POWER LOSS (W) LTC3548A Dual Synchronous 400mA/800mA, 2.25MHz Step-Down DC/DC Regulator FEATURES DESCRIPTION n High Efficiency: Up to 95% The LTC 3548A is a dual, constant frequency, synchronous n Low Ripple (<35mV ) Burst Mode Operation step-down DC/DC converter. Intended for low power ap- P-P I = 40A plications, it operates from a 2.5V to 5.5V input voltage Q n 2.25MHz Constant Frequency Operation range and has a constant 2.25MHz switching frequency, n High Switch Current: 0.7A and 1.2A enabling the use of tiny, low cost capacitors and inductors n No Schottky Diodes Required 1mm or less in height. Each output voltage is adjustable n Low R Internal Switches: 0.35 from 0.6V to 5V. Internal synchronous 0.35, 0.7A/1.2A DS(ON) n Current Mode Operation for Excellent Line power switches provide high efficiency without the need and Load Transient Response for external Schottky diodes. n Short-Circuit Protected A user-selectable mode input is provided to allow the user n Low Dropout Operation: 100% Duty Cycle to trade-off ripple noise for low power efficiency. Burst n Ultralow Shutdown Current: I <1A Q Mode operation provides the highest efficiency at light n Output Voltages from 5V down to 0.6V loads, while pulse-skipping mode provides the lowest n Power-On Reset Output ripple noise at light loads. n Externally Synchronizable Oscillator n To further maximize battery life, the P-channel MOSFETs Optional External Soft-Start n are turned on continuously in dropout (100% duty cycle), Small Thermally Enhanced MSOP and 3mm 3mm and both channels draw a total quiescent current of only DFN Packages 40A. In shutdown, the device draws <1A. APPLICATIONS L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective n owners. Protected by U.S. Patents including 5481178, 6580258, 6304066, 6127815, 6498466, PDAs/Palmtop PCs 6611131. n Digital Cameras n Cellular Phones n Wireless and DSL Modems TYPICAL APPLICATION Efficiency/Power Loss Curves 2.5V/1.8V at 400mA/800mA Step-Down Regulators 100 1 2.5V 90 V IN 1.8V 2.5V TO 5.5V 80 10F 0.1 100k 70 RUN/SS2 V RUN/SS1 IN 60 MODE/SYNC POR RESET 50 0.01 4.7H 2.2H V V OUT1 OUT2 1.8V 2.5V SW2 SW1 40 LTC3548A 22pF 22pF 800mA 400mA 30 0.001 20 V = 3.3V IN V V FB1 FB2 Burst Mode OPERATION 10 887k 887k GND NO LOAD ON OTHER CHANNEL 4.7F 280k 442k 10F 0.0001 0 1 10 100 1000 3548A TA01 LOAD CURRENT (mA) 3548A TA02 3548afa 1 EFFICIENCY (%)LTC3548A ABSOLUTE MAXIMUM RATINGS (Note 1) V Voltage ...................................................0.3V to 6V Operating Junction Temperature Range IN V , V Voltages ................................... 0.3V to 1.5V (Notes 2, 5) ............................................ 40C to 125C FB1 FB2 RUN/SS1, RUN/SS2 Voltages .......... 0.3V to V + 0.3V Storage Temperature Range .................. 65C to 150C IN MODE/SYNC Voltage ....................... 0.3V to V + 0.3V Lead Temperature (Soldering, 10 sec) IN SW1, SW2 Voltages ......................... 0.3V to V + 0.3V MSOP ...............................................................300C IN POR Voltage ................................................. 0.3V to 6V PIN CONFIGURATION TOP VIEW TOP VIEW V 1 10 V FB1 FB2 V 1 10 V FB1 FB2 RUN/SS1 2 9 RUN/SS2 RUN/SS1 2 9 RUN/SS2 V 3 11 8 POR V 3 11 8 POR IN IN SW1 4 7 SW2 SW1 4 7 SW2 MODE/SYNC NC 5 6 NC 5 6 MODE/SYNC MSE PACKAGE 10-LEAD PLASTIC MSOP DD PACKAGE T = 125C, = 45C/W, = 10C/W JMAX JA JC 10-LEAD (3mm s 3mm) PLASTIC DFN EXPOSED PAD (PIN 11) IS PGND, MUST BE SOLDERED TO GND T = 125C, = 45C/W, = 10C/W JMAX JA JC EXPOSED PAD (PIN 11) IS PGND, MUST BE SOLDERED TO GND ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3548AEDD PBF LTC3548AEDD TRPBF LFKV 10-Lead (3mm 3mm) Plastic DFN 40C to 125C LTC3548AEMSE PBF LTC3548AEMSE TRPBF LTFKW 10-Lead Plastic MSOP 40C to 125C LTC3548AIDD PBF LTC3548AIDD TRPBF LFKV 40C to 125C 10-Lead (3mm 3mm) Plastic DFN LTC3548AIMSE PBF LTC3548AIMSE TRPBF LTFKW 10-Lead Plastic MSOP 40C to 125C 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. For more information on lead free part marking, go to: