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Infineon touts 900V superjunction MOSFETs

Posted: 05 Mar 2008     Print Version  Bookmark and Share

Keywords:CoolMOS superjunction MOSFET  SMPS 


Infineon Technologies AG has introduced what it claims as the industry's first 900V superjunction MOSFETs designed for high-efficiency switched-mode power supply (SMPS), industrial and renewable energy applications.

The energy-saving CoolMOS 900V power MOSFET family overcomes the "silicon limit" in power transistor manufacturing, and provides an alternative for high-voltage designs using standard Transistor Outline (TO) packages. With extremely low static and dynamic losses, the CoolMOS 900V family enables design of more efficient and cost-effective topologies for such applications as LCD TVs, solar power generation systems, PC "silverbox" power supplies and lighting systems.

The Infineon CoolMOS family of power transistors uses an innovative technology approach to overcome the silicon limit, a characteristic of MOSFET semiconductors in which doubling of voltage blocking capability leads to a five-fold increase in Rds(on) (on-state resistance). In overcoming the silicon limit, the CoolMOS 900V devices achieve the industry's lowest Rds(on) per package type. On-state resistances of 0.12Ω in a TO-247 package, 0.34Ω in a TO-220 package and 1.2Ω in D-PAK packages are at least 75 percent lower than can be achieved in such packages using conventional 900V MOSFETs. Because of the low Rds(on), the CoolMOS 900V devices can offer an FOM (figure-of-merit, calculated as on-state resistance times gate charge) as low as 34Ω*nanocoulomb, which results in extremely low conduction, driving and switching losses, and leads to increased efficiency.

Efficeint power designs
The combination of high blocking voltage with low conduction and switching losses in the CoolMOS 900V family enables designers to develop more efficient power system topologies for a wide range of applications.

For example, quasi-resonant flyback designs for LCD TV power supplies can benefit from a higher flyback voltage, which provides a longer primary duty cycle with reduced peak current, true zero-voltage switching and significantly lower voltage stress on the secondary side. Because of their very low on-resistance, a single CoolMOS 900V products in a TO-220-FP package can be used in such a design, rather than the two or more TO-220-FP packages that must be used with conventional 900V MOSFETS. Compared to the most common solution today, which uses 600V MOSFETs, a CoolMOS 900V solution gives a premium efficiency of more than 0.5 percent.

CoolMOS 900V devices can be used to design "silverbox" PC power supplies with a single-transistor forward (STF) topology, achieving the required high output power while still being compliant with the "80 PLUS program," an industry initiative to ensure that PC power supplies are at least 80 percent efficient. The STF topology is easier to design, and has a simplified driver stage and reduced parts count, resulting in cost improvements without efficiency disadvantages, compared to such other solutions as two-transistor-forward topologies.

In solar power-generating systems, more photovoltaic converter panels can be placed in series instead of in parallel connection, if the MOSFET voltage hits 900V. The series connection reduces cabling power losses and costs, with cabling costs alone cut by a factor of two when changing from 600V to 900V devices.

The CoolMOS devices also allow improved design of Power Factor Correction (PFC) supplies and lighting ballasts, because they permit designers to accept a higher DC link or input voltage. For example, high-power applications that use three-phase PFC and PWM stages with DC link voltages of up to 750V will see such benefits as higher power density from having the industry's lowest Rds(on) in a small package, such as the TO-247.

Ballast designs for lamps that are fed from a three-phase mains supply, such as special discharge lamps used in comfort lighting and electronic lamp ballasts for street lights and greenhouse heating lamps, will also benefit from topologies based on the CoolMOS 900V family.

CoolMOS 900V family members will be available in several industry-standard packages, including devices with Rds(on) of 120mΩ, 340mΩ and 1,200mΩ in TO-247, TO-220, TO-220FP and D-PAK packages, respectively. In addition, 500mΩ, 800 mΩ and 1000 mΩ devices will be available.

Samples of the 340mΩ device in TO-220, TO-220FP and TO-247 packages, and of the 1,200mΩ part in a D-PAK, are available now. The volume price for a 120mΩ part in a TO-247 package will be below Rs.138.17 ($3.50).

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