DESCRIPTION
The LTC®1643A is a Hot SwapTMcontroller that allows a board to be safely inserted and removed from a live PCI-Bus slot. Two external N-channel transistors control the 3.3V and 5V supplies while on-chip switches control the –12V and 12V supplies. All supply voltages can be ramped up at a programmable rate. An electronic circuit breaker protects all four supplies against overcurrent faults. The foldback current limit feature limits current spikes and power dissipation when shorts occur and allows boards with large capacitances to be powered up without tripping the circuit breaker.

FEATURES
■ Allows Safe Board Insertion and Removal from a Live PCI Slot
■ Works on either a Motherboard (LTC1643AH) or CompactPCITM Card (LTC1643AL/LTC1643AL-1)
■ Controls –12V, 3.3V, 5V, 12V Supplies
■ Programmable Foldback Current Limit with Circuit Breaker
■ User-Programmable Supply Voltage Power-Up Rate
■ High Side Drive for External N-Channel MOSFETs
■ –12V and 12V On-Chip Switches
■ Fault and Power-Good Outputs
■ Available in a Narrow 16-Lead SSOP Package

APPLICATIONS
■ PCI-Based Servers
■ CompactPCI Compliant Boards