LT3509 Dual 36V, 700mA Step-Down Regulator Fea T Descrip T n Two 700mA Switching Regulators with Internal The LT 3509 is a dual, current mode, step-down switching Power Switches regulator, with internal power switches each capable of n Wide 3.6V to 36V Operating Range providing 700mA output current. This regulator provides a n Overvoltage Lockout Protects Circuit Through 60V compact and robust solution for multi-rail systems in harsh Supply Transients environments. It incorporates several protection features n Short-Circuit Robust including overvoltage lockout and cycle-by-cycle current n Low Dropout Voltage: 95% Maximum Duty Cycle limit. Thermal shutdown provides additional protection. n Adjustable 300kHz to 2.2MHz Switching Frequency The loop compensation components and the boost diodes Synchronizable Over the Full Range are integrated on-chip. Switching frequency is set by a n Uses Small Inductors and Ceramic Capacitors single external resistor. External synchronization is also n Integrated Boost Diodes possible. The high maximum switching frequency allows n Internal Compensation the use of small inductors and ceramic capacitors for low n Thermally Enhanced 14-Lead (4mm 3mm) ripple. Constant frequency operation above the AM band DFN and 16 Lead MSOP Packages avoids interference with radio reception, making the LT3509 well suited for automotive applications. Each regulator has an independent shutdown and soft-start control pin. a T When both converters are powered down, the common n Automotive Electronics circuitry enters a low current shutdown state. n Industrial Controls L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective n Wall Transformer Regulation owners. n Networking Devices n CPU, DSP, or FPGA Power Typical a T 3.3V and 5V Dual Output Step-Down Converter Efficiency 6.5V TO 36V (TRANSIENT TO 60V) 90 2.2F V BD IN 85 V = 5V OUT BOOST1 BOOST2 80 0.1F 0.1F 6.8H 10H V = 3.3V OUT 3.3V 5V SW1 SW2 75 700mA 700mA LT3509 31.6k 70 53.6k DA1 DA2 MBRM140 MBRM140 65 22F FB1 FB2 60 10F RUN/SS1 RUN/SS2 V = 12V 1nF IN 55 SYNC RT f = 700kHz 1nF SW 10.2k GND 10.2k 50 60.4k 0.2 0.0 0.1 0.3 0.4 0.5 0.6 0.7 LOAD CURRENT (A) 3509 TA01a f = 700kHz SW 3509 TA01b 3509fd 1 For more information www.linear.com/LT3509 EFFICIENCY (%) ion pplica ions pplica ion uresLT3509 a Te Maxi Mu M r a T (Note 1) V Pin (Note 2) ........................................................60V Storage Temperature Range .................. 65C to 150C IN BD Pin .......................................................................20V Lead Temperature (Soldering, 10 sec.) BOOST Pins ..............................................................60V MSOP Package .................................................300C BOOST Pins above SW .............................................30V RUN/SS, FB, RT, SYNC pins ........................................6V Operating Junction Temperature Range (Notes 3, 6) LT3509E ............................................ 40C to 125C LT3509I ............................................. 40C to 125C LT3509H ............................................ 40C to 150C pin con F T TOP VIEW TOP VIEW DA1 1 14 FB1 DA1 1 16 FB1 BOOST1 2 13 RUN/SS1 BOOST1 2 15 RUN/SS1 SW1 3 12 BD SW1 3 14 AGND V 4 13 BD IN 15 V 4 11 SYNC 17 IN V 5 12 SYNC IN SW2 5 10 RT 6 11 RT SW2 BOOST2 7 10 RUN/SS2 BOOST2 6 9 RUN/SS2 DA2 8 9 FB2 DA2 7 8 FB2 MSE PACKAGE 16-LEAD PLASTIC MSOP DE14 PACKAGE = 43C/W, = 4.3C/W JA JC 14-LEAD (4mm 3mm) PLASTIC DFN EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB = 43C/W, = 4.3C/W JA JC EXPOSED PAD (PIN 15) IS GND, MUST BE SOLDERED TO PCB Der in F Ma T LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT3509EDE PBF LT3509EDE TRPBF 3509 14-Lead (4mm 3mm) Plastic DFN 40C to 125C LT3509IDE PBF LT3509IDE TRPBF 3509 14-Lead (4mm 3mm) Plastic DFN 40C to 125C LT3509EMSE PBF LT3509EMSE TRPBF 3509 16-Lead Plastic MSOP with Exposed Pad 40C to 125C LT3509IMSE PBF LT3509IMSE TRPBF 3509 16-Lead Plastic MSOP with Exposed Pad 40C to 125C LT3509HMSE PBF LT3509HMSE TRPBF 3509 16-Lead Plastic MSOP with Exposed Pad 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. For more information on lead free part marking, go to: