LT4254

Features:

Allows Safe Board Insertion and Removal from 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


Application

Hot Board Insertion
Electronic Circuit Breaker/Power Bussing
Industrial High Side Switch/Circuit Breaker
24V Industrial/Alarm Systems
 12V and 24V Distributed Power Systems


Pinout




Specifications

Supply Voltage (VCC) .................................. 0.3 to 44V
Input Voltage (SENSE, PWRGD) ................. 0.3 to 44V
Input Voltage (GATE) .................................. 0.3 to 50V
Input Voltage (FB, UV, OPEN) ..................... 0.3 to 44V
Input Voltage (OV) ...................................... 0.3 to 18V
Input Voltage (RETRY) ............................... 0.3 to 15V
Minimum Input Voltage (TIMER) ......................... 0.3V
Maximum Input Current (TIMER) ....................... 100mA
Operating Temperature
LT4254C ................................................. 0°C to 70°C
LT4254I ............................................. 40°C to 85°C
Storage Temperature Range ................  65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C

Description

The LT®4254 is a high voltage Hot SwapTM 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 VCC provides programmable undervoltage and overvoltage protection.

The LT4254 is available in a 16-lead SSOP package.