LTC4251/LTC4251-1/ LTC4251-2 Negative Voltage Hot Swap Controllers in SOT-23 FEATURES DESCRIPTION n Allows Safe Board Insertion and Removal from a The LTC 4251/LTC4251-1/LTC4251-2 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 Programmable Timer Programmable undervoltage and overvoltage detectors n Programmable Undervoltage/Overvoltage Protection disconnect the load whenever the input supply exceeds n Low Profile (1mm) ThinSOT Package the desired operating range. The supply input is shunt regulated, allowing safe operation with very high supply voltages. A multifunction timer delays initial start-up and APPLICATIONS controls the circuit breakers response time. n Hot Board Insertion The LTC4251 UV/OV thresholds are designed to match the n Electronic Circuit Breaker standard telecom operating range of 43V to 75V. The n 48V Distributed Power Systems LTC4251-1 UV/OV thresholds extend the operating range n Negative Power Supply Control to encompass 36V to 72V. The LTC4251-2 implements n Central Office Switching a UV threshold of 43V only. n Programmable Current Limiting Circuit n High Availability Servers All parts are available in the 6-Pin SOT-23 package. n Disk Arrays L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and Hot Swap and ThinSOT are trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATION 48V, 2.5A Hot Swap Controller Start-Up Behavior 48RTN R * IN + 48RTN 10k C GATE L LOAD (SHORT PIN) 500mW 100F 5V/DIV R1 V OUT 402k C D IN IN V IN 1% 1F DDZ13B** Q1 SENSE UV/OV GATE IRF530S 2.5A/DIV C1 LTC4251 10nF 3 TIMER SENSE R2 1 R C R V 32.4k EE S V OUT 10 0.02 1% 20V/DIV C C C T 2 150nF 18nF 4 425112 TA01 48V 425112 TA02 1ms/DIV *TWO 0.25W RESISTORS IN SERIES FOR R ON THE PCB ARE RECOMMENDED. IN **DIODES, INC. RECOMMENDED FOR HARSH ENVIRONMENTS 425112fd 1 For more information www.linear.com/4251LTC4251/LTC4251-1/ LTC4251-2 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 LTC4251-2 LTC4251C/LTC4251-1C/LTC4251-2C ........ 0C to 70C T = 125C, = 256C/W JMAX JA LTC4251I/LTC4251-1I/LTC4251-2I ........40C to 85C Storage Temperature Range .................. 65C to 150C Lead Temperature (Soldering, 10 sec) ...................300C ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC4251CS6 PBF LTC4251CS6 TRPBF LTUQ 6-Lead Plastic SOT-23 0C to 70C LTC4251IS6 PBF LTC4251IS6 TRPBF LTUR 6-Lead Plastic SOT-23 40C to 85C LTC4251-1CS6 PBF LTC4251-1CS6 TRPBF LTQU 6-Lead Plastic SOT-23 0C to 70C LTC4251-1IS6 PBF LTC4251-1IS6 TRPBF LTQV 6-Lead Plastic SOT-23 40C to 85C LTC4251-2CS6 PBF LTC4251-2CS6 TRPBF LTK6 6-Lead Plastic SOT-23 0C to 70C LTC4251-2IS6 PBF LTC4251-2IS6 TRPBF LTAAZ 6-Lead Plastic SOT-23 40C to 85C Consult LTC Marketing for parts specified with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: