POWER LOSS (W) LTC3646/LTC3646-1 40V, 1A Synchronous Step-Down Converter FEATURES DESCRIPTION n Wide Input Voltage Range: 4.0V to 40V The LTC 3646 is a high efficiency, step-down DC/DC n 1A Guaranteed Output Current converter with internal high side and synchronous power n High Efficiency: Up to 95% FETs. It draws only 140A typical DC supply current in n Wide Output Voltage Range Burst Mode operation at no load while maintaining output n LTC3646: 2.0V to 30V voltage regulation. n LTC3646-1: 0.6V to 15V The LTC3646 can supply up to a 1A load, and its combina- n 1% Accurate Reference Voltage tion of Burst Mode operation, integrated power switches n Internal or External Compensation and low quiescent current provides high efficiency over a n Switching Frequency Adjustable and Synchronizable: broad range of load currents. Alternatively, it can be used 200kHz to 3MHz in forced continuous mode for ripple sensitive applications. n Selectable High Efficiency Burst Mode Operation or The LTC3646 has a wide 4.0V to 40V input range and its Forced Continuous Mode n patented controlled on-time architecture and 0.6V refer- 14 Lead 3mm 4mm DFN or Thermally Enhanced ence voltage allow for large step-down ratios without 16-Lead MSOP Packages the risk of output overvoltage. The frequency may be set between 200kHz and 3.0MHz with a program resistor or APPLICATIONS synchronized to an external clock. n Point of Load Power Supplies The internal soft-start, short-circuit protection and volt- n Intermediate Bus Power age rating make the LTC3646 a robust part ideal for high n Automotive Applications voltage applications. L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks and Hot Swap is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 6580258, 5481178, 5994885, 6304066, 5847554, 6476589, 6774611. TYPICAL APPLICATION Efficiency Curve 100 1.0 V IN BOOST PVIN V = 12V IN V = 5V 40V MAX OUT 90 f = 1MHz SVIN 0.1F LTC3646 V = 3.3V OUT 80 0.8 RUN 3.3H V OUT SW INTV 70 CC 5V 10F MODE/SYNC 1A 60 0.6 ITH 50 V RT SWITCH ON 40 0.4 CONTROL EXTV CC 30 V = 5V OUT 412k 4.7F V = 3.3V 20 OUT 0.2 + 15F V FB 10 0.6V 0 0 SGND PGND 0.001 0.01 0.1 1 56.2k LOAD CURRENT (A) 3646 TA01a 3646 TA01b 36461fc 1 For more information www.linear.com/LTC3646 EFFICIENCY (%)LTC3646/LTC3646-1 ABSOLUTE MAXIMUM RATINGS (Notes 1, 7) PVIN, SVIN Supply Voltage ........................ 0.3V to 45V EXTV Voltage ........................................... 0.3V to 6V CC SW Voltage (DC) ........................... 0.3V to PVIN + 0.3V RUN Voltage............................................... 0.3V to 45V BOOST SW Voltage ................................... 0.3V to 6V PGOOD .......................................0.3V to INTV + 0.3V CC V Voltage ................................................ 0.3V to 33V Operating Junction Temperature Range ON MODE/SYNC, RT, ITH, (Notes 2, 7) ............................................ 40C to 150C V Voltage ................................0.3V to INTV + 0.3V Storage Temperature Range .................. 65C to 150C FB CC INTV Voltage ............................................ 0.3V to 6V Lead Temperature (Soldering, 10 sec) MSE ..........300C CC PIN CONFIGURATION TOP VIEW TOP VIEW SGND 1 14 SVIN SGND 1 16 SVIN V 2 13 RUN FB V 2 15 RUN FB ITH 3 12 EXTV ITH 3 14 EXTV CC CC 15 17 RT 4 13 INTV CC RT 4 11 INTV PGND CC V 5 PGND 12 BOOST ON V 5 10 BOOST PGOOD 6 11 SW ON MODE/SYNC 7 10 PVIN PGOOD 6 9 SW NC 8 9 PVIN MODE/SYNC 7 8 PVIN MSE PACKAGE 16-LEAD PLASTIC MSOP DE PACKAGE T = 150C, = 38C/W JMAX JA 14-LEAD (4mm 3mm) PLASTIC DFN EXPOSED PAD (PIN 17) IS PGND, MUST BE SOLDERED TO PCB T = 150C, = 43C/W JMAX JA EXPOSED PAD (PIN 15) IS PGND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3646EDE PBF LTC3646EDE TRPBF 3646 14-Lead (4mm 3mm) Plastic DFN 40C to 85C LTC3646IDE PBF LTC3646IDE TRPBF 3646 14-Lead (4mm 3mm) Plastic DFN 40C to 125C LTC3646HDE PBF LTC3646HDE TRPBF 3646 14-Lead (4mm 3mm) Plastic DFN 40C to 150C LTC3646EMSE PBF LTC3646EMSE TRPBF 3646 16-Lead Plastic MSOP 40C to 85C LTC3646IMSE PBF LTC3646IMSE TRPBF 3646 16-Lead Plastic MSOP 40C to 125C LTC3646HMSE PBF LTC3646HMSE TRPBF 3646 16-Lead Plastic MSOP 40C to 150C LTC3646EDE-1 PBF LTC3646EDE-1 TRPBF 36461 14-Lead (4mm 3mm) Plastic DFN 40C to 85C LTC3646IDE-1 PBF LTC3646IDE-1 TRPBF 36461 14-Lead (4mm 3mm) Plastic DFN 40C to 125C LTC3646HDE-1 PBF LTC3646HDE-1 TRPBF 36461 14-Lead (4mm 3mm) Plastic DFN 40C to 150C LTC3646EMSE-1 PBF LTC3646EMSE-1 TRPBF 36461 16-Lead Plastic MSOP 40C to 85C LTC3646IMSE-1 PBF LTC3646IMSE-1 TRPBF 36461 16-Lead Plastic MSOP 40C to 125C LTC3646HMSE-1 PBF LTC3646HMSE-1 TRPBF 36461 16-Lead Plastic MSOP 40C to 150C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. 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