Synchronous step-down circuit

Abstract

The utility model relates to the technical field of synchronous step-down circuits, and provides a synchronous step-down circuit, which comprises an input end filter capacitor C1, a switch tube Q1, a synchronous tube Q2, an energy storage inductor L1, an output end filter capacitor C2, a PWM (Pulse-Width Modulation) controller, an input end and an output end. Wherein the C1 is used for ripple suppression of an input power supply, the Q1 controls magnetizing and discharging of the L1, and the Q2 is switched on after the Q1 is switched off, so that inductance energy is transmitted to the output end. The L1 is responsible for energy storage and transfer, the C2 smoothly outputs voltage, and the PWM controller accurately controls on-off actions of the Q1 and the Q2. According to the utility model, the GaN field effect transistor MOSFET is adopted to replace a traditional silicon-based MOSFET and is used as the switch tube Q1 and the synchronous tube Q2, so that the working efficiency of the circuit is remarkably improved, the power consumption is reduced, and the overall efficiency is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of synchronous buck circuits, in particular to a synchronous buck circuit. Background Art

[0002] As one of the common DC-DC converters, the synchronous buck circuit is widely used in various electronic devices and systems, responsible for converting higher DC voltage into lower DC voltage to meet the needs of different loads. Traditional synchronous buck circuit designs usually use silicon-based MOSFETs (metal oxide semiconductor field effect transistors) as switching elements. Although these circuits perform well in many applications, they still face some inherent limitations. Specifically, their efficiency is usually capped at around 95%, which means that a considerable portion of the electrical energy is lost in the form of heat energy, which requires a heat dissipation device to maintain normal operating temperature. In addition, due to the physical characteristics of silicon-based MOSFETs, the operating frequency of these circuits is generally not high, usually in the range of 300KHz to 1MHz, which limits the response speed and miniaturization capability of the power supply system. The synchronous buck circuit design on the current market, due to the above-mentioned efficiency bottlenecks and heat dissipation problems, often leads to increased system design complexity, not only requiring a larger physical space to install heat sinks or fans, but also may affect the performance and life of peripheral components due to high heat. At the same time, the lower operating frequency limits the trend of miniaturization and lightweighting of the circuit, especially in portable electronic devices and high-density power modules, which is a significant shortcoming.

[0003] Therefore, seeking technical solutions to improve the efficiency and frequency of synchronous buck circuits and improve heat dissipation performance has become an urgent need in the industry. Utility Model Content

[0004] In order to solve the problems existing in the background technology, the utility model provides a synchronous buck circuit, comprising:

[0005] Input filter capacitor C1;

[0006] The switch tube Q1 is used to control the magnetization and discharge process of the energy storage inductor L1;

[0007] The synchronous tube Q2 cooperates with the switch tube Q1 to realize the energy transmission in the inductor L1 to the output end;

[0008] Inductor L1, used to store and transfer energy;

[0009] Output filter capacitor C2, C2 is connected in parallel to the output end to smooth the output voltage

[0010] A PWM controller is used to generate a PWM signal to control the on and off of the switch tube Q1 and the on and off of the synchronous tube Q2;

[0011] An input terminal, used for receiving input power;

[0012] An output terminal, used to provide power after voltage reduction processing;

[0013] The switch tube Q1 and the synchronous tube Q2 are both gallium nitride GaN field effect transistor MOSFET;

[0014] C1 is connected between the input power supply and Q1 for input ripple suppression;

[0015] Q1 and Q2 are connected in series with L1 respectively. Q1 controls the magnetization process of L1, and Q2 is turned on immediately after Q1 is turned off to release the inductor energy.

[0016] In a preferred solution, the synchronous tube Q2 is turned on when the switch tube Q1 is turned off, and the inductor L1 is discharged through Q2.

[0017] In a preferred solution, when the switch tube Q1 is turned on, the inductor L1 is magnetized, and the current increases linearly to charge the output capacitor C2.

[0018] The beneficial effects achieved by the utility model are:

[0019] First, the utility model uses gallium nitride GaN field effect transistor MOSFET as the switch tube Q1 and the synchronous tube Q2. Compared with the traditional silicon-based MOSFET, GaN MOSFET has lower on-resistance and switching loss, and has no internal diode, which effectively eliminates the diode loss, so that the efficiency of the entire circuit is significantly improved under the same working conditions, which can exceed 95%. This not only means higher energy conversion efficiency, but also directly reduces the loss of electrical energy converted into heat energy, thereby reducing the energy consumption of the system. The improvement of circuit efficiency and the reduction of heat generated reduce the requirements for the heat dissipation system, reduce or eliminate additional heat dissipation devices such as heat sinks or fans, simplify the thermal management of the system, and also reduce the heat dissipation burden and extend the service life of surrounding components.

[0020] Second, the high-speed switching characteristics of GaN MOSFET allow the circuit to operate at a higher frequency, beyond the range of 300K-1000K, improving the dynamic response capability of the power system, which is particularly beneficial for situations that require rapid load change response, such as high-performance computing and high-frequency communication equipment.

[0021] Third, the combination of high efficiency and high frequency operation enables the synchronous buck circuit to achieve the same power output in a smaller volume, thus improving the power density. This helps to achieve miniaturization and lightweight of electronic devices, especially for portable devices and space-constrained applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of the utility model. DETAILED DESCRIPTION

[0023] 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.

[0024] Reference Figure 1 , a synchronous buck circuit, including an input filter capacitor C1; a switch tube Q1, used to control the magnetization and discharge process of the energy storage inductor L1; a synchronous tube Q2, which cooperates with the switch tube Q1 to realize the energy transmission in the inductor L1 to the output end; the inductor L1 is used to store and transfer energy; an output filter capacitor C2, C2 is connected in parallel to the output end, and is used to smooth the output voltage. A PWM controller is used to generate a PWM signal, control the conduction and cutoff of the switch tube Q1, and the conduction of the synchronous tube Q2; the input end is used to receive the input power supply; the output end is used to provide the power supply after the voltage reduction process; the switch tube Q1 and the synchronous tube Q2 are both gallium nitride GaN field effect transistor MOSFET; C1 is connected between the input power supply and Q1, and is used for input ripple suppression; Q1 and Q2 are respectively connected in series with L1, Q1 controls the magnetization process of L1, and Q2 is immediately turned on after Q1 is turned off to realize the release of the inductor energy. The synchronous tube Q2 is turned on when the switch tube Q1 is turned off, and the inductor L1 is discharged through Q2. When the switch tube Q1 is turned on, the inductor L1 is magnetized, and the current increases linearly to charge the output capacitor C2.

[0025] Embodiment 1, in this embodiment, the core components of the synchronous buck circuit are input filter capacitor C1, gallium nitride (GaN) MOSFET switch tube Q1, synchronous tube Q2, energy storage inductor L1, output filter capacitor C2 and PWM controller. Among them, C1 and C2 use electrolytic capacitors or ceramic capacitors with low ESR values ​​to ensure good filtering performance; L1 selects a winding inductor of appropriate specifications according to the required output current and frequency characteristics; Q1 and Q2 use GaNMOSFET with low on-resistance and fast switching characteristics, such as enhanced HEMT (High Electron Mobility Transistor) structure.

[0026] C1 is connected between the input power supply and Q1 to suppress the input ripple; Q1 and Q2 are connected in series with L1, Q1 controls the magnetization process of L1, and Q2 is turned on immediately after Q1 is turned off to release the inductor energy; C2 is connected in parallel to the output end to smooth the output voltage. The PWM controller generates a control signal according to the preset duty cycle to accurately control the switching timing of Q1, and the conduction of Q2 is controlled by the dead time to avoid the shoot-through phenomenon.

[0027] By adjusting the PWM controller settings, such as frequency and duty cycle, the circuit efficiency, output ripple, and transient response can be optimized. The frequency should be selected taking into account the resonant characteristics of the inductor and capacitor to ensure maximum stability and efficiency.

[0028] For different power levels and application requirements, adjust in the following ways:

[0029] Frequency adjustment: PWM controller allows users to set the operating frequency through external resistors or digital interfaces, ranging from a few kHz to a few MHz, to meet the requirements of response speed and size in different application scenarios. High-frequency operation is suitable for products that require fast dynamic response and high integration.

[0030] Power level adjustment: By changing the capacity of inductor L1 and capacitors C1 and C2, and appropriately selecting the rated current and voltage of the switch tube, it can adapt to power requirements from a few watts to hundreds of watts or even kilowatts. In high-power applications, a multi-phase design may be required to disperse heat and current, using a set of Q1, Q2, L1 and C2 combinations for each phase.

[0031] Embodiment 2, this embodiment relates to heat dissipation and packaging. Considering the high efficiency characteristics of GaN MOSFET, although the heat generation of GaN devices themselves is reduced, in extremely high power density applications, heat sinks, heat pipes or liquid cooling systems are used to ensure long-term stable operation. Package selection: Use packaging materials with excellent thermal conductivity, such as ceramic packaging, to improve thermal management efficiency. At the same time, optimize the circuit board layout to ensure a good heat flow path and reduce heat accumulation.

[0032] 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 synchronous buck circuit, characterized in that: include: Input filter capacitor C1; The switch tube Q1 is used to control the magnetization and discharge process of the energy storage inductor L1; The synchronous tube Q2 cooperates with the switch tube Q1 to realize the energy transmission in the inductor L1 to the output end; Inductor L1, used to store and transfer energy; Output filter capacitor C2, C2 is connected in parallel to the output end to smooth the output voltage; A PWM controller is used to generate a PWM signal to control the on and off of the switch tube Q1 and the on and off of the synchronous tube Q2; An input terminal, used for receiving input power; An output terminal is used to provide power after voltage reduction processing; The switch tube Q1 and the synchronous tube Q2 are both gallium nitride GaN field effect transistor MOSFET; C1 is connected between the input power supply and Q1 for input ripple suppression; Q1 and Q2 are connected in series with L1 respectively. Q1 controls the magnetization process of L1, and Q2 is turned on immediately after Q1 is turned off to release the inductor energy.

2. The synchronous buck circuit according to claim 1, characterized in that: The synchronous tube Q2 is turned on when the switch tube Q1 is turned off, and the inductor L1 is discharged through Q2.

3. The synchronous buck circuit according to claim 1, characterized in that: When the switch tube Q1 is turned on, the inductor L1 is magnetized, and the current increases linearly to charge the output capacitor C2.

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