What this -48V hot swap controller does on the backplane
The Texas Instruments TPS2399DGK is a single-channel hot swap controller designed for -48V telecom and industrial backplanes. It manages inrush current during card insertion and provides overcurrent protection with a programmable current limit, fault timeout, and slew rate. The part includes auto-retry and undervoltage lockout (UVLO) as built-in features, and it operates from a -80V to -36V supply rail, drawing 700 µA of supply current. Housed in an 8-VSSOP package, it is rated for the industrial temperature range of -40°C to 85°C, making it suitable for outdoor telecom cabinets, base stations, and -48V distributed power systems where board swapping happens live.
Supply voltage and what it means for your -48V rail
The -80V to -36V supply range covers the full tolerance band of a nominal -48V telecom bus, including transients and battery float voltages. If your backplane runs at -48V nominal with a -36V brownout threshold and -60V transient peaks, this controller stays within its operating window. The UVLO feature can be set to hold off the external MOSFET until the rail is above a safe minimum, preventing partial turn-on that would cook the pass element.
Programmable protection — setting the inrush and fault behavior
Three programmable parameters — current limit, fault timeout, and slew rate — let you tailor the startup ramp and fault response to the load capacitance and system coordination. A slow slew rate limits inrush into a bank of bulk capacitors; a fast fault timeout clears a short before the upstream breaker trips. The auto-retry feature means the controller will keep trying to restart after a fault, which is useful for transient loads but can be a nuisance if the fault is permanent — plan your retry count with external logic if needed.
Package and mounting — fits the 8-VSSOP footprint
The TPS2399DGK comes in an 8-VSSOP surface-mount package, 3.00 mm width. The Tube shipping medium is typical for prototype and low-volume builds.
Lifecycle and sourcing — active, no LTB concern
It is ROHS3 compliant.