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lowpowerZONE Products for the week of December 8, 2008
Vishay Says…
Si7718DN: Siliconix Releases First 20-V and 30-V n-Channel TrenchFET Gen III Power MOSFETs With TurboFET Technology For Low Switching Losses and Faster Switching
Devices Feature On-Resistance Times Gate Charge FOM Down To 76.6 mΩ-nC at 4.5 V and 117.60 mΩ-nC at 10 V in PowerPAK 1212-8 Package Type
Vishay Intertechnology, Inc. has expanded its family of Gen III TrenchFET power MOSFETs with the release of two 20-V and two 30-V n-channel devices that are the first to offer TurboFET technology, which utilizes a new charge balanced drain structure to lower the gate charge by up to 45%, enabling significantly lower switching losses and faster switching.
The 20-V SiS426DN device offers the industry’s lowest on-resistance times gate charge for a device with this voltage rating in the 3-mm by 3-mm PowerPAK 1212-8 footprint. This key figure of merit (FOM) for MOSFETs in dc-to-dc converters is 76.6 mΩ-nC at 4.5 V and 117.60 mΩ-nC at 10 V for the SiS426DN, which features a low typical gate charge of 13.2 nC at a 4.5-V gate drive and 28 nC at a 10-V gate drive.
Compared to the closest competing devices, these specifications represent a reduction in gate charge of 45 % at 4.5 V and 36 % at 10 V, and a 50 % lower FOM. Lower gate charge translates into more efficient switching at all frequencies, and in particular gives the designer the option to operate at higher frequencies, which enables the use of smaller passive components in dc-to-dc converters.
Vishay’s 30-V TurboFET offering includes the new Si7718DN in the PowerPAK 1212-8, and the Si7784DP in the PowerPAK SO-8. Both MOSFETs offer typical gate charge of 13.7 nC at 4.5 V and 30 nC at 10 V, and on-resistance times gate charge FOMs of 112.34 mΩ-nC at 4.5 V and 180 mΩ-nC at 10 V. A PowerPAK SO-8 version of the 20-V SiS426DN device, the SiR496DP, is also available for high-current applications. All devices released today are halogen-free and 100% Rg and UIS tested.
EN-Genius Says…
Vishay’s Siliconix has continuously pushed the envelope with power MOSFETs. They continue to do so with these new devices reducing gate charge by considerable percentages, thereby making switching more efficient and allowing higher switching frequencies to be specified by designers.
Taking the Si7718DN as an example, offered in PowerPak 1212-8, the absolute maximum ratings are for drain-source voltage of 30 V, gate-source of ±20 V, and a package-limited continuous drain current of 35 A up to 70ºC with a maximum power dissipation of 43 W.
The total gate charge of the Si7718DN is a typical 30 nC at 10 V gate-source (10 A drain current) and 13.7 nC at 4.5 V. The gate resistance at 1 MHz is 750 mΩ.
Rds(on) at 10 V is a typical 4.8 mΩ (6 mΩ maximum) and 6.5 mΩ at 4.5 V (8.2 mΩ maximum). Similar numbers are available from the SO-8 version of the part, the Si7784DP. The 20 V parts are the SiS426DN (1212-8) and the SiR496DP (SO-8).
The reduction in gate charge in these third-generation parts is significant and will allow a lot of existing designs to migrate to higher switching frequencies, maintaining efficiency while reducing the real estate used by circuit passives – or by increasing efficiency at the presently-used switching frequencies of those designs. The parts will get into buck converters of all kinds but mostly in portables such as notebook computers.
No pricing was noted in the news release but they are certain to be extremely competitive. All four parts are both sampling and in production.
Data Sheet Si7718DN
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