Power failure detection circuit

Abstract

The utility model relates to a power failure detection circuit which is characterized in that an alternating current signal source AC is respectively connected with a first loop and a second loop, a voltage stabilizing diode Z1 and a triode Q2 are connected in series, one end of the voltage stabilizing diode Z1 is connected with the first loop and the second loop, and one end of the triode Q2 is connected with the first loop and the second loop; when the AC signal source AC is a positive half-cycle signal, the AC current passes through the first loop; when the AC signal source AC is a negative half-cycle signal, the AC current passes through the second loop; when the voltage generated by the alternating current voltage in the common component capacitor C1 of the first loop and the second loop is greater than a preset value, the voltage stabilizing diode Z1 is broken down and conducted to present a voltage stabilizing state; when the protection circuit works, the base electrode of the triode Q2 generates a preset voltage, so that the triode Q2 is conducted, the voltage of the emitting electrode is lowered, a low-level trigger signal is generated, and the protection circuit is triggered to work.

Description

Technical Field

[0001] The utility model relates to the technical field of circuits, in particular to a power-off detection circuit. Background Art

[0002] Generally, in a power supply circuit, when the output power is constant and the input voltage is too low, the efficiency will be low. When the input voltage is lower than a certain value, a protective action needs to be taken to shut down the circuit. The conventional approach is to control the switching power supply by detecting the bus voltage as a control signal. Utility Model Content

[0003] The utility model aims to detect when the power input voltage is too low and output a level jump signal when the power input voltage is too low, so as to control the switch of the switching power supply, and proposes a power failure detection circuit.

[0004] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0005] A power failure detection circuit, comprising:

[0006] AC signal source AC, first circuit, second circuit, voltage stabilizing diode Z1, transistor Q2;

[0007] The AC signal source AC is connected to the first loop and the second loop respectively, the voltage stabilizing diode Z1 and the transistor Q2 are connected in series, one end of the voltage stabilizing diode Z1 is connected to the first loop and the second loop, and one end of the transistor Q2 is connected to the first loop and the second loop;

[0008] When the AC signal source AC is a positive half-cycle signal, the AC current passes through the first loop; when the AC signal source AC is a negative half-cycle signal, the AC current passes through the second loop; when the voltage generated by the AC voltage in the common component capacitor C1 of the first loop and the second loop is greater than the preset value, the voltage-stabilizing diode Z1 will be broken down and turned on, presenting a voltage-stabilizing state; the base of the transistor Q2 will generate a preset voltage, thereby turning on the transistor Q2, pulling down the voltage of the emitter, generating a low-level trigger signal, and triggering the protection circuit to work.

[0009] Preferably, the first loop includes a resistor R1, a diode D1, a capacitor C1, a diode D4, and a resistor R2.

[0010] Preferably, one end of the resistor R1 is connected to an AC signal source AC, the resistor R1 is connected in series with the diode D1, the diode D1 is connected in series with the capacitor C1, the capacitor C1 is connected in series with the diode D4, and the diode D4 is connected in series with the resistor R2.

[0011] Preferably, the second loop includes a resistor R2, a diode D3, a capacitor C1, a diode D2, and a resistor R1.

[0012] Preferably, the resistor R2 is connected in series with the diode D3, the diode D3 is connected in series with the capacitor C1, the capacitor C1 is connected in series with the diode D2, and the diode D2 is connected in series with the resistor R1.

[0013] Preferably, the power-off detection circuit is connected to the input end of the switching power supply chip.

[0014] Preferably, the first loop and the second loop share a capacitor C1, a resistor R1 and a resistor R2.

[0015] Preferably, the power-off detection circuit includes adding a separate analog circuit detection circuit, and detecting the bus voltage through a separate ADC chip.

[0016] Preferably, the voltage stabilizing diode Z1 is used to prevent false triggering and improve the reliability and stability of the circuit. Preferably, the number of the set of blocks located above the positioning frame is four, and the number of the set of blocks located below the positioning frame is two.

[0017] Compared with the prior art, the power-off detection circuit in the embodiment of the utility model comprises: an AC signal source AC, a first loop, a second loop, a voltage-stabilizing diode Z1, and a transistor Q2; the AC signal source AC is respectively connected to the first loop and the second loop, the voltage-stabilizing diode Z1 and the transistor Q2 are connected in series, one end of the voltage-stabilizing diode Z1 is connected to the first loop and the second loop, and one end of the transistor Q2 is connected to the first loop and the second loop; when the AC signal source AC is a positive half-cycle signal, the AC current passes through the first loop; when the AC signal source AC is a negative half-cycle signal, the AC current passes through the first loop. through the second loop; when the voltage generated by the AC voltage in the common component capacitor C1 of the first loop and the second loop is greater than the preset value, the voltage stabilizing diode Z1 will be broken down and turned on, presenting a voltage stabilizing state; the base of the transistor Q2 generates a preset voltage, thereby turning on the transistor Q2, pulling down the voltage of the emitter, generating a low-level trigger signal, triggering the protection circuit to work, and adding a power-off detection circuit at the input end of the switching power supply chip to realize power-off detection of the input voltage, thereby shutting down the power supply, forming a reliable protection function, and realizing AC power drop protection; it has the effect of not requiring a separate power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] By reading the following detailed description with reference to the accompanying drawings, the above and other purposes, features and advantages of the exemplary embodiments of the present disclosure will become readily understood. In the accompanying drawings, several embodiments of the present disclosure are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0019] Figure 1 A schematic diagram of a power failure detection circuit proposed by the utility model;

[0020] Figure 2 A schematic diagram of another power-off detection circuit proposed by the utility model;

[0021] In the figure: 1 AC signal source, 2 first circuit, 3 second circuit, 4 voltage regulator diode, 5 transistor. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present disclosure.

[0023] The specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0024] Reference Figure 1-2 , shows a schematic diagram of a power-off detection circuit of an embodiment of the utility model, including:

[0025] AC signal source AC, first circuit, second circuit, voltage stabilizing diode Z1, transistor Q2;

[0026] The AC signal source AC is connected to the first loop and the second loop respectively, the voltage stabilizing diode Z1 and the transistor Q2 are connected in series, one end of the voltage stabilizing diode Z1 is connected to the first loop and the second loop, and one end of the transistor Q2 is connected to the first loop and the second loop;

[0027] When the AC signal source AC is a positive half-cycle signal, the AC current passes through the first loop; when the AC signal source AC is a negative half-cycle signal, the AC current passes through the second loop; when the voltage generated by the AC voltage in the common component capacitor C1 of the first loop and the second loop is greater than the preset value, the voltage stabilizing diode Z1 will be broken down and turned on, presenting a voltage stabilizing state; the base of the transistor Q2 will generate a preset voltage, thereby turning on the transistor Q2, pulling down the voltage of the emitter, generating a low-level trigger signal, and triggering the protection circuit to work. The circuit of the embodiment of the utility model only needs a few simple discrete components to realize the protection function of the trigger protection circuit.

[0028] In a preferred embodiment, the first loop includes a resistor R1, a diode D1, a capacitor C1, a diode D4, and a resistor R2.

[0029] In the first loop, one end of the resistor R1 is connected to the AC signal source AC, the resistor R1 is connected in series with the diode D1, the diode D1 is connected in series with the capacitor C1, the capacitor C1 is connected in series with the diode D4, and the diode D4 is connected in series with the resistor R2.

[0030] In a preferred embodiment, the second loop includes a resistor R2, a diode D3, a capacitor C1, a diode D2, and a resistor R1.

[0031] In the second loop, the resistor R2 is connected in series with the diode D3, the diode D3 is connected in series with the capacitor C1, the capacitor C1 is connected in series with the diode D2, and the diode D2 is connected in series with the resistor R1.

[0032] Specifically, the AC signal source AC refers to an electronic device that can generate an AC signal output, usually composed of an oscillator, an amplifier, a filter, etc. The type, waveform, frequency, amplitude, etc. of the output signal can be adjusted by controlling the input signal.

[0033] It should be noted that the electric detection circuit of the embodiment of the utility model is connected to the input end of the switching power supply chip. Specifically, the input end of the switching power supply chip can be connected to the AC signal source AC, and the embodiment of the utility model does not impose too many restrictions on this.

[0034] In the embodiment of the utility model, a power-off detection circuit is added to the input end of the switching power supply chip to realize power-off detection of the input voltage, thereby shutting down the power supply, forming a reliable protection function, and realizing AC power drop protection; it has the effect of not requiring a separate power supply.

[0035] The voltage stabilizing diode Z1 of the embodiment of the utility model can be used to prevent false triggering and improve the reliability and stability of the circuit.

[0036] The characteristic of the Zener diode is that when the PN junction breaks down in reverse, its current can vary within a wide range while the voltage remains basically unchanged, thereby playing a voltage stabilizing role. Zener diodes are classified according to the breakdown voltage and are widely used in voltage stabilizing circuits and limiting circuits.

[0037] Specifically, the transistor Q2 in the embodiment of the utility model is a PNP transistor. The PNP transistor includes an emitter, a collector, and a base. The transistor in which current flows into from the emitter E has the highest emitter potential and the lowest collector potential. The PNP transistor uses Veb to control positrons from the emitter region through the base region and incident on the collector region.

[0038] In the embodiment of the utility model, the first loop and the second loop include common components, which can share the capacitor C1, the resistor R1 and the resistor R2, saving costs and reducing circuit complexity.

[0039] In another specific implementation, the power-off detection circuit may include adding a separate analog circuit detection circuit and detecting the bus voltage through a separate ADC chip to replace the above-mentioned circuit scheme. In another technical scheme, the power-off detection circuit may be an added separate analog circuit detection circuit, and a separate ADC chip may be used to detect the bus voltage, which can also achieve the corresponding function. The cost will increase and software design is required to cooperate.

[0040] In the above description of this specification, unless otherwise clearly specified and limited, the terms "fixed", "installed", "connected" or "connected" should be understood in a broad sense. For example, with regard to the term "connection", it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements. Therefore, unless otherwise clearly defined in this specification, those skilled in the art can understand the specific meanings of the above terms in this utility model according to the specific circumstances.

[0041] According to the above description of this specification, those skilled in the art may also understand that the terms used below, such as "up", "down", "front", "back", "left", "right", "length", "width", "thickness", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential", "center", "longitudinal", "lateral", "clockwise" or "counterclockwise", etc., which indicate the orientation or position relationship, are based on the orientation or position relationship shown in the drawings of this specification, and are only for the purpose of facilitating the explanation of the scheme of the utility model and simplifying the description, rather than explicitly or implicitly indicating that the device or element involved must have the specific orientation, be constructed and operate in a specific orientation. Therefore, the above-mentioned orientation or position relationship terms cannot be understood or interpreted as limitations on the scheme of the utility model.

[0042] In addition, the terms "first" or "second" used in this specification to refer to numbers or ordinals are only used for descriptive purposes and cannot be understood as explicitly or implicitly indicating relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this specification, the meaning of "plurality" is at least two, such as two, three or more, etc., unless otherwise clearly and specifically defined.

[0043] Although this specification has shown and described a plurality of embodiments of the utility model, it is obvious to those skilled in the art that such embodiments are provided by way of example only. Those skilled in the art will think of many changes, modifications and alternatives without departing from the idea and spirit of the utility model. It should be understood that in the process of practicing the utility model, various alternatives to the embodiments of the utility model described herein may be adopted. The attached claims are intended to define the scope of protection of the utility model, and therefore cover the modular composition, equivalent or alternatives within the scope of these claims.

Claims

1. A power failure detection circuit, characterized in that: include: AC signal source AC, first circuit, second circuit, voltage stabilizing diode Z1, transistor Q2; The AC signal source AC is connected to the first loop and the second loop respectively, the voltage stabilizing diode Z1 and the transistor Q2 are connected in series, one end of the voltage stabilizing diode Z1 is connected to the first loop and the second loop, and one end of the transistor Q2 is connected to the first loop and the second loop; When the AC signal source AC is a positive half-cycle signal, the AC current passes through the first loop; when the AC signal source AC is a negative half-cycle signal, the AC current passes through the second loop; when the voltage generated by the AC voltage in the common component capacitor C1 of the first loop and the second loop is greater than the preset value, the voltage-stabilizing diode Z1 will be broken down and turned on, presenting a voltage-stabilizing state; the base of the transistor Q2 will generate a preset voltage, thereby turning on the transistor Q2, pulling down the voltage of the emitter, generating a low-level trigger signal, and triggering the protection circuit to work.

2. The power-off detection circuit according to claim 1, characterized in that: The first loop includes a resistor R1, a diode D1, a capacitor C1, a diode D4 and a resistor R2.

3. The power-off detection circuit according to claim 2, characterized in that: One end of the resistor R1 is connected to the AC signal source AC, the resistor R1 is connected in series with the diode D1, the diode D1 is connected in series with the capacitor C1, the capacitor C1 is connected in series with the diode D4, and the diode D4 is connected in series with the resistor R2.

4. The power-off detection circuit according to claim 3, characterized in that: The second loop includes a resistor R2, a diode D3, a capacitor C1, a diode D2, and a resistor R1.

5. The power-off detection circuit according to claim 4, characterized in that: The resistor R2 is connected in series with the diode D3, the diode D3 is connected in series with the capacitor C1, the capacitor C1 is connected in series with the diode D2, and the diode D2 is connected in series with the resistor R1.

6. The power failure detection circuit according to claim 1, characterized in that: The power-off detection circuit is connected to the input end of the switching power supply chip.

7. The power failure detection circuit according to claim 1, characterized in that: The first loop and the second loop share a capacitor C1 , a resistor R1 and a resistor R2 .

8. The power-off detection circuit according to claim 1, characterized in that: The power-off detection circuit includes adding a separate analog circuit detection circuit and detecting the bus voltage through a separate ADC chip.

9. The power-off detection circuit according to claim 1, characterized in that: The voltage stabilizing diode Z1 is used to prevent false triggering and improve the reliability and stability of the circuit.

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