A high-current dc-dc step-down power supply module

Abstract

The utility model discloses a kind of large-current DC-DC step-down power supply module, including input terminal J1, for accessing external DC power supply;Self-restoring fuse F1, connect input terminal J1 with the VIN pin of step-down control chip, for providing overcurrent protection;Step-down control chip, for voltage conversion;Output terminal J2, for output current after step-down;Energy storage inductance L1, the SW pin of step-down control chip is connected with output terminal J2;Free-wheeling diode D2, parallel between energy storage inductance L1 and ground;Filter capacitor group, for inhibiting ripple;Voltage-dividing feedback resistance R1 and R3, for sampling output voltage and feedback to control loop.The utility model is realized overcurrent automatic reset protection by self-restoring fuse, utilizes voltage-dividing feedback network to realize output voltage dynamic regulation, and it is combined to inhibit broadband ripple interference with multistage filter capacitor group, effectively solve the problem that protection mechanism is unreliable in traditional scheme, voltage regulation precision is low, ripple suppression ability is weak.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and more specifically, to a high-current DC-DC step-down power supply module and its control circuit and status indication system. Background Technology

[0002] In high-current applications such as industrial automation control and communication base station power supply, traditional step-down power supply modules face numerous technical bottlenecks. Existing solutions generally suffer from low conversion efficiency, large output ripple, and slow dynamic response when dealing with a wide range of input voltages. Especially under a wide input voltage range of 8-24V, conventional designs often struggle to balance low-voltage startup performance with high-voltage operating stability.

[0003] In existing technologies, overcurrent protection for step-down power supply modules often relies on one-time-use fuses, requiring manual replacement after a failure, which severely impacts the continuous operation capability of the equipment. Regarding output voltage regulation, traditional solutions use fixed voltage divider resistor networks, which cannot achieve dynamic and precise adjustment of the output voltage. Furthermore, most modules lack intuitive status indicators, making it difficult for operators to promptly grasp the power supply's operating status.

[0004] Regarding ripple suppression, conventional designs typically employ a single capacitor filter, which is insufficient to effectively suppress wide-band interference. Especially under high current output, inductor saturation can exacerbate output voltage fluctuations. Feedback control loop designs also present a trade-off between response speed and stability, making them prone to output voltage drops or overshoots during rapid load switching.

[0005] To address the aforementioned issues, existing technologies urgently need improvement. Utility Model Content

[0006] The purpose of this invention is to provide a high-current DC-DC step-down power supply module and its control circuit and status indication system, which has the advantages of automatic overcurrent recovery protection, dynamic output voltage adjustment, wideband ripple suppression and visual monitoring of working status.

[0007] The above-mentioned technical objective of this utility model is achieved through the following technical solution:

[0008] A high-current DC-DC step-down power supply module, including

[0009] Input terminal J1 is used to connect an external DC power supply;

[0010] The self-resetting fuse F1 is connected to the input terminal J1 and the VIN pin of the buck control chip U2 to provide overcurrent protection;

[0011] The step-down control chip U2 is used for voltage conversion;

[0012] Output terminal J2 is used to output the stepped-down current;

[0013] The energy storage inductor L1 is connected to the SW pin of the step-down control chip U2 and the output terminal J2;

[0014] The freewheeling diode D2 is connected in parallel between the energy storage inductor L1 and ground;

[0015] The filter capacitor bank includes capacitors C1 and C2 at the input end and capacitors C7 and C8 at the output end, used to suppress ripple.

[0016] Voltage divider feedback resistors R1 and R3 are used to sample the output voltage and feed it back to the control loop.

[0017] Furthermore, the input and output terminals of the buck control chip U2 are equipped with bypass capacitors C3, C4, C5 and C6 to ensure the stability and loop response of the buck control chip U2.

[0018] Furthermore, it also includes an error amplifier circuit U1A, whose input is connected to voltage divider feedback resistors R1 and R3, and whose output is connected to the FB pin of the buck control chip U2, for dynamically adjusting the output voltage.

[0019] Furthermore, the error amplifier circuit U1A is provided with an enable control interface, which activates the buck control chip U2 to output to the status indicator unit when the external control signal V_Control≥4V.

[0020] The status indicator unit includes a power input indicator LED1 and an output / fault indicator LED2.

[0021] Furthermore, it also includes a current mirror detection circuit, which includes a transistor T1, whose first pin is connected to the input signal terminal J3, and whose second pin is connected to the FB pin of the buck control chip U2 for sampling the output current.

[0022] In summary, this utility model has the following beneficial effects:

[0023] Analysis revealed that voltage follower circuits built with discrete components cannot simultaneously meet the demands of a wide input voltage range and high current output, and their feedback control accuracy is insufficient. Further research showed that introducing a dedicated buck control chip can effectively improve conversion efficiency, and combining it with multi-stage filtering and closed-loop feedback control can achieve precise voltage tracking. Based on this, a design approach was developed with buck conversion as the core, supplemented by multiple protection and filtering features, aiming to construct a compact and stable power module.

[0024] Overcurrent automatic reset protection is achieved through a self-resetting fuse, dynamic adjustment of output voltage is achieved through a voltage divider feedback network, broadband ripple interference is suppressed by a multi-stage filter capacitor bank, and the working status is monitored in real time by a status indicator unit. This effectively solves the technical problems of unreliable protection mechanism, low voltage regulation accuracy, weak ripple suppression capability and lack of status monitoring in traditional solutions. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the high-current DC-DC step-down power supply module described in this utility model. Detailed Implementation

[0026] To make the technical means, creative features, objectives and effects of this utility model easier to understand, the present utility model will be further described below in conjunction with the illustrations and specific embodiments.

[0027] like Figure 1 As shown, this utility model proposes a high-current DC-DC step-down power supply module, comprising an input terminal J1, a resettable fuse F1, a step-down control chip U2, an output terminal J2, an energy storage inductor L1, a freewheeling diode D2, a filter capacitor bank, and a voltage divider feedback resistor. The input terminal J1 is connected to an external DC power supply. The resettable fuse F1 is connected in series in the input circuit. The step-down control chip U2 performs voltage conversion. The energy storage inductor L1 and the freewheeling diode D2 form a current freewheeling path. The filter capacitor bank is distributed at both the input and output terminals, and the voltage divider feedback resistor constitutes a voltage sampling network.

[0028] Among them, the self-resetting fuse F1 is an electronic component with automatic reset function after overcurrent protection. It can be implemented using a polymer positive temperature coefficient device, which limits the current through its own impedance change in the event of an overload, ensuring circuit safety. The buck control chip U2 is a voltage conversion device integrating a switching transistor and a drive circuit, which can be implemented using a pulse width modulation controller, controlling the output voltage by adjusting the duty cycle. The energy storage inductor L1 is an inductor element that stores magnetic field energy, maintaining the continuity of the load current during the switching cycle. The freewheeling diode D2 is a semiconductor device that provides a path for inductor discharge, which can be implemented using a Schottky diode, reducing voltage spikes during switching. The filter capacitor bank is a filter network composed of multiple capacitors, which can be implemented using a combination of electrolytic capacitors and ceramic capacitors, suppressing low-frequency and high-frequency ripple respectively. The voltage divider feedback resistor is a series-connected precision resistor network, which can be implemented using metal film resistors, accurately dividing the voltage and feeding it back to the control loop.

[0029] Specifically, after the external DC power supply is connected through input terminal J1, it undergoes overcurrent protection via resettable fuse F1, and then enters the buck control chip U2 for voltage conversion. Energy storage inductor L1 and freewheeling diode D2 work together to store energy when the switching transistor is on and release it when it is off to maintain load power. The input filter capacitor bank removes high-frequency power supply noise, while the output filter capacitor bank smooths the output voltage ripple. A voltage divider feedback resistor acquires the output voltage signal in real time and adjusts the duty cycle of the buck control chip U2 through closed-loop control to ensure that the output voltage accurately tracks changes in the input voltage. This architecture, through integrated control chip and optimized filtering network, achieves stable output over a wide voltage range.

[0030] Through the above technical solution, this application can maintain precise consistency between the output voltage and the input voltage within a wide input voltage range of 8-24V, while providing high drive current capability. Closed-loop feedback control effectively suppresses the impact of input voltage fluctuations on the output, and multi-stage filtering design significantly reduces output ripple. The integrated buck control chip U2, combined with optimized peripheral circuitry, achieves a compact circuit layout while ensuring performance, making it suitable for space-constrained industrial equipment applications.

[0031] This application further proposes to set bypass capacitors C3, C4, C5 and C6 at the input and output terminals of the buck control chip U2.

[0032] In this context, a bypass capacitor is an energy storage element connected in parallel between the power supply and ground. It can be implemented using ceramic or electrolytic capacitors and is used to absorb transient current fluctuations in the power supply line. Input bypass capacitors filter out high-frequency noise introduced by the input power line, providing a stable DC voltage for the internal circuitry of the chip. Output bypass capacitors suppress high-frequency ripple generated at switching nodes, maintaining the smoothness of the output voltage. Combinations of capacitors with different capacitance values ​​form a wideband filter network. Low-frequency capacitors store charge to cope with sudden load changes, while high-frequency capacitors respond quickly to transient current variations.

[0033] Specifically, bypass capacitors C3 and C4 at the input are connected in parallel between the power supply pin of the buck controller chip U2 and ground. This filters out high-frequency interference signals in the input circuit, preventing power fluctuations from affecting the chip's internal reference voltage. At the output, bypass capacitors C5 and C6 are connected in parallel between the switching node and ground to absorb voltage spikes generated by switching actions, reducing output ripple. This multi-capacitor parallel structure, through a combination of different capacitance values, maintains charge reserves in the low-frequency range using large-capacity capacitors and rapidly releases charge in the high-frequency range using small-capacity capacitors, forming complementary filtering characteristics. This design reduces high-frequency noise interference in the control loop, improves the purity of the voltage feedback signal, and thus enhances the loop's response speed and control accuracy.

[0034] Through the above technical solution, this application can effectively suppress high-frequency interference of input power supply and output switching noise, improve the dynamic response capability of control loop, ensure stable operation of buck control chip U2 under wide voltage input conditions, and avoid output voltage instability or loop oscillation caused by power supply fluctuations.

[0035] This application further proposes an error amplifier circuit U1A, whose input is connected to voltage divider feedback resistors R1 and R3, and whose output is connected to the FB pin of a buck control chip U2, for dynamically adjusting the output voltage.

[0036] In this circuit, error amplifier circuit U1A refers to an operational amplifier with differential input and single-ended output, used to compare the deviation between the actual output voltage and the target voltage. Voltage divider feedback resistors R1 and R3 are a resistor network connected in series between the output terminal and ground, used to proportionally reduce the output voltage to the input range of the error amplifier. The FB pin is the voltage feedback terminal of the buck control chip U2, specifically, it can establish a reference potential through an internal reference voltage source, used to receive external error signals to adjust the switching duty cycle. Dynamic output voltage adjustment refers to real-time correction of output parameters based on input voltage fluctuations and load changes, specifically achieved by changing the on-time of the PWM signal, used to maintain a strict following relationship between the output voltage and the input signal.

[0037] Specifically, the voltage divider feedback resistor proportionally attenuates the output voltage before inputting it to the inverting input of the error amplifier, where it is compared with a preset reference voltage at the non-inverting input. When the input voltage fluctuates within the range of 8-24V, the compensation voltage output by the error amplifier acts on the FB pin, forcing the buck converter chip to adjust the duty cycle of its switching frequency. This closed-loop control mechanism ensures that the output voltage always follows the input voltage changes, while actively adjusting the on-time of the power switch to compensate for the line voltage drop, thus maintaining the output current carrying capacity over a wide input voltage range. The introduction of the error amplifier replaces the fixed voltage divider network in the traditional open-loop structure, so that the voltage tracking accuracy is no longer limited by the resistor matching degree. At the same time, feedback control is achieved through a single-stage amplifier circuit, simplifying the circuit structure required to achieve high-precision tracking.

[0038] This solution requires only a single operational amplifier and voltage divider resistors to form a closed-loop control. Existing technologies limit the output current at low input voltages due to line impedance, while this solution actively compensates for voltage drop losses by dynamically adjusting the duty cycle, and simultaneously solves the problems of voltage tracking accuracy and output load capacity through single-stage closed-loop control.

[0039] This application further proposes that the error amplifier circuit U1A is equipped with an enable control interface. When the external control signal reaches the preset voltage threshold, the buck control chip U2 is activated to output to a status indicator unit, which includes a power input indicator LED1 and an output / fault indicator LED2.

[0040] The enable control interface refers to a logic trigger circuit based on a voltage comparator. Specifically, it can be implemented using a comparator with hysteresis characteristics. When the external control signal voltage exceeds a set threshold, an enable signal is generated to control the startup and shutdown of the buck control chip U2. This interface uses a threshold voltage as the activation condition to avoid unnecessary power consumption caused by false triggering.

[0041] The status indication unit is a visual feedback module composed of discrete light-emitting devices. Specifically, it can be implemented using a dual-color LED connected in series with a current-limiting resistor. The power input indicator LED1 is driven by detecting the on / off state of the input voltage, while the output / fault indicator LED2 is driven by monitoring the internal protection signal of the buck controller chip U2 or an abnormal output voltage state. This unit achieves separate monitoring of input and output states through independent circuit design.

[0042] Specifically, when the external control signal voltage reaches or exceeds 4V, the enable control interface outputs a high-level signal to the enable pin of the buck control chip U2, triggering the chip to enter the working state. At this time, the power input indicator LED1 lights up according to the input voltage status; it remains constantly lit if the input voltage is normal, and turns off if the input voltage is interrupted. The output / fault indicator LED2 monitors the output status of the buck control chip U2 in real time. When an overcurrent, short circuit, or overheating fault is detected, it switches to a red flashing mode; during normal operation, it remains constantly green. Through the coordinated operation of the two indicator lights, operators can directly determine whether the power input is normal and whether there are any abnormalities in the output.

[0043] Through the above technical solution, this application solves the problems of inability to dynamically control the output status and lack of visual feedback under a wide input voltage range, and realizes intelligent start-stop control and rapid fault location of the power module. Operators can directly identify the input power supply on / off status, output load working status, and fault types such as overcurrent and short circuit through the indicator light color and flashing pattern, and complete status diagnosis without the need for external testing equipment.

[0044] This application further proposes a current mirror detection circuit, which includes a transistor T1, whose first pin is connected to the input signal terminal J3 and whose second pin is connected to the FB pin of the buck control chip U2 for sampling the output current.

[0045] The current mirror detection circuit refers to a detection unit that achieves input-output current matching through the current mirroring characteristics of semiconductor devices. Specifically, it can be implemented using bipolar transistors (BPTs) or field-effect transistors (FETs), utilizing the base-emitter or gate-source current ratio to construct a mirror loop. Connecting the first pin of transistor T1 to the input signal terminal J3 directly introduces the input current signal into the control terminal of the semiconductor device. This can be achieved using a collector-drain connection, enabling real-time acquisition of the input signal through physical pins. Connecting the second pin to the FB pin of the buck converter chip U2 connects the mirrored current output to the voltage feedback control node. This can be implemented using metal wires or printed circuit board traces, using the reference voltage of the FB pin to constrain the transmission path of the mirrored current.

[0046] Specifically, the current mirror detection circuit establishes a correspondence between the input and output currents through the current mirroring characteristic of transistor T1. When the current at the input signal terminal J3 changes, the first pin of transistor T1 receives the current change signal, and the second pin synchronously generates a proportionally proportional mirror current. This mirror current is transmitted to the FB pin of the buck control chip U2. Due to the constant characteristic of the internal reference voltage of the FB pin, the mirror current is forced to maintain a strict match with the input current. By adjusting the resistance values ​​of the voltage divider resistors, the output voltage is made to linearly follow the input voltage, thereby eliminating the current detection error caused by traditional sampling resistors.

[0047] Through the above technical solution, this application effectively solves the problem of output voltage inaccuracy caused by insufficient current sampling accuracy over a wide input voltage range. It achieves accurate matching of input and output current through a lossless current mirroring mechanism, ensuring real-time tracking of the output voltage to the input voltage, while reducing system power consumption and improving response speed.

[0048] In this document, the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inner", "outer", "vertical", and "horizontal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the purpose of clarifying the technical solution and for the convenience of description, and therefore should not be construed as limiting the present utility model.

[0049] In this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, which includes not only the elements listed but also other elements not expressly listed.

[0050] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A high-current DC-DC step-down power supply module, characterized in that, include Input terminal J1 is used to connect an external DC power supply; The self-resetting fuse F1 is connected to the input terminal J1 and the VIN pin of the buck control chip U2 to provide overcurrent protection; The step-down control chip U2 is used for voltage conversion; Output terminal J2 is used to output the stepped-down current; The energy storage inductor L1 is connected to the SW pin of the step-down control chip U2 and the output terminal J2; The freewheeling diode D2 is connected in parallel between the energy storage inductor L1 and ground; The filter capacitor bank includes capacitors C1 and C2 at the input end and capacitors C7 and C8 at the output end, used to suppress ripple. Voltage divider feedback resistors R1 and R3 are used to sample the output voltage and feed it back to the control loop.

2. The high-current DC-DC step-down power supply module according to claim 1, characterized in that, The input and output terminals of the buck control chip U2 are equipped with bypass capacitors C3, C4, C5 and C6 to ensure the stability and loop response of the buck control chip U2.

3. The high current DC-DC buck power supply module of claim 1, wherein, It also includes an error amplifier circuit U1A, whose input is connected to voltage divider feedback resistors R1 and R3, and whose output is connected to the FB pin of the buck control chip U2, for dynamically adjusting the output voltage.

4. The high current DC-DC buck power supply module of claim 3, wherein, The error amplifier circuit U1A is equipped with an enable control interface. When the external control signal V_Control≥4V, the buck control chip U2 is activated and outputs to the status indicator unit. The status indicator unit includes a power input indicator LED1 and an output / fault indicator LED2.

5. The high-current DC-DC step-down power supply module according to claim 1, characterized in that, It also includes a current mirror detection circuit, which includes a transistor T1, whose first pin is connected to the input signal terminal J3 and whose second pin is connected to the FB pin of the buck control chip U2 for sampling the output current.

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