In summary, selecting the appropriate input supply to power a system is not a trivial task. A poor implementation can oscillate between supplies, cause power brownouts, or damage the input supplies by allowing reverse current. A PowerPath controller selects and controls the switches through which power flows to the system, employing MOSFET switches to multiplex the input supplies to a common load. The LTC4417 is a 3-input prioritizer for 2.5V to 36V supplies, selecting the highest priority valid supply to power the load. The LTC4417 controller also protects the load from reversed inputs up to −42V. The LTC4419 two-channel monolithic power prioritizer operates with supplies between 1.8 and 18V. The LTC4419 powers the load from the higher priority main supply, switching to the backup supply during primary brownout or power loss conditions. In addition to the LTC4419 functionality, the LTC4420 provides undervoltage monitoring and optional disconnect of the V2 backup supply, preventing deep discharge and potential damage to rechargeable batteries.