The LTC4417, from Linear Technology, is a 3-input prioritizer for supplies in the 2.5V to 36V range, selecting the highest priority valid supply to power the load. Priority is defined by pin assignment, with V1 being the highest priority and V3 the lowest. A supply is considered valid after it has been inside a voltage window for 256ms. This valid voltage window is set by 1.5% accurate undervoltage and overvoltage thresholds. The LTC4417 controller also protects the load from reversed inputs up to −42V. Multiple LTC4417s can be cascaded for prioritizing more than three supplies. PowerPath switching is implemented by external back-to-back P-channel MOSFETs protected by integrated 6V gate clamps. Carefully designed fast switch control blocks reverse and cross-conduction current while preventing output voltage droop. A low 28µA operating current, sub-1µA draw from the lower standby supplies, and a shutdown mode make the controller ideal for battery powered systems.