LT3645 36V 500mA Step-Down Regulator and 200mA LDO FEATURES DESCRIPTION n Wide Input Range: The LT 3645 is a dual output regulator combining a 500mA Operation from 3.6V to 36V buck regulator and a 200mA low dropout linear regula- Overvoltage Lockout Protects Circuit Through tor (LDO). The wide input voltage range of 3.6V to 36V 55V Transients on Input makes the LT3645 suitable for regulating power from a n 500mA Output Current Switching Regulator wide variety of sources, including 24V industrial supplies n High Switching Frequency: 750kHz and automotive batteries. Its high operating frequency n 200mA Low Dropout Linear Regulator allows the use of tiny, low cost inductors and capacitors, 1.2V to 16V Input 0.8V to 8V Output resulting in a very small solution. 310mV Dropout Voltage V to OUT2 CC2 Cycle-by-cycle current limit and frequency foldback pro- n Precision Programmable Undervoltage Lockout vide protection against shorted outputs. Soft-start and n Short-Circuit Robust frequency foldback eliminate input current surge during n Internal Soft-Start start-up. n <2A Shutdown Current n The linear regulator operates from the V pin at voltages Small Thermally Enhanced 16-Lead (3mm 3mm) CC2 down to 1.2V. It supplies 200mA of output current with a QFN and 12-Lead MSE Packages typical dropout voltage of 310mV. Other features of the LT3645 include a <2A shutdown, APPLICATIONS short circuit protection, soft-start and thermal shutdown. n The LT3645 is available in the thermally enhanced 16-lead Automotive CMOS Image Sensors n (3mm 3mm) QFN package, or a 12-lead MSE package. Industrial/Automotive Micro-Controller Supply L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATION 3.3V/5V Step-Down Converter Buck Regulator Ef ciency 90 0.1F V = 5V OUT BOOST 15H 5V 6.2V TO 36V V SW IN 300mA 80 1F LT3645 V = 3.3V OUT 52.3k DA 10F FB 70 ON OFF EN/UVLO 10k 60 EN2 PGOOD NPG V CC2 V = 12V 3.3V IN OUT2 50 200mA 0 100 300 400 500 200 31.6k LOAD CURRENT (mA) 2.2F FB2 3645 TA01b GND 10k 3645 TA01a 3645f 1 EFFICIENCY (%)LT3645 ABSOLUTE MAXIMUM RATINGS (Note 1) EN2, NPG Voltages .................................... 0.3V to 16V V , EN/UVLO (Note 5) ........................0.3V to 55V IN Operating Junction Temperature Range (Note 2) BOOST Voltage.55V LT3645E ............................................ 40C to 125C BOOST Above SW Voltage ..............................25V LT3645I ............................................. 40C to 125C V Voltage .............................................. 0.3V to 16V CC2 LT3645H ............................................ 40C to 150C V Voltage .............................................. 0.3V to 8V OUT2 Storage Temperature Range .................. 65C to 150C FB, FB2 Voltages .......................................... 0.3V to 6V Lead Temperature (Soldering, 10 sec) ...........300C PIN CONFIGURATION TOP VIEW 16 15 14 13 TOP VIEW NC 1 12 NC EN/UVLO 1 12 NPG NC 2 11 V IN 17 FB 2 11 EN2 GND 3 13 NPG 3 10 BOOST GND 10 FB2 GND 4 DA 9 OUT2 EN2 4 9 SW BOOST 5 8 V CC2 5 6 7 8 SW 6 7 V IN MSE PACKAGE 12-LEAD PLASTIC MSOP = 40C/W, = 5C/W TO 10C/W JA JC UD PACKAGE EXPOSED PAD (PIN 13) IS GND, MUST BE SOLDERED TO PCB 16-LEAD (3mm 3mm) PLASTIC QFN = 58.7C/W, = 7.1C/W JA JC EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT3645EUD PBF LT3645EUD TRPBF LFVS 16-Lead Plastic QFN 40C to 125C LT3645IUD PBF LT3645IUD TRPBF LFVS 16-Lead Plastic QFN 40C to 125C LT3645EMSE PBF LT3645EMSE TRPBF 3645 12-Lead Plastic MSOP 40C to 125C LT3645IMSE PBF LT3645IMSE TRPBF 3645 12-Lead Plastic MSOP 40C to 125C LT3645HMSE PBF LT3645HMSE TRPBF 3645 12-Lead Plastic MSOP 40C to 150C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. *The temperature grade is identi ed by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based nish parts. For more information on lead free part marking, go to: