Features

• Allows Safe Insertion into Live CompactPCI^TM or PCI Express^TM Backplane
• 8-Bit ADC Monitors Current and Voltage
• I²C^TM/SMBus Interface
• dI/dt Controlled Soft Start
• Simultaneous or Sequenced Turn-On
• ±20V Absolute Maximum Rating for ±12V Supplies
• No External Gate Capacitor Required
• Dual-Level Circuit Breaker and Current Limit
• Bus Precharge Output
• Power Good Input with Timeout
• Optional Latchoff or Autoretry After Faults
• Alerts Host After Faults
• Integrated LOCAL_PCI_RST# Logic
• 36-Pin SSOP and 38-Pin (5mm × 7mm) QFN Packages

Typical Application

Description

The LTC4245 Hot Swap controller allows a board to be safely inserted and removed from a live backplane in multiple supply systems such as CompactPCI and PCI Express. Using four external N-channel pass transistors, the board supply voltages can be ramped up at an adjustable rate and in any desired sequence. An I²C interface and onboard ADC allow monitoring of board current, voltage and fault status for each supply.

The device features adjustable dI/dt controlled soft start and foldback limited inrush current. A dual-level timed circuit breaker and fast current limit protect each supply against overcurrent faults. A power good input with timeout allows a downstream supply monitor to disconnect the board supplies. The device can be configured to function without a –12V supply or with an extra 3.3V supply instead of a 5V supply.

The controller has additional features to interrupt the host when a fault has occurred, notify when output power is good, detect insertion of a load card and power-up in either the on or off state.