-48V hot swap controller in 8-SOIC
The MAX5921FESA+ is a single-channel hot swap controller from Analog Devices, designed for -48V telecom and networking power distribution. It integrates programmable circuit breaker, current limit, overvoltage protection (OVP), and undervoltage lockout (UVLO) — the four protection axes that govern inrush and fault handling on a -48V rail. Operating from -80V to -20V supply with a quiescent current of 700 µA, the controller manages the external pass FET without an internal switch — the channel count is 1, and the fault response includes auto retry, fault timeout, and thermal limit.
Protection programmability and fault behavior
The four programmable features — circuit breaker threshold, current limit, OVP, and UVLO — let the designer set the trip points for the specific load and supply tolerance. The auto-retry behavior means the controller attempts to restart after a fault timeout, which is useful for transient line faults but requires careful coordination with downstream converters that may latch off. The thermal limit provides a secondary protection layer if the external FET exceeds its safe operating area — the controller shuts down and cools before retrying. The 700 µA supply current is the controller's own draw; the external pass FET's gate charge and switching losses are additional.
Package, temperature grade, and compliance
The tube packaging is typical for prototype and low-volume builds; for reel quantities, confirm the tape-and-reel variant.