-48V hot swap controller in 8-SOIC
The Maxim Integrated MAX5921EESA+ is a single-channel hot swap controller designed for -48V power rails, packaged in an 8-pin SOIC (0.154" width, 3.90 mm body) for surface-mount assembly. It manages inrush current and provides overcurrent protection when a card or module is plugged into a live backplane, typical in telecom and industrial -48V distributed-power systems. The controller operates from -80V down to -20V, drawing 700 µA supply current, and integrates programmable circuit breaker, current limit, overvoltage protection (OVP), and undervoltage lockout (UVLO) thresholds.
External MOSFET required
The MAX5921EESA+ does not include an internal pass switch, so the BOM must add an external N-channel MOSFET and a sense resistor to handle the load current. This gives the designer control over the FET's RDS(on) and current rating to match the specific load — a 48 V / 5 A card needs a different FET than a 48 V / 1 A line card. The external FET also simplifies thermal management: the heat dissipates in the FET's package, not in the controller.
Programmable protection and auto-retry
The controller supports programmable circuit breaker and current-limit thresholds, plus OVP and UVLO setpoints, via external resistor dividers. The auto-retry feature (listed among the part's features) means the controller will repeatedly attempt to restart after a fault clears, which is useful for transient overloads in telecom line cards. A fault timeout and thermal-limit circuit prevent sustained overstress on the external FET.
Temperature grade and environment
Rated for -40°C to 85°C operating temperature, the MAX5921EESA+ suits outdoor telecom cabinets, base stations, and industrial equipment where the ambient temperature can swing through the full industrial range. The 8-SOIC package is standard reflow-friendly, MSL 1 typically for Maxim SOIC parts — no special bake needed if the moisture-barrier bag is intact.
Lifecycle and sourcing
The MAX5921EESA+ carries an active lifecycle status and is ROHS3 compliant.