MAX1556

19-3336; Rev 0; 7/04 KIT ATION EVALU E L B AVAILA www.DataSheet4U.com 16µA IQ, 1.2A PWM Step-Down DC-DC Converters General Description Features ♦ Up to 97% Efficiency ♦ 95% Efficiency at 1mA Load Current ♦ Low 16µA Quiescent Current ♦ 1MHz PWM Switching ♦ Tiny 3.3µH Inductor ♦ Selectable 3.3V, 2.5V, 1.8V, 1.5V, 1.3V, 1.0V, and Adjustable Output ♦ 1.2A Guaranteed Output Current (MAX1556) ♦ Voltage Positioning Optimizes Load-Transient Response ♦ Low 27µA Quiescent Current in Dropout ♦ Low 0.1µA Shutdown Current ♦ No External Schottky Diode Required ♦ Analog Soft-Start with Zero Overshoot Current ♦ Small, 10-Pin, 3mm x 3mm TDFN Package MAX1556/MAX1557 The MAX1556/MAX1557 are low-operating-current (16µA), fixed-frequency step-down regulators. High efficiency, low-quiescent operating current, low dropout, and minimal (27µA) quiescent current in dropout make these converters ideal for powering portable devices from 1-cell Li-ion or 3-cell alkaline/NiMH batteries. The MAX1556 delivers up to 1.2A; has pin-selectable 1.8V, 2.5V, and 3.3V outputs; and is also adjustable. The MAX1557 delivers up to 600mA; has pin-selectable 1V, 1.3V, and 1.5V outputs; and is also adjustable. The MAX1556/MAX1557 contain a low-on-resistance internal MOSFET switch and synchronous rectifier to maximize efficiency and dropout performance while minimizing external component count. A proprietary topology offers the benefits of a high fixed-frequency operation while still providing excellent efficiency at ...