POWER LOSS (mW) LTC3642 High Efficiency, High Voltage 50mA Synchronous Step-Down Converter FEATURES DESCRIPTION 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 12A 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: 12A 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 LTC3642s 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 With its wide 4.5V to 45V input range and internal Only Three External Components Required for Fixed overvoltage monitor capable of protecting the part through Output Versions n 60V surges, the LTC3642 is a robust converter suited for Low Profile (0.75mm) 3mm 3mm DFN and regulating a wide variety of power sources. Additionally, Thermally-Enhanced MS8E Packages the LTC3642 includes a precise run threshold and soft-start feature to guarantee that the power system start-up is APPLICATIONS well-controlled in any environment. n 4mA to 20mA Current Loops The LTC3642 is available in the thermally enhanced n Industrial Control Supplies 3mm 3mm DFN and MS8E packages. n Distributed Power Systems n L, LT, LTC, LTM, Burst Mode, Linear Technology, and the Linear logo are registered trademarks Portable Instruments 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 Efficiency and Power Loss vs Load Current TYPICAL APPLICATION 100 V = 10V IN 95 100 5V, 50mA Step-Down Converter EFFICIENCY 90 150H V OUT V IN V SW 5V IN 85 10 5V TO 45V 50mA LTC3642-5 1F 10F POWER LOSS RUN V OUT 80 HYST SS I 75 1 SET GND 70 3642 TA01a 65 0.1 0.1 1 10 100 LOAD CURRENT (mA) 3642 TA01b 3642fc 1 EFFICIENCY (%)LTC3642 ABSOLUTE MAXIMUM RATINGS (Note 1) V Supply Voltage ..................................... 0.3V to 60V Operating Junction Temperature Range IN SW Voltage (DC) ........................... 0.3V to (V + 0.3V) (Note 2) ..................................................40C to 125C IN RUN Voltage .............................................. 0.3V to 60V Storage Temperature Range ...................65C to 150C HYST, I , SS Voltages ............................... 0.3V to 6V Lead Temperature (Soldering, 10 sec) SET V ............................................................... 0.3V to 6V MS8E ................................................................ 300C FB V (Fixed Output Versions) ....................... 0.3V to 6V OUT PIN CONFIGURATION TOP VIEW TOP VIEW SW 1 8 GND SW 1 8 GND V 2 7 HYST IN 9 V 2 9 7 HYST IN GND GND I 3 6 V /V I V /V SET OUT FB 3 6 SET OUT FB SS 4 5 RUN SS RUN 4 5 MS8E PACKAGE 8-LEAD PLASTIC MSOP DD PACKAGE T = 125C, = 40C/W, = 5-10C/W JMAX JA JC 8-LEAD (3mm 3mm) PLASTIC DFN EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB T = 125C, = 43C/W, = 3C/W JMAX JA JC EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3642EMS8E PBF LTC3642EMS8E TRPBF 8-Lead Plastic MSOP 40C to 125C LTDTH LTC3642EMS8E-3.3 PBF LTC3642EMS8E-3.3 TRPBF 8-Lead Plastic MSOP 40C to 125C LTDYN LTC3642EMS8E-5 PBF LTC3642EMS8E-5 TRPBF 8-Lead Plastic MSOP 40C to 125C LTDYQ LTC3642IMS8E PBF LTC3642IMS8E TRPBF LTDTH 8-Lead Plastic MSOP 40C to 125C LTC3642IMS8E-3.3 PBF LTC3642IMS8E-3.3 TRPBF 8-Lead Plastic MSOP 40C to 125C LTDYN LTC3642IMS8E-5 PBF LTC3642IMS8E-5 TRPBF LTDYQ 8-Lead Plastic MSOP 40C to 125C LTC3642EDD PBF LTC3642EDD TRPBF 8-Lead (3mm 3mm) Plastic DFN 40C to 125C LDTJ LTC3642EDD-3.3 PBF LTC3642EDD-3.3 TRPBF LDYM 8-Lead (3mm 3mm) Plastic DFN 40C to 125C LTC3642EDD-5 PBF LTC3642EDD-5 TRPBF 8-Lead (3mm 3mm) Plastic DFN 40C to 125C LDYP LTC3642IDD PBF LTC3642IDD TRPBF 40C to 125C LDTJ 8-Lead (3mm 3mm) Plastic DFN LTC3642IDD-3.3 PBF LTC3642IDD-3.3 TRPBF 8-Lead (3mm 3mm) Plastic DFN 40C to 125C LDYM LTC3642IDD-5 PBF LTC3642IDD-5 TRPBF 40C to 125C LDYP 8-Lead (3mm 3mm) Plastic DFN Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: