Linear Technology’s new LTC3408 is a high-efficiency, 1.5-MHz, synchronous buck regulator with an integrated bypass MOSFET that can deliver up to 600 mA of continuous output current from a tiny 8-lead DFN package. The on-chip bypass MOSFET has an RDSON of only 0.08 Ω, minimizing power loss in the bypass mode. The LTC3408 uses a constant frequency, current mode architecture, which operates from an input voltage range of 2.5 V to 5 V, making it ideal for single cell Li-Ion cellular applications. The output can be dynamically programmed from 0.3V to 3.5V to optimize the efficiency of CDMA and WCDMA power amplifiers, increasing battery life. At output voltages above 3.6 V, an internal bypass P-Channel MOSFET transistor connects V OUT directly to BATTERY with a dropout of less than a 50 mV (at 600 mA), minimizing power loss through the inductor. Its 1.5-MHz switching frequency allows utilization of tiny, low-cost capacitors and inductors less than 1 mm in height. The combination of tiny externals and a 3-mm × 3-mm DFN package makes the LTC3408 optimal for space-constrained cellular phones.
For more information, visit www.linear.com.