1.25MHz,600mA,PWM降压BUCK DC/DC，工作电压范围为2.5-5.5V，RT8009 是单节锂电池手持电子设备（如手机、PDAs和其他手持式终端设备）的理想选择。
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.
RT8009  Internal synchronous rectifier with low R_DS(ON) dramatically reduces conduction loss at PWM mode. RT8009 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.

• RT8009  +2.5V to +5.5V Input Range
• RT8009  Adjustable Output From 0.5V to V_IN
• RT8009  1.0V, 1.2V, 1.3V, 1.5V, 1.8V, 2.5V and 3.3V Fixed/Adjustable Output Voltage
• RT8009  600mA Output Current
• RT8009  95% Efficiency
• RT8009  No Schottky Diode Required
•RT8009   1.25MHz Fixed-Frequency PWM Operation
• RT8009  Small SOT-23-5 and TSOT-23-5 Package
• RT8009  RoHS Compliant and 100% Lead (Pb)-Free

• Cellular Telephones
• Personal Information Appliances
• Wireless and DSL Modems
• MP3 Players
• Portable Instruments