Features

• Allows Safe Insertion Into a Live Backplane
• 10-Bit ADC Monitors Currents and Voltages
• I²C/SMBus Interface
• Wide Operating Voltage Range: 2.9V to 29V
• dI/dt Controlled Soft-Start
• High Side Drive for External N-Channel MOSFETs
• No External Gate Capacitors Required
• Input Overvoltage/Undervoltage Protection
• Optional Latchoff or Auto-Retry After Faults
• Alert Host After Faults
• Inrush Current Limit with Foldback
• Available in 32-Pin (5mm × 5mm) QFN and 36-Pin SSOP Packages

Typical Application

Description

The LTC4222 Hot Swap controller allows two power paths to be safely inserted and removed from a live backplane. Using external N-channel pass transistors, board supply voltages and inrush currents are ramped up at an adjustable rate. An I²C interface and onboard ADC allows for monitoring of current, voltage and fault status for each channel.

The device features adjustable, analog, foldback current limit circuits and a Soft-Start circuit that sets the dI/dt of the inrush currents. An I²C interface may configure the part to latch off or automatically restart after the LTC4222 detects a fault on either channel.

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 either automatically upon insertion or wait for an I²C command to turn on.