LTC3646/LTC3646-1 40V, 1A Synchronous Step-Down Converter FEATURESDESCRIPTION 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 140µA 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 Forced Continuous Mode The LTC3646 has a wide 4.0V to 40V input range and its n 14 Lead 3mm × 4mm DFN or Thermally Enhanced patented controlled on-time architecture and 0.6V refer- 16-Lead MSOP Packages ence voltage allow for large step-down ratios without 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 APPLICATIONEfficiency Curve 100 1.0 VIN PVIN BOOST VIN = 12V 40V MAX 90 VOUT = 5V f = 1MHz SVIN 0.1µF RUN LTC3646 80 VOUT = 3.3V 0.8 3.3µH VOUT POWER LOSS (W) INTVCC SW 70 10µF 5V MODE/SYNC 1A 60 0.6 ITH 50 RT SWITCH VON CONTROL 40 0.4 EXTVCC EFFICIENCY (%) 30 VOUT = 5V 412k 4.7µF 20 VOUT = 3.3V 0.2 + – 15µF VFB 10 0.6V 0 0 SGND PGND 56.2k 0.001 0.01 0.1 1 LOAD CURRENT (A) 3646 TA01a 3646 TA01b 36461fc For more information www.linear.com/LTC3646 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Block Diagram Operation Applications Information Typical Applications Typical Application Related Parts