The APL5505/6/7 is micropower, low noise , low dropout regulators with a reset function (regulator input (APL5505) or specific voltage(APL5506/7) monitoring), and internal delay circuit, set to detect 3.9V or 4.2V. Operate from 3V to 6V input voltage and deliver up to 500mA. Typical output noise is just 180uVRMS with an external 0.01uF bypass capacitor connected in BP pin and the typical dropout voltage is only 300mV at 500mA loading. Design with an internal P-channel MOSFET pass transistor, the APL5505/6/7 maintains a low supply current, independent of the load current and dropout voltage. Other features include reverse current protection, thermal-shutdown protection, current limit protection to ensure specified output current and controlled short-circuit current. The APL5505/6/ 7 regulators come in miniature SOP-8, TSSOP-8 and MSOP-8 packages.