The TPS2051BDG4 is a single-channel high-side power switch from Texas Instruments, built for general-purpose power distribution with a typical on-resistance of 70 mOhm. That figure governs the voltage drop across the switch at full load: at 500 mA the drop is about 35 mV, which keeps the output voltage well within the 4.75 V minimum for a USB 2.0 downstream port.
Built-in fault protection trims the BOM
Three protection circuits are integrated: fixed current limiting, over-temperature shutdown, and under-voltage lockout (UVLO). The over-temperature trip protects the die if the load fault persists, and UVLO holds the switch off until the input supply rises above the threshold. This protection set is standard for USB hub and host port implementations where the port must survive a shorted cable without damage to the upstream supply.
For a procurement desk qualifying a new BOM line, this avoids the supply-chain gymnastics of a phase-out part. The base product number is TPS2051, so any PCN or datasheet revision will roll under that root — watch for the suffix (-BDG4) when matching date codes or alternate package variants.