The FPF1320/21 is a Dual-Input Single-Output (DISO) load switch consisting of two sets of slew-rate controlled, low on-resistance, P-channel MOSFET switches and integrated analog features. The slew-rate-controlled turn-on characteristic prevents inrush current and the resulting excessive voltage droop on the power rails. The input voltage range operates from 1.5V to 5.5V to align with the requirements of low-voltage portable device power rails. FPF1320/21 performs seamless power-source transitions between two input power rails using the SEL pin with advanced break-before-make operation.FPF1320/21 has a TRCB function to block unwanted reverse current from output to input during ON/OFF states. The switch is controlled by logic inputs of the SEL and EN pins, which are capable of interfacing directly with low-voltage control signals (GPIO).FPF1321 has 65Ω on-chip load resistor for output quick discharge when EN is LOW.FPF1320/21 is available in 1.0mm x 1.5mm WLCSP, 6-bump, with 0.5mm pitch.