The TPPM0304 provides a regulated power output for systems that have multiple input sources and require a constant voltage source with a low-dropout voltage. This is a single output, multiple input, intelligent power source selection device with a low-dropout regulator for either 5VCC or 5VAUX inputs, and a low- resistance bypass switch for the 3.3VAUX input. Transitions may occur from one input supply to another without generating a glitch, outside of the specification range, on the 3.3-V output. The device has an incorporated reverse blocking scheme to prevent excess leakage from the input terminals in the event that the output voltage is greater than the input voltage. The input voltage is prioritized in the following order: 5VCC, 5VAUX, and 3.3VAUX.