AO3402

AO3402 is an Alpha & Omega Semiconductor N-channel MOSFET in a SOT-23 package, rated at 30 V drain-source voltage and 4 A drain current, with on-resistance below 52 mΩ at 10 V gate drive and below 85 mΩ at 2.5 V gate drive — a load switch and DC-DC switch for battery-powered and space-constrained designs, documented in AOS's datasheet Rev 6.1 with its own marking document. Selection advice: read the two on-resistance figures as a pair — this part is specified at low gate voltages, which suits it to logic-driven load switching, but the resistance at 2.5 V drive is over 60% higher than at 10 V, so conduction loss in a 3.3 V-driven design must be budgeted on the 2.5 V row, not the headline row. Match the full code: the AO3402 sits among look-alike SOT-23 MOSFET codes (AO3400, AO3401) with different polarities and resistance tables, and a one-digit error changes the device. The 4 A rating is a package-limited maximum — continuous current is set by board copper and ambient temperature. Parameters verified against Alpha & Omega Semiconductor documentation.