Two-channel hot swap controller for 3V to 12V backplanes
The Analog Devices LTC1421IG-2.5#PBF is a two-channel hot swap controller designed to manage inrush current and provide fault protection on 3V to 12V supply rails. It integrates undervoltage lockout (UVLO) and a latched fault response, with programmable circuit breaker, fault timeout, and slew rate control to tailor the turn-on profile to the load capacitance. No internal pass FETs are included — the controller drives external N-channel MOSFETs, giving the designer flexibility to size the power path for the actual load current.
Programmable inrush and fault handling
Three programmable features — circuit breaker threshold, fault timeout, and slew rate — let the designer set the soft-start ramp and overcurrent trip point to match the board's bulk capacitance and load profile. The circuit breaker can be configured for a latched-off or auto-retry response; this part uses a latched fault, so a fault condition holds the output off until the supply is cycled or the part is reset. UVLO ensures the controller stays off until the input rail is above the programmed threshold, preventing partial turn-on during brownout conditions. Supply current draw is 1.5 mA typical, making it suitable for always-on backplane monitoring.
For dual-sourcing or alternate package options, the LTC1647-3IGN#PBF offers a similar two-channel hot swap controller with auto-retry instead of latched fault, also in a 24-SSOP package with the same programmable features. The LTC1645IS8#PBF adds sequencing capability but uses an 8-pin SOIC package with only latched fault and no fault timeout.