BUY RT9203 https://www.utsource.net/itm/p/1322531.html
Step-down DC/DC Converter
Description: The RT9203 is a high performance, low quiescent current, low dropout linear regulator. It is designed to provide a regulated output voltage from an input voltage as low as 2.2V and up to 6V. The device is capable of supplying up to 500mA of output current and features a low dropout voltage of only 0.4V. Features: Output voltage range: 1.2V to 5.5V Output current up to 500mA Low dropout voltage: 0.4V Low quiescent current: 40μA High accuracy: ±2% Over-temperature protection Over-current protection Short-circuit protection Thermal shutdown Applications: Battery-powered systems Portable electronics Personal digital assistants (PDAs) Cellular phones Handheld instruments Digital cameras Notebook computers MP3 players (For reference only)