The LTC4253A-ADJ negative voltage Hot Swap controller allows a board to be safely inserted and removed from a live backplane. Output current is controlled by three stages of current-limiting: a timed circuit breaker, active current limiting and a fast feedforward path that limits peak current under worst-case catastrophic fault conditions. The LTC4253A-ADJ latches off after a circuit fault. Undervoltage and overvoltage detectors with adjustable thresholds and hystereses disconnect the load whenever the input supply exceeds the desired operating range. The LTC4253A-ADJ's supply input is shunt-regulated, allowing safe operation with very high supply voltages. A multifunction timer delays initial start-up and controls the circuit breaker's response time. The circuit breaker's response time can be accelerated by sensing excessive MOSFET drain voltage. An adjustable soft-start circuit controls MOSFET inrush current at start-up. Three power good outputs can be sequenced to enable external power modules at start-up or disable them if the circuit breaker trips. The LTC4253A-ADJ is available in 20-pin SSOP and 20-pin (4mm × 4mm) QFN packages.
