1.25MHz, 600mA, High Efficiency PWM Step-Down DC/DC Converter

The RT8009 is a high-efficiency pulse-width-modulated (PWM) step-down DC-DC converter. Capable of delivering 600mA output current over a wide input voltage range from 2.5 to 5.5V, the RT8009 is ideally suited for portable electronic devices that are powered from 1-cell Li-ion battery or from other power sources within the range such as cellular phones, PDAs and handy-terminals.
Internal synchronous rectifier with low R_DS(ON) dramatically reduces conduction loss at PWM mode. No external Schottky diode is required in practical application. The RT8009 automatically turns off the synchronous rectifier while the inductor current is low and enters discontinuous PWM mode. This can increase efficiency at light load condition.
The RT8009 enters Low-Dropout mode when normal PWM cannot provide regulated output voltage by continuously turning on the upper P-MOSFET. RT8009 enter shutdown mode and consumes less than 0.1μA when EN pin is pulled low.
The switching ripple is easily smoothed-out by small package filtering elements due to a fixed operation frequency of 1.25MHz. This along with small SOT-23-5 and TSOT-23-5 package provides small PCB area application. Other features include soft start, lower internal reference voltage with 2% accuracy, over temperature protection, and over current protection.