The BD3506F/EFV is an ultra-low dropout linear regulator for chipset that can achieve ultra-low voltage input to ultra-low voltage output. By using N-MOS FET for built-in power transistor, the regulator can be used at ultra-low I/O voltage difference up to voltage difference generated by ON resistor (Ron = 120 m/100 m). Because by reducing the I/O voltage difference, large current (Iomax = 2.5A) output is achieved and conversion loss can be reduced, switching power supply can be replaced. BD3506F/EFV does not need any choke coil, diode for rectification and power transistor which are required for switching power supply, total cost of the set can be reduced and compact size can be achieved for the set. Using external resistors, optional output from 0.65V to 2.5V can be set. In addition, since voltage output start-up time can be adjusted by using the NRCS terminal, it is possible to meet the power supply sequence of the set.