The BD3550HFN / BD3551HFN / BD3552HFN ultra low-dropout linear chipset regulator operates from a very low input supply, and offers ideal performance in low input voltage to low output voltage applications. It incorporates a built-in N-MOSFET power transistor to minimize the input-to-output voltage differential to the ON resistance (RON=400mO / 200mO / 100mO) level. By lowering the dropout voltage in this way, the regulator realizes high current output (Iomax=0.5A / 1.0A / 2.0A) with reduced conversion loss, and thereby obviates the switching regulator and its power transistor, choke coil, and rectifier diode. Thus, the BD355XHFN is designed to enable significant package profile downsizing and cost reduction. An external resistor allows the entire range of output voltage configurations between 0.65 and 2.7V, while the NRCS (soft start) function enables a controlled output voltage ramp-up, which can be programmed to whatever power supply sequence is required.