The RT8024PB is a high-efficiency pulse-width-modulated (PWM) step-down DC-DC converter. Capable of delivering 400mA output current over a wide input voltage range from 2.5V to 5.5V, the RT8024PB  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 RT8024  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 RT8024PB  enters Low-Dropout mode when normal PWM cannot provide regulated output voltage by continuously turning on the upper P-MOSFET. RT8024PB  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 1.5MHz. 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.

Note :
Richtek Green products are :
► RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.
► Suitable for use in SnPb or Pb-free soldering processes.

• +2.5V to +5.5V Input Range
• Adjustable Output From 0.6V to V_IN
• 1.0V, 1.2V, 1.5V, 1.8V, 2.5V and 3.3V Fixed/Adjustable Output Voltage
• 400mA Output Current, 1A Peak Current
• 95% Efficiency
• No Schottky Diode Required
• 1.5MHz Fixed-Frequency PWM Operation
• Small SOT-23-5 and TSOT-23-5 Package
• RoHS Compliant and Halogen Free

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

(TOP VIEW)
SOT-23-5/TSOT-23-5

Figure 1. Fixed Voltage Regulator
with R2 = 300kΩ to 60kΩ so the I_R2 = 2μA to 10μA,
and (R1 x C1) should be in the range between 3x10^-6 and 6x10^-6 for component selection.

Figure 2. Adjustable Voltage Regulator