Hot swap controller for -48V telecom backplanes
The MAX5939EESA is a single-channel hot swap controller designed for -48V telecom and networking applications. It manages the inrush current when a board is plugged into a live backplane, preventing glitches and connector damage. Operating from -20V to -80V, it covers the standard -48V telecom rail with margin for transients. The 700 µA supply current is low enough to keep the controller's own dissipation negligible in the thermal budget.
Programmable protection and fault handling
The controller integrates a programmable circuit breaker, current limit, fault timeout, and latched fault response. Overvoltage protection (OVP) and undervoltage lockout (UVLO) are also programmable, so the same part can be tuned for different board power profiles. A thermal limit shuts down the external pass FET if the die temperature exceeds the threshold — a last-resort safeguard if the heatsinking is marginal or airflow fails.
The supplier device package is 8-SOIC, with the same footprint as the industry-standard SO-8. No external switch is integrated — an external N-channel MOSFET must be added to handle the load current.
Active production and compliance
Note that the part is marked RoHS non-compliant. If your BOM requires RoHS-10/10 exemption-free compliance, confirm the date-code restrictions or evaluate a lead-free alternative from the same family.