LT4250H Datasheet

• Allows Safe Board Insertion and Removal from a Live –48V Backplane
• Circuit Breaker Immunity to Voltage Steps and Current Spikes
• Programmable Inrush and Short-Circuit Current Limits
• Pin Compatible with LT1640L/LT1640H
• Operates from –18V to –80V
• Programmable Overvoltage Protection
• Programmable Undervoltage Lockout
• Power Good Control Output
• Bell-Core Compatible ON/OFF Threshold

• Central Office Switching
• –48V Distributed Power Systems
• Negative Power Supply Control

The LT4250H are 8-pin, negative 48V Hot Swap^™ controllers that allow a board to be safely inserted and removed from a live backplane. Inrush current is limited to a programmable value by controlling the gate voltage of an external N-channel pass transistor. The pass transistor is turned off if the input voltage is less than the programmable undervoltage threshold or greater than the overvoltage threshold. A programmable current limit protects the system against shorts. After a 500μs timeout the current limit activates the electronic circuit breaker. The PWRGD (LT4250H) signal can be used to directly enable a power module. The LT4250H for modules with a high enable input.

The LT4250H are available in 8-pin PDIP and SO packages