LTC4235 Dual 12V Ideal Diode-OR and Single Hot Swap Controller with Current Monitor Fea T Descrip T TM n Ideal Diode-OR and Inrush Current Control for The LTC 4235 offers ideal diode-OR and Hot Swap Redundant Supplies functions for two 12V power rails by controlling external n N-channel MOSFETs. MOSFETs acting as ideal diodes Low Loss Replacement for Power Schottky Diodes n replace two high power Schottky diodes and the associ- Enables Safe Board Insertion into a Live Backplane n ated heat sinks, saving power and board area. A Hot Swap 9V to 14V Operation n control MOSFET allows a board to be safely inserted and Current Monitor Output n removed from a live backplane by limiting inrush current. Controls N-Channel MOSFETs The supply output is also protected against short-circuit n Limits Peak Fault Current in 1s faults with a foldback current limit and circuit breaker. n Adjustable Current Limit with Foldback n Adjustable Current Limit Fault Delay The LTC4235 regulates the forward voltage drop across n 0.5s Ideal Diode Turn-On and Turn-Off Time the MOSFETs to ensure smooth current transfer from one n Smooth Switchover without Oscillation supply to the other without oscillation. The ideal diodes n Fault and Power Good Outputs turn on quickly to reduce the load voltage droop during n LTC4235-1: Latch Off After Fault supply switchover. If the input supply fails or is shorted, n LTC4235-2: Automatic Retry After Fault a fast turn-off minimizes reverse-current transients. n 20-Pin 4mm x 5mm QFN Package A current sense amplifier translates the voltage across the sense resistor to a ground referenced signal. The LTC4235 allows turn-on/off control, and reports fault and power a T good status for the supply. n Redundant Power Supplies L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and Hot n High Availability Systems and Servers Swap is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 7920013, 8022679. n Telecom and Network Infrastructure Typical a T Ideal Diode-OR with Hot Swap Application Smooth Supply Switchover SiR158DP 12V IN2 0.1F SiR158DP 0.003 SiR158DP IN1 12V 12V IN1 1V/DIV 7A + 0.1F 0.1F C LOAD IN2 1V/DIV I IN1 + 13.7k CPO1 IN1 DGATE1 CPO2 IN2 DGATE2 REG SENSE SENSE HGATE OUT 2A/DIV ON FAULT I 2k IN2 2A/DIV LTC4235 PWRGD 4235 TA01b 200ms/DIV IMON ADC EN INTV CC GND D2OFF FTMR 0.1F 0.1F 4235 TA01a 4235f 1 For more information www.linear.com/LTC4235 ion pplica ions pplica ion uresLTC4235 a T e Maxi Mu M r a T (Notes 1, 2) Supply Voltages CPO1, CPO2 (Note 3) ............................. 0.3V to 35V IN1, IN2 .................................................. 0.3V to 24V DGATE1, DGATE2 (Note 3) ..................... 0.3V to 35V INTV ..................................................... 0.3V to 7V HGATE (Note 4) ..................................... 0.3V to 35V CC + + REG ...........................SENSE 5V to SENSE + 0.3V OUT ....................................................... 0.3V to 24V Input Voltages Average Currents ON, D2OFF, EN ...................................... 0.3V to 24V FAULT, PWRGD ....................................................5mA FTMR .....................................0.3V to INTV + 0.3V INTV ...............................................................10mA CC CC + SENSE , SENSE ................................... 0.3V to 24V Operating Ambient Temperature Range Output Voltages LTC4235C ................................................ 0C to 70C IMON ....................................................... 0.3V to 7V LTC4235I .............................................40C to 85C FAULT, PWRGD ...................................... 0.3V to 24V Storage Temperature Range .................. 65C to 150C p c F T TOP VIEW 20 19 18 17 1 16 PWRGD SENSE + SENSE 2 15 FAULT IN1 3 14 ON 21 INTV 4 13 D2OFF CC GND 5 12 REG 6 11 IMON IN2 7 8 9 10 UFD PACKAGE 20-LEAD (4mm 5mm) PLASTIC QFN T = 125C, = 43C/W (NOTE 5) JMAX JA EXPOSED PAD (PIN 21) PCB GND CONNECTION OPTIONAL o r D i n F Ma T LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC4235CUFD-1 PBF LTC4235CUFD-1 TRPBF 42351 20-Lead (4mm x 5mm) Plastic QFN 0C to 70C LTC4235CUFD-2 PBF LTC4235CUFD-2 TRPBF 42352 20-Lead (4mm x 5mm) Plastic QFN 0C to 70C LTC4235IUFD-1 PBF LTC4235IUFD-1 TRPBF 42351 20-Lead (4mm x 5mm) Plastic QFN 40C to 85C LTC4235IUFD-2 PBF LTC4235IUFD-2 TRPBF 42352 20-Lead (4mm x 5mm) Plastic QFN 40C to 85C Consult LTC Marketing for parts specified with wider operating temperature ranges. For more information on lead free part marking, go to: