Power failure voltage detection circuit applied to 12V compatible 24V system
The power-down voltage detection circuit, designed with hardware circuitry, solves the problems of delay and resource consumption in 12V/24V systems during voltage drops, achieving fast and reliable power-down detection and ensuring the stability and data security of the vehicle's electronic systems.
Patent Information
- Application Number
- CN202511648776.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-12
- Publication Date
- 2026-02-06
AI Technical Summary
When the power supply voltage drops suddenly, the existing 12V/24V dual-voltage system suffers from problems such as long delay, high CPU resource consumption, and high system power consumption in traditional power failure detection, which can lead to data loss or malfunction of the vehicle equipment.
A power-down voltage detection circuit was designed, which includes an input power supply, a reference voltage source, a voltage divider branch, and a voltage comparator. The circuit achieves rapid detection through hardware circuitry and uses a voltage selection module to automatically select a threshold voltage signal based on the voltage level, and outputs a power-down detection signal.
It enables rapid power failure detection of 12V and 24V systems, avoiding the delay and resource consumption of traditional software detection, improving the reliability and versatility of the system, and ensuring the stability and data security of the vehicle's electronic system under voltage fluctuations.
Smart Images
Figure CN121476693A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of power failure voltage detection technology, specifically a power failure voltage detection circuit for a 12V compatible 24V system. Background Technology
[0002] Commercial vehicles and construction machinery commonly use 12V / 24V dual-voltage systems. These systems are prone to sudden voltage drops ("power failures") during operation due to engine starting, heavy load switching, and other factors. This can lead to data loss or malfunction of critical components such as the vehicle's ECU, instrument panel, and entertainment system. Therefore, rapid and reliable power failure detection, along with allowing sufficient time for data backup and safe shutdown procedures, has become a core technological challenge in ensuring the reliability of vehicle electronic systems. Currently, automotive electronics typically detect power loss in the main power supply in two steps: 1. A resistor divider or operational amplifier circuit converts the input voltage into a lower voltage and sends it to the ADC port of the MCU; 2. The software program module repeatedly compares the value collected by the ADC port with a set threshold at a certain period, and executes the corresponding program logic if the trigger condition is met.
[0003] The above-mentioned voltage drop detection has the following defects: 1. From the voltage drop to the MCU triggering protection, there is a delay of ADC sampling time, software polling cycle, and software filtering and debouncing time. The total delay is usually several milliseconds to tens of milliseconds. In the case of rapid voltage drop, this delay may cause the protection measures to fail. 2. The initialization and data reading of the ADC module, as well as the continuous voltage comparison and judgment, all require the participation of the MCU core, which consumes CPU calculation cycles and memory resources; 3. The continuous operation of the ADC module and its related software tasks will increase the overall power consumption of the system.
[0004] To address the aforementioned issues, this application proposes a power-down voltage detection circuit for a 12V-compatible 24V system. Summary of the Invention
[0005] The purpose of this invention is to provide a power-down voltage detection circuit for a 12V-compatible 24V system, so as to solve the problems mentioned in the background art.
[0006] To achieve the above objectives, the present invention provides the following technical solution: a power-down voltage detection circuit for a 12V compatible 24V system, comprising: an input power supply, a reference voltage source, a first voltage divider branch, a second voltage divider branch, a voltage selection module, and a voltage comparator. The reference voltage source is used to provide a stable reference voltage; The first voltage divider branch is used to divide the input power supply to generate a first voltage divider signal; The second voltage divider branch is used to divide the input power supply to generate a second voltage divider signal; The input terminal of the voltage selection module is connected to the first voltage divider branch and the second voltage divider branch, and is used to automatically select the first voltage divider signal / the second voltage divider signal as the threshold voltage signal output according to the voltage level of the input power supply. The first input terminal of the voltage comparator is connected to the threshold voltage signal output by the voltage selection module, the second input terminal of the voltage comparator is connected to the reference voltage source, and the output terminal of the voltage comparator outputs a power failure detection signal. Specifically, when the voltage of the input power supply is lower than the threshold corresponding to the current voltage level, the power failure detection signal output by the voltage comparator is valid.
[0007] As a further explanation of the present invention, the first voltage divider branch is composed of resistors R3 and R9 connected in series, and is used to generate a 12V system threshold voltage V1. The second voltage divider branch consists of resistors R3, R4, and R9. Resistors R4 and R9 are connected in parallel and then in series with resistor R3 to generate the 24V system threshold voltage V2.
[0008] As a further explanation of the present invention, the input power supply is BAT+ / BAT-; the reference voltage source is 2.5V; For a 12V system, when BAT+ / BAT- is lower than the set value V1 (V1 set value equals 2.5×(R3+R9) / R9), the voltage comparator U2 outputs a low power-down detection signal, generating a valid signal. For a 24V system, when BAT+ / BAT- is lower than the set value V2, the set value V2 is equal to 2.5×(R3+R4 / / R9) / (R4 / / R9), and the voltage comparator U2 outputs a low power-down detection signal, generating a valid signal; when BAT+ / BAT- is higher than the set value V2, the voltage comparator U2 outputs a high power-down detection signal. Where / / represents the parallel resistance value.
[0009] As a further explanation of the present invention, the voltage selection module includes a switching transistor; The voltage divider node of the first voltage divider branch is connected to the first input terminal of the voltage comparator; The voltage divider node of the second voltage divider branch is connected to the control electrode of the switching transistor through resistor R2; The first conducting terminal of the switching transistor is grounded, and the second conducting terminal of the switching transistor is connected to the first input terminal of the voltage comparator through resistor R8; When the input power supply is at the first voltage level, the voltage division of the second voltage divider branch is insufficient to turn on the switching transistor, and the voltage at the first input terminal of the voltage comparator is determined by the first voltage divider branch. When the input power supply is at the second voltage level, the voltage division of the second voltage divider branch turns on the switch, and the resistor R2 is connected in parallel to a part of the first voltage divider branch, thereby changing the voltage at the first input terminal of the voltage comparator so that the threshold voltage signal corresponds to the second voltage level.
[0010] As a further explanation of the present invention, a third voltage-dividing branch is also included; The third voltage divider branch is composed of resistor R1, resistor R7 and transistor Q1. Resistors R1 and R7 form the third voltage divider branch, generating the threshold voltage V3.
[0011] As a further explanation of the present invention, the threshold voltage V3 is equal to 2.5V×(R1+R7) / R7.
[0012] As a further explanation of the present invention, the base of the transistor Q1 is connected to the voltage divider point of the threshold voltage V3; Q1 is turned on when the input power supply voltage is higher than V3, which is used to suppress false alarms during the voltage recovery phase; When the input power supply voltage is higher than V3 and lower than V2, the power failure detection signal is low. When the input power supply voltage is higher than V1 and lower than V3, the power failure detection signal is high.
[0013] As a further explanation of the present invention, the transistor Q1 is an NPN transistor, and its collector is connected to the feedback network of the voltage comparator. When the transistor Q1 is turned on, it pulls up the threshold of the voltage comparator to form a detection hysteresis interval, and the hysteresis voltage difference is ≥1V.
[0014] As a further explanation of the present invention, the reference voltage source adopts a bandgap reference circuit, which generates 2.5V VREF_2V5 from a +5VCC power supply through a voltage regulator, with a temperature coefficient ≤50ppm / ℃.
[0015] As a further explanation of the present invention, the output terminal of the voltage comparator outputs a power-down detection signal connected to the external interrupt pin of the microcontroller to trigger the interrupt service routine.
[0016] Compared with the prior art, the beneficial effects of the present invention are: This invention achieves rapid power failure detection of a dual-voltage system of 12V and 24V through hardware circuit design, avoiding the problems of long delay, high CPU resource consumption, and high system power consumption in traditional software detection methods. This circuit can quickly output an effective power failure detection signal when the voltage drops, allowing the system enough time to perform data backup and safe shutdown procedures, thereby effectively ensuring the reliability of the vehicle's electronic system. At the same time, the voltage selection module in the circuit can automatically select an appropriate threshold voltage signal according to the voltage level of the input power supply, making the circuit compatible with both 12V and 24V systems, improving the circuit's versatility and flexibility. Attached Figure Description
[0017] Figure 1 This is a block diagram of the power-down voltage detection circuit of the present invention applied to a 12V compatible 24V system; Figure 2 This is a block diagram of the MCU power unlock control circuit of the present invention. Detailed Implementation
[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Example 1:
[0019] Please see Figure 1-2 This invention provides a technical solution: a power-down voltage detection circuit for a 12V compatible 24V system, comprising: an input power supply, a reference voltage source, a first voltage divider branch, a second voltage divider branch, a voltage selection module, and a voltage comparator. The reference voltage source provides a stable reference voltage. The first voltage divider branch divides the input power supply to generate a first voltage divider signal. The second voltage divider branch divides the input power supply to generate a second voltage divider signal. The input terminal of the voltage selection module is connected to the first and second voltage divider branches and is used to automatically select the first voltage divider signal / second voltage divider signal as a threshold voltage signal output according to the voltage level of the input power supply. The first input terminal of the voltage comparator is connected to the threshold voltage signal output by the voltage selection module, the second input terminal of the voltage comparator is connected to the reference voltage source, and the output terminal of the voltage comparator outputs a power-down detection signal. When the voltage of the input power supply is lower than the threshold corresponding to the current voltage level, the power-down detection signal output by the voltage comparator is valid.
[0020] Specifically, the hardware circuit design enables rapid power failure detection of a dual-voltage system of 12V and 24V, avoiding the problems of long delays, high CPU resource consumption, and high system power consumption in traditional software detection methods.
[0021] In practical applications, the fluctuation range of the input power supply may be large, while the reference voltage source can always provide a stable reference voltage to ensure the accuracy of detection. The first and second voltage divider branches are optimized for 12V and 24V systems, respectively, to generate appropriate voltage divider signals. The voltage selection module automatically switches according to the voltage level of the input power supply and selects the corresponding voltage divider signal as the threshold voltage signal, thereby realizing adaptive detection of systems with different voltage levels. When the input power supply voltage drops below the threshold corresponding to the current voltage level, the voltage comparator will immediately output a valid power failure detection signal so that the system can take timely countermeasures to protect the equipment from the effects of voltage fluctuations.
[0022] As a further explanation of the present invention, the first voltage divider branch is composed of resistors R3 and R9 connected in series, and is used to generate a 12V system threshold voltage V1; the second voltage divider branch is composed of resistors R3, R4 and R9, wherein resistors R4 and R9 are connected in parallel and then connected in series with resistor R3, and is used to generate a 24V system threshold voltage V2.
[0023] Specifically, the voltage selection module is implemented by controlling the switching transistor through the second voltage divider branch. This chip can automatically select the conduction path according to the voltage level of the input power supply. When the input is 12V, the second voltage divider branch controls the switching transistor to transmit the voltage divider signal generated by the first voltage divider branch as the threshold voltage signal to the voltage comparator. When the input is 24V, the voltage divider signal generated by the second voltage divider branch is transmitted as the threshold voltage signal to the voltage comparator. The voltage comparator is composed of a high-precision, low-offset operational amplifier. Its positive input terminal is connected to the reference voltage source, and its negative input terminal is connected to the threshold voltage signal output by the voltage selection module. When the input power supply voltage drops below the threshold corresponding to the current voltage level, the output level of the voltage comparator flips and immediately outputs a valid power-down detection signal.
[0024] As a further explanation of the present invention, the input power supply is BAT+ / BAT-; the reference voltage source is 2.5V; For a 12V system, when BAT+ / BAT- is lower than the set value V1 (V1 set value equals 2.5×(R3+R9) / R9), the voltage comparator U2 outputs a low power-down detection signal, generating a valid signal. For a 24V system, when BAT+ / BAT- is lower than the set value V2, the set value V2 is equal to 2.5×(R3+R4 / / R9) / (R4 / / R9), and the voltage comparator U2 outputs a low power-down detection signal, generating a valid signal; when BAT+ / BAT- is higher than the set value V2, the voltage comparator U2 outputs a high power-down detection signal; where / / represents the parallel resistance value.
[0025] Specifically, in practical applications, when the system power supply voltage begins to drop for various reasons, the voltage comparator can quickly respond to this change. For a 12V system, once the voltage between BAT+ and BAT- falls below the threshold V1 determined by R3 and R9, the output of voltage comparator U2 immediately changes to a low level. This change signifies the generation of a valid power-down detection signal, which the system can then use to implement appropriate protection measures. Similarly, in a 24V system, when the voltage drops below the threshold V2 determined by R3, R4, and R9, a similar power-down detection mechanism is triggered. It is worth noting that when the 24V system power supply voltage recovers and exceeds V2, the output of voltage comparator U2 returns to a high level, indicating that the system voltage has returned to its normal range and no power-down processing is required. This design not only improves the system's reliability but also enhances its adaptability to different voltage levels.
[0026] As a further explanation of the present invention, the voltage selection module includes a switching transistor; the voltage dividing node of the first voltage dividing branch is connected to the first input terminal of the voltage comparator; the voltage dividing node of the second voltage dividing branch is connected to the control terminal of the switching transistor through resistor R2; the first conducting terminal of the switching transistor is grounded, and the second conducting terminal of the switching transistor is connected to the first input terminal of the voltage comparator through resistor R8. When the input power supply is at the first voltage level, the voltage division of the second voltage divider branch is insufficient to turn on the switching transistor, and the voltage at the first input terminal of the voltage comparator is determined by the first voltage divider branch. When the input power supply is at the second voltage level, the voltage division of the second voltage divider branch turns on the switching transistor, connecting resistor R2 in parallel to a part of the first voltage divider branch, thereby changing the voltage at the first input terminal of the voltage comparator, so that the threshold voltage signal corresponds to the second voltage level.
[0027] Specifically, the on / off state of the switching transistor is directly controlled by the voltage division of the second voltage divider branch. At the first voltage level, such as a 12V system, the voltage division generated by the second voltage divider branch is too low to drive the switching transistor into the on state. Therefore, the voltage at the first input terminal of the voltage comparator is entirely determined by the first voltage divider branch, ensuring the accuracy of power-down detection at this voltage level. However, at the second voltage level, such as a 24V system, the voltage division generated by the second voltage divider branch increases, sufficient to turn on the switching transistor. This change causes resistor R2 to be connected in parallel to a portion of the first voltage divider branch, thereby adjusting the voltage value at the first input terminal of the voltage comparator. This allows the threshold voltage signal to accurately correspond to the power-down detection requirements of the 24V system, automatically adapting to different voltage levels and achieving compatible detection for both 12V and 24V systems, greatly improving the circuit's practicality and reliability.
[0028] As a further explanation of the present invention, the reference voltage source adopts a bandgap reference circuit, which generates 2.5V VREF_2V5 from a +5VCC power supply through a voltage regulator, with a temperature coefficient ≤50ppm / ℃.
[0029] Specifically, the bandgap reference circuit can control the fluctuation of VREF_2V5 within a very small range, ensuring that the voltage comparator can judge the input voltage based on the accurate reference voltage, thereby effectively improving the detection accuracy and reliability of the entire power-down voltage detection circuit.
[0030] As a further explanation of the present invention, the output terminal of the voltage comparator outputs a power-down detection signal connected to the external interrupt pin of the microcontroller to trigger the interrupt service routine.
[0031] Specifically, when the system voltage drops below the set threshold voltage, the voltage comparator will quickly flip its output state and output a valid power failure detection signal. This signal is directly sent to the microcontroller's external interrupt pin. After detecting the interrupt signal, the microcontroller will immediately respond and execute the pre-written interrupt service routine. The interrupt service routine saves critical data, shuts down unnecessary peripherals to reduce power consumption, or starts the backup power supply, etc., to ensure that the system can operate safely and orderly in the event of a power failure, thereby effectively improving the stability and anti-interference capability of the entire system.
[0032] In this embodiment, rapid power-down detection of a dual-voltage system of 12V and 24V is achieved through hardware circuit design, avoiding the problems of long delay, high CPU resource consumption, and high system power consumption in traditional software detection methods. When the input power supply voltage begins to drop for various reasons, the voltage comparator can quickly respond to this change and output a valid power-down detection signal when the voltage drops below a set threshold. This signal is sent to the external interrupt pin of the microcontroller to trigger the interrupt service routine, enabling the system to take timely countermeasures, thereby effectively protecting the device from the effects of voltage fluctuations and improving the stability and anti-interference capability of the entire system. Example 2:
[0033] Please see Figure 1-2 Based on Embodiment 1, a third voltage divider branch is also included; the third voltage divider branch is composed of resistor R1, resistor R7 and transistor Q1, and resistor R1 and resistor R7 form the third voltage divider branch to generate threshold voltage V3.
[0034] In this circuit, the base of transistor Q1 is driven by resistors R1 and R7 in the third voltage divider branch. Its collector participates in voltage selection through resistor R2 (conducting in a 24V system) and is connected to the voltage comparator feedback network through resistor R8 to form hysteresis.
[0035] Specifically, transistor Q1 acts as a switching element, with its base connected to the output of the third voltage divider branch. When the voltage output by the third voltage divider branch reaches the conduction threshold of transistor Q1, transistor Q1 turns on, thereby stabilizing the threshold voltage V3 at a preset value. This threshold voltage V3 serves as a reference voltage for another power-down detection path and is compared with the input power supply voltage. When the input power supply voltage drops below the threshold voltage V3, the corresponding voltage comparator outputs a valid power-down detection signal. This signal is also sent to the external interrupt pin of the microcontroller to trigger the interrupt service routine for that voltage level, thereby achieving rapid power-down detection of the other voltage in the 12V and 24V dual-voltage system.
[0036] As a further explanation of the present invention, the threshold voltage V3 is equal to 2.5V×(R1+R7) / R7, and the base of transistor Q1 is connected to the voltage divider point of the threshold voltage V3; Q1 is turned on when the input power supply voltage is higher than V3, which is used to suppress false alarms during the voltage recovery phase; when the input power supply voltage is higher than V3 and lower than V2, the power-down detection signal is low; when the input power supply voltage is higher than V1 and lower than V3, the power-down detection signal is high.
[0037] Specifically, when the input power supply voltage is within the range of V1 to V3, the system determines that it is in the primary power-down state and outputs a high-level signal; when the voltage is in the range of V2 to V3, a voltage buffer band is formed through the conduction characteristics of transistor Q1, and the comparator output remains at a low level to avoid false triggering caused by voltage fluctuations; only when the voltage is continuously lower than V3 will the second power-down detection interrupt be triggered. The hierarchical detection mechanism not only ensures the compatibility of the 12V and 24V dual systems, but also realizes the anti-interference capability of the voltage recovery stage through hardware circuitry, effectively improving the reliability of the system in complex power supply environments.
[0038] As a further explanation of the present invention, transistor Q1 is an NPN transistor, and its collector is connected to the feedback network of the voltage comparator. When transistor Q1 is turned on, it pulls up the threshold of the voltage comparator to form a detection hysteresis interval, and the hysteresis voltage difference is ≥1V.
[0039] Specifically, when the input power supply voltage drops from a high level to V3, the output state of the voltage comparator flips for the first time; when the voltage rises back to V3+1V, it will trigger a reverse flip, forming a clear voltage hysteresis characteristic. This detection circuit with hysteresis characteristics exhibits good stability in a 12V / 24V dual power supply system and is suitable for applications with stringent power reliability requirements, such as automotive electronic equipment and industrial controllers.
[0040] In this embodiment, a hysteresis detection circuit constructed using the third voltage divider branch and transistor Q1 enables graded power-down monitoring of a 12V / 24V dual-voltage system. When the input power supply voltage is between V1 and V3, the system enters a primary warning state and outputs a high-level signal. When the voltage is between V2 and V3, a voltage buffer band of over 1V is formed through the conduction characteristics of transistor Q1. At this time, the comparator output remains low to suppress false alarms caused by power fluctuations. Only when the voltage remains below the V3 threshold will the second power-down detection interruption be triggered. Specifically, the alarm state will be lifted when the input power supply voltage rises from a low level to V3+1V, forming a clear voltage hysteresis characteristic. Through the dual-channel detection mechanism and hysteresis voltage control, the power supply reliability in applications such as automotive electronic devices and industrial controllers is effectively improved while ensuring the compatibility of the 12V / 24V system.
[0041] 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.
Claims
1. A power-down voltage detection circuit for a 12V-compatible 24V system, comprising: The input power supply, reference voltage source, first voltage divider branch, second voltage divider branch, voltage selection module, and voltage comparator are characterized by: The reference voltage source is used to provide a stable reference voltage; The first voltage divider branch is used to divide the input power supply to generate a first voltage divider signal; The second voltage divider branch is used to divide the input power supply to generate a second voltage divider signal; The input terminal of the voltage selection module is connected to the first voltage divider branch and the second voltage divider branch, and is used to automatically select the first voltage divider signal / the second voltage divider signal as the threshold voltage signal output according to the voltage level of the input power supply. The first input terminal of the voltage comparator is connected to the threshold voltage signal output by the voltage selection module, the second input terminal of the voltage comparator is connected to the reference voltage source, and the output terminal of the voltage comparator outputs a power failure detection signal. Specifically, when the voltage of the input power supply is lower than the threshold corresponding to the current voltage level, the power failure detection signal output by the voltage comparator is valid.
2. The power-down voltage detection circuit for a 12V compatible 24V system according to claim 1, characterized in that: The first voltage divider branch is composed of resistors R3 and R9 connected in series, and is used to generate the 12V system threshold voltage V1. The second voltage divider branch consists of resistors R3, R4, and R9. Resistors R4 and R9 are connected in parallel and then in series with resistor R3 to generate the 24V system threshold voltage V2.
3. The power-down voltage detection circuit for a 12V compatible 24V system according to claim 1, characterized in that: The input power supply is BAT+ / BAT-; the reference voltage source is 2.5V; For a 12V system, when BAT+ / BAT- is lower than the set value V1 (V1 set value equals 2.5×(R3+R9) / R9), the voltage comparator U2 outputs a low power-down detection signal, generating a valid signal. For a 24V system, when BAT+ / BAT- is lower than the set value V2, the set value V2 is equal to 2.5×(R3+R4 / / R9) / (R4 / / R9), and the voltage comparator U2 outputs a low power-down detection signal, generating a valid signal; when BAT+ / BAT- is higher than the set value V2, the voltage comparator U2 outputs a high power-down detection signal. Where / / represents the parallel resistance value.
4. The power-down voltage detection circuit for a 12V compatible 24V system according to claim 1, characterized in that: The voltage selection module includes a switching transistor; The voltage divider node of the first voltage divider branch is connected to the first input terminal of the voltage comparator; The voltage divider node of the second voltage divider branch is connected to the control electrode of the switching transistor through resistor R2; The first conducting terminal of the switching transistor is grounded, and the second conducting terminal of the switching transistor is connected to the first input terminal of the voltage comparator through resistor R8; When the input power supply is at the first voltage level, the voltage division of the second voltage divider branch is insufficient to turn on the switching transistor, and the voltage at the first input terminal of the voltage comparator is determined by the first voltage divider branch. When the input power supply is at the second voltage level, the voltage division of the second voltage divider branch turns on the switch, and the resistor R2 is connected in parallel to a part of the first voltage divider branch, thereby changing the voltage at the first input terminal of the voltage comparator so that the threshold voltage signal corresponds to the second voltage level.
5. The power-down voltage detection circuit for a 12V compatible 24V system according to claim 1, characterized in that: It also includes the third voltage-sharing branch; The third voltage divider branch is composed of resistor R1, resistor R7 and transistor Q1. Resistors R1 and R7 form the third voltage divider branch, generating the threshold voltage V3.
6. The power-down voltage detection circuit for a 12V compatible 24V system according to claim 5, characterized in that: The threshold voltage V3 is equal to 2.5V×(R1+R7) / R7.
7. A power-down voltage detection circuit for a 12V-compatible 24V system according to claim 6, characterized in that: The base of transistor Q1 is connected to the threshold voltage V3 divider point; Q1 is turned on when the input power supply voltage is higher than V3, which is used to suppress false alarms during the voltage recovery phase; When the input power supply voltage is higher than V3 and lower than V2, the power failure detection signal is low. When the input power supply voltage is higher than V1 and lower than V3, the power failure detection signal is high.
8. A power-down voltage detection circuit for a 12V compatible 24V system according to claim 6, characterized in that: The transistor Q1 is an NPN transistor, and its collector is connected to the feedback network of the voltage comparator. When the transistor Q1 is turned on, it pulls up the threshold of the voltage comparator to form a detection hysteresis interval with a hysteresis voltage difference ≥1V.
9. The power-down voltage detection circuit for a 12V compatible 24V system according to claim 1, characterized in that: The reference voltage source adopts a bandgap reference circuit, which generates 2.5V VREF_2V5 from a +5VCC power supply through a voltage regulator, with a temperature coefficient ≤50ppm / ℃.
10. The power-down voltage detection circuit for a 12V compatible 24V system according to claim 1, characterized in that: The output of the voltage comparator outputs a power-down detection signal, which is connected to the external interrupt pin of the microcontroller to trigger the interrupt service routine.