What this -48V hot swap controller does on the board
The Texas Instruments TPS2391DGKR is a single-channel hot swap controller designed for -48V telecom and industrial power rails. It manages the inrush current when a board is plugged into a live backplane, preventing glitches and connector damage. The controller relies on an external N-channel MOSFET — there is no internal switch, so the pass FET and sense resistor are your choice for the load current you need. It operates from a -80V to -36V supply, which covers the standard -48V telecom bus with headroom for transients. The chip itself draws 700 µA from the rail. Three programmable features — current limit, fault timeout, and slew rate — let you tune the startup ramp and fault response to match the downstream capacitance and system protection philosophy. Auto retry is built in: after a fault clears, the controller attempts to restart the load without a power cycle. Undervoltage lockout (UVLO) holds the FET off until the supply is within range. The industrial temperature grade (-40°C to 85°C) suits outdoor telecom cabinets and factory-floor installations.
Package and mounting — field-service reality
The TPS2391DGKR comes in an 8-VSSOP package (3.00 mm width, 0.118" pitch). That is a small, surface-mount part — fine for a pick-and-place line, but not something you swap in the field with a soldering iron and tweezers. If this is a field-replaceable board, socket the controller or plan for board-level rework. The tape-and-reel or cut-tape option is standard for production volume.
Lifecycle and sourcing — no obsolescence worry
The TPS2391DGKR is listed as Active with ROHS3 compliance. No end-of-life notice, no last-time-buy pressure.