison circuit and transmit the judgment to the MCU module 6 in the form of a level signal.

[0029] The timing control module 9 is connected to the MCU module 6 and the reference current module 2, and is used to receive the timing signal and control the reference current module 2 to work periodically.

[0030] In a specific embodiment, the power supply module 1 can be a DC regulated power supply and a reference current source to provide the required operating voltage and reference current to the circuit, respectively, which will not be elaborated here; the reference current module 2 can be a current mirror circuit to copy and transmit the input reference current; the power detection module 3 can use a power transistor voltage divider circuit to detect the port voltage on the MCU module 6; the switch control module 4 can be a power transistor circuit, controlled by the operating voltage, and transmits the signal output by the power detection module 3; the detection control module 5 can use a switch control circuit and a power voltage divider circuit, with the switch control circuit controlling the operation of the power voltage divider circuit, and the power voltage divider circuit controlling the operating voltage of the input MCU module 6. The detection is performed; the aforementioned MCU module 6 can be an MCU circuit, which integrates many components such as an arithmetic unit, a controller, a memory, and input / output devices, to realize functions such as signal processing, data storage, module control, and timing control, and to provide the port voltage to be detected for the detection control module 5; the aforementioned sample-and-hold module 7 can be a sample-and-hold circuit, controlled by the MCU module 6, to realize the sampling and holding processing of the signal; the aforementioned state judgment module 8 uses a comparator circuit to judge the overvoltage and undervoltage of the input signal; the aforementioned timing control module 9 uses a power transistor circuit to receive the timing signal output by the MCU module 6, control the periodic operation of the power transistor circuit, and then control the reference current module 2 to periodically output the reference current.

[0031] Example 2, based on Example 1, please refer to... Figure 2 and Figure 3 The power supply module 1 includes a working voltage source; the MCU module 6 includes an MCU chip; the detection and control module 5 includes a first inverter INV1 and a first power transistor M1.

[0032] Specifically, the first terminal of the operating voltage source is connected to the drain of the first power transistor M1, the gate of the first power transistor M1 is connected to the second terminal of the first inverter INV1, and the first terminal of the first inverter INV1 is connected to the third IO terminal of the MCU chip.

[0033] In a specific embodiment, the first power transistor M1 can be an N-channel depletion-type MOSFET to control the transmission of the operating voltage source.

[0034] Furthermore, the detection and control module 5 also includes an eighth power transistor Q8, a sixth power transistor Q6, and a seventh power transistor Q7;

[0035] Specifically, the drain of the eighth power transistor Q8 is connected to the source of the first power transistor M1, the source of the eighth power transistor Q8 is connected to the source of the sixth power transistor Q6 and the substrate of the seventh power transistor Q7, the gate of the sixth power transistor Q6 is connected to the cathode of the seventh power transistor Q7 and the drain of the sixth power transistor Q6, and the drain of the seventh power transistor Q7 is connected to the gate of the seventh power transistor Q7, the gate of the eighth power transistor Q8 and the second IO terminal of the MCU chip.

[0036] In a specific embodiment, the eighth power transistor Q8, the sixth power transistor Q6, and the seventh power transistor Q7 form a power voltage divider circuit to perform voltage division and detection processing on the input operating voltage. The eighth power transistor Q8, the sixth power transistor Q6, and the seventh power transistor Q7 can all be P-channel depletion-type MOSFETs.

[0037] It should be noted that for power transistors without a mentioned substrate, the substrate of the power transistor is connected to the source of the power transistor, which will not be elaborated here.

[0038] Furthermore, the sample-and-hold module 7 includes a first operational amplifier OP1, a first control transistor J1, a second operational amplifier OP2, and a first capacitor C1;

[0039] Specifically, the non-inverting input of the first operational amplifier OP1 is connected to the drain of the seventh power transistor Q7, the inverting input of the first operational amplifier OP1 is connected to the output of the first operational amplifier OP1 and the drain of the first control transistor J1, the gate of the first control transistor J1 is connected to the third IO terminal of the MCU chip, the source of the first control transistor J1 is connected to the non-inverting input of the second operational amplifier OP2 and connected to ground through the first capacitor C1, and the inverting input of the second operational amplifier OP2 is connected to the output of the second operational amplifier OP2 and the state judgment module 8.

[0040] In a specific embodiment, the first operational amplifier OP1 and the second operational amplifier OP2 can both be selected, but are not limited to the LF353 operational amplifier; the first control transistor J1 can be a junction field-effect transistor, which is controlled by the third IO terminal of the MCU chip.

[0041] Furthermore, the power supply module 1 also includes a reference current source IREF; the reference current module 2 includes a ninth power transistor M9, a tenth power transistor M10, a twelfth power transistor M12, an eleventh power transistor M11, and a second resistor R2;

[0042] Specifically, the first terminal of the reference current source IREF is connected to the third terminal of the working voltage source. The second terminal of the reference current source IREF is connected to the drain of the ninth power transistor M9, the gate of the ninth power transistor M9, the gate of the tenth power transistor M10, the gate of the twelfth power transistor M12, and the drain of the first power transistor M1. The cathode of the ninth power transistor M9 and the source of the tenth power transistor M10 are both grounded. The sources of the eleventh power transistor M11 and the twelfth power transistor M12 are both grounded. The gate of the eleventh power transistor M11 is connected to the fourth IO terminal of the MCU chip through the second resistor R2. The drain of the twelfth power transistor M12 is connected to the drain of the seventh power transistor Q7. The drain of the tenth power transistor M10 is connected to the power detection module 3.

[0043] In a specific embodiment, the ninth power transistor M9, the tenth power transistor M10, and the twelfth power transistor M12 can all be N-channel depletion-type MOSFETs to form a current mirror circuit to replicate and transmit the reference current; the eleventh power transistor M11 can be an N-channel depletion-type MOSFET to control the transmission of the reference current.

[0044] Furthermore, the timing control module 9 includes a third resistor R3 and a thirteenth power transistor M13;

[0045] Specifically, one end of the third resistor R3 is connected to the fifth IO terminal of the MCU chip, the other end of the third resistor R3 is connected to the gate of the thirteenth power transistor M13, the source of the thirteenth power transistor M13 is grounded, and the drain of the thirteenth power transistor M13 is connected to the gate of the eleventh power transistor M11.

[0046] In a specific embodiment, the aforementioned thirteenth power transistor M13 can be an N-channel depletion-type MOS transistor, controlled by a timing signal output from the fifth IO terminal of the MCU chip. The timing signal controls the thirteenth power transistor M13 to perform periodic shutdown operations, which is generated by the MCU chip in conjunction with a clock chip (not shown in the figure), and will not be elaborated here.

[0047] Furthermore, the power detection module 3 includes a first resistor R1, a second power transistor M2, a third power transistor M3, and a fourth power transistor M4; the MCU module 6 also includes a port voltage source.

[0048] Specifically, the port voltage source is connected to the drain of the second power transistor M2 through the first resistor R1. The source of the second power transistor M2 is connected to the source of the third power transistor M3 and the substrate of the fourth power transistor M4. The gate of the third power transistor M3 is connected to the drain of the third power transistor M3 and the source of the fourth power transistor M4. The gate of the second power transistor M2 is connected to the gate of the fourth power transistor M4, the drain of the tenth power transistor M10, and the switch control module 4.

[0049] In a specific embodiment, the second power transistor M2, the third power transistor M3, and the fourth power transistor M4 form a power voltage divider circuit to detect the port voltage of the MCU chip port; the first resistor R1 can perform voltage divider control and ESD protection control.

[0050] Furthermore, the switch control module 4 includes a fifth power transistor M5;

[0051] Specifically, the gate of the fifth power transistor M5 is connected to the second terminal of the working voltage source, the drain of the fifth power transistor M5 is connected to the drain of the fourth power transistor M4, the substrate of the fifth power transistor M5 is grounded, and the source of the fifth power transistor M5 is connected to the first IO terminal of the MCU chip and the state judgment module 8.

[0052] In a specific embodiment, the fifth power transistor M5 can be an N-channel depletion-type MOSFET, triggered by the operating voltage source, and used to transmit the signal output by the power detection module 3.

[0053] Furthermore, the state determination module 8 includes a first comparator A1, a second inverter INV2, a first switching transistor VT1, a first power supply VCC1, and a fourth resistor R4;

[0054] Specifically, the non-inverting input of the first comparator A1 is connected to the output of the second operational amplifier OP2, the inverting input of the first comparator A1 is connected to the source of the fifth power transistor M5, the output of the first comparator A1 is connected to the first terminal of the second inverter INV2, the second terminal of the second inverter INV2 is connected to the base of the first switching transistor VT1, the collector of the first switching transistor VT1 is connected to the first power supply VCC1, and the emitter of the first switching transistor VT1 is connected to the sixth IO terminal of the MCU chip and connected to the ground terminal through the fourth resistor R4.

[0055] Furthermore, the state determination module 8 also includes a second comparator A2, a third inverter INV3, and a voltage threshold.

[0056] Specifically, the non-inverting input of the second comparator A2 is connected to the output of the second operational amplifier OP2, the inverting input of the second comparator A2 is connected to the voltage threshold, the output of the second comparator A2 is connected to the first terminal of the third inverter INV3, and the second terminal of the third inverter INV3 is connected to the base of the first switching transistor VT1.

[0057] In a specific embodiment, both the first comparator A1 and the second comparator A2 can be selected as LM393 comparators. The first comparator A1 is used to determine whether the port voltage exceeds the operating voltage, and the second comparator A2 is used to determine whether the operating voltage is undervoltage. The first switching transistor VT1 can be an NPN transistor to transmit the signal to the MCU chip.

[0058] This invention discloses a low-power, low-voltage detection circuit for an MCU. A reference current source IREF provides a reference current to the detection and control module 5 and the power detection module 3 via power transistors M9, M10, and M12. The transmission of the reference current is controlled by the fourth I / O pin of the MCU chip, which controls the shutdown of the eleventh power transistor M11, thereby controlling the normal operation of the control circuit. The third I / O pin of the MCU chip outputs a low level, controlling the first control transistor J1 to conduct. The first inverter INV1 inverts and amplifies the first power transistor M1, driving its conduction. Power transistors Q7, Q8, and Q6 perform voltage division detection on the operating voltage source. The voltage detection result is received by the second I / O pin of the MCU chip and the first operational amplifier OP1, and sampled through the first capacitor C1. Simultaneously, the first resistor R1 and the third... Power transistors M3, M2, and M4 detect the port voltage of the MCU chip, which is then transmitted to the MCU chip via the fifth power transistor M5. After sampling and holding, the third terminal of the MCU chip outputs a high level, and the first power transistor M1 is turned off, stopping the detection of the working voltage. The first comparator A1 compares the input port-detected voltage signal with the sampled and held voltage signal. If the port-detected voltage signal is greater than the sampled and held voltage signal, the MCU chip determines that the port voltage is abnormal. The second comparator A2 performs an undervoltage judgment by comparing the input sampled and held voltage signal with the voltage threshold. In the timing control module 9, the fifth IO terminal of the MCU chip outputs a timing signal, which periodically controls the eleventh power transistor M11 to turn off, controlling the reference current to be transmitted periodically, and then controlling the circuit to perform periodic voltage detection.

[0059] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0060] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A micro-power low-voltage detection circuit for MCU, characterized in that, The micro-power low-voltage detection circuit for MCU comprises a power module, a reference current module, an energy detection module, a switch control module, a detection control module, an MCU module, a sample and hold module, a state judgment module, and a timing control module; The power module is configured to provide the operating voltage and the reference current required by the MCU module; The reference current module is connected with the power module, the energy detection module, the detection control module, and the MCU module, configured to copy the reference current through a current mirror circuit and transmit it to the energy detection module and the detection control module, and control the working state of the current mirror circuit through a power tube circuit; The energy detection module is connected with the power module, configured to receive the reference current and detect the port voltage of the MCU module, and output a first voltage signal; The switch control module is connected with the energy detection module and the power module, configured to receive the operating voltage and transmit the first voltage signal to the MCU module and the state judgment module; The detection control module is connected with the power module and the MCU module, configured to control the connection with the power module through a switch control circuit, receive the reference current, and detect the operating voltage input to the MCU module, and output a second voltage signal; The MCU module is configured to receive the signals output by the energy detection module, the detection control module, and the state judgment module through an MCU circuit, output a control signal through the MCU circuit to control the working of the reference current module, the sample and hold module, and the detection control module, output a timing signal, and control the periodic working of the timing control module; The sample and hold module is connected with the detection control module and the MCU module, configured to control the sampling and holding working of a sample and hold circuit through the control signal, sample and hold the second voltage signal through the sample and hold circuit, and output a third voltage signal; The state judgment module is connected with the sample and hold module, the switch control module, and the MCU module, configured to perform overvoltage and undervoltage judgment on the third voltage signal and the first voltage signal through a comparison circuit, and transmit the result in the form of a level signal to the MCU module; The timing control module is connected with the MCU module and the reference current module, configured to receive the timing signal and control the periodic working of the reference current module.

2. The micro-power low voltage detection circuit for MCU according to claim 1, wherein, The power module comprises an operating voltage source; the MCU module comprises an MCU chip; and the detection control module comprises a first inverter and a first power tube; The first end of the operating voltage source is connected with the drain of the first power tube, the gate of the first power tube is connected with the second end of the first inverter, and the first end of the first inverter is connected with the third IO end of the MCU chip.

3. The micro-power low voltage detection circuit for MCU according to claim 2, wherein, The detection control module further comprises an eighth power tube, a sixth power tube, and a seventh power tube. The drain electrode of the eighth power tube is connected with the source electrode of the first power tube, the source electrode of the eighth power tube is connected with the source electrode of the sixth power tube and the substrate of the seventh power tube, the gate electrode of the sixth power tube is connected with the source electrode of the seventh power tube and the drain electrode of the sixth power tube, the drain electrode of the seventh power tube is connected with the gate electrode of the seventh power tube, the gate electrode of the eighth power tube and the second IO end of the MCU chip.

4. The micro-power low voltage detection circuit for MCU according to claim 3, wherein, The sampling and holding module comprises a first operational amplifier, a first control tube, a second operational amplifier and a first capacitor; The non-inverting terminal of the first operational amplifier is connected with the drain electrode of the seventh power tube, the inverting terminal of the first operational amplifier is connected with the output terminal of the first operational amplifier and the drain electrode of the first control tube, the gate electrode of the first control tube is connected with the third IO end of the MCU chip, the source electrode of the first control tube is connected with the non-inverting terminal of the second operational amplifier and the ground terminal through the first capacitor, and the inverting terminal of the second operational amplifier is connected with the output terminal of the second operational amplifier and the state judgment module.

5. The micro-power low voltage detection circuit for MCU according to claim 4, wherein, The power module further comprises a reference current source, and the reference current module comprises a ninth power tube, a tenth power tube, a twelfth power tube, an eleventh power tube and a second resistor. The first end of the reference current source is connected with the third end of the working voltage source, the second end of the reference current source is connected with the drain electrode of the ninth power tube, the gate electrode of the ninth power tube, the gate electrode of the tenth power tube, the gate electrode of the twelfth power tube and the drain electrode of the eleventh power tube, the source electrode of the ninth power tube and the source electrode of the tenth power tube are both connected with the ground, the source electrode of the eleventh power tube and the source electrode of the twelfth power tube are both connected with the ground, the gate electrode of the eleventh power tube is connected with the fourth IO end of the MCU chip through the second resistor, the drain electrode of the twelfth power tube is connected with the drain electrode of the seventh power tube, and the drain electrode of the tenth power tube is connected with the electric energy detection module.

6. The micro-power low voltage detection circuit for MCU according to claim 5, wherein, The timing control module comprises a third resistor and a thirteenth power tube. One end of the third resistor is connected with the fifth IO end of the MCU chip, the other end of the third resistor is connected with the gate electrode of the thirteenth power tube, the source electrode of the thirteenth power tube is connected with the ground, and the drain electrode of the thirteenth power tube is connected with the gate electrode of the eleventh power tube.

7. The micro-power low voltage detection circuit for MCU according to claim 5, wherein, The electric energy detection module comprises a first resistor, a second power tube, a third power tube and a fourth power tube, and the MCU module further comprises a port voltage source. The port voltage source is connected with the drain electrode of the second power tube through the first resistor, the source electrode of the second power tube is connected with the source electrode of the third power tube and the substrate of the fourth power tube, the gate electrode of the third power tube is connected with the drain electrode of the third power tube and the source electrode of the fourth power tube, the gate electrode of the second power tube is connected with the gate electrode of the fourth power tube, the drain electrode of the tenth power tube and the switch control module.

8. The micro-power low voltage detection circuit for MCU according to claim 7, wherein, The switch control module comprises a fifth power tube. The gate electrode of the fifth power tube is connected with the second end of the working voltage source, the drain electrode of the fifth power tube is connected with the drain electrode of the fourth power tube, the substrate of the fifth power tube is connected with the ground, the source electrode of the fifth power tube is connected with the first IO end of the MCU chip and the state judgment module.

9. The micro-power low voltage detection circuit for MCU according to claim 8, wherein, The state judgment module comprises a first comparator, a second inverter, a first switch tube, a first power supply and a fourth resistor. The noninverting terminal of the first comparator is connected to the output terminal of the second operational amplifier, the inverting terminal of the first comparator is connected to the source of the fifth power tube, the output terminal of the first comparator is connected to the first terminal of the second inverter, the second terminal of the second inverter is connected to the base of the first switch tube, the collector of the first switch tube is connected to the first power supply, and the emitter of the first switch tube is connected to the sixth IO terminal of the MCU chip and the ground terminal through the fourth resistor.

10. The micro-power low voltage detection circuit for MCU according to claim 9, wherein, The state judgment module further comprises a second comparator, a third inverter and a voltage threshold value; The noninverting terminal of the second comparator is connected to the output terminal of the second operational amplifier, the inverting terminal of the second comparator is connected to the voltage threshold value, the output terminal of the second comparator is connected to the first terminal of the third inverter, and the second terminal of the third inverter is connected to the base of the first switch tube.

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