RT9201

Preliminary RT9201 High Efficiency PWM Step-Down DC-DC Converter General Description The RT9201 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 RT9201 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. Four operational modes are available: PWM, PSM, LowDropout and shut-down modes. Internal synchronous rectifier with low RDS(ON) dramatically reduces conduction loss at PWM mode. No external Schottky diode is required in practical application. The RT9201 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 RT9201 enters PSM (pulse-skipping mode) at extremely light load condition. The equivalent switching frequency is reduced to increase the efficiency in PSM. The RT9201 enters Low-Dropout mode when normal PW M cannot provide regulated output voltage by continuously turning on the upper P-MOSFET. RT9201 enters shut-down 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 800kHz. This along with small DFN package provides small PCB area application. Other features include s...