A power supply polarity protection circuit

Abstract

The present invention provides a polarity protection circuit, wherein an input power supply is rectified by a rectifier diode D1 and filtered by a capacitor, an output direct current voltage is connected to a drain of a transistor Q1, an input power supply of an inductor L2 is rectified by a rectifier diode D2, and then filtered by a capacitor, an output voltage is connected to a collector of an optical coupler U3B through an overvoltage protection diode, an emitter of the optical coupler U3B is connected to a grid of the transistor Q1, and a source of the transistor Q1 is output to a terminal; a source of the transistor Q2 is connected to a ground terminal of the inductor L1, a drain is connected to a cathode of a photosensitive diode U3A, a grid is connected to resistors R5 and R6 of a power supply circuit, an anode of the photosensitive diode U3A is connected to a resistor R8, the resistor R8 is connected to a positive electrode of an output power supply, and a negative electrode of the inductor L2 is connected to a positive electrode of the output power supply. The power supply polarity protection circuit of the present invention can detect the polarity of input and output power supplies, and automatically cut off when the polarity of the power supply is incorrectly connected, thereby effectively protecting electronic equipment, improving the reliability of the electronic equipment, and extending the service life of the electronic equipment.

Description

Technical Field

[0001] The present invention relates to a protection circuit, and more particularly to a power supply polarity protection circuit. Background Art

[0002] At present, various electronic devices require the use of a DC external power supply in some usage scenarios. In this case, the polarity of the input terminal of the electronic device must be the same as the polarity of the DC power supply to ensure the normal operation of the electronic device. If the polarity is connected incorrectly, the electronic device may not work properly at best, or even burn out, or even cause a major accident, resulting in significant losses.

[0003] Chinese invention patent application 2008103004047 published on September 2, 2009 discloses a power polarity protection circuit, which uses two comparator amplifiers U1 and U2 and four transistors for power polarity protection. However, the circuit has the disadvantages of high cost and cannot adapt to the reality that existing intelligent electronic devices have various voltages. Therefore, it is necessary to improve this type of circuit and develop a polarity protection circuit with a simple circuit structure, adaptability to the requirements of various terminal devices for different external power supplies, and high circuit flexibility. Summary of the invention

[0004] In view of this, it is necessary to propose an output voltage polarity protection circuit to protect electronic equipment from losses caused by negligent polarity reversal when an external DC power supply is connected, thereby protecting electronic equipment and personal safety.

[0005] The technical solution of the present invention is:

[0006] A power polarity protection circuit includes an input power supply, and further includes an inductor L1, an inductor L2, a rectifier diode D1, a rectifier diode D2, an electrolytic capacitor C1, a ceramic capacitor C2, a ceramic capacitor C3, an electrolytic capacitor C4, a resistor R1, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R8, a resistor R10, a transistor Q1, a transistor Q2, a photosensitive diode U3A, an optical coupler U3B, and a diode ZD1. The input power supply is rectified by the rectifier diode D1, and then filtered by the electrolytic capacitor C1 and the ceramic capacitor C2. The output DC voltage is connected to the drain of the transistor Q1. The input power supply of the inductor L2 is rectified by the rectifier diode D1. The output voltage is rectified by the rectifier diode D2 and then filtered by the electrolytic capacitor C4 and the ceramic capacitor C3. The output voltage is connected to the collector of the optocoupler U3B through the overvoltage protection diode ZD1. The emitter of the optocoupler U3B is connected to the gate of the transistor Q1. The source of the transistor Q1 is output to the terminal device. The source of the transistor Q2 is connected to the ground terminal of the inductor L1, and the drain of the transistor Q2 is connected to the cathode of the photosensitive diode U3A; the gate of the transistor Q2 is connected to the resistor R5 and the resistor R6 of the power supply circuit, the anode of the photosensitive diode U3A is connected to the resistor R8, and is connected to the positive electrode of the output power supply through R8, and the negative electrode of the inductor L2 is connected to the positive electrode of the output power supply.

[0007] Furthermore, the transistor Q1 and the transistor Q2 may be NPN transistors.

[0008] Furthermore, the transistor Q1 and the transistor Q2 may be PNP transistors.

[0009] Furthermore, the transistor Q1 and the transistor Q2 may be N-channel MOS field effect transistors.

[0010] Furthermore, the transistor Q1 and the transistor Q2 may be P-channel MOS field effect transistors.

[0011] The power polarity protection circuit of the present invention can automatically detect the input and output AC voltage, current, and power factor, and can effectively protect electronic equipment when the power polarity is incorrectly connected, thereby improving the safety and reliability of electronic equipment and extending the service life of electronic equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 : A schematic diagram of the power supply polarity protection circuit composition of the present invention. DETAILED DESCRIPTION

[0013] The present invention will be further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0014] Please refer to Figure 1The schematic diagram of the power polarity protection circuit of the present invention comprises an inductor L1, an inductor L2, a rectifier diode D1, a rectifier diode D2, an electrolytic capacitor C1, a ceramic capacitor C2, a ceramic capacitor C3, an electrolytic capacitor C4, a resistor R1, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R8, a resistor R10, a transistor Q1, a transistor Q2, a photodiode U3A, an optocoupler U3B, a diode ZD1 and other original components.

[0015] The working process of the circuit is explained as follows: the input power is rectified by the rectifier diode D1, and then filtered by the electrolytic capacitor C1 and the ceramic capacitor C2 to form a DC voltage connected to the drain (or collector) of the transistor Q1. The other input power is rectified by the rectifier diode D2, and then filtered by the electrolytic capacitor C4 and the ceramic capacitor C3. Then it is connected to the collector of the optocoupler U3B through the output overvoltage protection diode ZD1. The emitter of the optocoupler U3B is connected to the gate (or base) of the transistor Q1, and the source (or The source (or emitter) of the transistor Q2 is directly output to the terminal device, such as batteries, LED lamps and other equipment. The source (or emitter) of the transistor Q2 is connected to the ground terminal of the inductor L1, and the drain (or collector) of the transistor Q2 is connected to the cathode of the photodiode U3A; the gate (or base) of the transistor Q2 is connected to the resistor R5 and the resistor R6 of the power supply circuit, the anode of the photodiode U3A is connected to the resistor R8, and is connected to the positive electrode of the output power supply through R8. The negative electrode of the inductor L2 must be connected to the positive electrode of the output power supply.

[0016] When the polarity of the output circuit is connected correctly, resistors R5 and R6 divide the voltage to supply power to the gate of Q2, and transistor Q2 is turned on by the forward driving power supply. The photodiode U3A is also turned on as the transistor Q2 is turned on. The function of resistor R8 is to provide the photodiode U3A with a suitable working current. The conduction of the photodiode U3A turns on the optocoupler U3B, and the power supply voltage of the inductor L2 is transmitted to the gate (or base) of the transistor Q1, driving the transistor Q1 to turn on and accurately supplying the output voltage to the terminal device. The function of the diode ZD1 is to ensure that the voltage of the inductor L2 is within the safe driving voltage range of the transistor Q1.

[0017] When the polarity connection of the output circuit is wrong, the circuit connection is abnormal, the gate power supply voltage of the transistor Q2 is the reverse bias drive voltage, and the transistor Q2 is in the cut-off state, so the photodiode U3A is also in the cut-off state, causing the optocoupler U3B to be in the cut-off state as well, further causing the gate (or base) of the transistor Q1 to be cut off due to the lack of output drive bias voltage, so there is no output voltage to the terminal device, thereby achieving the purpose of protecting the input power supply and the terminal device.

[0018] As other embodiments of the present invention, the transistor Q1 and the transistor Q2 may be NPN transistors, PNP transistors, N-channel MOS field effect transistors or P-channel MOS field effect transistors. The connection relationship between the gate, drain and source of the MOS field effect transistor is the same as the connection method of the base, collector and emitter of the NPN transistor, and the application principle is the same, which will not be repeated here.

[0019] The above description is only an embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A power polarity protection circuit, comprising an input power supply, characterized in that: The invention comprises an inductor L1, an inductor L2, a rectifier diode D1, a rectifier diode D2, an electrolytic capacitor C1, a ceramic capacitor C2, a ceramic capacitor C3, an electrolytic capacitor C4, a resistor R1, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R8, a resistor R10, a transistor Q1, a transistor Q2, a photosensitive diode U3A, an optical coupler U3B, and a diode ZD1. The transistor Q1 and the transistor Q2 are any one of an NPN transistor or a PNP transistor. The input power supply of the inductor L1 is rectified by the rectifier diode D1, and then filtered by the electrolytic capacitor C1 and the ceramic capacitor C2. The output DC voltage is connected to the input end of the transistor Q1. The input power supply of the inductor L2 is rectified by the rectifier diode D2, and then filtered by the electrolytic capacitor C4 and the ceramic capacitor C3. The output voltage is connected to the collector of the optical coupler U3B through the overvoltage protection diode ZD1. The optical coupler U3B The emitter is connected to the control end of the transistor Q1, the output end of the transistor Q1 is output to the terminal device, the output end of the transistor Q2 is connected to the negative electrode of the inductor L1, and the input end of the transistor Q2 is connected to the cathode of the photosensitive diode U3A; the control end of the transistor Q2 is connected to the resistor R5 and the resistor R6 of the power supply circuit, the other end of the resistor R5 is connected to the negative electrode of the inductor L1, and the other end of the resistor R6 is connected to the positive electrode of the output power supply. The two ends of the resistor R1 are respectively connected to the input end and the output end of the transistor Q1, the two ends of the resistor R3 are respectively connected to the control end of the transistor Q1 and the positive electrode of the output power supply, the two ends of the resistor R4 are respectively connected to the negative electrode of the inductor L1 and the negative electrode of the output power supply, the two ends of the resistor R10 are respectively connected to the negative electrode of the rectifier diode D2 and the collector of the optocoupler U3B, the anode of the photosensitive diode U3A is connected to the resistor R8, and is connected to the positive electrode of the output power supply through R8, and the negative electrode of the inductor L2 is grounded.

2. The power polarity protection circuit according to claim 1, characterized in that: The transistor Q1 and the transistor Q2 are both N-channel MOS field effect transistors.

3. The power polarity protection circuit according to claim 1, characterized in that: The transistor Q1 and the transistor Q2 are both P-channel MOS field effect transistors.

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