Features

• Allows Safe Board Insertion and Removal from a Live Backplane
• Controls Supply Voltage from 10.8V to 80V
• 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
• Open MOSFET Detection
• 1% Over and Undervoltage Detection Accuracy
• Available in a 16-Lead SSOP Package

Typical Application

Description

The LT4256-3 is a high voltage Hot Swap™ 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 80V. The part features an open-circuit detect (OPEN) output that indicates abnormally low load current conditions.

The LT4256-3 also 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 asserts low and the LT4256-3 either automatically restarts after a time-out delay or latches off until the UV pin is cycled low (depending on the status of the RETRY pin).

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.

The LT4256-3 is available in a 16-lead SSOP package.