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MOSFETs offer better thermal performance

Posted: 24 Jan 2007 ?? ?Print Version ?Bookmark and Share

Keywords:MOSFET? PolarPAK? power management? Vishay? heat management?

PolarPAK MOSFET from Vishay

Vishay Intertechnology Inc. is adding new n-channel 20V, 30V and 40V devices to its PolarPAK family of power MOSFETs with double-sided cooling, giving designers a new way to reduce system size and cost through better MOSFET thermal performance.

Aimed at synchronous rectification, point-of-load converters and OR-ing applications in telecom and data communications systems, Vishay said the four new devices promise up to 48 percent better on-resistance and 12 percent better on-resistance-times-gate-charge performance than the next-best devices on the market with double-sided cooling.

Double-sided cooling
These improved specifications translate into lower conduction and switching losses that reduce power consumption in end systems. The dual heat dissipation paths provided by PolarPAK's double-sided cooling construction allow high current densities in systems with forced air cooling, enabling more compact designs and/or the ability to reduce the number of paralleled MOSFETs. To the extent that paralleling is needed at all, PolarPAK simplifies such designs with its straightforward pin-out, minimizing inductance from board layouts, thus improving efficiency especially at higher frequencies.

The new PolarPAK devices share the same footprint area as the standard SO-8 yet are twice as thin, with a height profile of just 0.8mm. On-resistance for the new 20V SiE810DF and SiE808DF, 30V SiE806DF and 40V SiE812DF ranges from 1.4 milliohms to 2.6 milliohms. Their on-resistance-times-gate-charge figure of merit (FOM) is exceptionally low as well. With FOMs of 127.5 and 135.2, respectively, the 30V and 40V devices offer nearly the same FOM for synchronous rectification applications while allowing the choice of the higher rating for applications that can use the additional headroom provided by the 40V breakdown voltage device.

Minimizing switching losses
For applications where minimizing switching losses is more critical than low conduction losses, Vishay is also releasing two PolarPAK devices with somewhat higher on-resistance. At a 10V gate drive, the 30V SiE830DF is rated for 4.2 milliohms and the 40V SiE832DF is rated at 5.5 milliohms.

In addition to their reduced power consumption and thermal management benefits, Vishay Siliconix PolarPAK power MOSFETs are designed to give manufacturers maximum flexibility, reliability and ease in handling. A fixed footprint and pad layout, independent of die size across the range of the family, eliminates the need for re-design when newer generations of silicon are introduced. Their standard leadframe and plastic encapsulation construction provide better die protection.

Samples and production quantities of the new PolarPAK power MOSFETs are available today, with lead times of eight to 10 weeks for larger orders.

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