From Scenarios to Numbers: First Understand the Difficulties of Low-Voltage High-Current

In scenarios such as industrial control, power tools, and new energy vehicle on-board systems, power supply requirements with 3.3V input and 24V/600W output are becoming increasingly common. However, behind these parameters, the biggest headache for engineers lies in current. To achieve a 600W power output, the theoretical input current under 3.3V input is approximately 182A, and considering circuit losses, the actual current may exceed 200A. What does this mean? The current for ordinary household electricity is only about a dozen amps, while this power supply needs to handle a current intensity equivalent to that of more than a dozen households using electricity simultaneously.

The challenges brought by high current are straightforward: the PCB board needs to have copper foil of at least 30mm in width and 2oz in thickness to carry such a large current; the on-resistance loss of the MOSFET will rise sharply as the current increases, and the efficiency may drop below 85%; if the thermal design is slightly improper, components will be damaged due to overheating.

Limitations of Traditional Solutions: Why Can’t the BOOST Topology Withstand It?

When facing high current, many engineers first think of using the traditional BOOST topology. This topology has a simple structure and mature control, making it a common solution for low-voltage boost conversion. However, under 200A current, its shortcomings will be infinitely amplified.

A single MOSFET can hardly meet the 200A current requirement. If a 100A MOSFET is selected, 3-4 of them usually need to be connected in parallel to meet the current requirement of more than 200A. But parallel connection will lead to current sharing issues—uneven current distribution easily causes individual MOSFETs to be overloaded; inductors suitable for high current are also difficult to select, requiring special inductors wound with copper strips, which are large in size and high in cost, and will further reduce efficiency due to copper loss; even if component issues are solved, the total loss may still exceed 100W, and the volume of the heat sink will account for a large proportion of the total volume of the power supply.

Breakthrough Paths

1. Multi-Phase Parallel Connection: Split High Current into Low Current

The core logic to solve the high-current problem is to disperse current stress. Using a multi-phase BOOST parallel solution to split 200A into 4 channels of 50A, with each channel controlled independently, can simplify the problem.

Multi-phase parallel connection has three obvious advantages: each channel only needs to handle 50A current, making MOSFET selection easier; through phase interleaving control, the input and output ripple can be significantly reduced, and the volume of the filter can be halved; if one channel fails, other channels can automatically share the current, improving system reliability.

In terms of component selection, the MOSFET is the key. MOSFETs optimized for low-voltage high-current scenarios have low on-resistance, which can effectively reduce losses, and high consistency, which can solve the current sharing problem during parallel connection. For example, Heketai’s HKT series MOSFETs, with D2PAK packaging that has good thermal conductivity, have low temperature rise under 50A current and do not require additional heat sinks.

2. Architecture Reconstruction: Change from Boost to Buck

If the application scenario allows (e.g., battery-powered systems), reconstructing the system architecture is a more thorough solution. By connecting multiple 3.3V batteries in series, the input voltage can be increased to 26.4V, and at this point, the input current for 600W output is only about 23A.

After the voltage is increased, the topology can be changed from boost to buck. The buck topology has higher efficiency under the same power, and the reduced current also simplifies component selection, PCB design, and thermal management. However, this solution requires handling the management of series-connected batteries and is only suitable for battery-powered scenarios.

Pitfall Avoidance Guide for Thermal Management and PCB Layout

Regardless of which solution is selected, thermal management and PCB layout are the final lines of defense.

When laying copper on the PCB, prioritize increasing the copper foil area of the MOSFET drain to at least 10 cm², and then drill 3-5 thermal vias to connect to the inner-layer ground copper foil, transferring heat to the entire PCB; during multi-phase parallel connection, MOSFETs should be arranged symmetrically to ensure consistent current path lengths and reduce current sharing errors; if space permits, a 0.5mm thick thermal pad can be attached above the MOSFETs and connected to the metal case to further reduce temperature rise.

For low-voltage high-current requirements such as 3.3V to 24V/600W, Heketai provides suitable MOSFETs and technical support. The HKT series MOSFETs, with their characteristics of low on-resistance and high consistency, can solve the core problems of multi-phase parallel connection; at the same time, Heketai can also provide tools such as thermal simulation reports and PCB layout guides to help engineers quickly implement solutions.

Conclusion

The challenge of converting 3.3V to 24V/600W essentially lies in balancing current stress and system efficiency. The solution is either to disperse current through multi-phase parallel connection or to reduce current by reconstructing the architecture—and selecting the right components can make this balance much easier. Heketai’s HKT series MOSFETs, with their low-loss and high-consistency characteristics, serve as a bridge to solving low-voltage high-current problems. If you are also facing similar low-voltage high-current design challenges, you may try starting with current dispersion or architecture reconstruction, and then matching them with appropriate components; the problem might then be solved smoothly.

Company Introduction

Founded in 1992, Heketai is a high-tech enterprise specializing in electronic components, integrating R&D, design, production, and sales. It is also recognized as a "Zhuan Jing Te Xin" enterprise (a Chinese government designation for enterprises focusing on specialized, refined, characteristic, and innovative development). The company focuses on providing cost-effective component supply and customized services to meet the R&D needs of enterprises.

Product Portfolio

• Covers semiconductor packaging materials, passive components (such as resistors, capacitors, and inductors);
• Includes active and power devices: MOSFETs, TVS diodes, Schottky diodes, Zener diodes, fast recovery diodes, bridge rectifiers, diodes, transistors, and power devices;
• Also offers power management ICs and other products, enabling one-stop procurement for R&D and production needs.

Two Intelligent Manufacturing Centers

• South China Manufacturing Center (Huizhou) : Covers 75,000 m²;
• Southwest Manufacturing Center (Nanchong) : Covers 35,000 m²;
• Equipped with over 3,000 sets of advanced equipment and testing instruments in total.
• In 2024, 3 new semiconductor material subsidiaries were established to control production capacity and delivery efficiency from the source.

Packaging and Testing OEM Services

• Supports custom sample production and small-batch trial production;
• Backed by more than 100 patented technologies and certified management systems (ISO9001, IATF16949), ensuring the "quality first" principle is implemented in every link from R&D to delivery.

Adhering to the core values of "Customer-Centric, Innovation-Driven", Heketai is committed to providing stable and reliable components for enterprises.

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Sales Hotline: 18823438533 (WeChat ID: same as the phone number)Company Tel: 0755-82565333Email Address: hkt@heketai.com

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