New MOSFET Technology Accelerates Greening of Electronic Products

In the "greening" of modern electronic products, many seemingly tiny components have played a huge role. With the improvement of the process, every 1% improvement in efficiency means that more power and heat can be saved. From computers to servers and even base stations, the “greening” of the power system is accelerating.

Recently, MOSFET suppliers Fairchild and NXP Semiconductors have announced breakthroughs in the structure and process of low- and medium-voltage MOSFETs, effectively reducing the MOSFET's on-resistance (RDSon) and further reducing conduction losses.

"The efficiency is particularly important for applications that never shut down, such as server or telecom equipment power supplies," said Chen Jianzhong, senior product director at Fairchild Semiconductor. Fairchild earlier released the FDMS86500L, a 60V MOSFET product using its proprietary Shielded Gate technology, which achieves an on-resistance as low as 2.5mΩ in a 5x6mm Power56 package.

To improve the efficiency of these power supplies, the key is to reduce the on-resistance to reduce conduction losses; the Other key is to reduce the switching noise. The on-resistance of the MOSFET is related to the temperature. The higher the temperature is, the higher the on-resistance is. The two factors affect each other and form a vicious cycle. Therefore, reducing the on-resistance is a key factor for the MOSFET to drive high-efficiency power supply design.

Therefore, the challenge for next-generation MOSFETs for energy-saving applications is to reduce conduction loss while also taking into account other parameters, including lower conduction losses, and lower heat dissipation. In addition, due to the lower switching noise, the Qgd (or Cgd) that can be effectively reduced using the Shielded Gate technology is also used.

"Conceptually, as long as the voltage and current meeting time is shortened, the switching noise can be reduced," said Chen Jianzhong. Shielded Gate technology and traditional channel technology can reduce the intersection time by an average of 50% compared to the traditional channel technology, thus achieving lower switching noise, and even more than 50% reduction compared to traditional technology.

Fairchild's low- and medium-voltage MOSFETs are targeted at applications such as servers, telecommunications power supplies, LED lighting, and power tools. Chen Jianzhong pointed out that in these applications, there are several applications that have very high performance and efficiency requirements, such as server or base station power supplies, which are never shut down, and require high heat dissipation, efficiency, and reliability. Therefore, these markets are The requirements are particularly stringent. In addition to energy saving and environmental protection, such applications also need to save electricity, so the efficiency of power supply design must be improved.

For example, a server rack contains approximately four power supplies, each with a power of 2 kWh, which equals a server rack containing 8 kWh of power. This year, the number of servers worldwide is expected to reach 8.7 million, and the power and electricity costs are astonishing.

The FDMS86500L can achieve approximately 1% more efficiency in server cabinet applications. Each power supply converts approximately 20 W of power per hour, which means that each server cabinet can save 700,800 W per year. On average, each server rack can save $105 in electricity bills per year, and with 1 million server racks, the annual savings can reach $114,318,000.

However, in addition to servers and telecommunications equipment, the electronics industry has more innovative applications that require energy-efficient power supply designs. “In the future, there are several trends that will affect semiconductor design and applications in the electronics industry, including healthcare applications, security controls, mobile device interconnection, and energy-efficient devices.” Simon McLean, Vice President of Global Marketing, NXP Standard Products Division Say.

In particular, energy-saving equipment, McLean stressed that the future "green" concept in addition to emphasizing the product's recyclable features, but also must be added to the product design process to reduce the product's power consumption concept, in order to achieve real energy-saving goals.

Based on its past experience in the automotive field, NXP has introduced its NextPower series of Power MOSFET products into the computing, consumer and embedded markets. We hope to expand its NextPower market through the automotive industry's extreme emphasis on stability and performance.

"Encapsulation is a big feature of our products." McLean said, "NXP's LFPAK uses copper wire instead of normal wire. This package has the same footprint as many other similar products in the industry, allowing customers to have more The flexibility of choice, but the performance in welding, pressure, and other traditional packaging technology."

The LFPAK copper wire is exposed and is not placed in the package. The copper wire of the general PowerSO8 is located inside the package, but according to NXP, this design will make the copper wire vulnerable to damage due to PCB thermal or mechanical stress. In comparison, LFPAK is less likely to have such problems.

NXP stated that customers often choose multiple supply sources for factors such as price and supply stability. Therefore, ensuring the compatibility of packages makes LFPAK more competitive. The Power-SO8/LFPAK package used in its product line is compatible with many similar products in the industry, including Infineon's SuperSO8, Fairchild's Power 56, Vishay's PowerPak SO8, NEC's HVSON-8, and ST's PowerFlat 6x5. And Renesas LFPAK and so on.

NextPower is based on NXP's Trench 6 trench technology. However, it also uses another Superjunction technology to create deeper trenches. This allows the component to have lower on-resistance but faster switching frequency. "Usually, to reduce the on-resistance, it must be at the expense of other parameters, and NextPower is to try to keep each parameter in a better state." McLean said.

In general, when the on-resistance decreases, the switching speed also becomes slower. "These MOSFETs improve performance by achieving a balance between six key parameters," said McLean. These parameters include low on-resistance, lower Qoss, low Miller charge (Qgd), safe operating area (SOA), low gate charge (Qg), and rated junction temperature (Tj(max)).

The lower Qoss helps to reduce the losses between the drain and source pins. When the voltage at the output pin changes, it helps to reduce the energy loss in the output capacitor (Coss). Low Qgd helps reduce switching losses and high frequency switching times; better SOA means overload and fault conditions are tolerated; low Qg reduces losses in gate drive circuitry; and good (Tj(max)) allows LFPAK Packaged components can be adapted to harsh application environments.

NXP's NextPower part uses the capacity of the Global Foundries Singapore plant, but the proportion is not high, only about 10%. According to reports, NXP and Global Foundries have signed exclusive contracts. The equipment used to produce NXP components in the GlobalFoundries Singapore factory is purchased by NXP. Therefore, NXP ensures that it has priority in all cases. In addition, product assembly and testing were conducted at NXP's own plant in the Philippines.

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