TWI688187B - Voltage monitoring system and method thereof - Google Patents

Abstract

A voltage monitoring system is provided. The voltage monitoring system is configured to monitor a power voltage supplied to a functional circuit, and includes a clock signal generating circuit, a reference voltage generating circuit and a low voltage reset module (LVR). The clock signal generating circuit generates a clock signal. The reference voltage generating circuit generates a reference voltage, and refreshes the reference voltage according to the clock signal. In a normal mode, the low voltage reset module continuously executes a voltage detection function for detecting whether the power voltage is lower than a first voltage threshold. When the power voltage is lower than the first voltage threshold, the low voltage reset module outputs a reset signal to reset the functional circuit. In a power saving mode, the low voltage reset module discontinuously and periodically executes the voltage detection function according to the clock signal.

Description

Voltage monitoring system and method

The invention relates to a voltage monitoring system, in particular to a voltage monitoring system and method with a low voltage reset detection function with low power consumption.

In order to extend the usage time, most battery-powered devices generally enter the power-saving mode when the functional circuit is not operated, which is also called the power-down mode ) To reduce power consumption.

In addition, since the battery-powered power supply voltage will decrease with time, in order to avoid the functional voltage damage caused by too low power supply voltage drop, a low-voltage reset (LVR) circuit is set to monitor the power supply voltage Whether it is lower than a voltage threshold, if it is, the low voltage reset circuit will output a reset signal to reset the functional circuit, thereby protecting the functional circuit.

However, in the power saving mode, the power consumption of the low voltage reset circuit needs to be further reduced in order to more effectively extend the battery life.

The purpose of the present invention is to propose a voltage monitoring system which has lower power consumption and is suitable for a power saving mode to solve the above-mentioned conventional problems.

In order to achieve the purpose of the invention, the present invention provides a voltage monitoring system for monitoring a power supply voltage provided to a functional circuit. The voltage monitoring system includes a clock signal to generate electricity Circuit, a reference voltage generating circuit and a low voltage reset module. The clock signal generating circuit is used to generate a clock signal. The reference voltage generating circuit is used to generate a reference voltage and update the reference voltage according to the clock signal. In a first mode, the low voltage reset module continuously executes a voltage detection function to detect whether the power supply voltage is lower than a first voltage threshold, when the power supply voltage is lower than the first voltage threshold, the low The voltage reset module outputs a reset signal to reset the functional circuit; in a second mode, the low voltage reset module periodically and discontinuously performs the voltage detection function according to the clock signal. The first voltage threshold corresponds to the reference voltage.

In one embodiment, the low voltage reset module includes a low voltage reset circuit and a power consumption control unit. The low voltage reset circuit is used to perform a voltage detection function. In the second mode, the power consumption control unit is based on The clock signal periodically turns on or off the low voltage reset circuit.

In an embodiment, the power consumption control unit includes a first judgment unit that generates a start signal of the low voltage reset circuit according to the clock signal and a start condition.

In one embodiment, the power consumption control unit includes a second determination unit that generates a mask signal for blocking the output signal of the low voltage reset circuit according to the clock signal and a mask condition.

In an embodiment, in the second mode, when the power supply voltage is lower than a second voltage threshold, the low voltage reset module performs the voltage detection function periodically and discontinuously according to a first frequency, and When the power supply voltage is higher than a second voltage threshold, the low voltage reset module performs the voltage detection function periodically and discontinuously according to a second frequency, and the second frequency is lower than the first frequency.

In one embodiment, the clock signal generation circuit includes an oscillator and a counter, the oscillator outputs an oscillation signal, the counter counts according to the oscillation signal, and periodically generates an update according to a pre-designed amount The signal is given to the reference voltage generating circuit.

In one embodiment, the clock signal generation circuit includes an oscillator and a counter. The oscillator outputs an oscillation signal. The counter counts according to the oscillation signal. The power consumption control unit includes A first judgment unit is included, which controls the low voltage reset circuit to be in an activated state or an off state according to a starting condition and a count value output by the counter.

In one embodiment, the first mode is a normal mode, and the second mode is a power saving mode.

In order to achieve the purpose of the invention, the present invention provides a voltage monitoring method for monitoring a power supply voltage provided to a functional circuit. The voltage monitoring method includes the following steps: providing a clock signal generating circuit to generate a clock signal; providing a reference voltage generating circuit to generate a reference voltage, wherein the reference voltage generating circuit updates the reference voltage according to the clock signal; providing a The low voltage reset module performs a voltage detection function to detect whether the power supply voltage is lower than a first voltage threshold, and when the power supply voltage is lower than the first voltage threshold, the low voltage reset module outputs A reset signal to reset the functional circuit, where the first voltage threshold corresponds to the reference voltage; in a first mode, a low voltage reset module is used to continuously perform a voltage detection function; in a second mode, use The low voltage reset module periodically and discontinuously performs the voltage detection function according to the clock signal.

In one embodiment, the voltage monitoring method further includes generating a mask signal for blocking the output signal of the low voltage reset module according to the clock signal and a mask condition.

10: Voltage regulator circuit

101: Operating voltage

11: Linear low-drop circuit

20: Low voltage reset module

201: Reset signal

21: Low voltage reset circuit

211, TH1: first voltage threshold

212: output signal

22: Power consumption control unit

221, 231: Start signal

23, 23a: First judgment unit

24, 24a: second judgment unit

241: Mask signal

25: Select unit

26: OR gate

30: Reference voltage generating circuit

301, 311: Reference voltage

31: Band gap circuit

40: Clock signal generation circuit

401: Clock signal

41: Oscillator

411: Oscillation signal

42: counter

421: count value

422: Update signal

50: Functional circuit

VDD: power supply voltage

TH2: Second voltage threshold

T0~T8: Period

P0~P5: time point

EN: Start signal input

Figure 1 is a block diagram of the voltage monitoring system of the present invention.

FIG. 2 is a block diagram of an embodiment of the voltage monitoring system of the present invention.

FIG. 3 is a block diagram of an embodiment of the power consumption control unit of the voltage monitoring system of the present invention.

FIG. 4 is a timing diagram of operation signals of an embodiment of the power consumption control unit of the voltage monitoring system of the present invention.

FIG. 5 is a timing diagram of operation signals of an embodiment of the voltage monitoring system of the present invention.

FIG. 6 is a timing diagram of operation signals of another embodiment of the voltage monitoring system of the present invention.

FIG. 7 is a flowchart of the voltage monitoring method of the present invention.

FIG. 8 is a flowchart of an embodiment of the voltage monitoring method of the present invention.

The embodiments of the present invention will be described in detail below in conjunction with the drawings and examples, so as to fully understand and implement the implementation process of how the present invention uses technical means to solve technical problems and achieve technical effects.

Please refer to FIG. 1, which is a block diagram of the voltage monitoring system of the present invention. As shown in Figure 1, the voltage monitoring system of the present invention is suitable for a power supply system. The power supply system includes a voltage stabilizing circuit 10. The input end of the voltage stabilizing circuit 10 is electrically connected to a power supply end. The voltage stabilizing circuit 10 can convert the power supply voltage VDD on the power supply end into the operating voltage 101 required by the functional circuit 50. In one embodiment, the voltage stabilizing circuit 10 can be a linear low-dropout circuit (LDO).

In practical applications, the power supply system is usually installed on a mobile device and uses a battery as the power supply. Therefore, after a long period of use, the voltage of the battery will gradually decrease. When the power supply voltage VDD is lower than a voltage threshold, the functional circuit 50 of the mobile device may be damaged or malfunction. Therefore, the voltage monitoring system of the present invention can monitor the power supply voltage VDD and has lower power consumption.

As shown in FIG. 1, the voltage monitoring system includes a clock signal generating circuit 40, a reference voltage generating circuit 30, and a low voltage reset module 20. The clock signal generating circuit 40 can generate the clock signal 401. The reference voltage generating circuit 30 can generate the reference voltage 301 and update the parameters according to the clock signal 401 Test voltage 301. In an embodiment, the reference voltage generating circuit 30 may be a bandgap circuit; the clock signal generating circuit 40 may include an oscillator 41 and a counter 42. The low voltage reset module 20 and the reference voltage generating circuit 30 share the clock signal 401 of the clock signal generating circuit 40, which can allow the bandgap refresh of the low voltage reset module 20 and the reference voltage generating circuit 30 Time synchronization, and can also save the gate count (gate count).

The low voltage reset module 20 can perform a voltage detection function to detect whether the power supply voltage VDD is lower than the first voltage threshold 211, and when the low voltage reset module 20 determines that the power supply voltage VDD is lower than the first voltage threshold When the value is 211, the low-voltage reset module 20 outputs a reset signal 201 to reset the functional circuit 50, thereby avoiding damage or malfunction of the functional circuit 50. The mobile device usually has a normal mode and a power saving mode. In the normal mode, the functional circuit 50 operates normally and consumes higher energy in order to ensure the normal function; in the power saving mode, in order to extend the use time, the functional circuit 50 Sleep or shut down to reduce power consumption.

In one embodiment, the low-voltage reset module 20 may include a low-voltage reset circuit 21 and a power consumption control unit 22. The low-voltage reset circuit 21 is used to perform the above-described voltage detection function, and the power consumption control In the power saving mode, the unit 22 can periodically turn on or off the low voltage reset circuit 21 according to the clock signal 401.

Since the power consumption of the low-voltage reset module 20 is much lower than the power consumption of the functional circuit 50, in the normal mode, the low-voltage reset module 20 can continuously perform the voltage detection function to detect whether the power system is in real time There is a sudden voltage drop. In the power saving mode, in order to further reduce the power consumption of the low voltage reset module 20, the low voltage reset module 20 may periodically and discontinuously perform the voltage detection function according to the clock signal 401; in other words, the voltage The detection function is performed intermittently, and when the voltage detection function is not performed, the power consumption of the low voltage reset module 20 is extremely low, thereby effectively reducing the power consumption of the low voltage reset module 20 in the power saving mode Power consumption.

It should be noted that the first voltage threshold 211 corresponds to the reference voltage 301, that is, the first voltage threshold 211 can be obtained from the reference voltage 301, for example, the low voltage reset module 20 can include a voltage divider circuit, Divide the reference voltage 301 to obtain the first voltage threshold 211. The first voltage threshold 211 may be 1.5V, for example. The above-mentioned 1.5V first voltage threshold 211 is only an example, and of course the first voltage threshold 211 is also It can be other values, and is not limited to the range enumerated in the present invention; in another embodiment, the low voltage reset module 20 can use multiple voltage thresholds, and multiple voltage divider circuits can be used for the reference voltage 301 divides voltage to obtain different voltage thresholds. The technology in this area is well known to those skilled in the art, so it will not be described here.

Please refer to FIG. 5, which is a timing diagram of operation signals of an embodiment of the voltage monitoring system of the present invention. In the figure, before the time point P0, the voltage monitoring system is in the normal mode, so the voltage detection function is continuously executed; after the time point P0, the voltage monitoring system enters the power saving mode, the voltage detection function is executed intermittently, also That is, the voltage monitoring system only performs the voltage detection function during the periods T0, T1, T2, T3, and T4, and turns off the voltage detection function during other periods, thereby effectively reducing power consumption. As shown in FIG. 5, when the voltage monitoring system performs the voltage detection function during the period T4, it can detect that the power supply voltage VDD is lower than the first voltage threshold TH1, and then the low voltage reset module 20 sends out the reset signal 201 To functional circuit 50.

Please refer to FIGS. 2 to 4, which are block diagrams of an embodiment of the voltage monitoring system of the present invention, block diagrams of an embodiment of the power consumption control unit of the present invention, and operation signal timing diagrams. In this embodiment, the voltage monitoring system includes a low voltage reset circuit 21, a first judgment unit 23, a second judgment unit 24, a selection unit 25, a bandgap circuit 31, an oscillator 41 and One counter 42. The low voltage reset circuit 21 is used to perform the above voltage detection function, and the band gap circuit 31 can output a reference voltage 311 to the low voltage reset circuit 21.

The oscillator 41 is used to output an oscillation signal 411, which is a periodic signal. The counter 42 can count according to the oscillation signal 411 and according to a predetermined number (predetermined counting amount) periodically generates an update signal 422 to the reference voltage generating circuit 30. For example, the pre-designed number can be 1000, the counter 42 can count 1000 times and return to zero, and output the update signal 422; thus, the period of the update signal 422 is 1000 times the oscillation signal 411, and the frequency of the oscillation signal 411 To update the signal 422 by a factor of 1,000, the counter 42 can be used as a frequency divider or a frequency downconverter. The above "1000 times" is only an example, not a limitation of the present invention; in practical applications, the user can set the multiple relationship between the frequency of the update signal 422 and the oscillation signal 411.

The first determining unit 23 can generate a start signal 231 of the low voltage reset circuit 21 according to the clock signal 401 and a start condition. In the power saving mode, the low voltage reset circuit 21 performs the voltage detection function intermittently and periodically. Therefore, in an embodiment, the start condition may be when the count value is within a specific range, the first The judging unit 23 generates an activation signal 231 to the activation signal input EN of the low voltage reset circuit 21, and activates the low voltage reset circuit 21 to perform the above-mentioned voltage detection function to determine whether a reset signal is generated; For the numerical value, the first determining unit 23 does not generate the activation signal 231, so the low voltage reset circuit 21 does not perform the above voltage detection function, thereby achieving the effect of saving power consumption.

In one embodiment, the start condition can be set to "count value less than or equal to 2", so when the count value is reached, the first determining unit 23 generates the start signal 231 to the start signal input EN of the low voltage reset circuit 21 to start The low voltage reset circuit 21 performs the above-mentioned voltage detection function. When the count values are 0, 1, and 2, the start signal 231 is at a high level. Therefore, the low voltage reset circuit 21 starts to perform the voltage detection function at other count values. The activation signal 231221 is at a low level, so the low voltage reset circuit 21 does not activate and consumes no energy. Thereby, the effect that the low voltage reset circuit 21 is periodically turned on and off to reduce power consumption can be achieved.

The low voltage reset circuit 21 performs the voltage detection function to protect the functional circuit 50. Therefore, the output signal of the low voltage reset circuit 21 must have high accuracy, but in the power saving mode, the low voltage reset circuit 21 will be periodically The ground is frequently turned on and off, and the low voltage reset circuit 21 A preparation time is required, and the output signal of the low-voltage reset circuit 21 is meaningless during the preparation time and cannot be provided to the functional circuit 50. Therefore, in an embodiment, the second determining unit 24 may generate a mask signal 241 for blocking the output signal 212 of the low voltage reset circuit 21 according to the clock signal 401 and a mask condition. This masking condition corresponds to the period immediately after the low voltage reset circuit 21 is turned on, to avoid the meaningless signal being transmitted to the functional circuit 50 and causing the functional circuit 50 to malfunction.

The selection unit 25 receives the mask signal 241 and the output signal 212 of the low voltage reset circuit 21. When the selection unit 25 receives the mask signal 241 or the mask signal 241 is in the enabled state, it does not output The output signal 212 of the low voltage reset circuit 21; conversely, when the selection unit 25 does not receive the mask signal 241 or the mask signal 241 is in a disabled state, the output of the low voltage reset circuit 21 is output Signal 212. In an embodiment, the mask condition may be "count value equal to 0", so when the count value 421 is 0, the mask signal 241 is at a high level, which is an enabled state, so the selection unit 25 does not The output signal 212 of the low voltage reset circuit 21 is output as shown in FIG. 4.

Therefore, in one embodiment, when the pre-designed number of the counter 42 is set to 1000 and the start condition is set to "count value is less than or equal to 2", in the power saving mode, when the count value is 0, 1, 2 , The first determining unit 23 generates a high-level start signal 231 to the start signal input EN of the low voltage reset circuit 21 to start the low voltage reset circuit 21 to perform the above voltage detection function, and when the count value is 3~999 , The first judging unit 23 generates a high-level start signal 231, the low voltage reset circuit 21 does not perform the voltage detection function, and then the count value is reset to zero, repeating the above operations, thereby monitoring the state of the power supply voltage and reducing Power consumption. In addition, in another embodiment, the voltage monitoring system may add a second judgment unit 24 and the mask condition is set to "count value equal to 0", so when the count value is 0, the selection unit 25 does not output a low voltage reset circuit The output signal of 21 avoids the malfunction of the functional circuit 50.

FIG. 3 is a block diagram of an embodiment of the power consumption control unit of the present invention. In the figure, the selection unit 25 is implemented by the OR gate 26, and the enable state of the reset signal 201 is the low level L, for example, Ground voltage. The activation condition of the first judgment unit 23a is "count value is less than or equal to 2", and the masking condition of the second judgment unit 24a is "count value is equal to 0". Therefore, when the count value 421 is 0, the first judgment unit 23a outputs The high level signal H, the low voltage reset circuit 21 is activated, and the second judgment unit 24a also outputs the high level signal H, so whether the output signal of the low voltage reset circuit 21 is H or L or the output signal 201 of the gate 26 is H, which is the disabled state of the reset signal 201, so the functional circuit 50 will not be reset, thereby blocking the signal generated when the low voltage reset circuit 21 is just started.

When the count value 421 is 1, the first judgment unit 23a outputs the high level signal H, and the second judgment unit 24a outputs the low level signal L, so the output signal 201 of the OR gate 26 corresponds to the output signal 212 of the low voltage reset circuit 21 . When the low voltage reset circuit 21 detects that the power supply voltage is lower than the voltage threshold, the low voltage reset circuit 21 outputs the low level signal L, so that the output signal 201 of the OR gate 26 is the low level signal L, which is the reset signal 201 Is enabled, the functional circuit 50 is reset; otherwise, the low voltage reset circuit 21 detects that the power supply voltage is higher than the voltage threshold, the low voltage reset circuit 21 outputs a high level signal H, and the functional circuit 50 is not heavy Set.

Please refer to FIG. 6, which is a timing diagram of operation signals of another embodiment of the voltage monitoring system of the present invention. This embodiment differs from the previous embodiment in that this embodiment uses two voltage thresholds and activates or shuts down the low voltage reset circuit 21 at different frequencies at different stages. As shown in FIG. 6, the voltage monitoring system of this embodiment uses a first voltage threshold TH1 and a second voltage threshold TH2. The second voltage threshold TH2 is higher than the first voltage threshold TH1. In the power saving mode (that is, after time point P3), when the power supply voltage VDD is higher than the second voltage threshold TH2 (that is, between time point P3 and time point P4), the low voltage reset module 20 can perform the voltage detection function periodically and discontinuously according to a second frequency; when the power supply voltage VDD is lower than the second voltage threshold TH2 (ie, after the time point P4), the low voltage reset module 20 The voltage detection function can be performed periodically and discontinuously according to a first frequency, and the second frequency is lower than the first frequency.

As shown in Figure 6, between time point P3 and time point P4, the voltage detection function is executed during the period T0, T1, T2, but not executed in other periods; and after the time point P4, the voltage detection function is in the period T3, T4, T5, T6, T7, and T8 are executed, and during the period T8, it is detected that the power supply voltage is lower than the first voltage threshold TH1. Since it is closer to the first voltage threshold TH1, the voltage detection function is executed more frequently to confirm that the power supply voltage can be detected in time when the power voltage is lower than the first voltage threshold TH1, and a reset signal is sent to protect the functional circuit.

Please refer to FIG. 7, which is a flowchart of the voltage monitoring method of the present invention. The voltage monitoring method of the present invention can be used to monitor a power supply voltage provided to a functional circuit, and the voltage monitoring method includes steps S71-S76. In step S71, a clock signal generating circuit is provided to generate a clock signal. In step S72, a reference voltage generating circuit is provided to generate a reference voltage. The reference voltage generating circuit updates the reference voltage according to the clock signal. In step S73, a low voltage reset module is provided to perform a voltage detection function for detecting whether the power supply voltage is lower than a first voltage threshold, when the power supply voltage is lower than the first voltage threshold, the low voltage The reset module outputs a reset signal to reset the functional circuit. The first voltage threshold 211 corresponds to the reference voltage 301.

In step S74, it is determined whether to enter the power saving mode, if yes, step S75 is executed; if not, step S76 is executed. In step S75, the low voltage reset module is used to periodically and discontinuously perform the voltage detection function according to the clock signal 401. In step S76, the low voltage reset module is used to continuously perform the voltage detection function. The above-mentioned clock signal generating circuit, reference voltage generating circuit, low voltage reset module, and related operations have been described in the foregoing, so they will not be repeated here.

Please refer to FIG. 8, which is a flowchart of an embodiment of the voltage monitoring method of the present invention. The operation of the embodiment of the voltage monitoring method in the power-saving mode will be described below, and the operation in the normal mode is similar to that described in FIG. 7, so it will not be repeated here. As shown in FIG. 8, the embodiment of the voltage monitoring method includes steps S81-S84.

In step S81, a band gap circuit, an oscillator, and a counter are provided. The oscillator outputs an oscillation signal. The counter counts according to the oscillation signal. The band gap circuit generates a reference voltage and updates the reference voltage according to the clock signal.

In step S82, a low voltage reset module is provided to perform a voltage detection function to determine whether to output a reset signal. In step S83, a first judgment unit is provided, and one of the startup conditions of the first judgment unit is set, and the first judgment unit is used to generate a startup signal of the low voltage reset circuit according to the count value of the counter and the startup condition.

In step S84, a second judgment unit is provided, and a masking condition of the second judgment unit is set, and the second judgment unit is used to generate an output for blocking the output of the low voltage reset circuit according to the count value of the counter and the masking condition A mask signal. In step S85, according to the activation signal and the mask signal, the activation state and the shutdown state of the low voltage reset module are periodically controlled.

In one embodiment, as shown in Figure 4, the pre-designed number of counters can be set to 1000, the start condition can be set to "count value is less than or equal to 2" and the masking condition can be set to "count value equal to 0", in In the power saving mode, when the count values are 0, 1, 2, the first judgment unit generates a high-level start signal to the start signal input terminal of the low voltage reset circuit to start the low voltage reset circuit to perform the voltage detection function, And when the count value is 0, the selection unit does not output the output signal of the low voltage reset circuit to avoid the malfunction of the functional circuit. When the count value is 3~999, the first judgment unit generates a high level start signal, the low voltage reset circuit does not perform the voltage detection function, and then the count value is reset to zero, repeat the above operation, thereby monitoring the status of the power supply voltage At the same time, it also reduces power consumption, and at the same time avoids the problem that the low voltage reset circuit is frequently started and the initial signal is unstable, which may cause the functional circuit to malfunction. It should be noted that the above-mentioned pre-designed number of counters, start-up conditions and masking conditions are only examples and not limitations.

Although the present invention has been disclosed as the foregoing embodiments, it is not intended to limit the present invention. Any person familiar with similar arts can make some changes and modifications without departing from the spirit and scope of the present invention. The scope of patent protection shall be determined by the scope of the patent application attached to this specification.

10: Voltage regulator circuit

101: Operating voltage

20: Low voltage reset module

201: Reset signal

21: Low voltage reset circuit

211: first voltage threshold

22: Power consumption control unit

221: Start signal

30: Reference voltage generating circuit

301: Reference voltage

40: Clock signal generation circuit

401: Clock signal

50: Functional circuit

VDD: power supply voltage

Claims (8)

A voltage monitoring system for monitoring a power supply voltage provided to a functional circuit. The voltage monitoring system includes: a clock signal generating circuit that generates a clock signal; a reference voltage generating circuit that generates a reference voltage, and Update the reference voltage according to the clock signal; and a low voltage reset module, in a first mode, the low voltage reset module continuously performs a voltage detection function to detect whether the power supply voltage is below A first voltage threshold, when the power supply voltage is lower than the first voltage threshold, the low voltage reset module outputs a reset signal to reset the functional circuit, in a second mode, the low The voltage reset module periodically and discontinuously executes the voltage detection function according to the clock signal, wherein the first voltage threshold corresponds to a reference voltage; the low voltage reset module further includes: a low voltage reset Setting circuit, the low voltage reset circuit is used to perform the voltage detection function; and a power consumption control unit, in the second mode, the power control unit is periodically turned on or off according to the clock signal The low voltage resets the circuit. The voltage monitoring system as described in item 1 of the patent application scope, wherein the power consumption control unit includes a first judgment unit that generates the low voltage reset circuit according to the clock signal and a starting condition A start signal. The voltage monitoring system as described in item 2 of the patent application range, wherein the power consumption control unit includes a second judgment unit, the second judgment unit generates a signal for blocking the low voltage according to the clock signal and a mask condition A mask signal of the output signal of the voltage reset circuit. The voltage monitoring system as described in item 1 of the patent application scope, wherein in the second mode, when the power supply voltage is lower than a second voltage threshold, the low voltage reset module is cycled according to a first frequency The voltage detection function is executed discontinuously and discontinuously, and when the power supply voltage is higher than a second voltage threshold, the low voltage reset module executes the voltage periodically and discontinuously according to a second frequency Detection function, wherein the second frequency is lower than the first frequency. The voltage monitoring system as described in item 1 of the patent application, wherein the clock signal generation circuit includes an oscillator and a counter, the oscillator outputs an oscillation signal, the counter counts according to the oscillation signal, and according to A pre-designed number periodically generates an update signal to the reference voltage generating circuit. The voltage monitoring system as described in item 1 of the patent application scope, wherein the clock signal generating circuit includes an oscillator and a counter, the oscillator outputs an oscillation signal, the counter counts according to the oscillation signal, the power The consumption control unit includes a first judgment unit, which controls the low voltage reset circuit to be in an activated state or an off state according to a starting condition and a count value output by the counter. The voltage monitoring system as described in item 1 of the patent application, wherein the first mode is a normal mode, and the second mode is a power saving mode. A voltage monitoring method for monitoring a power supply voltage provided to a functional circuit, the voltage monitoring method includes: providing a clock signal generating circuit to generate a clock signal; providing a reference voltage generating circuit to generate a reference voltage , Where the reference voltage generation circuit updates the reference voltage according to the clock signal; a low voltage reset module is provided to perform a voltage detection function for detecting the power Whether the source voltage is lower than a first voltage threshold, when the power voltage is lower than the first voltage threshold, the low voltage reset module outputs a reset signal to reset the functional circuit, wherein the first A voltage threshold corresponds to the reference voltage; in a first mode, the low voltage reset module is used to continuously perform the voltage detection function; and in a second mode, the low voltage reset module is used according to the time The pulse signal performs the voltage detection function periodically and discontinuously, wherein the second mode further includes generating a mask for blocking the output signal of the low voltage reset module according to the clock signal and a mask condition Hood signal.

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