The LTC4244/LTC4244-1 are Hot SwapTM controllers that allow a board to be safely inserted into and removed from a CompactPCITM bus slot. External N-channel transistors control the 5V and 3.3V supplies while on-chip switches control the 12V supplies. The 3.3V and 5V supplies can be ramped up at an adjustable rate. Electronic circuit breakers protect all four supplies against overcurrent faults. After the power-up cycle is complete, the TIMER pin capacitor serves as auxiliary VCC allowing the LTC4244/ LTC4244-1 to function without interruption in the presence of voltage spikes on the 12VIN supply. The PWRGD output indicates when all four supplies are within tolerance. The OFF/ON pin is used to cycle 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#.