CompactPCI hot swap — two-rail control in a 16-SSOP
The LTC1646CGN#PBF from Analog Devices is a Hot Swap Controller specifically designed for CompactPCI™ backplane applications. It manages inrush current and fault protection on two independent channels, each monitoring a 3.3V and a 5V supply rail. The controller draws 1.5 mA from the supply and integrates programmable features — circuit breaker threshold, current limit, fault timeout, and slew rate — to tailor the turn-on profile to the load capacitance.
Two channels, no internal switches — external MOSFETs required
This is a controller-only part — there are no internal pass elements. Each channel drives an external N-channel MOSFET that sits in the power path. The two channels let you sequence or independently protect two CompactPCI slots, or one slot with separate 3.3V and 5V rails. The 0°C to 70°C commercial temperature grade fits indoor rack-mount equipment, not extended-temperature or outdoor telecom cabinets.
Programmable protection — circuit breaker, current limit, fault timeout, slew rate
Four programmable parameters give the designer control over the hot-swap event. The circuit breaker threshold sets the overcurrent trip point; the current limit clamps the MOSFET gate during startup; the fault timeout window distinguishes a transient from a hard short; and the slew rate pin programs the output voltage ramp. Latched fault behavior means the controller stays off after a fault until the input is cycled or the fault is cleared — a deliberate choice for backplane environments where automatic retry could cause repeated power cycling.
Active lifecycle — no LTB risk
The LTC1646CGN#PBF carries an Active product status with ROHS3 compliance.
Sourcing and fit for the BOM
Because the part is active and carries no internal switch, the BOM cost is split between the controller and the external MOSFETs — a trade-off that gives the designer freedom to pick the FET RDS(on) and package that match the slot current budget. The 16-SSOP footprint (3.90 mm width) is a common outline, and the surface-mount assembly is standard.