The LTC1644 is a Hot SwapTM controller that allows a board to be safely inserted and removed from a CompactPCI bus slot. External N-channel transistors control the 3.3V/5V supplies, while on-chip switches control the 12V and 12V supplies. The 3.3V and 5V supplies can be ramped up at a programmable rate. Electronic circuit breakers protect all four supplies against overcurrent faults. The PWRGD output indicates when all of the supply voltages are within tolerance. The OFF/ON pin is used to cycle the board power or reset the circuit breaker. The PRECHARGE output can be used to bias the bus I/O pins during card insertion and extraction. PCI_RST# is combined on-chip with HEALTHY# in order to generate LOCAL_PCI_RST#.