Siliconix Debuts Si91841/Si91843 LDO Regulators

Siliconix Inc. (Santa Clara, CA) announced two new 150mA, low-noise, low dropout (LDO) regulators designed for use in battery-powered equipment such as cell phones, wireless handsets and modems, PDAs, notebooks, pagers, and digital cameras.

The Si91841 and Si91843 feature a low ground current of only 110µA at 150mA, ideal for low-voltage, battery-operated power systems, and a low dropout voltage of 130mV, prolonging battery life in

portable electronics. The devices' ultra-low noise output provides a quiet voltage source, while an external noise-bypass capacitor further reduces noise levels for RF systems and other applications requiring low output

noise to just 30µV(rms).

Designed to maintain regulation while delivering 300mA peak output current

in applications with high surge currents at turn-on, the Si91841 and Si91843 are available in a range of 14 fixed-output voltage options from 1.8V to 5.0V. Both devices feature a 1.5-percent guaranteed output-voltage accuracy, a fast start-up time of 50µsecs, and a fast transient

response of 30µsecs or less. A built-in, active, pull-down clamp circuit improves transient response and regulation by actively sinking current from the output if it exceeds the desired regulation voltage. The Si91841 discharges the output during shutdown mode through a 100-ohm n-channel MOSFET, while the Si91843 maintains an open circuit on the output.

Packaged in a five-pin SOT23, the Si91841 and Si91843 may be used with low-ESR

ceramic capacitors or tantalum capacitors, giving designers a flexible choice of magnetic components.

Samples and production quantities of the Si91841 and Si91843 are available now with lead times of 6 to 10 weeks for larger

orders. Pricing for US delivery in 100,000-piece quantities is $0.39.