FEATURES • High Efficiency: Up to 96% • 2.5V to 5.5V Input Voltage Range • 1MHz Constant Frequency Operation • No Schottky Diode Required • Low Dropout Operation:100% Duty Cycle • PFM Mode for High Efficiency in Light Load • Over temperature Protected • Low Quiescent Current: 40μA • Short Circuit Protection • Over Voltage Protection • Inrush Current Limit and Soft Start • SOT23-5 package 

APPLICATIONS • Cellular and Smart Phones • Wireless and DSL Modems • PDAs • Portable Instruments • Digital Still and Video Cameras • PC Cards

 GENERAL DESCRIPTION The ZCC3420 is a high-efficiency monolithic synchronous buck regulator using a constant frequency, current mode architecture. The device is available in an adjustable version. Supply current with no load is 40uA and drops to <1uA in shutdown. The 2.5V to 5.5V input voltage range makes the ZCC3420 ideally suited for single Li-Ion battery powered applications. 100% duty cycle provides low dropout operation, extending battery life in portable systems. PWM/PFM mode operation provides very low output ripple voltage for noise sensitive applications. Switching frequency is internally set at 1MHz, allowing the use of small surface mount inductors and capacitors. Low output voltages are easily supported with the 0.6V feedback reference voltage. The ZCC3420 is offered in a low profile (1mm) 5-pin, thin SOT package, and is available in an adjustable version.