Siliconix Adds 3 Level-Shifted Little Foot SwitchesMay 19, 1999 by Jeff Shepard
Vishay Siliconix (Santa Clara,CA) announced the release of three new level-shifted Little Foot load switches, each of which allows a low-voltage microcontroller to control loads on a range of different voltage rails. The new Little Foot TSOP-6 devices include higher performance variations of competing parts, while introducing the first device of this type with 1.8V operating voltage, the Si3685DV. Designed to facilitate multiple rail voltages in cell phones and portable computers, all three load switches are claimed to set on-resistance records for this device type, with Rds(on) as low as 80 milliohms when switching 4.5V loads. In addition to prolonging battery life, the new devices featured integrated n-channel level-shift circuitry that saves space by eliminating the need for an external MOSFET to give a true ground referenced low-voltage logic input. Only a resistor is needed for a complete solution."The need for a level-shifted load switches is becoming common in notebook computers and other mobile systems as more and more components are going to lower voltages, while certain loads, such as disk drives, and power amplifiers remain at 5-V and higher voltage rails," said Evan Lambka, Product Marketing Manger at Vishay Siliconix.The new devices are claimed to give designers a choice of operating voltages to suit the headroom needs of various systems. The n-channel component of each device can be driven by logic signals as low as 1.5V and features internal ESD protection up to 3000V. The devices also an have adjustable slew-rate feature intended to allow designers to avoid the effects of surge currents that could affect microcontroller or battery monitor operation if loads are turned on too quickly. Pricing for U.S. delivery only in 100,000-piece quantities starts at $0.36.