LT4256-3 Positive High Voltage Hot Swap Controller with Open-Circuit Detect FEATURES DESCRIPTIO TM Allows Safe Board Insertion and Removal from a The LT 4256-3 is a high voltage Hot Swap controller that Live Backplane allows a board to be safely inserted and removed from a Controls Supply Voltage from 10.8V to 80V live backplane. An internal driver controls the high side Foldback Current Limiting N-channel MOSFET gate for supply voltages ranging from Open Circuit and Overcurrent Fault Detect 10.8V to 80V. The part features an open-circuit detect Drives an External N-Channel MOSFET (OPEN) output that indicates abnormally low load current Automatic Retry or Latched Off Operation conditions. After Overcurrent Fault The LT4256-3 also features an adjustable analog foldback Programmable Supply Voltage Power-Up Rate current limit. If the supply remains in current limit for more Open MOSFET Detection than a programmable time, the N-channel MOSFET shuts 1% Over and Undervoltage Detection Accuracy off, the PWRGD output asserts low and the LT4256-3 Available in a 16-Lead SSOP Package either automatically restarts after a time-out delay or U latches off until the UV pin is cycled low (depending on the APPLICATIO S status of the RETRY pin). Hot Board Insertion The PWRGD output indicates when the output voltage Electronic Circuit Breaker/Power Bussing rises above a programmed level. An external resistor Industrial High Side Switch/Circuit Breaker string from V provides programmable undervoltage and CC 24V/48V Industrial/Alarm Systems overvoltage protection. Ideally Suited for 12V, 24V and 48V Distributed The LT4256-3 is available in a 16-lead SSOP package. Power Systems , LTC and LT are registered trademarks of Linear Technology Corporation. 48V Telecom Systems Hot Swap is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATIO 48V, 2A Hot Swap Controller 0.020 V IRF540 OUT LT4256-3 Start-Up Behavior V IN 48V 48V + 2A SMAT70A C CMPZ5241BS L (SHORT PIN) 11V V IN 50V/DIV V SENSE CC CONTACT BOUNCE 51k 64.9k 36.5k 10nF 10 V 100 OUT 50V/DIV UV GATE LT4256-3 INRUSH V 0.01F OUT CURRENT 4.02k 4.02k 500mA/DIV FB OV PWRGD C = 225F L 4.02k 50V/DIV PWRGD OPEN PWRGD 42563 TA02 4256 TA01 2.5ms/DIV UV = 36V TIMER RETRY GND OV = 73V GND 33nF PWRGD = 40V 42563fa 1 U ULT4256-3 UUW ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) TOP VIEW Supply Voltage (V ) ................................ 0.3 to 100V CC ORDER PART UV 1 16 V CC SENSE, PWRGD ....................................... 0.3 to 100V NUMBER OV 2 15 SENSE GATE Voltage (Note 2) .................... 0.3V to V + 10V CC LT4256-3CGN NC 3 14 NC GATE Maximum Current ..................................... 200A OPEN 4 13 GATE LT4256-3IGN V .......................................................... 3V to 100V OUT PWRGD 5 12 V OUT FB, UV, OPEN ............................................. 0.3 to 44V NC 6 11 NC OV .............................................................. 0.3 to 18V RETRY 7 10 FB GN PART MARKING RETRY ........................................................ 0.3 to 15V GND 8 9 TIMER TIMER Voltage ......................................... 0.3V to 4.3V 42563 GN PACKAGE Maximum Input Current (TIMER) ....................... 100A 42563I 16-LEAD PLASTIC SSOP T = 125C, = 130C/W Operating Temperature JMAX JA LT4256-3C ............................................. 0C to 70C Order Options Tape and Reel: Add TR Lead Free: Add PBF Lead Free Tape and Reel: Add TRPBF LT4256-3I ......................................... 40C to 85C Lead Free Part Marking: