AUR9503 is a low-noise and high-PSRR LDO linear voltage regulator which operates from 2.5V to 5.5V and provides up to 150mA output current. AUR9503 achieves ultra low quiescent current to be ideally used with green operational portable products. Fixed output voltage options are provided with an internal built-in feedback circuit and optimized for stable operations with small 1μF ceramic output capacitors for excellent transient performance. EN pin enables the main chip operation and enables the output to be turned off to allow reduced power consumption in shutdown mode with a smaller than 0.1μA shutdown current. The low dropout voltage is 100mV at a load current of 150mA for system power efficiency. An internal current limit circuit is designed and operated as a short circuit protection for the regulator output pin.