General Description
The MAX1820/MAX1821 low-dropout, pulse-width-modulated (PWM) DC-DC buck regulators are optimized to provide power to the power amplifier (PA) in WCDMA cell phones; however, they may be applied in many other applications where high efficiency is a priority. The supply voltage range is from 2.6V to 5.5V, and the guaranteed output current is 600mA; 1MHz PWM switching allows for small external components, while skip mode reduces quiescent current to 180µA with light loads.

Features
♦ Dynamically Adjustable Output from 0.4V to 3.4V (MAX1820)
♦ Programmable Output from 1.25V to 5.5V (MAX1821)
♦ SYNC to 13MHz External Clock (MAX1820X)
♦ SYNC to 19.8MHz External Clock (MAX1820Y)
♦ NO SYNC, Internal 1MHz Oscillator (MAX1820Z)
♦ Low Quiescent Current
    180µA (typ) in Skip Mode
    0.1µA (typ) in Shutdown Mode
♦ No External Schottky Diode Required
♦ 600mA Guaranteed Output Current
♦ 0% to 100% Duty-Cycle Operation
♦ 150mV Dropout at 600mA Load (Including RDC of External Inductor)
♦ µMAX or UCSP Packaging

Applications
    WCDMA Cell Phone Power Amplifiers
    PDA, Palmtop, and Notebook Computers
    Microprocessor Core Supplies
    Digital Cameras
    PCMCIA and Network Cards
    Hand-Held Instruments