The CMPWR330 is a dual input regulator with a fully integrated VAUX switch capable of delivering up to 400mA continuously at 3.3V. The input is taken from three independent voltage sources on a prioritized basis. Power is always taken in priority using the order of VCC, VSBY, and VAUX. When VCC, (5V) or VSBY is present, the device automatically enables the regulator and produces a stable 3.3V output at VOUT. When only VAUX (3.3V) is present, the device provides a low impedance direct connection (0.25Ω TYP.) from VAUX to VOUT. All the necessary control circuitry needed to provide a smooth and automatic transition between all three supplies has been incorporated. This allows the VCC input supply to be dynamically switched without loss of output voltage. The CMPWR330 is housed in an 8-pin SOIC package and is available with RoHS compliant lead-free finishing.