Dual 3 A USB port power switch with I²C current budgeting
The Microchip UCS2112T-2-V/G4 is a dual-channel high-side power switch designed for USB and general-purpose port power control. Each of its two outputs can deliver up to 3 A, with a typical on-resistance of 40 mOhm that keeps conduction losses low enough for the 20-QFN exposed pad to handle without forced airflow. What sets this part apart from a basic on/off load switch is the I²C and SMBus interface: a host controller can read the current draw on each port and set the current-limit threshold independently, enabling dynamic power budgeting in multi-port hubs or industrial USB outlets.
At 3 A per channel, the 40 mOhm typical Rds(on) produces 0.36 W of I²R loss per port. With both channels loaded, the total 0.72 W must be sunk through the 20-VFQFN exposed pad to the PCB copper plane. The UVLO fault protection on the logic supply prevents the switch from turning on with a brown-out Vcc, which avoids indeterminate output states during power sequencing.
The part is ROHS3 compliant. The 4x4 mm QFN package with exposed pad is MSL-rated per the JEDEC standard.