What the MAX5921AESA+ is and where it fits
The Maxim Integrated MAX5921AESA+ is a single-channel hot swap controller designed for -48V power systems, the standard voltage in telecom central offices, base stations, and -48V battery-backed industrial equipment. It manages the inrush current and protects against overcurrent, overvoltage, and undervoltage faults — all without an internal pass FET, so the designer selects the external MOSFET that matches the load current and thermal budget. The controller draws 700 µA from the supply rail and operates over the industrial temperature range of -40°C to 85°C, making it suitable for outdoor cabinets and unventilated enclosures.
Programmable protection and fault handling
The MAX5921AESA+ integrates programmable circuit breaker, current limit, overvoltage protection (OVP), and undervoltage lockout (UVLO), giving the designer control over the turn-on threshold and the fault-trip level. On a fault, the auto-retry feature cycles the output — useful for clearing transient overloads without a manual reset. The thermal limit shuts down the controller if the die temperature exceeds safe operating area, protecting both the IC and the external MOSFET.
Package and mounting
Housed in an 8-pin SOIC (0.154" body width, 3.90 mm width), the MAX5921AESA+ is a surface-mount part that reflows on a standard lead-free profile. The small footprint keeps board area low, but the external MOSFET and sense resistor will dominate the hot-swap circuit's real estate.
Sourcing and lifecycle
It is ROHS3 compliant.