LTC3642 High Efficiency, High Voltage 50mA Synchronous Step-Down Converter FEATURESDESCRIPTION n Wide Input Voltage Range: 4.5V to 45V The LTC®3642 is a high efficiency, high voltage step-down n Tolerant of 60V Input Transients DC/DC converter with internal high side and synchronous n Internal High Side and Low Side Power Switches power switches that draws only 12μA typical DC sup- n No Compensation Required ply current at no load while maintaining output voltage n 50mA Output Current regulation. n Low Dropout Operation: 100% Duty Cycle The LTC3642 can supply up to 50mA load current and n Low Quiescent Current: 12µA features a programmable peak current limit that provides n 0.8V Feedback Voltage Reference a simple method for optimizing efficiency in lower current n Adjustable Peak Current Limit applications. The LTC3642’s combination of Burst Mode® n Internal and External Soft-Start operation, integrated power switches, low quiescent cur- n Precise RUN Pin Threshold with Adjustable rent, and programmable peak current limit provides high Hysteresis efficiency over a broad range of load currents. n 3.3V, 5V and Adjustable Output Versions n Only Three External Components Required for Fixed With its wide 4.5V to 45V input range and internal Output Versions overvoltage monitor capable of protecting the part through n Low Profile (0.75mm) 3mm × 3mm DFN and 60V surges, the LTC3642 is a robust converter suited for Thermally-Enhanced MS8E Packages regulating a wide variety of power sources. Additionally, the LTC3642 includes a precise run threshold and soft-start APPLICATIONS feature to guarantee that the power system start-up is well-controlled in any environment. n 4mA to 20mA Current Loops n The LTC3642 is available in the thermally enhanced Industrial Control Supplies n 3mm × 3mm DFN and MS8E packages. Distributed Power Systems n Portable Instruments L, LT, LTC, LTM, Burst Mode, Linear Technology, and the Linear logo are registered trademarks and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the n Battery-Operated Devices property of their respective owners. n Automotive Power Systems TYPICAL APPLICATIONEfficiency and Power Loss vs Load Current 100 VIN = 10V 5V, 50mA Step-Down Converter 95 100 EFFICIENCY POWER LOSS (mW) 90 150µH V VOUT IN VIN SW 5V TO 45V 5V 85 10 1µF LTC3642-5 10µF 50mA POWER LOSS RUN VOUT 80 HYST SS EFFICIENCY (%) ISET 75 1 GND 70 3642 TA01a 65 0.1 0.1 1 10 100 LOAD CURRENT (mA) 3642 TA01b 3642fc 1 Document Outline FEATURES DESCRIPTION APPLICATIONS TYPICAL APPLICATION ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION ORDER INFORMATION ELECTRICAL CHARACTERISTICS TYPICAL PERFORMANCE CHARACTERISTICS PIN FUNCTIONS BLOCK DIAGRAM OPERATION APPLICATIONS INFORMATION TYPICAL APPLICATIONS PACKAGE DESCRIPTION REVISION HISTORY TYPICAL APPLICATION RELATED PARTS