2:1 power mux for dual-supply handover
The TPS2113PW is a 2:1 source selector switch from Texas Instruments, designed to autonomously or manually select between two input power rails and deliver a single output. It integrates two N-channel MOSFETs with internal switch drive, so the pass elements and the control logic share one 8-TSSOP package. The 2:1 input ratio means the part steers one of two supply inputs to the output, with a typical 1 ms turn-on delay and 5 ms turn-off delay that define the handover transient. The 55 µA quiescent supply current keeps the standby budget tight in battery-powered gear.
1.25 A output — load budget and derating
The 1.25 A continuous output rating sets the ceiling for the combined load current. In a typical handheld application drawing 800 mA to 1 A, the 25 % headroom covers inrush from a GSM burst or motor start without tripping the current limit. The N-channel FETs have low Rds(on) at 3.3 V gate drive, but the on-resistance rises as the input approaches the 2.8 V undervoltage threshold — budget extra drop at the low end.