CN211629858U - Input undervoltage protection circuit and switching power supply system - Google Patents
Input undervoltage protection circuit and switching power supply system Download PDFInfo
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- CN211629858U CN211629858U CN202020498017.5U CN202020498017U CN211629858U CN 211629858 U CN211629858 U CN 211629858U CN 202020498017 U CN202020498017 U CN 202020498017U CN 211629858 U CN211629858 U CN 211629858U
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Abstract
The utility model relates to an input under-voltage protection circuit and switching power supply system, through the start-up module that semiconductor switch tube constitutes, be less than preset voltage value at input voltage, control switch module switches on when inputing under-voltage promptly. And after the switch module is switched on, the control port is pulled high to a high level, so that the switch power supply stops working, and the input undervoltage protection is realized. Based on this, through the starting module that semiconductor switch tube device constitutes, the nimble switching device type selection of cooperation switch module is favorable to reducing the cost and the components and parts quantity of input undervoltage protection circuit, is convenient for provide input undervoltage protection on the module power of small volume, high power density.
Description
Technical Field
The utility model relates to a switching power supply technical field especially relates to an input undervoltage protection circuit and switching power supply system.
Background
A switching power supply, also called an exchange power supply or a switching converter, is a high-frequency power conversion device, and is a kind of power supply. The function of the switching power supply is to convert a level voltage into a voltage or current required by the user terminal through different types of architectures. When the control chip of the switching power supply obtains power supply, the switching power supply is electrified to work. With the progress of power electronic technology, switching power supplies are continuously developed to high power density, high efficiency and high reliability. The input under-voltage protection is an important means for ensuring the reliability of the switching power supply, and can be used for preventing the module power supply from being started to cause the damage of the power supply or a load circuit because the input voltage does not rise to the normal input voltage range in the starting process of the module power supply.
The traditional input undervoltage protection circuit is mainly realized through an operational amplifier circuit, and the circuit realization mode has the disadvantages of more required components, complex circuit, high cost and difficult application in a module power supply with small volume and high power density.
SUMMERY OF THE UTILITY MODEL
Therefore, the input undervoltage protection circuit and the switching power supply system are necessary to be provided aiming at the defects that the traditional input undervoltage protection circuit is mainly realized through an operational amplifier circuit, and the circuit realization mode has many required components, complex circuit, high cost and difficult application in a module power supply with small volume and high power density.
An input brown-out protection circuit, comprising:
the switch module is used for pulling the control port to a high level when the switch module is conducted so as to stop the switch power supply;
and the starting module comprises one or more semiconductor switching tubes and is used for controlling the switching-on of the switching module when the input voltage is smaller than a preset voltage value.
The input under-voltage protection circuit controls the switch module to be switched on when the input voltage is smaller than a preset voltage value, namely, the input under-voltage through the starting module formed by the semiconductor switch tube. And after the switch module is switched on, the control port is pulled high to a high level, so that the switch power supply stops working, and the input undervoltage protection is realized. Based on this, through the starting module that semiconductor switch tube device constitutes, the nimble switching device type selection of cooperation switch module is favorable to reducing the cost and the components and parts quantity of input undervoltage protection circuit, is convenient for provide input undervoltage protection on the module power of small volume, high power density.
In one embodiment, the starting module is used for connecting a power supply voltage end and a reference voltage end of the switching power supply control chip; when the switch module is conducted, the port is controlled to be pulled high according to the power supply voltage of the switch power supply control chip and the reference voltage drop.
In one embodiment, the semiconductor switch tube comprises a triode.
In one embodiment, the switching module comprises a three terminal switching device.
In one embodiment, the starting module comprises a first current limiting resistor, a first voltage dividing resistor, a second voltage dividing resistor, a first transistor, a second transistor and a voltage stabilizing diode;
one end of the first current-limiting resistor is used for connecting the input voltage, and the other end of the first current-limiting resistor is connected with the cathode of the voltage stabilizing diode; the anode of the voltage-stabilizing diode is used for grounding; the base electrode of the first transistor is connected with the common end of the first current-limiting resistor and the cathode of the voltage-stabilizing diode, and the collector electrode of the first transistor is connected with the base electrode of the second transistor; the emitter of the second crystal triode is used for being connected with the input voltage; the collector of the second transistor is used for connecting the power supply voltage end; one end of the first voltage-dividing resistor is used for being connected with the power supply voltage end, one end of the first voltage-dividing resistor is connected with the second voltage-dividing resistor, the other end of the second voltage-dividing resistor is connected with the switch module, and an emitter of the first transistor is connected with a common end of the first voltage-dividing resistor and the second voltage-dividing resistor.
In one embodiment, the switch module comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor and a reference power supply;
the input voltage is used for being output to the first resistor and output to a grounding end through the second resistor, the reference power supply reference end is connected to a common end of the first resistor and the second resistor, the third resistor is connected to the reference voltage end and the common end of the first resistor and the second resistor, the anode of the reference power supply is used for being grounded, the cathode of the reference power supply is connected to the other end of the second voltage-dividing resistor, the fourth resistor is connected between the cathode of the reference power supply and the control port, and the fifth resistor is connected between the control port and the grounding end.
In one embodiment, the capacitor further comprises a first capacitor;
the first capacitor is connected in parallel to two ends of the second resistor.
In one embodiment, the capacitor further comprises a second capacitor;
the second capacitor is connected in parallel to two ends of the fifth resistor.
In one embodiment, the reference power supply comprises a TL431 reference power supply.
A switching power supply system comprises a switching power supply and the input undervoltage protection circuit of any one of the embodiments.
According to the switching power supply system, the switching module is controlled to be switched on when the input voltage is smaller than the preset voltage value, namely, the input undervoltage is generated through the starting module formed by the semiconductor switching tube. And after the switch module is switched on, the control port is pulled high to a high level, so that the switch power supply stops working, and the input undervoltage protection is realized. Based on this, through the starting module that semiconductor switch tube device constitutes, the nimble switching device type selection of cooperation switch module is favorable to reducing the cost and the components and parts quantity of input undervoltage protection circuit, is convenient for provide input undervoltage protection on the module power of small volume, high power density.
Drawings
FIG. 1 is a block diagram of an under-voltage protection circuit according to an embodiment;
FIG. 2 is a schematic diagram of an under-voltage protection circuit according to an embodiment;
FIG. 3 is a schematic diagram of an under-voltage protection circuit according to another embodiment.
Detailed Description
For better understanding of the objects, technical solutions and technical effects of the present invention, the present invention will be further explained with reference to the accompanying drawings and embodiments. It is to be noted that the following examples are only for explaining the present invention and are not intended to limit the present invention.
The embodiment of the utility model provides an input undervoltage protection circuit.
Fig. 1 is a block diagram of an input under-voltage protection circuit according to an embodiment, and as shown in fig. 1, the input under-voltage protection circuit according to an embodiment includes a switch module 100 and a start module 101:
the switch module 100 is configured to pull up the control port FB to a high level when the switch module is turned on, so that the switching power supply stops working;
the starting module 101 includes one or more semiconductor switching tubes, and is configured to control the switching module 100 to be turned on when the input voltage VIN is smaller than a preset voltage value.
As shown in fig. 1, the starting module 101 detects an input voltage VIN, and controls the switching module 100 to be turned on when the input voltage VIN is smaller than a preset voltage value. The input voltage VIN is smaller than the preset voltage value and is used for representing the input undervoltage of the switching power supply.
In one embodiment, the starting module 101 is formed by a semiconductor switch tube, and includes a switch tube such as a triode or a MOS transistor, and the switch tube converts an external signal into a control signal according to a switching characteristic of the switch tube, so as to control the switch module 100 to be turned on. It should be noted that the starting module 101 controls the switch module 100 to be turned on when the input voltage VIN is smaller than the preset voltage value, otherwise controls the switch module 100 to be turned off.
In one embodiment, the switch module 100 may employ various switching devices. The switching module 100 is turned on or off by turning on or off the switching device. As a preferred embodiment, the switch module 100 may be a three-terminal switch device, including a transistor, a MOS transistor, a relay, or a reference power supply. The starting module 101 realizes the connection or disconnection between one switching end and the other switching end of the three-terminal switching device by changing signals of state ends in the three-terminal switching device.
In one embodiment, the starting module 101 is configured to connect a power supply voltage VCC terminal and a reference voltage VREF terminal of a switching power supply control chip; when the switch module 100 is turned on, the control port FB is pulled high according to the power supply voltage VCC and the reference voltage VREF of the switch power supply control chip.
In one embodiment, fig. 2 is a circuit diagram of an input under-voltage protection circuit according to an embodiment, as shown in fig. 2, the start module 101 includes a first current-limiting resistor R8, a first voltage-dividing resistor R6, a second voltage-dividing resistor R7, a first transistor Q1, a second transistor Q2, and a zener diode D1;
one end of the first current-limiting resistor R8 is used for connecting the input voltage VIN, and the other end of the first current-limiting resistor R8 is connected to the cathode of the zener diode D1; the anode of the voltage stabilizing diode D1 is used for grounding; the base electrode of the first transistor Q1 is connected with the common end of the first current-limiting resistor R8 and the cathode of the voltage stabilizing diode D1, and the collector electrode of the first transistor Q1 is connected with the base electrode of the second transistor Q2; an emitter of the second transistor Q2 is used for connecting the input voltage VIN; the collector of the second transistor Q2 is used for connecting the power supply voltage VCC end; one end of the first voltage-dividing resistor R6 is connected to the VCC terminal, the other end of the first voltage-dividing resistor R6 is connected to the second voltage-dividing resistor R7, the other end of the second voltage-dividing resistor R7 is connected to the switch module 100, and the emitter of the first transistor Q1 is connected to the common terminal of the first voltage-dividing resistor R6 and the second voltage-dividing resistor R7
In one embodiment, as shown in fig. 2, the switch module 100 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, and a reference power supply T1;
the input voltage VIN is used for being output to the first resistor R1 and being output to a ground terminal through the second resistor R2, the reference power supply T1 reference terminal is connected to a common terminal of the first resistor R1 and the second resistor R2, the third resistor R3 is connected to the reference voltage VREF terminal and a common terminal of the first resistor R1 and the second resistor R2, an anode of the reference power supply T1 is used for being grounded, a cathode of the reference power supply T1 is connected to the other end of the second voltage-dividing resistor R7, the fourth resistor R4 is connected between a cathode of the reference power supply T1 and the control port FB, and the fifth resistor R5 is connected between the control port FB and the ground terminal.
As shown in fig. 2, when the input voltage VIN is lower than the set value, the voltage value of the reference terminal of the reference power supply T1 is lower than the reference value of the reference power supply T1, the cathode and the anode of the reference power supply T1 are turned off, the input voltage VIN supplies power to the start module 101 through the first current-limiting resistor R8, the second voltage-dividing resistor R7, the first transistor Q1 and the zener diode D1, and the voltage value of the control port FB is increased through the voltage division of the second voltage-dividing resistor R7, the fourth resistor R4 and the fifth resistor R5, so that the switching power supply stops operating. Meanwhile, as the cathode and the anode of the reference power supply T1 are turned off, the start module 101 divides the voltage through the first voltage dividing resistor R6, the second voltage dividing resistor R7, the fourth resistor R4 and the fifth resistor R5, so that the switching module 100 outputs the insufficient working voltage to the switching power supply control chip, the control chip does not work, and the reference voltage VREF of the control chip is zero.
When the input voltage VIN is lower than the set value, the switching power supply stops working, the voltage of the reference end of the control chip is zero, the input undervoltage protection set value is divided by the first resistor R1, the second resistor R2 and the third resistor R3, and the calculation formula is as follows:
RA is a parallel resistance of the second resistor R2 and the third resistor R3, Vz is a reference value of the reference power supply T1, and Vs1 is a starting voltage value of the switching power supply.
When the switching power supply normally works, the input voltage VIN is reduced, the reference voltage VREF port voltage of the control core is 5V, and the calculation formula is as follows:
then the process of the first step is carried out,
setting:
RB is the parallel resistance of the first resistor R1 and the second resistor R2, Vz is the reference value of the reference power supply T1, and Vs2 is the undervoltage protection voltage value of the switching power supply. The third resistor R3 and the reference voltage VREF port of the control chip form a hysteresis circuit, and the hysteresis width is Vk.
In one embodiment, the reference power supply T1 is TL 431.
In one embodiment, fig. 3 is a circuit diagram of an input under-voltage protection circuit according to another embodiment, and as shown in fig. 3, the input under-voltage protection circuit according to another embodiment further includes a first capacitor C1;
the first capacitor C1 is connected in parallel across the second resistor R2.
A second capacitor C2;
the second capacitor C2 is connected in parallel across the fifth resistor R5.
Through first electric capacity C1 and second electric capacity C2, absorb the noise on the pin, reduce the influence to the circuit, first electric capacity C1 can also reduce the harmful effects of input voltage VIN ripple to the undervoltage protection circuit of inputing simultaneously.
In the input under-voltage protection circuit of any of the embodiments, the start module 101 formed by the semiconductor switch tube controls the switch module 100 to be turned on when the input voltage VIN is smaller than the preset voltage value, that is, the input under-voltage. After the switch module 100 is turned on, the control port FB is pulled high to a high level, so that the switching power supply stops working, and input under-voltage protection is realized. Based on this, the starting module 101 formed by the semiconductor switch device is matched with the switch module 100 for flexible switch device type selection, which is beneficial to reducing the cost and the number of components of the input undervoltage protection circuit and is convenient for providing input undervoltage protection on a module power supply with small volume and high power density.
The embodiment of the utility model provides a still provide a switching power supply system.
A switching power supply system comprises a switching power supply and the input undervoltage protection circuit of any one of the embodiments.
In the switching power supply system, the starting module 101 formed by the semiconductor switching tube controls the switching module 100 to be switched on when the input voltage VIN is smaller than a preset voltage value, that is, the input voltage is under-voltage. After the switch module 100 is turned on, the control port FB is pulled high to a high level, so that the switching power supply stops working, and input under-voltage protection is realized. Based on this, the starting module 101 formed by the semiconductor switch device is matched with the switch module 100 for flexible switch device type selection, which is beneficial to reducing the cost and the number of components of the input undervoltage protection circuit and is convenient for providing input undervoltage protection on a module power supply with small volume and high power density.
The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above examples only represent some embodiments of the present invention, and the description thereof is more specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.
Claims (10)
1. An input brown-out protection circuit, comprising:
the switch module is used for pulling the control port to a high level when the switch module is conducted so as to stop the switch power supply;
and the starting module comprises one or more semiconductor switching tubes and is used for controlling the switching-on of the switching module when the input voltage is smaller than a preset voltage value.
2. The input under-voltage protection circuit of claim 1, wherein the start-up module is configured to connect a power supply voltage terminal and a reference voltage terminal of a switching power supply control chip; when the switch module is conducted, the control port is pulled high to a high level according to the power supply voltage and the reference voltage of the switch power supply control chip.
3. The undervoltage protection circuit of claim 1, wherein the semiconductor switching tube comprises a triode.
4. The undervoltage protection circuit of claim 1, wherein the switching module comprises a three-terminal switching device.
5. The input brown-out protection circuit of claim 2, wherein the start-up module comprises a first current-limiting resistor, a first voltage-dividing resistor, a second voltage-dividing resistor, a first transistor, a second transistor, and a zener diode;
one end of the first current-limiting resistor is used for connecting the input voltage, and the other end of the first current-limiting resistor is connected with the cathode of the voltage stabilizing diode; the anode of the voltage-stabilizing diode is used for grounding; the base electrode of the first transistor is connected with the common end of the first current-limiting resistor and the cathode of the voltage-stabilizing diode, and the collector electrode of the first transistor is connected with the base electrode of the second transistor; the emitter of the second crystal triode is used for being connected with the input voltage; the collector of the second transistor is used for connecting the power supply voltage end; one end of the first voltage-dividing resistor is used for being connected with the power supply voltage end, one end of the first voltage-dividing resistor is connected with the second voltage-dividing resistor, the other end of the second voltage-dividing resistor is connected with the switch module, and an emitter of the first transistor is connected with a common end of the first voltage-dividing resistor and the second voltage-dividing resistor.
6. The input under-voltage protection circuit according to claim 5, wherein the switch module comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor and a reference power supply;
the input voltage is used for being output to the first resistor and output to a grounding end through the second resistor, the reference power supply reference end is connected to a common end of the first resistor and the second resistor, the third resistor is connected to the reference voltage end and the common end of the first resistor and the second resistor, the anode of the reference power supply is used for being grounded, the cathode of the reference power supply is connected to the other end of the second voltage-dividing resistor, the fourth resistor is connected between the cathode of the reference power supply and the control port, and the fifth resistor is connected between the control port and the grounding end.
7. The undervoltage input protection circuit of claim 6, further comprising a first capacitor;
the first capacitor is connected in parallel to two ends of the second resistor.
8. The undervoltage protection circuit of claim 6, further comprising a second capacitor;
the second capacitor is connected in parallel to two ends of the fifth resistor.
9. The brown-out input protection circuit of claim 6, wherein the reference supply comprises a TL431 reference supply.
10. A switching power supply system comprising a switching power supply and an undervoltage protection circuit according to any one of claims 1 to 9.
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| CN202020498017.5U CN211629858U (en) | 2020-04-07 | 2020-04-07 | Input undervoltage protection circuit and switching power supply system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113708341A (en) * | 2021-09-04 | 2021-11-26 | 广西普德新星电源科技有限公司 | Undervoltage protection circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113708341A (en) * | 2021-09-04 | 2021-11-26 | 广西普德新星电源科技有限公司 | Undervoltage protection circuit |
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Address after: 510000 room 306, 3rd floor, 43 Sicheng Road, software park, Tianhe District, Guangzhou City, Guangdong Province Patentee after: GUANGZHOU ZHIYUAN ELECTRONICS Co.,Ltd. Address before: 510665 room 517, 1023 Gaopu Road, Tianhe Software Park, Tianhe District, Guangzhou City, Guangdong Province Patentee before: GUANGZHOU ZHIYUAN ELECTRONICS Co.,Ltd. |
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