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New Complementary LITTLE FOOT® Power MOSFET Enables Low-Cost "Instant Power-Up" For Desktop PCs
MALVERN, PENNSYLVANIA - August 31, 1999 - A new power MOSFET device that gives desktop computer manufacturers an affordable way to provide users with a quasi instant power-up feature was announced today by Vishay Intertechnology. Designed specifically to facilitate the next generation of PCs implementing ACPI and OnNow, the new Vishay Siliconix Si4501DY switches the two voltage rails supplied by an ATX power supply. Allowing part of the circuit to be isolated and powered from the standby supply, the main power supply and fan can be turned off while the computer is in the standby mode, thus giving the appearance of the computer being off.
Consisting of complementary n- and p-channel MOSFETs connected together internally and packaged in a LITTLE FOOT® SO-8, these components function together as a single-pole double-throw switch with one control input. On-resistance at a 4.5-V gate drive is 18 milliohms for the n-channel component and 42 milliohms for the p-channel a record for a complementary device in this package type. These low rDS(on) ratings allow the Si4501DY to control currents up to 9 A, which makes the Si4501DY particularly useful in designs where several loads may be grouped together.
"Instant power-up from a very low power standby mode is a feature that will become increasingly desirable as the PC evolves into an essential part of running the home," said Evan Lambka, Product Marketing Manager at Vishay Siliconix. "The Si4501DY allows this capability to be implemented inexpensively and to reduce the frequency with which PCs must be booted."
Allowing a limited part of the computer's system to run from a standby power supply in isolation from the main power supply is the most efficient way to provide the apparent off-state and instant power-up. In providing this function, the Si4501DY's n-channel component functions as the main power switch, while the p-channel component serves as the standby power switch. The ability to use the Si4501DY in a complementary, common-gate architecture makes it ideal for the power selector application because this ensures that at no time will both switches be in the "on" state.
For highly cost-sensitive designs, Vishay Siliconix is introducing a second device, the Si4500DY, which performs the same functions as the Si4501DY with higher maximum on-resistance ratings of 30 milliohms for the n-channel component and 65 milliohms for the p-channel component at a 4.5-V gate drive.
Samples and production quantities of the Si4501DY and Si4500DY are available now, with lead times of 8 to 10 weeks for larger orders.
Vishay Intertechnology, Inc., a Fortune 1000 Company listed on the NYSE (VSH), is one of the world's largest manufacturers
of discrete semiconductors (diodes, MOSFETs, and infrared optoelectronics) and passive electronic components (resistors, inductors,
and capacitors). These components are used in virtually all types of electronic devices and equipment, in the industrial,
computing, automotive, consumer, telecommunications, military, aerospace, power supplies, and medical markets. Vishay’s product
innovations, successful acquisition strategy, and "one-stop shop" service have made it a global industry leader. Vishay can
be found on the Internet at www.vishay.com.