Features

• Allows Safe Insertion into Live Backplane
• 8-Bit ADC Monitors Current and Voltage
• I2C/SMBus Interface
• Wide Operating Voltage Range: 2.9V to 15V
• 20μs (LTC4215) or 420μs (LTC4215-2) Circuit Breaker Timeout
• dI/dt Controlled Soft-Start
• High Side Drive for External N-Channel MOSFET
• No External Gate Capacitor Required
• Input Overvoltage/Undervoltage Protection
• Optional Latchoff or Auto-Retry After Faults
• Alerts Host After Faults
• Inrush Current Limit with Foldback
• Available in 24-Pin (4mm × 5mm) QFN Package
• LTC4215 also available in 16-Lead Narrow SSOP Package

Typical Application

Description

The LTC4215/LTC4215-2 Hot Swap controllers allow a board to be safely inserted and removed from a live backplane. Using an external N-channel pass transistor, board supply voltage and inrush current are ramped up at an adjustable rate. An I²C interface and onboard ADC allow for monitoring of load current, voltage and fault status.

The device features adjustable foldback current limit and a soft-start pin that sets the dI/dt of the inrush current. An I²C interface may configure the part to latch off or automatically restart after the LTC4215 detects a current limit fault.

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.

The LTC4215 has a 20μs circuit breaker filter for applications that require a fast fault response time and it defaults to latchoff after an overcurrent fault. The LTC4215-2 has an extended 420μs circuit breaker filter for applications where supply transients may exceed 20μs and it defaults to restart automatically after an overcurrent fault.