The MAX5900ACEUT-T is a Hot Swap Controller from the Simple Swapper™ series, designed to manage inrush current and protect against fault conditions when boards are inserted into a live backplane. It operates from a -9V to -100V supply, drawing only 500 µA from the rail — the quiescent load is negligible in a typical networking line card where the backplane supplies tens of amps. The controller does not include an internal pass element; an external N-channel MOSFET must be added between the supply input and the load. This single-channel controller supports one independent hot-swap rail.
What the programmable features mean for the BOM
Programmable features include Auto Retry, Circuit Breaker, Current Limit, Fault Timeout, Slew Rate, and UVLO — each set with external resistors or capacitors, giving the designer control over the startup ramp, overcurrent threshold, and retry behavior without firmware involvement. The Fault Timeout and Latched Fault options let the system choose between automatic recovery after an overcurrent event or a hard latch-off that requires a power cycle — a decision that depends on whether the load is a capacitor bank or a processor core. Thermal Limit protection shuts down the external FET if the junction temperature exceeds the safe operating area — a backup safeguard if the heatsinking is marginal at high ambient.
Housed in a 6-pin SOT-23-6 (Supplier Device Package SOT-23-6), the footprint occupies roughly 3 mm × 3 mm — the tight pitch suits dense line-card layouts where board area is at a premium. Surface-mount assembly with no exposed thermal pad; the external FET handles the power dissipation, so the controller itself stays cool even at full rated voltage.
Temperature grade and environment
The Applications field lists Networking; the wide negative supply range also suits -48V telecom plants where the controller manages the insertion of a line card onto a -48V backplane.
Lifecycle and compliance
RoHS non-compliant. Verify your BOM's lead-free requirement before specifying; if the assembly line is RoHS-only, a Pb-free alternative or exemption waiver may be needed.