Features

• Allows Safe Board Insertion and Removal from a Live Backplane
• Controls Supply Voltage from 10.8V to 36V
• Foldback Current Limiting
• Open Circuit and Overcurrent Fault Detect
• Drives an External N-Channel MOSFET
• Automatic Retry or Latched Off Operation After Overcurrent Fault
• Programmable Supply Voltage Power-Up Rate
• Undervoltage and Overvoltage Protection
• Open MOSFET Detection
• Available in 16-Lead SSOP Package

Typical Application

Description

The LT®4254 is a high voltage Hot Swap^TM controller that allows a board to be safely inserted and removed from a live backplane. An internal driver controls the high side N-channel MOSFET gate for supply voltages ranging from 10.8V to 36V. The part features an open-circuit detect (OPEN) output that indicates abnormally low load current conditions.

The LT4254 features an adjustable analog foldback current limit. If the supply remains in current limit for more than a programmable time, the N-channel MOSFET shuts off, the PWRGD output goes low and the LT4254 either automatically restarts after a time-out delay or latches off until the UV pin is cycled low. The RETRY pin sets whether the part will automatically restart after an overcurrent fault or if it will latch off until the UV pin is cycled low.

The PWRGD output indicates when the output voltage rises above a programmed level. An external resistor string from V_CC provides programmable undervoltage and overvoltage protection.

Hot Swap is a trademark of Linear Technology Corporation.