A large-current buck converter supporting single-channel and double-channel output automatic switching and a control method thereof

Abstract

This invention discloses a high-current BUCK converter and its control method that support automatic switching between single-channel output and dual-channel parallel output. The BUCK converter includes a first output channel, a second output channel connected in parallel with it, and a control module. The control module acquires the load state by collecting inductor current signals and automatically controls the enabling or disabling of the second output channel according to the load size, thereby adaptively switching between single-channel output mode and dual-channel parallel output mode. Under light or medium load conditions, only the first output channel is enabled to reduce static power consumption and drive losses; under heavy load conditions, the first and second output channels are connected in parallel to share the output current and reduce current stress on power devices. This invention can also combine PFM and PWM modulation methods and suppress mode jitter through hysteresis control, thereby achieving high-efficiency and high-reliability power conversion over a wide load range, suitable for high-current power management chip applications.

Description

Technical Field

[0001] This invention belongs to the field of power management integrated circuit technology, specifically relating to a DC / DC step-down power converter, and more particularly to a high-current BUCK converter and its control method that supports automatic switching between single-channel output and dual-channel parallel output. Background Technology

[0002] BUCK-type DC-DC converters are widely used in consumer electronics, communication equipment, industrial control, and automotive electronics due to their high efficiency, stable output, and mature structure. As the integration of electronic systems continues to increase, load current demands are exhibiting a wide range of variations from light to heavy loads, placing higher demands on power management chips to maintain high efficiency and reliability across this broad load range.

[0003] In existing technologies, fixed multiphase or multi-parallel BUCK converter structures are typically used to meet high current output requirements. However, such structures still require multiple output channels to operate under light or medium load conditions, leading to increased conduction and drive losses, thus reducing light-load efficiency and increasing static power consumption. Conversely, while BUCK converters with a single output channel have higher efficiency under light load conditions, they are prone to problems such as power transistor current stress concentration and significantly increased conduction losses under heavy load conditions, making it difficult to balance efficiency and output capability over a wide load range.

[0004] Therefore, there is an urgent need for a BUCK converter solution that can automatically adjust the number of output channels according to the load condition, so as to achieve low power consumption operation and high current output under light load and heavy load conditions respectively, thereby improving overall energy efficiency and system adaptability. Summary of the Invention

[0005] The purpose of this invention is to provide a high-current BUCK converter and its control method that support automatic switching between single and dual channels. By automatically controlling the on / off state of the output channel according to the load condition, it can achieve high-efficiency operation over a wide load range and effectively reduce the conduction loss of power devices.

[0006] To achieve the above objectives, this invention provides a high-current BUCK converter that supports automatic switching between single-channel output and dual-channel parallel output, comprising: an input terminal for receiving an external input voltage; an output terminal for providing a stable output voltage to a load; a first output channel connected between the input terminal and the output terminal for providing output current to the load under light and medium load conditions; a second output channel connected in parallel with the first output channel between the input terminal and the output terminal, controlled by a separate enable signal, and only activated under heavy load conditions to jointly provide output current to the load; and a control module connected to both the first and second output channels for acquiring current information reflecting the load state and controlling the enabling or disabling of the second output channel according to the load state, thereby achieving automatic switching between single-channel output mode and dual-channel parallel output mode. Both the first and second output channels include power switching transistors and their corresponding drive circuits, and the specific topology of the output channels is not limited.

[0007] Based on the aforementioned BUCK converter, this invention also provides a control method for a high-current BUCK converter that supports automatic switching between single-channel and dual-channel operation, comprising the following steps: Step 1: Acquire the inductor current signal of the BUCK converter to obtain current information reflecting the current load size; Step 2: Compare the current information with a preset load threshold to determine the load range of the current load; Step 3: When the load is determined to be in a light or medium load range, control the BUCK converter to operate in single-channel output mode (light load PFM control mode, medium load PWM control mode), making only the first output channel work; Step 4: When the load is determined to be in a heavy load range, control the BUCK converter to operate in dual-channel output mode, making the first and second output channels work simultaneously and output current in parallel to the load.

[0008] Through the above steps, the number of output channels of the BUCK converter is adaptively adjusted. Compared with the prior art, the present invention has at least the following beneficial effects: 1. Under light and medium load conditions, only the first output channel is activated, effectively reducing static power consumption and drive loss, and improving light load efficiency; 2. Under heavy load conditions, the first output channel and the second output channel are connected in parallel, reducing the current stress and conduction loss of individual power devices and improving the high current output capability; 3. Automatic mode switching can be achieved over a wide load range without manual intervention, improving system operating efficiency and reliability; 4. It is suitable for power management chip application scenarios with wide input voltage and high current loads, and has good engineering practical value. Attached Figure Description

[0009] Figure 1 is a structural block diagram of the high-current BUCK converter that supports automatic switching between single and dual channels according to the present invention;

[0010] Figure 2 is a schematic diagram of the BUCK converter described in this invention in single-channel operating mode (medium load);

[0011] Figure 3 is a schematic diagram of the BUCK converter described in this invention in dual-channel operating mode (heavy load);

[0012] Figure 4 is a flowchart illustrating the control method described in this invention. Detailed Implementation

[0013] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0014] Example 1: BUCK converter structure with single and dual output channels in parallel

[0015] The BUCK converter includes: 1. A Power Loop: This module provides the voltage reference, current reference, and clock for the entire chip. 2. A Control Loop: This includes an EA (Electronic Array Controller), a PWM comparator, two sets of Logic & Driver circuits, two sets of Power stages, resistor R4, and capacitors C4 and C5. The positive input of the EA comparator is connected to Vref, the negative input to Vfb, and the output to the positive input of the PWM comparator. The EA comparator compares the feedback voltage Vfb provided by the external circuit with the Vref provided by the Power Loop, acquiring real-time changes in the output voltage. One end of R4 is connected to the output of EA, and the other end is connected to one end of C4. The other end of C4 is connected to ground. One end of C5 is connected to the output of EA, and the other end is connected to ground. R4, C4, and C5 together provide frequency compensation for EA and also serve as the dominant poles of the entire circuit, giving the circuit good frequency characteristics. The output of the EA comparator is connected to the positive input of the PWM comparator, and the negative input of the PWM comparator is connected to the Sensor module. The two are compared in the PWM comparator to generate a PWM wave. Its output is connected to the input of the Logic & Driver module as the reference for generating control logic. After generating control logic, the output of the Logic & Driver module is connected to the input of the Power stage module to control the on / off state of the upper and lower power transistors. 3. Sensor Module: Includes Current Sense and Mode Control. The input of the Current Sense module is connected to the connection point between inductor L and the Power stage module. Its output is connected to the input of the Mode Control module and the negative input of the PWM module. The output of the Mode Control module generates a control signal to control the opening and closing of the two output channels. 4. Output Circuit: Diode D1, capacitor C1, and inductor L1 constitute the first output channel. L1 serves as the power inductor of the first output channel and is connected to one of the Power stage outputs in the control loop. D1 and C1 form a bootstrap circuit. The anode of D1 is connected to VDD5V provided by the Power loop, and the cathode is connected to C2. The other end of C2 is connected to the first output channel. The second output channel has the same structure as the first output channel, consisting of diode D2, capacitor C2, and inductor L2. The two channels are connected in parallel to VOUT at the output terminals of power inductors L1 and L2, and are jointly connected to the load. Both the first and second output channels include an upper power switch and a lower power switch, which can be a MOSFET, DMOS, or other equivalent power device. 5. Peripheral circuit: includes resistors R1, R2, and R3 and capacitor C2. R1 and R2 serve as feedback voltage acquisition resistors, connected from the total output terminal to R1, then to R2, and finally to ground. The connection point of R1 and R2 is connected to the negative input terminal of the EA module in the control loop.One end of resistor R3 is connected to VOUT, and the other end is connected to ground. One end of capacitor C2 is connected to VOUT, and the other end is connected to ground. R3 acts as a load, and C2 acts as a filter capacitor. At the same time, R3 and C2 together provide frequency compensation for the entire circuit, optimizing the frequency characteristics of the circuit.

[0016] The circuit structure diagram is shown below under light and medium load conditions. Figure 2 As shown, the control module outputs the enable signal EN_PWM_1, which only turns on the first output channel, while the second output channel remains off. This reduces drive and conduction losses. The enable signal EN_PWM_1 enables the Logic & Driver 1 module to drive the Power stage 1 module and connect it to the power inductor L1 to form the first output channel. Under heavy load conditions, the circuit structure diagram is as follows: Figure 3 As shown, that is, in Figure 2 Based on this, while keeping the first channel open, the control module enables the Logic & Driver 2 module with the EN_PWM_2 signal to drive the Power stage 2 module and connect it to the external inductor L2 to form the second output channel, so that the first output channel and the second output channel work in parallel to share the output current and reduce the current stress of individual power devices.

[0017] Example 2: Load Detection and Mode Determination Based on Inductor Current

[0018] The SENSOR module includes an inductor current sampling unit and a mode control unit. The inductor current sampling unit is used to acquire the inductor current signal from a first output channel or a second output channel. This inductor current signal can be a peak current, average current, or an equivalent representation. Figure 4 As shown, the mode control unit compares the acquired current signal with a preset load threshold to determine the current load state. When the inductor current is less than the first threshold, the load is determined to be in the light load range; when the inductor current is between the first and second thresholds, the load is determined to be in the medium load range; when the inductor current is greater than the second threshold, the load is determined to be in the heavy load range. When the mode control unit determines that the load is in the light or medium load range, it outputs the enable signal EN_PWM_1, putting the circuit in single-output mode; when the mode control unit determines that the load is in the heavy load range, it keeps the enable signal EN_PWM_1 unchanged and simultaneously outputs the enable signal EN_PWM_2, enabling the second output channel to work in parallel with the first output channel, at which point the circuit is in dual-output mode.

[0019] Example 3: Mode switching control with hysteresis characteristics

[0020] To prevent frequent output channel switching caused by load current fluctuations around a threshold, the control module further includes hysteresis control logic. When switching from single-channel to dual-channel operating mode, a first switching threshold is used; when switching from dual-channel to single-channel operating mode, a second switching threshold lower than the first switching threshold is used. By setting the hysteresis range, mode jitter can be effectively suppressed, improving system stability and output voltage continuity.

[0021] Example 4: Optional Implementation of Control Modulation Method

[0022] The BUCK converter can employ pulse frequency modulation (PFM) under light load conditions, PWM under medium load conditions, and dual-channel parallel output under heavy load conditions, thereby further improving the conversion efficiency over a wide load range. The switching between single-channel and dual-channel operating modes can be coordinated with the modulation mode switching, or they can be implemented independently.

[0023] Example 5: Integrated Circuit Implementation

[0024] The BUCK converter is implemented as a single chip, with the first output channel, the second output channel, the control module, and the protection circuit all integrated within the same semiconductor chip. The semiconductor chip can be implemented using BCD technology, CMOS technology, or other semiconductor technologies suitable for power integration.

[0025] The BUCK converter also integrates overcurrent protection, overtemperature protection, undervoltage lockout, and zero-crossing detection modules to improve system safety and reliability.

[0026] In summary, by introducing an automatic output channel switching mechanism based on load status, this invention enables the BUCK converter to operate in low-power single-channel mode under light load conditions and provide high-current output in dual-channel parallel mode under heavy load conditions. It achieves a balance between efficiency and output capability over a wide load range and has good application prospects.

Claims

1. A high-current BUCK converter supporting automatic switching between single-channel output and dual-channel parallel output, characterized in that, include: The input terminal is used to receive external input voltage. The output terminal is used to provide a stable output voltage to the load. The first output channel is connected between the input terminal and the output terminal and is used to provide output current to the load; The second output channel is connected in parallel with the first output channel, between the input and output terminals. The control module is connected to both the first and second output channels to acquire current information reflecting the load status and to control the enabling or disabling of the second output channel according to the load status, thereby achieving automatic switching between single-channel output mode and dual-channel parallel output mode. Under light or medium load conditions, only the first output channel is enabled; under heavy load conditions, the first and second output channels are enabled to output in parallel to share the output current.

2. The BUCK converter according to claim 1, characterized in that: The first and second output channels each include an upper power switch, a lower power switch, and a corresponding gate drive circuit, forming a synchronous rectification BUCK converter topology. The control module includes an inductor current sampling unit for acquiring the inductor current signal of the first and / or second output channels, wherein the inductor current signal is a peak current, an average current, or an equivalent representation thereof. The control module further includes a load determination unit for comparing the inductor current signal with at least one preset load threshold to determine whether the current load is in a light load range, a medium load range, or a heavy load range. The control module includes hysteresis control logic, which uses a first switching threshold when switching from a single-channel output working mode to a dual-channel parallel output working mode, and uses a second switching threshold lower than the first switching threshold when switching from a dual-channel parallel output working mode to a single-channel output working mode, to avoid frequent switching of working modes. The BUCK converter uses PFM mode under light load conditions, PPWM mode under medium load conditions, and PWM mode under heavy load conditions, enabling dual-channel parallel output.

3. A control method for controlling a BUCK converter as described in claim 1, characterized in that, Includes the following steps: The inductor current signal of the BUCK converter is acquired to obtain current information reflecting the current load size; the current information is compared with a preset load threshold to determine the load range of the current load; when the load is in the light load or medium load range, the BUCK converter is controlled to operate in single-output mode, making only the first output channel work; when the load is in the heavy load range, the BUCK converter is controlled to operate in dual-parallel output mode, making the first output channel and the second output channel work simultaneously.

4. The control method according to claim 3, characterized in that: During the switching process between single-output mode and dual-parallel output mode, a hysteresis interval is introduced to suppress mode jitter caused by load current fluctuations.

5. The control method according to claim 3, characterized in that: The BUCK converter is integrated as a single chip and manufactured using BCD, CMOS, or other power integration processes.

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