Inductor-Free Charge Pump Powers White Backlights

Measuring just 1 mm high in a ThinSOT-23 package and requiring no inductor, the REG71055 buck-boost converter delivers 30 mA of output current for white LED backlights and LCDs in single-cell, Li-Ion powered applications. The device provides a fixed output voltage of 5.5 V across input voltages from 3V to 5.5V and features a quiescent current of 65 µA. Eliminating the need for an LDO regulator, the converter automatically steps the input voltage up or down to the required output of 2.5V, 2.7V, 3V, 3.3V, 5V, or 5.5V. A 1-MHz switching frequency is achieved using ceramic capacitors, as opposed to more costly tantalums. The device also includes over-temperature and over-current protection and automatically limits in-rush current. Price is $0.90 each /1,000. TEXAS INSTRUMENTS INC., Dallas, TX. (800) 477-8924.