EMC filter circuit and electronic equipment

Abstract

The invention provides an EMC filter circuit and electronic equipment, and the circuit comprises a DC input interface which receives an external DC input power supply; the anti-surge unit is used for limiting the surge voltage within a safe range; the anti-reverse connection unit is used for disconnecting a transmission path of the direct-current input power supply when the direct-current input power supply is reversely connected; and the filtering unit is used for filtering the output signal of the anti-reverse connection unit to obtain a direct-current output power supply so as to suppress electromagnetic interference. Electromagnetic interference can be effectively suppressed, and the reliability and the stability of the electronic equipment are improved; wherein the anti-surge unit can protect the electronic equipment from being impacted by surge voltage, so that the safety of the equipment is improved; the anti-reverse connection unit can prevent the electronic equipment from being damaged due to reverse connection of the polarity of the power supply, the usability of the equipment is improved, and meanwhile, the overall efficiency of the power supply is improved by utilizing low on-resistance of a field-effect tube; the filtering unit can filter clutters and interference signals in the power supply, pure direct-current power supply is provided for the electronic equipment, and the performance of the equipment is improved.

Description

Technical Field

[0001] The present invention relates to the field of integrated circuits, and in particular to an EMC filter circuit and electronic equipment. Background Art

[0002] Electromagnetic interference (EMI) is divided into two types: conducted interference and radiated interference. Conducted interference mainly refers to the interference signals generated by electronic devices interfering with each other through conductive media or common power lines; radiated interference refers to the interference signals generated by electronic devices being transmitted to another electrical network or electronic device through spatial coupling. For electronic devices such as detection systems, electromagnetic compatibility (EMC) issues can cause image anomalies, increased noise, and even damage to the equipment.

[0003] The components in traditional EMI filter circuits are often large in size, making them difficult to install in electronic devices with strict space requirements such as PCB boards. Different protection components have different response times, which may result in failure to provide protection in a timely manner in certain rapidly changing radiation or conduction situations. In addition, traditional anti-reverse connection solutions introduce additional resistors or diodes in the transmission path, resulting in a certain voltage drop during normal operation, which in turn causes energy loss and reduces the overall efficiency of the power supply.

[0004] Therefore, how to reduce the volume of EMI filter circuits, adapt to rapidly changing radiation or conduction conditions, and improve efficiency has become one of the problems that technical personnel in this field need to solve urgently.

[0005] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present invention and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because these solutions are described in the background technology section of the present invention. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide an EMC filter circuit and an electronic device to solve the problems of large size of the EMI filter circuit, different response times of different protection devices, low power efficiency, etc. in the prior art.

[0007] To achieve the above-mentioned object and other related objects, the present invention provides an EMC filter circuit, wherein the EMC filter circuit at least comprises:

[0008] DC input interface, surge protection unit, reverse connection protection unit and filter unit;

[0009] The DC input interface receives an external DC input power supply; the surge protection unit is connected to the output end of the DC input interface and is used to limit the surge voltage within a safe range;

[0010] The anti-reverse connection unit is connected to the output end of the anti-surge unit, and disconnects the transmission path of the DC input power supply when the DC input power supply is reversely connected;

[0011] The filtering unit is connected to the output end of the anti-reverse connection unit and is used for filtering the output signal of the anti-reverse connection unit to obtain a DC output power supply so as to suppress electromagnetic interference.

[0012] Optionally, the DC input interface is a standard input interface.

[0013] Optionally, the surge protection unit includes a varistor, a gas discharge tube, a first transient suppression diode, a first inductor and a second inductor;

[0014] The varistor is connected between the positive phase output terminal and the negative phase output terminal of the DC input interface;

[0015] The gas discharge tube is connected in parallel to both ends of the varistor;

[0016] The first end of the first inductor is connected to the positive phase output end of the DC input interface, and the second end serves as the positive phase output end of the surge protection unit;

[0017] A first end of the second inductor is connected to the inverting output end of the DC input interface, and a second end thereof serves as the inverting output end of the surge protection unit;

[0018] A cathode of the first transient voltage suppression diode is connected to the second end of the first inductor, and an anode of the first transient voltage suppression diode is connected to the first end of the second inductor.

[0019] More optionally, the surge protection unit further includes a fuse; the fuse is connected in series between the positive phase output terminal of the DC input interface and the first end of the first inductor.

[0020] More optionally, the filtering unit includes a capacitor module; the capacitor module is connected in parallel to the output end of the anti-reverse connection unit and provides the DC output power supply.

[0021] More optionally, the capacitor module includes N capacitors, where N is a natural number greater than or equal to 1; when N is greater than or equal to 2, the capacitors are connected in parallel.

[0022] More optionally, each capacitor is a ceramic capacitor or an electrolytic capacitor.

[0023] Optionally, the anti-reverse connection unit includes a resistor, a field effect transistor and a second transient voltage suppression diode;

[0024] The first end of the field effect tube is connected to the first output end of the surge protection unit, and the second end serves as the first output end of the reverse connection protection unit. When the DC input power supply is reversely connected, the field effect tube is turned off;

[0025] One end of the resistor is connected to the second output end of the surge protection unit, and the other end is connected to the control end of the field effect tube;

[0026] The anode of the second transient voltage suppression diode is connected to the second end of the field effect tube, and the cathode is connected to the control end of the field effect tube.

[0027] More optionally, the field effect tube is an NMOS tube, the drain of the NMOS tube serves as the first end, the source serves as the second end, and the gate serves as the control end; the first output end of the surge protection unit is the inverting output end, and the second output end is the non-inverting output end.

[0028] To achieve the above-mentioned purpose and other related purposes, the present invention further provides an electronic device, the electronic device at least comprising: an electric device and the above-mentioned EMC filter circuit;

[0029] The EMC filter circuit receives an external DC input power supply, filters the DC input power supply to obtain a DC output power supply, and the DC output power supply supplies power to the electrical equipment.

[0030] As described above, the EMC filter circuit and electronic equipment of the present invention have the following beneficial effects:

[0031] The EMC filter circuit and electronic device of the present invention can effectively suppress electromagnetic interference and improve the reliability and stability of electronic devices. Among them, the surge protection unit can protect the electronic device from the impact of surge voltage and improve the safety of the device. The anti-reverse connection unit can prevent the electronic device from being damaged due to the reverse polarity of the power supply and improve the usability of the device; at the same time, the low on-resistance of the field effect tube is used to improve the overall efficiency of the power supply. The filter unit can filter out clutter and interference signals in the power supply, provide a pure DC power supply for the electronic device, and improve the performance of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Shown is a schematic structural diagram of the EMC filter circuit of the present invention.

[0033] Figure 2 Shown is a block diagram of an electronic device of the present invention.

[0034] Component number description

[0035] 1 EMC filter circuit

[0036] 11 DC input interface

[0037] 12 Surge protection unit

[0038] 13. Anti-reverse connection unit

[0039] 14 Filter unit

[0040] 2 Electrical equipment DETAILED DESCRIPTION

[0041] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0042] See also Figure 1-2 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0043] like Figure 1 As shown, the present invention provides an EMC filter circuit 1, and the EMC filter circuit 1 includes:

[0044] A DC input interface 11 , a surge protection unit 12 , an anti-reverse connection unit 13 and a filter unit 14 .

[0045] like Figure 1 As shown, the DC input interface 11 receives an external DC input power source Vin.

[0046] Specifically, the DC input interface 11 is used to connect to an external DC input power supply to provide a stable power supply for the electronic device where the EMC filter circuit 1 is located. In this embodiment, the DC input interface 11 adopts a standard input interface and is connected to different power adapters or DC power supplies through a standard connection method to improve the adaptability. As an example, the standard input interface includes but is not limited to a C14 interface, a C20 interface, a C6 interface, and a C8 interface, which are not described one by one here.

[0047] like Figure 1 As shown, the surge protection unit 12 is connected to the output end of the DC input interface 11 and is used to limit the surge voltage within a safe range.

[0048] Specifically, the surge protection unit 12 is used to protect the electronic device where the EMC filter circuit 1 is located from the impact of surge voltage. When a surge occurs in the DC input power supply Vin, the surge protection unit 12 can respond quickly and limit the surge voltage within a safe range, thereby protecting the internal circuit of the electronic device; when the DC input power supply Vin is within the safe range and no surge occurs, the DC input power supply Vin is transmitted to the output end of the surge protection unit 12.

[0049] Specifically, in this embodiment, the surge protection unit 12 includes a varistor RV1, a gas discharge tube GDT1, a first transient suppression diode D1, a first inductor L1 and a second inductor L2. The varistor RV1 is connected between the positive phase output terminal and the negative phase output terminal of the DC input interface 11, and its rated voltage is higher than the working voltage of the electronic device (for example, if the DC input power Vin is 24V, a 47V varistor can be used; as an example, the rated voltage of the varistor is 1.5 times and above the peak value of the DC input power supply, including but not limited to 1.6 times, 1.8 times, 2 times, 2.5 times, 3 times); the varistor RV1 has a nonlinear volt-ampere characteristic. When the voltage on the varistor RV1 exceeds a certain value, its resistance value will drop sharply, allowing current to pass through, realizing voltage clamping, and the excess current is absorbed to achieve the purpose of protecting sensitive devices. The gas discharge tube GDT1 is connected in parallel to both ends of the varistor RV1, and its flow rate is greater than the possible surge current; in actual use, according to the working voltage and surge current requirements of the circuit, the flow rate and response voltage of the gas discharge tube are set (for example, if the DC input power supply Vin is 24V, a gas discharge tube with a response of 90V can be used; as an example, the voltage responded by the gas discharge tube is 3 times or more of the peak value of the DC input power supply, including but not limited to 4 times and 5 times), which can effectively protect the electronic equipment. The first end of the first inductor L1 is connected to the positive phase output end of the DC input interface 11, and the second end is used as the positive phase output end of the surge protection unit 12; the first end of the second inductor L2 is connected to the negative phase output end of the DC input interface 11, and the second end is used as the negative phase output end of the surge protection unit 12; the rated current of the first inductor L1 and the second inductor L2 is greater than the working current of the electronic equipment, which is used to filter out low-frequency interference signals and has a certain suppression effect on surges. The cathode of the first transient suppression diode D1 is connected to the second end of the first inductor L1 , and the anode is connected to the first end of the second inductor L2 ; the transient suppression diode D1 has fast response and high energy absorption capability, and can improve the surge protection effect.

[0050] As another implementation method, the surge protection unit 12 also includes a fuse BT1; the fuse BT1 is connected in series between the positive phase output end of the DC input interface 11 and the first end of the first inductor L1. When the current flowing through the fuse BT1 is greater than the set value, the fuse BT1 blows, thereby achieving the purpose of protecting the electronic equipment.

[0051] The surge protection unit 12 of the present invention is composed of components with fast response and high energy absorption capabilities such as varistors and transient suppression diodes, which can effectively protect the device when a surge voltage occurs; it also has a certain filtering function.

[0052] like Figure 1 As shown, the reverse connection protection unit 13 is connected to the output end of the surge protection unit 12, and disconnects the transmission path of the DC input power Vin when the DC input power Vin is reversely connected.

[0053] Specifically, the anti-reverse connection unit 13 uses unidirectional conductivity to prevent the electronic device from being damaged due to reverse polarity of the power supply; when the power polarity is connected correctly, the current flows through the anti-reverse connection unit 13 and enters the next-level circuit; when the power polarity is reversed, the anti-reverse connection unit 13 can prevent the current from flowing into the electronic device, thereby protecting the internal circuit of the device.

[0054] Specifically, in this embodiment, the anti-reverse connection unit 13 includes a resistor R1, a field effect transistor Q1 and a second transient suppression diode D2. Among them, the first end of the field effect transistor Q1 is connected to the first output end of the anti-surge unit 12, and the second end serves as the first output end of the anti-reverse connection unit 13; the field effect transistor Q1, as an anti-reverse connection element, has a lower on-resistance and a higher switching speed, improves the overall efficiency of the power supply, and meets the high-demand application environment. One end of the resistor R1 is connected to the second output end of the anti-surge unit 12 and serves as the second output end of the anti-reverse connection unit 13, and the other end is connected to the control end of the field effect transistor Q1. The anode of the second transient suppression diode D2 is connected to the second end of the field effect transistor Q1, and the cathode is connected to the control end of the field effect transistor Q1; the second transient suppression diode D2, as a protection device, protects the field effect transistor Q1, and can effectively protect the normal operation of the anti-reverse connection circuit. In this example, the field effect transistor Q1 is an NMOS tube, the drain of the NMOS tube is used as the first end, the source is used as the second end, and the gate is used as the control end; the first output end of the surge protection unit 12 is the inverting output end, and the second output end is the positive output end. That is, the drain of the NMOS tube is connected to the inverting output end of the surge protection unit 12, and the source is used as the inverting output end of the anti-reverse connection unit 13; one end of the resistor R1 is connected to the positive output end of the surge protection unit 12 and serves as the inverting output end of the anti-reverse connection unit 13, and the other end outputs the control signal of the NMOS tube. In actual use, the field effect transistor Q1 can also select other types of devices (for example, the logic level of the switch is opposite to that of the NMOS tube), and can also be set between the positive output end of the surge protection unit 12 and the positive output end of the anti-reverse connection unit 13, which will not be repeated here.

[0055] like Figure 1As shown, the filter unit 14 is connected to the output end of the anti-reverse connection unit 13, and is used to filter the output signal of the anti-reverse connection unit 13 to obtain a DC output power supply DVCC, so as to suppress electromagnetic interference.

[0056] Specifically, in the present embodiment, the filtering unit 14 includes a capacitor module; the capacitor module is connected in parallel to the output end of the anti-reverse connection unit 13, and provides a DC output power supply DVCC. As an example, the capacitor module includes N capacitors, N is a natural number greater than or equal to 1; when N is greater than or equal to 2, the capacitors are connected in parallel. In this example, N=2, and the first capacitor C1 and the second capacitor C2 are connected in parallel. In the manner of connecting multiple capacitors in parallel, capacitors with different capacitance values ​​have different response characteristics to signals of different frequencies. By using large capacitors and small capacitors in parallel, a wider frequency range can be adapted, thereby improving the overall filtering effect. The type of each capacitor is selected according to actual needs, including but not limited to ceramic capacitors or electrolytic capacitors.

[0057] In addition, the capacitor in the filter unit 14 can also form a filter structure with the inductor in the surge protection unit 12 to filter signals of different frequencies, thereby effectively suppressing electromagnetic interference. The inductor is used to filter low-frequency interference signals, and the capacitor is used to filter high-frequency interference signals.

[0058] The EMC filter circuit 1 of the present invention can effectively suppress electromagnetic interference signals, release accumulated charges, ensure signal stability, and meet EMC requirements; it can be widely used in electronic products such as detection systems to ensure product safety and increase service life.

[0059] like Figure 2 As shown, the present invention further provides an electronic device, which at least includes: an EMC filter circuit 1 and an electrical device 2.

[0060] The EMC filter circuit 1 receives an external DC input power Vin, and filters the DC input power Vin to obtain a DC output power DVCC; the DC output power DVCC supplies power to the electrical equipment 2.

[0061] Due to the filtering of the power supply by the EMC filter circuit 1, the electrical equipment 2 can obtain a pure DC power supply, thereby avoiding the influence of electronic interference on the power supply and ensuring the normal operation of the electrical equipment 2.

[0062] In summary, the present invention provides an EMC filter circuit and electronic equipment, including: a DC input interface, an anti-surge unit, an anti-reverse connection unit and a filter unit; the DC input interface receives an external DC input power supply; the anti-surge unit is connected to the output end of the DC input interface, and is used to limit the surge voltage within a safe range; the anti-reverse connection unit is connected to the output end of the anti-surge unit, and disconnects the transmission path of the DC input power supply when the DC input power supply is reversed; the filter unit is connected to the output end of the anti-reverse connection unit, and is used to filter the output signal of the anti-reverse connection unit to obtain a DC output power supply to suppress electromagnetic interference. The EMC filter circuit and electronic equipment of the present invention can effectively suppress electromagnetic interference and improve the reliability and stability of electronic equipment; wherein the anti-surge unit can protect electronic equipment from the impact of surge voltage and improve the safety of the equipment; the anti-reverse connection unit can prevent electronic equipment from being damaged due to the reverse polarity of the power supply, improve the ease of use of the equipment, and at the same time use the low on-resistance of the field effect tube to improve the overall efficiency of the power supply; the filter unit can filter out clutter and interference signals in the power supply, provide a pure DC power supply for the electronic equipment, and improve the performance of the equipment. Therefore, the present invention effectively overcomes the various shortcomings in the prior art and has a high industrial utilization value.

[0063] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. An EMC filter circuit, characterized in that: The EMC filter circuit at least comprises: DC input interface, surge protection unit, reverse connection protection unit and filter unit; The DC input interface receives an external DC input power supply; The surge protection unit is connected to the output end of the DC input interface and is used to limit the surge voltage within a safe range; The anti-reverse connection unit is connected to the output end of the anti-surge unit, and disconnects the transmission path of the DC input power supply when the DC input power supply is reversely connected; The filtering unit is connected to the output end of the anti-reverse connection unit and is used for filtering the output signal of the anti-reverse connection unit to obtain a DC output power supply so as to suppress electromagnetic interference.

2. The EMC filter circuit according to claim 1, characterized in that: The DC input interface is a standard input interface.

3. The EMC filter circuit according to claim 1, characterized in that: The surge protection unit includes a varistor, a gas discharge tube, a first transient voltage suppression diode, a first inductor and a second inductor; The varistor is connected between the positive phase output terminal and the negative phase output terminal of the DC input interface; The gas discharge tube is connected in parallel to both ends of the varistor; The first end of the first inductor is connected to the positive phase output end of the DC input interface, and the second end serves as the positive phase output end of the surge protection unit; A first end of the second inductor is connected to the inverting output end of the DC input interface, and a second end thereof serves as the inverting output end of the surge protection unit; A cathode of the first transient voltage suppression diode is connected to the second end of the first inductor, and an anode of the first transient voltage suppression diode is connected to the first end of the second inductor.

4. The EMC filter circuit according to claim 3, characterized in that: The surge protection unit further includes a fuse; the fuse is connected in series between the positive phase output end of the DC input interface and the first end of the first inductor.

5. The EMC filter circuit according to claim 1 or 3, characterized in that: The filtering unit includes a capacitor module; The capacitor module is connected in parallel to the output end of the anti-reverse connection unit and provides the DC output power supply.

6. The EMC filter circuit according to claim 5, characterized in that: The capacitor module includes N capacitors, where N is a natural number greater than or equal to 1; when N is greater than or equal to 2, the capacitors are connected in parallel.

7. The EMC filter circuit according to claim 6, characterized in that: Each capacitor is a ceramic capacitor or an electrolytic capacitor.

8. The EMC filter circuit according to claim 1, characterized in that: The anti-reverse connection unit includes a resistor, a field effect transistor and a second transient suppression diode; The first end of the field effect tube is connected to the first output end of the surge protection unit, and the second end serves as the first output end of the reverse connection protection unit. When the DC input power supply is reversely connected, the field effect tube is turned off; One end of the resistor is connected to the second output end of the surge protection unit, and the other end is connected to the control end of the field effect tube; The anode of the second transient voltage suppression diode is connected to the second end of the field effect tube, and the cathode is connected to the control end of the field effect tube.

9. The EMC filter circuit according to claim 8, characterized in that: The field effect tube is an NMOS tube, the drain of the NMOS tube serves as the first end, the source serves as the second end, and the gate serves as the control end; the first output end of the surge protection unit is the inverting output end, and the second output end is the non-inverting output end.

10. An electronic device, characterized in that: The electronic equipment at least comprises: an electrical device and an EMC filter circuit as described in any one of claims 1 to 9; The EMC filter circuit receives an external DC input power supply, filters the DC input power supply to obtain a DC output power supply, and the DC output power supply supplies power to the electrical equipment.

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