Switching power supply output filter circuit

Abstract

The utility model relates to the technical field of switching power supply circuits, and provides a switching power supply output filter circuit, comprising a first capacitor element C1 which is a multilayer ceramic capacitor MLCC and is used for providing low internal resistance filtering under a high frequency condition; the filter inductance element L1 is connected with the C1 in series and is used for storing energy and suppressing ripple current by the high impedance characteristic of an alternating current component; the second capacitor element C2 is an electrolytic capacitor or an MLCC and is used for further smoothing the output voltage; the first capacitor element C1 and the second capacitor element C2 are connected to an input voltage Uin and an output voltage Uout of two identical nodes. The high-frequency MLCC capacitor is adopted to replace an electrolytic capacitor for filtering, the size is reduced, power supply miniaturization is promoted, ripple waves are effectively restrained, smooth voltage is ensured, and system efficiency and stability are enhanced. The circuit design reduces the dependence on a large current-resistant capacitor, reduces the cost, improves the high-frequency performance, and enhances the environmental adaptability.

Description

Technical Field

[0001] The utility model relates to the technical field of switching power supply circuits, in particular to a switching power supply output filter circuit. Background Art

[0002] In modern electronic devices, switching power supplies are widely used in various devices due to their high conversion efficiency and miniaturization advantages, such as computers, communication equipment, household appliances, etc. However, switching power supplies will generate ripple current during operation, which not only affects the stability of power output, but also reduces the overall performance of the system and even affects the safe operation of the load.

[0003] Traditional switching power supply output rectification and filtering solutions generally use electrolytic capacitors for filtering. Although electrolytic capacitors have high capacity and can store more energy, they have some significant limitations. First, electrolytic capacitors have a weak tolerance for high-frequency ripple currents, and their internal high-frequency internal resistance is large, which makes it easy to heat up when processing high-frequency ripples. In severe cases, it may cause the electrolyte to dry up or even burst, greatly shortening the service life of the electrolytic capacitor. Secondly, the internal structure of the electrolytic capacitor is a liquid electrolyte. Over time, the electrolyte gradually evaporates, resulting in a decrease in capacitor performance. This is an issue that cannot be ignored for equipment that requires long-term stable operation.

[0004] In view of the deficiencies in the above-mentioned prior art, especially for low-voltage and high-current application environments, traditional electrolytic capacitor filtering solutions have been difficult to meet the increasingly improved performance requirements. Especially in high-temperature environments, the reliability problem of electrolytic capacitors is more prominent, limiting their scope of application. Therefore, developing a new filter circuit design to reduce the volume of filter capacitors, increase the service life of the circuit, and adapt to a wider operating temperature range has become a technical problem that the industry urgently needs to solve. It is against this background that the present utility model comes into being, and aims to provide an optimized switching power supply output filter circuit solution to overcome the defects existing in the prior art. Utility Model Content

[0005] In order to solve the problems existing in the background technology, the utility model provides a switching power supply output filter circuit, comprising:

[0006] The first capacitive element C1 is a multilayer ceramic capacitor MLCC, which is used to provide low internal resistance filtering under high frequency conditions;

[0007] The filter inductor element L1 is connected in series with C1 and is used for energy storage and high impedance characteristics to the AC component to suppress ripple current;

[0008] The second capacitive element C2 is an electrolytic capacitor or an MLCC, which is used to further smooth the output voltage;

[0009] The first capacitive element C1 and the second capacitive element C2 are connected to the same two nodes, the input voltage Uin and the output voltage Uout.

[0010] The beneficial effects achieved by the utility model are:

[0011] First, the utility model adopts multilayer ceramic capacitors MLCC with excellent high-frequency performance to replace traditional large-volume electrolytic capacitors for filtering, which significantly reduces the volume of the filter capacitors. Especially for low-voltage and high-current applications, this improvement greatly promotes the miniaturization and lightweight design of the power module, making it easy to integrate into compact electronic devices.

[0012] Second, the utility model reduces the reliance on electrolytic capacitors and avoids the problem of capacitor failure due to electrolyte drying, thereby significantly improving the service life of the entire power module. The solid-state structure of MLCC capacitors ensures long-term stability and reliability, and can maintain good working conditions even in high temperature environments, reducing the risk of component failure.

[0013] Third, by optimizing the circuit topology and reasonably configuring the filter inductor L1, the utility model effectively suppresses the ripple current in the output voltage. Even under the condition that the output current of the flyback switching power supply is intermittent, the output voltage can be ensured to be smooth and stable, thereby improving the efficiency and stability of the entire power supply system.

[0014] Fourth, the circuit design of the utility model reduces the dependence on capacitors with large current carrying capacity, so that C2 can select capacitors with smaller current carrying capacity, which not only reduces the cost but also enhances the adaptability of the circuit under different working conditions, especially in high-frequency working environments, the performance of the circuit is more outstanding. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the overall structure of the utility model. DETAILED DESCRIPTION

[0016] The technical solution of the utility model will be clearly and completely described below in conjunction with the drawings in the utility model. In addition, the forms of the various structures recorded in the following embodiments are merely illustrative, and the utility model is not limited to the various structures recorded in the following embodiments. All other implementations obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the utility model.

[0017] Reference Figure 1 , a switching power supply output filter circuit, comprising:

[0018] The first capacitive element C1 is a multilayer ceramic capacitor MLCC, which is used to provide low internal resistance filtering under high frequency conditions;

[0019] The filter inductor element L1 is connected in series with C1 and is used for energy storage and high impedance characteristics to the AC component to suppress ripple current;

[0020] The second capacitive element C2 is an electrolytic capacitor or an MLCC, which is used to further smooth the output voltage;

[0021] The first capacitive element C1 and the second capacitive element C2 are connected to the same two nodes, the input voltage Uin and the output voltage Uout.

[0022] The switching power supply output filter circuit of the utility model includes three key components: C1 is a multilayer ceramic capacitor MLCC, which has the characteristics of low internal resistance and resistance to high-frequency ripple current; L1 is a filter inductor, which is responsible for energy storage and provides high impedance to AC ripple, effectively suppressing ripple current; C2 is flexible and optional, and can be either an electrolytic capacitor or an MLCC, which can be adjusted according to actual application requirements to further optimize the filtering effect.

[0023] Considering the influence of the circuit topology of the switching power supply on the output rectification and filtering, especially the discontinuous output current of the flyback switching power supply, the utility model ensures that the filter capacitor can effectively absorb the large ripple current during the discontinuous period of the inductor current through a carefully designed circuit structure. In most cases, by adjusting the maximum on-duty cycle of the output rectifier to close to 0.5, the circuit can effectively cope with peak fluctuations of up to 4 times the output current.

[0024] Since the circuit operates at a higher frequency, MLCC capacitors are very suitable for this application due to their superior high-frequency performance and low internal resistance. The high-frequency characteristics allow the inductance of L1 to be greatly reduced, which is especially suitable for circuit topologies without built-in output inductors. By accurately calculating and matching the parameters of L1 and C1, the ripple current on C2 can be suppressed to the maximum extent, allowing C2 to use a capacitor type with lower current resistance.

[0025] The filter circuit can adapt to the requirements of different power levels and application environments by adjusting circuit parameters, such as inductance value, capacitance value and their tolerance range.

[0026] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A switching power supply output filter circuit, characterized in that: include: The first capacitive element C1 is a multilayer ceramic capacitor MLCC, which is used to provide low internal resistance filtering under high frequency conditions; The filter inductor element L1 is connected in series with C1 and is used for energy storage and high impedance characteristics to the AC component to suppress ripple current; The second capacitive element C2 is an electrolytic capacitor or an MLCC, which is used to further smooth the output voltage; The first capacitive element C1 and the second capacitive element C2 are connected to the same two nodes, the input voltage Uin and the output voltage Uout.

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