The BD3509MUV 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 (RONMAX=50mO) level. By lowering the dropout voltage in this way, the regulator realizes high current output (Iomax=4.0A) with reduced conversion loss, and thereby obviates the switching regulator and its power transistor, choke coil, and rectifier diode. Thus, the BD3509MUV are 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.·Internal high-precision reference voltage circuit (0.65V±1%)·Built-in VCC under voltage lock out circuit (VCC=3.80V)·NRCS (soft start) function reduces the magnitude of in-rush current·Internal Nch MOSFET driver offers low ON resistance (28mO typ)·Built-in current limit circuit (4.0A min)·Built-in thermal shutdown (TSD) circuit·Variable output (0.65 to 2.7V)·Incorporates high-power VQFN020V4040 package : 4.0x4.0x0.9(mm)·Tracking function