Power failure detection circuit
By combining a reference power supply, a logic control module, and a voltage regulator module, and utilizing PNP and NPN transistors to achieve power-down detection, the high cost problem in existing technologies is solved, and low-cost and effective power-down detection is achieved.
Patent Information
- Application Number
- CN202422836830.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-20
- Publication Date
- 2025-10-31
- Estimated Expiration
- 2034-11-20
AI Technical Summary
Existing power failure detection circuits mostly use watchdog modules, which results in high manufacturing costs.
The system employs a combination of a reference power supply, a logic control module, and a voltage regulator module. The voltage of the power supply under test is reduced by a first preset value by the voltage regulator module before being input to the logic control module. PNP and NPN transistors are used as switches to achieve power-down detection.
It reduces the manufacturing cost of power failure detection circuits, has a simple structure, and can promptly issue alarm signals to remind users or managers to take measures, thereby improving system reliability and data security.
Smart Images
Figure CN223502553U_ABST
Abstract
Description
Technical Field
[0001] This technology relates to the field of power failure detection, and in particular to power failure detection circuits. Background Technology
[0002] Power failure detection triggers an alarm when the power supply is interrupted, quickly notifying users or relevant management personnel so they can take timely action. In many environments, power failures can lead to data loss and equipment damage. Therefore, power failure detection is particularly important for enterprise data security, improving system reliability and data security. Existing power failure detection circuits often use watchdog modules, but watchdog modules are expensive to manufacture. Utility Model Content
[0003] This application aims to provide a power failure detection circuit that can reduce the cost of power failure detection circuits.
[0004] To achieve the above objectives, this application provides a power-down detection circuit, including a reference power supply, a power supply under test, a logic control module, and a voltage regulator module:
[0005] The logic control module includes a first branch and a second branch; the first branch and the second branch are respectively provided with a first switch and a second switch; the input terminal of the first switch is connected to the reference power supply, the output terminal of the first switch is connected to one end of a first resistor, and the other end of the first resistor is grounded; the control terminal of the second switch is connected to the output terminal of the first switch, the input terminal of the second switch is connected to the reference power supply and is configured to be connected to an alarm device through an alarm signal line, and the output terminal of the second switch is grounded;
[0006] The voltage regulator module is used to reduce the input voltage by a first preset value and then output it. The input terminal of the voltage regulator module is connected to the power supply under test, and the output terminal of the voltage regulator module is connected to the control terminal of the first switch. One end of the second resistor is connected between the voltage regulator module and the control terminal of the first switch, and the other end of the second resistor is grounded.
[0007] When the voltage between the input terminal and the control terminal of the first switch is greater than a second preset value, the input terminal and the output terminal of the first switch are connected, causing the voltage between the control terminal and the output terminal of the second switch to be greater than a third preset value. At this time, the input terminal and the output terminal of the second switch are connected.
[0008] The power-down detection circuit of this application uses a voltage regulator module to reduce the voltage of the power supply under test by a first preset value before inputting it into the logic control module, preventing the voltage of the power supply under test from being too high and damaging the circuit. For the logic control module, under normal circumstances, the difference between the voltage at the input terminal of the first switch and the voltage at the control terminal of the first switch is less than a second preset value, causing both the first and second switches to be in the open state. At this time, the reference power supply provides a high-level voltage signal to the alarm signal line. However, when the voltage of the power supply under test drops to a certain level, the difference between the voltage at the input terminal of the first switch and the voltage at the control terminal of the first switch exceeds the first preset value, and the input terminal and output terminal of the first switch are connected. This causes the difference between the voltage at the control terminal and the output terminal of the second switch to exceed a third preset value, and the input terminal and output terminal of the second switch are connected. Since the output terminal of the second switch is grounded, the alarm signal line is pulled low. The alarm device connected to the alarm signal line detects the change in the voltage signal of the alarm signal line and issues an alarm to remind the user. The power-down detection circuit of this application has a simple structure and a lower manufacturing cost than a watchdog module, which helps to save resources.
[0009] Optionally, the first switch is a PNP transistor, and the second switch is an NPN transistor. The input terminal of the first switch is the emitter, the output terminal is the collector, and the control terminal is the base; the input terminal of the second switch is the collector, the output terminal is the emitter, and the control terminal is the base.
[0010] Optionally, the second preset value and the third preset value are the on-state voltage of the first switch and the on-state voltage of the second switch, respectively.
[0011] Optionally, the voltage regulator module includes a three-terminal voltage regulator and a third resistor and a fourth resistor connected in series;
[0012] The first end of the third resistor is connected to the power supply under test, the second end of the third resistor is connected to the first end of the fourth resistor, and the second end of the fourth resistor is connected to the control terminal of the first switch.
[0013] The reference terminal of the three-terminal voltage regulator is connected between the third resistor and the fourth resistor, the cathode of the three-terminal voltage regulator is connected to the power supply under test, and the anode of the three-terminal voltage regulator is connected to the second terminal of the fourth resistor.
[0014] Optionally, the three-terminal regulator is an LR431 chip, and the formula for calculating the first preset value is:
[0015] U = (1 + R3 / R4)·U w ;
[0016] Wherein, U is the first preset value, R3 is the resistance value of the third resistor, R4 is the resistance value of the fourth resistor, and U w The voltage is the internal reference source voltage of the three-terminal regulator.
[0017] Optionally, a current limiting module is also connected in series between the voltage stabilizing module and the first switch.
[0018] Optionally, the current limiting module includes a fifth resistor and a sixth resistor connected in series. The first end of the fifth resistor is connected to the output terminal of the voltage regulator module, the second end of the fifth resistor is connected to the first end of the sixth resistor, and the second end of the sixth resistor is connected to the control terminal of the first switch.
[0019] The power failure detection circuit also includes a capacitor, the first end of which is connected between the fifth resistor and the sixth resistor, and the second end of which is grounded.
[0020] Optionally, the first branch further includes a seventh resistor, which is connected in series between the input terminal of the first switch and the reference power supply; the second branch further includes an eighth resistor, which is connected in series between the input terminal of the second switch and the reference power supply.
[0021] Optionally, a ninth resistor is connected in series between the output terminal of the first switch and the control terminal of the second switch.
[0022] Optionally, a tenth resistor is also included, which is disposed on the alarm signal line. Attached Figure Description
[0023] Figure 1 This is a topology diagram of the power-down detection circuit in an embodiment of this application. Detailed Implementation
[0024] To explain in detail the technical content, structural features, objectives and effects of this application, the following description is provided in conjunction with the embodiments and accompanying drawings.
[0025] Existing power failure detection circuits are implemented using watchdog modules, but watchdog modules are expensive because they include timer modules and register modules.
[0026] For this, please refer to Figure 1 This application discloses a power-down detection circuit, including a reference power supply U1, a power supply under test U2, a logic control module M1, and a voltage regulator module M2:
[0027] The logic control module M1 includes a first branch M11 and a second branch M12. The first branch M11 and the second branch M12 are respectively equipped with a first switch Q1 and a second switch Q2. The input terminal of the first switch Q1 is connected to a reference power supply U1, and the output terminal of the first switch Q1 is connected to one end of a first resistor R1, with the other end of the first resistor R1 grounded. The control terminal of the second switch Q2 is connected to the output terminal of the first switch Q1. The input terminal of the second switch Q2 is connected to the reference power supply U1 and is configured to connect to an alarm device via an alarm signal line L1. The output terminal of the second switch Q2 is grounded.
[0028] The voltage regulator module M2 is used to reduce the input voltage by a first preset value before outputting. The input terminal of the voltage regulator module M2 is connected to the power supply under test U2, and the output terminal of the voltage regulator module M2 is connected to the control terminal of the first switch Q1. One end of the second resistor R2 is connected between the voltage regulator module M2 and the control terminal of the first switch Q1, and the other end of the second resistor R2 is grounded.
[0029] When the voltage between the input terminal and the control terminal of the first switch Q1 is greater than the second preset value, the input terminal and the output terminal of the first switch Q1 are connected, causing the voltage between the control terminal and the output terminal of the second switch Q2 to be greater than the third preset value. At this time, the input terminal and the output terminal of the second switch Q2 are connected.
[0030] The power failure detection circuit of this application uses a voltage regulator module M2 to reduce the voltage of the tested power supply U2 by a first preset value before inputting it into the logic control module M1, preventing the voltage of the tested power supply U2 from being too high and damaging the circuit. For the logic control module M1, under normal circumstances, the difference between the voltage at the input terminal of the first switch Q1 and the voltage at the control terminal of the first switch Q1 is less than a second preset value, causing both the first switch Q1 and the second switch Q2 to be in the open state. At this time, the reference power supply U1 provides a high-level voltage signal to the alarm signal line L1. However, when the voltage of the tested power supply U2 drops to a certain level, the difference between the voltage at the input terminal of the first switch Q1 and the voltage at the control terminal of the first switch Q1 exceeds a first preset value. The input and output terminals of the first switch Q1 then conduct, causing the difference between the voltage at the control terminal and the output terminal of the second switch Q2 to exceed a third preset value. The input and output terminals of the second switch Q2 then conduct. Since the output terminal of the second switch Q2 is grounded, the alarm signal line L1 is pulled low. The alarm device connected to the alarm signal line L1 detects the change in the voltage signal of the alarm signal line L1 and issues an alarm to remind the user. The power-down detection circuit of this application has a simple structure and a lower manufacturing cost than a watchdog module, which helps to save resources.
[0031] In some embodiments, the first switch Q1 is a PNP transistor, and the second switch Q2 is an NPN transistor. The input terminal of the first switch Q1 is the emitter, the output terminal is the collector, and the control terminal is the base. The input terminal of the second switch Q2 is the collector, the output terminal is the emitter, and the control terminal is the base. For a PNP transistor, the transistor is in the on state when the voltage between the emitter and base is greater than the turn-on voltage (typically 0.7V), otherwise it is in the off state. For an NPN transistor, the transistor is in the on state when the voltage between the base and emitter is greater than the turn-on voltage (typically 0.7V), otherwise it is in the off state.
[0032] Specifically, the second preset value and the third preset value are the on-state voltages of the first switch Q1 and the second switch Q2, respectively.
[0033] In some embodiments, the voltage regulator module M2 includes a three-terminal voltage regulator Q3 and a third resistor R3 and a fourth resistor R4 connected in series. The first terminal of the third resistor R3 is connected to the power supply under test U2, the second terminal of the third resistor R3 is connected to the first terminal of the fourth resistor R4, and the second terminal of the fourth resistor R4 is connected to the control terminal of the first switch Q1. The reference terminal of the three-terminal voltage regulator Q3 is connected between the third resistor R3 and the fourth resistor R4, the cathode is connected to the power supply under test U2, and the anode is connected to the second terminal of the fourth resistor R4.
[0034] Specifically, the three-terminal regulator Q3 can be an LR431 chip, and the formula for calculating the first preset value is as follows:
[0035] U = (1 + R3 / R4)·U w ;
[0036] Where U is the first preset value (the voltage across the voltage regulator module M2), R3 is the resistance value of the third resistor R3, R4 is the resistance value of the fourth resistor R4, and U w This is the voltage of the internal reference source of the three-terminal regulator Q3.
[0037] Optionally, the voltage U of the internal reference source of the three-terminal regulator Q3 w =2.5V. Of course, it's not limited to this.
[0038] In some embodiments, a current limiting module M3 is also connected in series between the voltage regulator module M2 and the first switch Q1.
[0039] Specifically, the current limiting module M3 includes a fifth resistor R5 and a sixth resistor R6 connected in series. The first end of the fifth resistor R5 is connected to the output terminal of the voltage regulator module M2, and the second end of the fifth resistor R5 is connected to the first end of the sixth resistor R6. The second end of the sixth resistor R6 is connected to the control terminal of the first switch Q1. The power failure detection circuit also includes a capacitor C1. The first end of the capacitor C1 is connected between the fifth resistor R5 and the sixth resistor R6, and the second end of the capacitor C1 is grounded. This can filter the AC current in the circuit and improve the circuit's safety.
[0040] In some embodiments, the first branch M11 further includes a seventh resistor R7, which is connected in series between the input terminal of the first switch Q1 and the reference power supply U1. The second branch M12 further includes an eighth resistor R8, which is connected in series between the input terminal of the second switch Q2 and the reference power supply U1. The seventh resistor R7 and the eighth resistor R8 are pull-up resistors to prevent excessive current in the first branch M11 and the second branch M12.
[0041] Specifically, a ninth resistor R9 is connected in series between the output terminal of the first switch Q1 and the control terminal of the second switch Q2 to enhance the safety of the circuit.
[0042] In some embodiments, the power failure detection circuit further includes a tenth resistor R10, which is disposed on the alarm signal line L1 and can be used to detect the voltage signal on the alarm signal line L1.
[0043] In some embodiments, the reference power supply U1 can be a 3.3V reference voltage source. Of course, it is not limited to this. This is a technical means familiar to those skilled in the art and will not be described in detail here.
[0044] The following example illustrates the operation of the power-down detection circuit in this application:
[0045] Assume the first switch Q1 is a PNP transistor, the second switch Q2 is an NPN transistor, the input terminal of the first switch Q1 is the emitter, the output terminal is the collector, and the control terminal is the base. The input terminal of the second switch Q2 is the collector, the output terminal is the emitter, and the control terminal is the base. The three-terminal regulator Q3 is an LR431 chip, the resistance of the third resistor R3 is R3 = 10KΩ, the resistance of the fourth resistor R4 is R4 = 5.1KΩ, and the voltage of the internal reference source of the three-terminal regulator Q3 is U. w =2.5V, the reference voltage source provides a voltage of 3.3V, and the power supply U2 under test normally supplies a voltage of 12V.
[0046] The formula for calculating the first preset value is:
[0047] U = (1 + R3 / R4)·U w ;
[0048] Substituting the values above, we can see that the voltage of the three-terminal regulator Q3 is U = 7.4V.
[0049] Given that the supply voltage of the power supply U2 is 12V, the voltage across the second resistor R2 is:
[0050] 12V - 7.4V = 4.6V;
[0051] The base voltage of the first switch Q1 is also 4.6V, which is higher than the emitter voltage of 3.3V. Therefore, the first switch Q1 is not conducting. Since the first switch Q1 is not conducting, there is no voltage at the base of the second switch Q2. Therefore, the second switch Q2 is not conducting, and the signal output by the alarm signal line L1 is a high-level signal.
[0052] When the supply voltage of the power supply U2 under test is lower than 10V, the voltage across the second resistor R2 is already lower than:
[0053] 10V - 7.4V = 2.6V;
[0054] The voltage of the first switch Q1 is 0.7V lower than the emitter voltage of the first switch Q1, causing the first switch Q1 to conduct. At this time, the base level of the second switch Q2 is pulled high. The base level of the second switch Q2 is about 3V, so the second switch Q2 meets the conduction condition. Since the second switch Q2 and the alarm device connected to the alarm signal line L1 are connected in parallel, the alarm signal line L1 is pulled low to 0V, so the alarm device recognizes that the power supply U2 under test is in a power-off state.
[0055] The above-disclosed examples are merely preferred embodiments of this application and should not be construed as limiting the scope of this application. Therefore, any equivalent variations made in accordance with the claims of this application shall fall within the scope of this application.
Claims
1. A power-down detection circuit, characterized in that, Includes a reference power supply, the power supply under test, a logic control module, and a voltage regulator module: The logic control module includes a first branch and a second branch; the first branch and the second branch are respectively provided with a first switch and a second switch; the input terminal of the first switch is connected to the reference power supply, the output terminal of the first switch is connected to one end of a first resistor, and the other end of the first resistor is grounded; the control terminal of the second switch is connected to the output terminal of the first switch, the input terminal of the second switch is connected to the reference power supply and is configured to be connected to an alarm device through an alarm signal line, and the output terminal of the second switch is grounded; The voltage regulator module is used to reduce the input voltage by a first preset value and then output it. The input terminal of the voltage regulator module is connected to the power supply under test, and the output terminal of the voltage regulator module is connected to the control terminal of the first switch. One end of the second resistor is connected between the voltage regulator module and the control terminal of the first switch, and the other end of the second resistor is grounded. When the voltage between the input terminal and the control terminal of the first switch is greater than a second preset value, the input terminal and the output terminal of the first switch are connected, causing the voltage between the control terminal and the output terminal of the second switch to be greater than a third preset value. At this time, the input terminal and the output terminal of the second switch are connected.
2. The power failure detection circuit as described in claim 1, characterized in that, The first switch is a PNP transistor, and the second switch is an NPN transistor. The input terminal of the first switch is the emitter, the output terminal is the collector, and the control terminal is the base; the input terminal of the second switch is the collector, the output terminal is the emitter, and the control terminal is the base.
3. The power failure detection circuit as described in claim 2, characterized in that, The second preset value and the third preset value are the on-state voltage of the first switch and the on-state voltage of the second switch, respectively.
4. The power failure detection circuit as described in claim 1, characterized in that, The voltage regulator module includes a three-terminal voltage regulator and a third resistor and a fourth resistor connected in series; The first end of the third resistor is connected to the power supply under test, the second end of the third resistor is connected to the first end of the fourth resistor, and the second end of the fourth resistor is connected to the control terminal of the first switch. The reference terminal of the three-terminal voltage regulator is connected between the third resistor and the fourth resistor, the cathode of the three-terminal voltage regulator is connected to the power supply under test, and the anode of the three-terminal voltage regulator is connected to the second terminal of the fourth resistor.
5. The power failure detection circuit as described in claim 4, characterized in that, The three-terminal voltage regulator is an LR431 chip, and the formula for calculating the first preset value is: Wherein, U is the first preset value, R3 is the resistance value of the third resistor, R4 is the resistance value of the fourth resistor, and U w The voltage is the internal reference source voltage of the three-terminal regulator.
6. The power failure detection circuit as described in claim 1, characterized in that, A current limiting module is also connected in series between the voltage regulator module and the first switch.
7. The power failure detection circuit as described in claim 6, characterized in that, The current limiting module includes a fifth resistor and a sixth resistor connected in series. The first end of the fifth resistor is connected to the output end of the voltage regulator module, the second end of the fifth resistor is connected to the first end of the sixth resistor, and the second end of the sixth resistor is connected to the control end of the first switch. The power failure detection circuit also includes a capacitor, the first end of which is connected between the fifth resistor and the sixth resistor, and the second end of which is grounded.
8. The power failure detection circuit as described in claim 1, characterized in that, The first branch further includes a seventh resistor, which is connected in series between the input terminal of the first switch and the reference power supply; the second branch further includes an eighth resistor, which is connected in series between the input terminal of the second switch and the reference power supply.
9. The power failure detection circuit as described in claim 8, characterized in that, A ninth resistor is connected in series between the output terminal of the first switch and the control terminal of the second switch.
10. The power failure detection circuit as described in claim 1, characterized in that, It also includes a tenth resistor, which is disposed on the alarm signal line.