ML4854

www.fairchildsemi.com ML4854 Adjustable, Low-Current, 2-Cell Boost Regulator with Shutdown and Low Battery Detect Features 95% Efficiency at 200mA Load Current Integrated Peak Current Limit Variable Output Voltage Determined by External Resistors Variable On-time Pulse Frequency Modulation (PFM) Fully Internal Synchronous Rectifier (no external diodes) for High Efficiency and Low Peak Currents Low-Battery Detection Logic Controlled Shutdown with True Load Disconnect General Description The ML4854 is a low power boost regulator designed for low voltage DC to DC conversion in two-cell battery powered systems such as cell phones and PDAs. The converter starts up at 1.3V and has an operating input voltage range from 1.6V to 4.5V. After the start it operates at an input voltage as low as 0.8V. Output voltage can be adjusted by external resistors from 3.3V to 5V with a maximum load current of 0.5A. Quiescent current in shut down mode is less than 30µA, which maximizes the battery live time. The ON time changes with the input voltage to maintain the ripple current constant and to provide the highest efficiency over a wide load range, while maintaining low peak currents in the boost inductor. The combination of integrated synchronous rectification, variable frequency operation, and low supply current make ML4854 ideal for portable applications. The ML4854 is available in an 8 lead TSSOP package. Applications 2-3 alkaline/NiMH cells or 1 Li-Ion cell Operated Devi...