POWER LOSS (mW) LTC3809 No R , Low EMI, SENSE Synchronous DC/DC Controller FEATURES DESCRIPTION n No Current Sense Resistor Required The LTC 3809 is a synchronous step-down switching regu- n Selectable Spread Spectrum Frequency Modulation lator controller that drives external complementary power for Low Noise Operation MOSFETs using few external components. The constant n Constant Frequency Current Mode Operation for frequency current mode architecture with MOSFET V DS Excellent Line and Load Transient Response sensing eliminates the need for a current sense resistor n True PLL for Frequency Locking or Adjustment and improves ef ciency. (Frequency Range: 250kHz to 750kHz) For noise sensitive applications, the LTC3809 can be exter- n Wide V Range: 2.75V to 9.8V IN nally synchronized from 250kHz to 750kHz. Burst Mode is n Wide V Range: 0.6V to V OUT IN inhibited during synchronization or when the SYNC/MODE n 0.6V 1.5% Reference pin is pulled low to reduce noise and RF interference. To n Low Dropout Operation: 100% Duty Cycle further reduce EMI, the LTC3809 incorporates a novel n Selectable Burst Mode /Pulse-Skipping/Forced spread spectrum frequency modulation technique. Continuous Operation n Burst Mode operation provides high ef ciency operation Auxiliary Winding Regulation n at light loads. 100% duty cycle provides low dropout Internal Soft-Start Circuitry n operation, extending operating time in battery-powered Output Overvoltage Protection n systems. Micropower Shutdown: I = 9A Q n Tiny Thermally Enhanced Leadless (3mm 3mm) The switching frequency can be programmed up to 750kHz, DFN and 10-lead MSOP Packages allowing the use of small surface mount inductors and capacitors. APPLICATIONS The LTC3809 is available in tiny footprint thermally enhanced DFN and 10-lead MSOP packages. n 1- or 2-Cell Lithium-Ion Powered Devices L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation. n Portable Instruments No R is a trademark of Linear Technology Corporation. SENSE n All other trademarks are the property of their respective owners. Distributed DC Power Systems Protected by U.S. Patents including 5481178, 5929620, 6580258, 6304066, 5847554, 6611131, 6498466. Other Patents pending. TYPICAL APPLICATION Ef ciency and Power Loss vs Load Current 100 10k EFFICIENCY High Ef ciency, 550kHz Step-Down Converter V = 3.3V IN 90 1k V IN 2.75V TO 9.8V V = 4.2V V = 5V IN IN 10F LTC3809 80 100 V PLLLPF IN POWER LOSS SYNC/MODE TG 70 10 V = 4.2V IN 59k 2.2H V OUT V SW 2.5V FB 15k 2A 60 1 I BG TH 47F 187k FIGURE 10 CIRCUIT 470pF RUN IPRG V = 2.5V OUT GND 50 0.1 1 10 100 1000 10000 LOAD CURRENT (mA) 3809 TA01b 3809 TA01 3809fc 1 EFFICIENCY (%)LTC3809 ABSOLUTE MAXIMUM RATINGS (Note 1) Input Supply Voltage (V ) ........................ 0.3V to 10V Operating Temperature Range (Note 2)....40C to 85C IN PLLLPF, RUN, SYNC/MODE, Storage Temperature Range ...................65C to 125C IPRG Voltages ............................... 0.3V to (V + 0.3V) Junction Temperature (Note 3) ............................ 125C IN V , I Voltages ...................................... 0.3V to 2.4V Lead Temperature (Soldering, 10 sec) FB TH SW Voltage ......................... 2V to V + 1V (10V Max) MSOP Package .................................................300C IN TG, BG Peak Output Current (<10s) ......................... 1A PIN CONFIGURATION TOP VIEW TOP VIEW PLLLPF 1 10 SW PLLLPF 1 10 SW SYNC/MODE 2 9 V IN SYNC/MODE 2 9 V IN V 3 11 8 TG V 3 11 8 TG FB FB I 4 7 BG TH I 4 7 BG TH RUN 5 6 IPRG RUN 5 6 IPRG MSE PACKAGE 10-LEAD PLASTIC MSOP DD PACKAGE T = 125C, = 40C/W JMAX JA 10-LEAD (3mm 3mm) PLASTIC DFNs EXPOSED PAD (PIN 11) IS GND T = 125C, = 43C/W JMAX JA (MUST BE SOLDERED TO PCB) EXPOSED PAD (PIN 11) IS GND (MUST BE SOLDERED TO PCB) ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3809EDD PBF LTC3809EDD TRPBF LBQY 10-Lead (3mm 3mm) Plastic DFN 40C to 85C LTC3809EMSE PBF LTC3809EMSE TRPBF LTBQT 10-Lead Plastic MSOP 40C to 85C LEAD BASED FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3809EDD LTC3809EDD TR LBQY 40C to 85C 10-Lead (3mm 3mm) Plastic DFN LTC3809EMSE LTC3809EMSE TR LTBQT 10-Lead Plastic MSOP 40C to 85C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. For more information on lead free part marking, go to: