What this part is and where it fits
The Maxim Integrated MAX5901LAEUT is a Simple Swapper™ hot swap controller designed for negative-rail applications down to -100V. It integrates the internal pass switch, so the board layout stays compact — no external MOSFET to size and drive. The controller handles the inrush sequence, fault timeout, and auto-retry or latched fault response, depending on how you set the programmable features. Typical deployment is on networking line cards where a -48V telecom rail needs controlled insertion without glitching the backplane.
Supply range and what it means for the BOM
The -9V to -100V supply range covers the standard -48V telecom bus with margin for transients and longer cable runs. The 500 µA supply current is the controller's own draw.
Programmable protection — set it and trust it
The MAX5901LAEUT gives you programmable UVLO, slew rate, current limit, circuit breaker threshold, and fault timeout. That means you tune the startup ramp to avoid tripping the upstream breaker, and set the overcurrent limit to protect your downstream DC-DC converters. The auto-retry option is useful for remote equipment where a manual reset isn't practical — the controller keeps trying after a fault timeout. For safety-critical or serviceable slots, the latched fault option holds the output off until you cycle power.
Package and mounting
SOT-23-6, surface mount. Six pins, compact footprint. Fits on the cramped edge of a line card where board real estate is at a premium. The supplier device package is the same SOT-23-6, so no footprint ambiguity between the generic case code and the specific part marking.
Lifecycle and compliance
Note that this part is listed as RoHS non-compliant, so if your assembly line is restricted to RoHS materials, factor that into your BOM review. The operating temperature range of -40°C to 85°C covers industrial and telecom environments, including outdoor cabinets with passive cooling.