Hot swap controller for -48V backplanes
The Maxim Integrated MAX5901LAETT+T is a single-channel hot swap controller from the Simple Swapper™ series, designed to manage inrush current and protect downstream circuitry when boards are inserted into a live -48V backplane. It operates over a supply range of -100V to -9V, covering the standard -48V telecom bus with headroom for transients. The controller does not integrate a power switch internally — it drives an external N-channel MOSFET to pass the load current, which lets the designer size the pass element for the actual load current and thermal budget of the application.
Key protection and monitoring features
The device includes a programmable undervoltage lockout (UVLO) that allows the system designer to set the voltage at which the controller enables the external MOSFET, preventing operation below a safe bus voltage. A fault timeout and latched fault response ensure that a sustained overcurrent or short-circuit event shuts down the pass element and holds it off until the fault is cleared and the controller is reset. A thermal limit protects the controller itself from excessive die temperature during prolonged fault conditions. The quiescent supply current is 500 µA, low enough for always-on monitoring in power-sensitive backplane slots.
Temperature grade and deployment environment
Rated for operation from -40°C to 85°C, the MAX5901LAETT+T is suited for industrial-temperature environments: outdoor telecom cabinets, base stations, and factory-floor equipment where the ambient temperature can swing widely. The 6-TDFN (3x3 mm) package with an exposed pad helps conduct heat from the die to the PCB copper plane, which is important when the external MOSFET is switching high inrush currents and the controller's internal thermal limit is the last line of defense.
Lifecycle and sourcing
It is ROHS3 compliant.