Second Generation of STMicroelectronics MDmesh High-Voltage Power MOSFET Technology Increases Efficiency in Power Converters

MDmesh II devices cut on-resistance by up to 40%, increasing efficiency and system reliability and significantly reducing costs.

Geneva / 07 Jun 2005

Geneva, June 7, 2005 – STMicroelectronics (NYSE: STM), one of the world’s leading power semiconductor manufacturers, has introduced the first devices built using the second generation of the Company’s proprietary MDmesh™ high-voltage power MOSFET technology. Particularly suited to SMPS (Switch Mode Power Supplies), Power Factor Correction (PFC) and power adapters, the new devices offer significantly greater efficiencies than the first generation MDmesh products, enabling substantial cost reductions and increased system reliability in new power-converter designs.

The outstanding performance of ST’s MDmesh (Multiple Drain Mesh) technology is due to an innovative drain structure in which the drain is implemented as an array of partitions, with vertical p-type strips, as extension of the body, aligned with the thin, horizontal n-type source strips. In addition to the very low ON-resistance, this drain structure results in excellent dV/dt and avalanche characteristics. In the new generation of MDmesh technology, MDmesh II, further enhancements of the p-strip array have delivered a reduction of up to 40% in the RDS(ON) resistance value compared to the previous MDmesh generation, without sacrificing tight control of its temperature dependence. At the same time, further optimization of the gate finger and oxide layer in the overlaid horizontal source strips ensures perfect control of the internal gate resistance and intrinsic capacitances.

In addition to the substantial reduction in ON-state losses, the new devices also achieve lower switching losses. A controlled gate internal resistance results in reduced delay times and, in consequence, the faster switching times demanded for new, higher-efficiency SMPS designs. In addition, tightly controlled intrinsic capacitances guarantee low crossover time and a low gate charge, resulting in remarkable improvements in SMPS efficiency through simpler and cheaper gate drive circuitry. For example, the new STP25NM60N has an efficiency of 98% at 230Vac, with an output power of 250W, when tested with a L4981-based 300W PFC. The improvement in efficiency given by the new MDmesh MOSFET series is obtained at high operating frequencies and is coupled to lower temperatures, allowing significant equipment-size reduction with smaller magnetic components and smaller heat sinks.

Another benefit of the second generation MDmesh technology is the ability to handle higher currents at a lower VGS voltage used to drive the devices. The range of VGS has been changed to give optimized driving with good noise immunity and the same threshold spread. Moreover, the new generation of MDmesh technology allows even stricter specifications of RDS (ON), which, in turn, allows the use of smaller packages.

The first members of the new family include the STW25NM50N, STP25NM50N, STF25NM50N, STB25NM50N, which are 500V, 140mOhm devices housed in TO-247, TO-220,TO-220FP and D2PAK/I2PAK packages respectively; the STD12NM50N, STP12NM50N, STF12NM50N, STB12NM50N, which are 500V, 380mOhm devices housed in DPAK, TO-220,TO-220FP and D2PAK packages respectively; and the STW25NM60N, STP25NM60N, STF25NM60N, STB25NM60N 600V, 170mOhm devices housed in TO-247, TO-220,TO-220FP and D2PAK/I2PAK packages, respectively. These devices are ideal for a variety of power supply applications from 90W to 1000W.

500V, 140-milliohm devices already available in production volume.

Pricing ranges from $1.4 to $1.7, depending on the device, in 1,000-piece quantities

Further information is available at www.st.com/mosfet

About STMicroelectronics
STMicroelectronics is a global leader in developing and delivering semiconductor solutions across the spectrum of microelectronics applications. An unrivalled combination of silicon and system expertise, manufacturing strength, Intellectual Property (IP) portfolio and strategic partners positions the Company at the forefront of System-on-Chip (SoC) technology and its products play a key role in enabling today's convergence markets. The Company's shares are traded on the New York Stock Exchange, on Euronext Paris and on the Milan Stock Exchange. In 2004, the Company's net revenues were $8.76 billion and net earnings were $601 million. Further information on ST can be found at www.st.com.