The LM3940IS-3.3/NOPB is a Low Dropout Regulator designed to provide 3.3V from a 5V supply. The LM3940 is ideally suited for systems which contain both 5 and 3.3V logic, with prime power provided from a 5V bus. Because the regulator is a true low dropout regulator, it can hold its 3.3V output in regulation with input voltages as low as 4.5V.