POWER LOSS (mW) LTC3808 TM No R , Low EMI, SENSE Synchronous DC/DC Controller with Output Tracking FEATURES DESCRIPTIO Programmable Output Voltage Tracking The LTC 3808 is a synchronous step-down switching Sense Resistor Optional regulator controller that drives external complementary Spread Spectrum Modulation for Low Noise power MOSFETs using few external components. The Constant Frequency Current Mode Operation for constant frequency current mode architecture with MOSFET Excellent Line and Load Transient Response V sensing eliminates the need for a current sense DS Wide V Range: 2.75V to 9.8V resistor and improves efficiency. IN Wide V Range: 0.6V to V OUT IN Burst Mode operation provides high efficiency operation 0.6V 1.5% Reference at light loads. 100% duty cycle provides low dropout Low Dropout Operation: 100% Duty Cycle operation, extending operating time in battery-powered True PLL for Frequency Locking or Adjustment systems. (Frequency Range: 250kHz to 750kHz) The switching frequency can be programmed up to 750kHz, Selectable Burst Mode /Pulse Skipping/Forced allowing the use of small surface mount inductors and Continuous Operation capacitors. For noise sensitive applications, the LTC3808 Auxiliary Winding Regulation can be externally synchronized from 250kHz to 750kHz. Internal Soft-Start Circuitry Burst Mode is inhibited during synchronization or when Power Good Output Voltage Monitor the SYNC/MODE pin is pulled low to reduce noise and RF Output Overvoltage Protection interference. To further reduce EMI, the LTC3808 incorpo- Micropower Shutdown: I = 9A Q rates a novel spread spectrum frequency modulation Tiny Thermally Enhanced Leadless (4mm 3mm) technique. DFN or 16-lead SSOP Package U The LTC3808 is available in the tiny footprint thermally APPLICATIO S enhanced DFN package or 16-lead SSOP package. , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode One or Two Cell Lithium-Ion Powered Devices is a registered trademark of Linear Technology Corporation. No RSENSE is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective Notebook and Palmtop Computers, PDAs owners. Protected by U.S. Patents including 5481178, 5929620, 6580258, 6304066, 5847554, 6611131, 6498466. Other Patents pending. Portable Instruments Distributed DC Power Systems Efficiency and Power Loss vs Load Current TYPICAL APPLICATIO 100 10k EFFICIENCY High Efficiency, 550kHz Step-Down Converter V = 3.3V IN V 90 1k IN 2.75V TO 9.8V V = 4.2V 10F V = 5V IN IN 1M LTC3808 V IN 80 100 PLLLPF + SENSE SYNC/MODE TYPICAL POWER TG 70 10 LOSS (V = 4.2V) 59k PGOOD IN 2.2H V OUT V SW 2.5V FB 15k + 2A 60 1 I BG TH 47F 187k FIGURE 11 CIRCUIT RUN IPRG 220pF V = 2.5V OUT GND 50 0.1 1 10 100 1k 10k 3808 TA01 LOAD CURRENT (mA) 3808 TA01b 3808f 1 EFFICIENCY (%) U ULTC3808 ABSOLUTE MAXIMUM RATINGS (Note 1) Input Supply Voltage (V )........................ 0.3V to 10V TG, BG Peak Output Current (<10s)........................ 1A IN PLLLPF, RUN, SYNC/MODE, TRACK/SS, Operating Temperature Range (Note 2)... 40C to 85C + SENSE , IPRG Voltages ............ 0.3V to (V + 0.3V) Storage Ambient Temperature Range ... 65C to 125C IN V , I Voltages...................................... 0.3V to 2.4V Junction Temperature (Note 3)............................ 125C FB TH SW, SENSE Voltages......... 2V to V + 1V (10V Max) Lead Temperature (Soldering, 10 sec) IN PGOOD ..................................................... 0.3V to 10V GN16 Package .................................................. 300C PACKAGE/ORDER INFORMATION TOP VIEW TOP VIEW ORDER PART ORDER PART NUMBER NUMBER 1 GND 16 SW PLLLPF 1 14 SW 2 PLLLPF 15 SENSE SYNC/MODE 2 13 SENSE LTC3808EDE LTC3808EGN TRACK/SS 3 12 V 3 SYNC/MODE 14 V IN IN + + PGOOD 4 15 11 SENSE 4 TRACK/SS 13 SENSE V 5 10 TG FB 5 PGOOD 12 TG I 6 9 BG TH 6 V 11 BG FB DE PART RUN 7 8 IPRG 7 I 10 IPRG TH MARKING DE PACKAGE 8 RUN 9 GND 14-LEAD (4mm 3mm) PLASTIC DFN 3808 GN PACKAGE T = 125C, = 37C/W JMAX JA 16-LEAD PLASTIC SSOP EXPOSED PAD (PIN 15) IS GND (MUST BE SOLDERED TO PCB) T = 125C, = 130C/W JMAX JA Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The indicates specifications which apply over the full operating temperature range, otherwise specifications are at T = 25C. V = 4.2V unless otherwise noted. A IN PARAMETER CONDITIONS MIN TYP MAX UNITS Main Control Loops Input DC Supply Current (Note 4) Normal Operation 350 500 A Sleep Mode 105 150 A Shutdown RUN = 0V 9 20 A UVLO V = UVLO Threshold 200mV 9 20 A IN Undervoltage Lockout Threshold V Falling 1.95 2.25 2.55 V IN V Rising 2.15 2.45 2.75 V IN Shutdown Threshold of RUN Pin 0.8 1.1 1.4 V Start-Up Current Source TRACK/SS = 0V 0.65 1 1.35 A Regulated Feedback Voltage (Note 5) 0.591 0.6 0.609 V Output Voltage Line Regulation 2.75V < V < 9.8V (Note 5) 0.01 0.04 %/V IN Output Voltage Load Regulation I = 0.9V (Note 5) 0.1 0.5 % TH I = 1.7V 0.1 0.5 % TH V Input Current (Note 5) 9 50 nA FB Overvoltage Protect Threshold Measured at V 0.66 0.68 0.7 V FB 3808f 2 U W U U WWW