48V telecom backplane protection in a SOT-23-6
The Maxim Integrated MAX5903ABEUT is a single-channel hot swap controller from the Simple Swapper™ family, built for networking and telecom line cards that need controlled inrush and fault isolation on a 9V to 72V rail. It integrates both internal switches — the pass element and the current-sense path — so the board designer avoids external MOSFETs and sense resistors. The controller handles auto retry, fault timeout, thermal limit, and undervoltage lockout (UVLO) without extra supervisory ICs. The SOT-23-6 footprint keeps the BOM tight for dense backplane cards where every square millimetre counts.
Supply range — where this part fits
The 9V to 72V supply window is the deciding spec for fit. It covers the standard 48V telecom bus (nominal 48V, ringing up to 72V) and 24V industrial rails. If your system runs on 12V or 5V, this controller is overkill — look at the lower-voltage Simple Swapper variants. The 1 mA supply current is low enough that it won't steal headroom from the load budget on a typical line card.
Protection features — what they mean for the BOM
Programmable features include circuit breaker threshold, current limit, slew rate, and fault timeout, plus the built-in thermal limit and UVLO. That means one part replaces a discrete hot-swap controller plus a separate supervisor or timer IC. The auto-retry behaviour lets the card re-try after a fault without a power cycle — useful for transient overcurrent events on a backplane. The thermal limit protects the controller itself if the load draws excessive current for too long.
Temperature grade and environment
Rated for -40°C to 85°C ambient, this part suits outdoor telecom cabinets, factory-floor equipment, and central-office racks.
Lifecycle and sourcing
RoHS non-compliant per the record, so verify your assembly house's exemption policy if your BOM requires full RoHS compliance.