LTC4251B/LTC4251B-1/ LTC4251B-2 Negative Voltage Hot Swap Controllers in SOT-23 FEATURES DESCRIPTION n Allows Safe Board Insertion and Removal from a The LTC 4251B/LTC4251B-1/LTC4251B-2 negative voltage Live 48V Backplane Hot Swap controllers allow a board to be safely inserted n Floating Topology Permits Very High Voltage and removed from a live backplane. Output current is con- Operation trolled by three stages of current limiting: a timed circuit n Programmable Analog Current Limit with Circuit breaker, active current limiting and a fast feedforward path Breaker Timer that limits peak current under worst-case catastrophic n Fast Response Time Limits Peak Fault Current fault conditions. n Improved Ruggedness Shunt Regulator Programmable undervoltage and overvoltage detectors n Programmable Timer disconnect the load whenever the input supply exceeds n Programmable Undervoltage/Overvoltage Protection the desired operating range. The supply input is shunt n Low Profile 6-Lead SOT-23 (ThinSOT) Package regulated, allowing safe operation with very high supply voltages. A multifunction timer delays initial start-up and controls the circuit breakers response time. APPLICATIONS The LTC4251B UV/OV thresholds are designed to match n Hot Board Insertion the standard telecom operating range of 43V to 75V. The n Electronic Circuit Breaker LTC4251B-1 UV/OV thresholds extend the operating range n 48V Distributed Power Systems to encompass 36V to 72V. The LTC4251B-2 implements n Negative Power Supply Control a UV threshold of 43V only. The LTC4251B improves the n Central Office Switching ruggedness of the LTC4251 shunt regulator. n Programmable Current Limiting Circuit L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and n High Availability Servers Hot Swap and ThinSOT are trademarks of Linear Technology Corporation. All other trademarks n are the property of their respective owners. Disk Arrays TYPICAL APPLICATION 48V, 2.5A Hot Swap Controller Start-Up Behavior 48RTN R * IN + 48RTN 10k GATE C L LOAD (SHORT PIN) 500mW 5V/DIV 100F R1 V OUT 402k C D IN IN V IN 1% 1F DDZ13B** Q1 SENSE UV/OV GATE IRF530S 2.5A/DIV C1 LTC4251B 10nF 3 TIMER SENSE R2 1 R C V R 32.4k EE S V OUT 10 0.02 1% 20V/DIV C C T C 18nF 2 150nF 4 4251b12 TA01a 48V 4251b12 TA01b 1ms/DIV *TWO 0.25W RESISTORS IN SERIES FOR R ON THE PCB ARE RECOMMENDED. IN **DIODES, INC. RECOMMENDED FOR HARSH ENVIRONMENTS 4251b12f 1LTC4251B/LTC4251B-1/ LTC4251B-2 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1), All Voltages are Referred to V EE Current into V (100s Pulse) .............................100mA IN Minimum V Voltage ............................................ 0.3V IN TOP VIEW Gate, UV/OV, Timer Voltage........................ 0.3V to 16V SENSE 1 6 GATE Sense Voltage ............................................ 0.6V to 16V V 2 5 UV/OV* EE Current Out of Sense Pin (20s Pulse) .............. 200mA V 3 4 TIMER IN Maximum Junction Temperature .......................... 125C S6 PACKAGE Operating Temperature Range 6-LEAD PLASTIC SOT-23 *UV FOR LTC4251B-2 LTC4251BC/LTC4251BC-1/LTC4251BC-2 ....0C to 70C T = 125C, = 192C/W JMAX JA LTC4251BI/LTC4251BI-1/LTC4251BI-2 .. 40C to 85C Storage Temperature Range .................. 65C to 150C Lead Temperature (Soldering, 10 sec) ...................300C ORDER INFORMATION Lead Free Finish TAPE AND REEL (MINI) TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC4251BCS6 TRMPBF LTC4251BCS6 TRPBF LTGCT 6-Lead Plastic SOT-23 0C to 70C LTC4251BIS6 TRMPBF LTC4251BIS6 TRPBF LTGCT 6-Lead Plastic SOT-23 40C to 85C LTC4251BCS6-1 TRMPBF LTC4251BCS6-1 TRPBF LTGDV 6-Lead Plastic SOT-23 0C to 70C LTC4251BIS6-1 TRMPBF LTC4251BIS6-1 TRPBF LTGDV 6-Lead Plastic SOT-23 40C to 85C LTC4251BCS6-2 TRMPBF LTC4251BCS6-2 TRPBF LTGDW 6-Lead Plastic SOT-23 0C to 70C LTC4251BIS6-2 TRMPBF LTC4251BIS6-2 TRPBF LTGDW 6-Lead Plastic SOT-23 40C to 85C TRM = 500 pieces. *Temperature grades are identified by a label on the shipping container. Consult LTC Marketing for parts specified with wider operating temperature ranges. Consult LTC Marketing for information on lead based finish parts. For more information on lead free part marking, go to: