General Description
The Micrel MIC2245 is a high efficiency 4MHz pulse width modulated (PWM) synchronous buck (stepdown) regulator that features a LOWQ™ LDO standby mode that draws only 18µA of quiescent current. The MIC2245 allows an ultra-low noise, small size, and high efficiency solution for portable power applications.

Features
• 2.7 to 5.5V supply/input voltage
• Light load LOWQ™ LDO mode
    20µA quiescent current
    Low noise, 75µVrms
• 4MHz PWM mode
    Output current to 500mA
    >92% efficiency
    100% maximum duty cycle
• Adjustable output voltage option down to 1V
    Fixed output voltage options available
• Ultra-fast transient response
• Uses a tiny 1µH inductor
• Fully integrated MOSFET switches
• Micropower shutdown operation
• Thermal shutdown and current limit protection
• Pb-free 10-pin 3mm x 3mm MLF™ package
• –40°C to +125°C junction temperature range

Applications
• Cellular phones
• PDAs
• USB peripherals