Input under-voltage protection circuit based on reverse hysteresis comparator

Abstract

The utility model relates to an input under-voltage protection circuit based on a reverse hysteresis comparator. The input under-voltage protection circuit comprises an input voltage sampling circuit, a circuit which is connected with the input voltage sampling circuit and is used for supplying power to the reverse hysteresis comparator and providing reference voltage, and a reverse hysteresis comparator signal output circuit. The input voltage sampling circuit is used for carrying out voltage division sampling on an input voltage to generate a sampling voltage; the circuit for supplying power to the reverse hysteresis comparator and providing reference voltage is used for providing reference voltage and supplying power to the reverse hysteresis comparator; and the reverse hysteresis comparator signal output circuit compares the sampling voltage with the reference voltage, generates high and low signal levels according to hysteresis characteristics, and controls the on-off of a load power supply according to a reverse comparator output signal so as to realize under-voltage protection. According to the utility model, by introducing a hysteresis function, oscillation near a critical voltage is avoided, and the reliability of under-voltage protection is improved.

Description

Technical Field

[0001] This utility model relates to the field of input undervoltage protection circuit technology, and in particular to an input undervoltage protection circuit based on an inverse hysteresis comparator. Background Technology

[0002] In electronic devices, the stability of the input voltage is crucial for the normal operation of the equipment. When the input voltage falls below a certain threshold, it may cause abnormal operation or even damage to the equipment. Traditional undervoltage protection circuits typically use simple voltage comparators, but due to the lack of hysteresis, they are prone to oscillations near the critical voltage, leading to circuit malfunctions. Therefore, there is an urgent need for a circuit that can stably and reliably implement undervoltage protection. Summary of the Invention

[0003] The purpose of this invention is to provide an input undervoltage protection circuit based on a reverse hysteresis comparator, which can solve or at least alleviate one or more of the above-mentioned problems and other problems existing in the prior art.

[0004] To achieve the above objectives, this utility model provides an input undervoltage protection circuit based on a reverse hysteresis comparator, wherein the input undervoltage protection circuit based on the reverse hysteresis comparator includes:

[0005] The input voltage sampling circuit, and the circuit connected to the input voltage sampling circuit that supplies power to the inverse hysteresis comparator and provides a reference voltage, and the inverse hysteresis comparator signal output circuit;

[0006] The input voltage sampling circuit is used to perform voltage division sampling on the input voltage to generate a sampled voltage; the circuit that supplies power to the reverse hysteresis comparator and provides a reference voltage is used to provide a reference voltage and power to the reverse hysteresis comparator; the reverse hysteresis comparator signal output circuit compares the sampled voltage and the reference voltage, and generates high and low signal levels according to the hysteresis characteristics, and controls the on / off of the load power supply according to the output signal of the reverse comparator to achieve undervoltage protection.

[0007] In the input undervoltage protection circuit based on the reverse hysteresis comparator as described above, the input voltage sampling circuit is implemented using a resistor divider circuit.

[0008] In the input undervoltage protection circuit based on the reverse hysteresis comparator as described above, the input voltage sampling circuit includes a capacitor C117, one end of which is grounded; the other end of the capacitor C117 is connected to one end of a resistor R135, one end of a resistor R129, the negative terminal of a Zener diode ZD14, and the signal output circuit of the reverse hysteresis comparator, with the positive terminal of the Zener diode ZD14 grounded; the other end of the resistor R135 is connected to one end of a resistor R133, the other end of which is grounded; the other end of the resistor R129 is connected to one end of a resistor R130, the other end of which is connected to a circuit that powers the reverse hysteresis comparator and provides a reference voltage.

[0009] In the input undervoltage protection circuit based on the reverse hysteresis comparator as described above, the circuit that supplies power to the reverse hysteresis comparator and provides a reference voltage is implemented using a 431 circuit and a transistor signal control circuit.

[0010] In the input undervoltage protection circuit based on the reverse hysteresis comparator as described above, the circuit that powers the reverse hysteresis comparator and provides a reference voltage includes a transistor Q12. The base of transistor Q12 is connected to one end of resistor R122 and pin 2 of Zener diode ZD13. The other end of resistor R122 is connected to capacitor C115 and the collector of transistor Q12. The other end of capacitor C115 and pin 3 of Zener diode ZD13 are grounded. The collector of transistor Q12 is connected to one end of resistor R104. The other end of resistor R104 is connected to the input voltage sampling circuit. The emitter of transistor Q12 is connected to one end of resistor R121, one end of capacitor C114, and the power supply VCC terminal. The other end of resistor R121 is connected to pin 1 of Zener diode ZD13 and one end of resistor R123. The other end of resistor R123 is grounded, and the other end of capacitor C114 is grounded.

[0011] In the input undervoltage protection circuit based on the inverse hysteresis comparator as described above, the inverse hysteresis comparator signal output circuit includes an operational amplifier and a positive feedback resistor network.

[0012] In the input undervoltage protection circuit based on the inverse hysteresis comparator described above, the inverse hysteresis comparator signal output circuit includes a chip IC14, which is an operational amplifier. Pin 1 of the chip IC14 is connected to one end of resistor R142, one end of resistor R117, and one end of resistor R143. The other end of resistor R142 is connected to the power supply VCC terminal, and the other end of resistor R143 is grounded. The other end of resistor R117 is connected to pin 4 of the chip IC14. Pin 2 of the chip IC14 is grounded. Pin 3 of the chip IC14 is connected to one end of resistor R119 and one end of capacitor C116. The other end of resistor R119 is connected to the input voltage sampling circuit, and the other end of capacitor C116 is grounded. Pin 4 of chip IC14 is connected to the power supply VCC terminal and one end of capacitor C112, and the other end of capacitor C112 is grounded. Pin 5 of chip IC14 is connected to one end of capacitor C120 and one end of resistor R139, and the other end of capacitor C120 is grounded. The other end of resistor R139 is connected to the base of transistor Q14, the emitter of transistor Q14 is grounded, the collector of transistor Q14 is connected to one end of resistor R141, and the other end of resistor R141 outputs an undervoltage protection signal.

[0013] Compared with the prior art, the beneficial effects of this utility model are:

[0014] This novel input undervoltage protection circuit based on a reverse hysteresis comparator avoids oscillations near the critical voltage by introducing hysteresis, thus improving the reliability of undervoltage protection. The circuit has a simple structure, low cost, and is easy to implement, making it suitable for input undervoltage protection scenarios in various electronic devices. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of the input undervoltage protection circuit based on the reverse hysteresis comparator of this utility model.

[0016] Figure 2 This is a schematic diagram of the input voltage sampling circuit of this utility model.

[0017] Figure 3 This is a schematic diagram of the circuit structure of the present invention that supplies power to the reverse hysteresis comparator and provides a reference voltage.

[0018] Figure 4 This is a schematic diagram of the circuit structure of the inverse hysteresis comparator signal output circuit of this utility model.

[0019] In the diagram: 1. Input voltage sampling circuit; 2. Circuit that powers the inverse hysteresis comparator and provides a reference voltage; 3. Signal output circuit for the inverse hysteresis comparator. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0021] It should be noted that in the description of this utility model, the terms "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. The terms "first," "second," and similar words used in the description of this utility model do not indicate any order, quantity, or importance, but are only used to distinguish different components, and therefore should not be construed as limiting this utility model.

[0022] Furthermore, it should be understood that, for ease of description, the dimensions of the individual components shown in the accompanying drawings are not drawn to actual scale; for example, the thickness or width of some layers may be exaggerated relative to other layers.

[0023] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined or described in one figure, it will not need to be discussed or described in detail in the description of the subsequent figures.

[0024] Figure 1 This is an overall structural diagram of the input undervoltage protection circuit based on a reverse hysteresis comparator according to this utility model. The diagram shows the input voltage sampling circuit 1, the circuit 2 that powers the reverse hysteresis comparator and provides a reference voltage, and the signal output circuit 3 of the reverse hysteresis comparator.

[0025] like Figure 1-4 As shown, the circuit that powers the inverse hysteresis comparator and provides the reference voltage, as well as the circuit that outputs the inverse hysteresis comparator signal, are both connected to the input voltage sampling circuit.

[0026] Specifically, the input voltage sampling circuit is used to divide and sample the input voltage to generate a sampled voltage; the power supply and reference voltage circuit for the reverse hysteresis comparator is used to provide a reference voltage and power to the reverse hysteresis comparator; the reverse hysteresis comparator signal output circuit compares the sampled voltage and the reference voltage, and generates high and low signal levels according to the hysteresis characteristics. The output signal of the reverse comparator controls the on / off of the load power supply to achieve undervoltage protection.

[0027] Furthermore, the input voltage sampling circuit is implemented using a resistor divider circuit.

[0028] The input voltage sampling circuit includes capacitor C117, one end of which is grounded. The other end of capacitor C4 is connected to one end of resistor R135, one end of resistor R129, the negative terminal of Zener diode ZD14, and the signal output circuit of the reverse hysteresis comparator. The positive terminal of Zener diode ZD14 is grounded. The other end of resistor R135 is connected to one end of resistor R133, and the other end of resistor R133 is grounded. The other end of resistor R129 is connected to one end of resistor R130, and the other end of resistor R130 is connected to the circuit that powers the reverse hysteresis comparator and provides a reference voltage.

[0029] Furthermore, the circuit that powers the inverse hysteresis comparator and provides a reference voltage is implemented using a 431 circuit and a transistor signal control circuit, with the transistor acting as a switching element.

[0030] The circuit that powers the reverse hysteresis comparator and provides a reference voltage includes transistor Q12. The base of transistor Q12 is connected to one end of resistor R122 and pin 2 of Zener diode ZD13. The other end of resistor R122 is connected to capacitor C115 and the collector of transistor Q12. The other end of capacitor C115 and pin 3 of Zener diode ZD13 are grounded. The collector of transistor Q12 is connected to one end of resistor R104. The other end of resistor R104 is connected to the input voltage sampling circuit. The emitter of transistor Q12 is connected to one end of resistor R121, one end of capacitor C114, and the power supply VCC terminal. The other end of resistor R121 is connected to pin 1 of Zener diode ZD13 and one end of resistor R123. The other end of resistor R123 is grounded, and the other end of capacitor C114 is grounded.

[0031] Furthermore, the inverse hysteresis comparator signal output circuit includes an operational amplifier and a positive feedback resistor network.

[0032] The inverse hysteresis comparator signal output circuit includes chip IC14, which is an operational amplifier. Pin 1 of chip IC14 is connected to one end of resistor R142, one end of resistor R117, and one end of resistor R143. The other end of resistor R142 is connected to the power supply VCC terminal, and the other end of resistor R143 is grounded. The other end of resistor R117 is connected to pin 4 of chip IC14. Pin 2 of chip IC14 is grounded. Pin 3 of chip IC14 is connected to one end of resistor R119 and one end of capacitor C116, and the other end of resistor R119... Connected to the input voltage sampling circuit, the other end of capacitor C116 is grounded; pin 4 of chip IC14 is connected to the power supply VCC terminal and one end of capacitor C112, the other end of capacitor C112 is grounded; pin 5 of chip IC14 is connected to one end of capacitor C120 and one end of resistor R139, the other end of capacitor C120 is grounded, the other end of resistor R139 is connected to the base of transistor Q14, the emitter of transistor Q14 is grounded, the collector of transistor Q14 is connected to one end of resistor R141, and the other end of resistor R141 outputs an undervoltage protection signal.

[0033] Specifically, the input voltage sampling circuit uses a resistor divider circuit to proportionally reduce the input voltage to a range suitable for the comparator's operation. A reference voltage circuit provides power to the inverse hysteresis comparator and supplies power to this module. The inverse hysteresis comparator signal output circuit uses an operational amplifier and a positive feedback resistor network to implement the hysteresis function; the hysteresis range is determined by the resistor values. A transistor is used to compare the sampled voltage with the reference voltage and output high and low level signals based on the hysteresis characteristics. This transistor acts as a switching element, controlling the on / off state of the load power supply based on the comparator output signal to achieve undervoltage protection.

[0034] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A reverse hysteresis comparator based input under-voltage protection circuit, characterized in that, The input voltage sampling circuit (1), the reference voltage circuit (2) and the reverse hysteresis comparator signal output circuit (3) are connected.

2. The input under-voltage protection circuit based on a reverse hysteresis comparator according to claim 1, characterized in that, The input voltage sampling circuit (1) is realized by a resistance voltage dividing circuit.

3. The input under-voltage protection circuit based on a reverse hysteresis comparator according to claim 2, characterized in that, The input voltage sampling circuit (1) comprises a capacitor C117, one end of which is grounded, and the other end of which is connected with one end of a resistor R135, one end of a resistor R129, a negative electrode of a voltage stabilizing diode ZD14 and the reverse hysteresis comparator signal output circuit, and the positive electrode of the voltage stabilizing diode ZD14 is grounded; the other end of the resistor R135 is connected with one end of a resistor R133, and the other end of the resistor R133 is grounded; the other end of the resistor R129 is connected with one end of a resistor R130, and the other end of the resistor R130 is connected with the reference voltage circuit for the reverse hysteresis comparator.

4. The input under-voltage protection circuit based on a reverse hysteresis comparator of claim 1, wherein, The reference voltage circuit (2) for the reverse hysteresis comparator is realized by a 431 circuit and a triode signal control circuit.

5. The input under-voltage protection circuit based on a reverse hysteresis comparator according to claim 4, characterized in that, The reference voltage circuit (2) for the reverse hysteresis comparator comprises a triode Q12, the base of which is connected with one end of a resistor R122 and a pin 2 of a voltage stabilizing diode ZD13, the other end of the resistor R122 is connected with a capacitor C115 and the collector of the triode Q12, the other end of the capacitor C115 and a pin 3 of the voltage stabilizing diode ZD13 are grounded; the collector of the triode Q12 is connected with one end of a resistor R104, the other end of the resistor R104 is connected with the input voltage sampling circuit; the emitter of the triode Q12 is connected with one end of a resistor R121, one end of a capacitor C114 and a power supply VCC, the other end of the resistor R121 is connected with a pin 1 of the voltage stabilizing diode ZD13 and one end of a resistor R123, the other end of the resistor R123 is grounded, and the other end of the capacitor C114 is grounded.

6. An input under-voltage protection circuit based on a reverse hysteresis comparator according to claim 1 or 2 or 3 or 4 or 5, characterized in that, The reverse hysteresis comparator signal output circuit (3) comprises an operational amplifier and a positive feedback resistor network.

7. The input under-voltage protection circuit based on a reverse hysteresis comparator according to claim 6, characterized in that, The reverse hysteresis comparator signal output circuit (3) comprises a chip IC14, which is an operational amplifier; a pin 1 of the chip IC14 is connected with one end of a resistor R142, one end of a resistor R117 and one end of a resistor R143; the other end of the resistor R142 is connected with a power supply VCC terminal; the other end of the resistor R143 is grounded; the other end of the resistor R117 is connected with a pin 4 of the chip IC14; a pin 2 of the chip IC14 is grounded; a pin 3 of the chip IC14 is connected with one end of a resistor R119 and one end of a capacitor C116; the other end of the resistor R119 is connected with an input voltage sampling circuit; the other end of the capacitor C116 is grounded; the pin 4 of the chip IC14 is connected with the power supply VCC terminal and one end of a capacitor C112; the other end of the capacitor C112 is grounded; a pin 5 of the chip IC14 is connected with one end of a capacitor C120 and one end of a resistor R139; the other end of the capacitor C120 is grounded; the other end of the resistor R139 is connected with a base of a triode Q14; an emitter of the triode Q14 is grounded; a collector of the triode Q14 is connected with one end of a resistor R141; the other end of the resistor R141 outputs an under-voltage protection signal.

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