DC-DC input under-voltage protection circuit

Abstract

The embodiment of the utility model discloses a DC-DC input under-voltage protection circuit, which comprises a voltage dividing resistor R1, a resistor R2, a voltage stabilizer A1, a diode DZ1, a field effect transistor Q1, a resistor R3, a resistor R4, a capacitor C1 and a voltage dividing resistor R5, and is characterized in that the voltage dividing resistor R1, the resistor R2, the voltage stabilizer A1, the diode DZ1, the field effect transistor Q1, the resistor R3, the resistor R4, the capacitor C1 and the voltage dividing resistor R5 are included. Input voltage is detected through the voltage reference source of the voltage stabilizer A1, when power supply voltage is lower than a preset value, voltage is divided by the divider resistor R1 and the divider resistor R5, the reference voltage provided for the voltage stabilizer A1 is lower than the preset value, and the cathode of the voltage stabilizer A1 is changed from low level to high level, so that the grid electrode of the field effect transistor Q1 is changed from low level to high level, and the power supply voltage of the power supply is output. And the field effect transistor Q1 is turned from on to off, so that the power supply of the power supply to the motor is cut off, and motor damage caused by long-time undervoltage is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of DC-DC power supply, and in particular to a DC-DC input undervoltage protection circuit. Background Art

[0002] At present, DC-DC power supplies are widely used in switching equipment, access equipment, mobile communications, microwave communications, optical transmission, routers, automotive electronics, aerospace and other fields. However, there is a problem with the existing DC-DC power supply in practical applications. In the process of powering the motor, since the motor requires a large amount of power to operate, if the power value does not meet the requirement, the motor will not only fail to operate normally, but also cause damage to the motor if it is undervoltage for a long time, reducing the service life of the motor.

[0003] The above problems need to be solved urgently. Utility Model Content

[0004] In order to solve the related technical problems, the utility model provides a DC-DC input undervoltage protection circuit to solve the problems mentioned in the above background technology part.

[0005] To achieve the above purpose, the embodiment of the utility model adopts the following technical solutions:

[0006] An embodiment of the utility model provides a DC-DC input undervoltage protection circuit, which includes: a voltage-dividing resistor R1, a resistor R2, a voltage regulator A1, a diode DZ1, a field effect transistor Q1, a resistor R3, a resistor R4, a capacitor C1 and a voltage-dividing resistor R5; wherein, one end of the voltage-dividing resistor R1 is connected to the positive terminal DC+ of the power supply, one end of the resistor R2, and the drain of the field effect transistor Q1, the other end of the resistor R2 is connected to the negative electrode of the diode DZ1 and the cathode of the voltage regulator A1, the other end of the voltage-dividing resistor R1 is connected to one end of the voltage-dividing resistor R5, one end of the capacitor C1, and the reference end of the voltage regulator A1, the other end of the voltage-dividing resistor R5 is connected to the other end of the capacitor C1, the negative terminal DC- of the power supply, the anode of the voltage regulator A1, one end of the resistor R4, and one end of the resistor R3, the other end of the resistor R3 is connected to the source of the field effect transistor Q1, and the other end of the resistor R4 is connected to the positive electrode of the diode DZ1 and the gate of the field effect transistor Q1.

[0007] As an optional implementation, the voltage regulator A1 adopts an adjustable shunt regulator TL431.

[0008] As an optional implementation, the field effect transistor Q1 is an NPN MOS tube; the diode DZ1 is a voltage regulator diode.

[0009] The DC-DC input undervoltage protection circuit proposed in the embodiment of the utility model detects the input voltage through the voltage reference source of the voltage regulator A1. When the power supply voltage is lower than the preset value, the voltage is divided by the voltage divider resistor R1 and the voltage divider resistor R5, and the reference voltage provided to the voltage regulator A1 is less than the set value. The cathode of the voltage regulator A1 changes from a low level to a high level, so that the gate of the field effect tube Q1 changes from a low level to a high level, and the field effect tube Q1 changes from on to off, so that the power supply to the motor is disconnected, avoiding damage to the motor caused by long-term undervoltage. The resistance of the field effect tube Q1 in the DC-DC input undervoltage protection circuit proposed in the embodiment of the utility model is small, which greatly reduces the loss of the circuit, and the overall circuit structure is simple, low cost, stable and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate and understand the technical solutions in the embodiments of the present invention, the following briefly introduces the background technology of the present invention and the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the contents of the embodiments of the present invention and these drawings without paying any creative work.

[0011] Figure 1 This is a structural diagram of a DC-DC input undervoltage protection circuit provided in an embodiment of the utility model. DETAILED DESCRIPTION

[0012] In order to make the technical problems solved by the utility model, the technical solutions adopted and the technical effects achieved clearer, the technical solutions of the embodiments of the utility model will be further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the utility model.

[0013] Embodiment 1

[0014] Please refer to Figure 1 As stated, Figure 1The DC-DC input undervoltage protection circuit structure diagram provided by the embodiment of the utility model. As shown in the figure, the DC-DC input undervoltage protection circuit in this embodiment includes: a voltage divider resistor R1, a resistor R2, a voltage regulator A1, a diode DZ1, a field effect transistor Q1, a resistor R3, a resistor R4, a capacitor C1 and a voltage divider resistor R5. Specifically, in the present embodiment, one end of the voltage-dividing resistor R1 is connected to the positive terminal DC+ of the power supply, one end of the resistor R2, and the drain of the field effect transistor Q1, the other end of the resistor R2 is connected to the negative electrode of the diode DZ1 and the cathode of the voltage regulator A1, the other end of the voltage-dividing resistor R1 is connected to one end of the voltage-dividing resistor R5, one end of the capacitor C1, and the reference end of the voltage regulator A1, the other end of the voltage-dividing resistor R5 is connected to the other end of the capacitor C1, the negative terminal DC- of the power supply, the anode of the voltage regulator A1, one end of the resistor R4, and one end of the resistor R3, the other end of the resistor R3 is connected to the source of the field effect transistor Q1, and the other end of the resistor R4 is connected to the positive electrode of the diode DZ1 and the gate of the field effect transistor Q1.

[0015] Exemplarily, the voltage regulator A1 adopts an adjustable shunt regulator TL431, wherein the adjustable shunt regulator TL431 can be used as both a positive voltage reference and a negative voltage reference, because it is used as a shunt regulator and TL431 has a low output noise voltage.

[0016] Exemplarily, the field effect transistor Q1 is an NPN MOS transistor; the diode DZ1 is a voltage regulator diode.

[0017] Specifically, in the present embodiment, when the DC-DC input undervoltage protection circuit is working, the input voltage is detected by the voltage reference source of the voltage regulator A1. When the power supply voltage is lower than the preset value, the voltage is divided by the voltage divider resistors R1 and R5, and the reference voltage provided to the voltage regulator A1 is lower than the set value. The cathode of the voltage regulator A1 changes from a low level to a high level, so that the gate of the field effect transistor Q1 changes from a low level to a high level, and the field effect transistor Q1 changes from on to off, so that the power supply to the motor is disconnected, thereby avoiding damage to the motor caused by long-term undervoltage.

[0018] The field effect transistor Q1 in the DC-DC input undervoltage protection circuit proposed in the embodiment of the utility model adopts an NPN MOS tube, which has a small resistance and greatly reduces the loss of the circuit. In addition, the overall circuit structure is simple, the cost is low, and it is stable and reliable.

[0019] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention is described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A DC-DC input undervoltage protection circuit, characterized in that: include: A voltage-dividing resistor R1, a resistor R2, a voltage regulator A1, a diode DZ1, a field effect transistor Q1, a resistor R3, a resistor R4, a capacitor C1 and a voltage-dividing resistor R5; wherein, one end of the voltage-dividing resistor R1 is connected to the positive terminal DC+ of the power supply, one end of the resistor R2, and the drain of the field effect transistor Q1, the other end of the resistor R2 is connected to the negative terminal of the diode DZ1 and the cathode of the voltage regulator A1, the other end of the voltage-dividing resistor R1 is connected to one end of the voltage-dividing resistor R5, one end of the capacitor C1, and the reference end of the voltage regulator A1, the other end of the voltage-dividing resistor R5 is connected to the other end of the capacitor C1, the negative terminal DC- of the power supply, the anode of the voltage regulator A1, one end of the resistor R4, and one end of the resistor R3, the other end of the resistor R3 is connected to the source of the field effect transistor Q1, and the other end of the resistor R4 is connected to the positive terminal of the diode DZ1 and the gate of the field effect transistor Q1.

2. The DC-DC input undervoltage protection circuit according to claim 1, characterized in that: The voltage regulator A1 adopts an adjustable shunt regulator TL431.

3. The DC-DC input undervoltage protection circuit according to any one of claims 1 or 2, characterized in that: The field effect tube Q1 is an NPN MOS tube; the diode DZ1 is a voltage regulator diode.

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