POWER LOSS (mW) LTC3548 Dual Synchronous, 400mA/800mA, 2.25MHz Step-Down DC/DC Regulator FEATURES DESCRIPTION n High Ef ciency: Up to 95% The LTC 3548 is a dual, constant-frequency, synchronous n Very Low Quiescent Current: Only 40A step down DC/DC converter. Intended for low power ap- n Low Output Ripple Burst Mode Operation plications, it operates from 2.5V to 5.5V input voltage n 2.25MHz Constant-Frequency Operation range and has a constant 2.25MHz switching frequency, n High Switch Current: 0.7A and 1.2A allowing the use of tiny, low cost capacitors and inductors n No Schottky Diodes Required with a pro le 1mm. 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 ef ciency 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 noise ripple for low power ef ciency. Burst n Ultralow Shutdown Current: I < 1A Q Mode operation provides high ef ciency at light loads, n Output Voltages from 5V down to 0.6V while pulse-skipping mode provides low noise ripple at n Power-On Reset Output light loads. n Externally Synchronizable Oscillator n To further maximize battery runtime, the P-channel Small Thermally Enhanced MSOP and 3mm 3mm MOSFETs are turned on continuously in dropout (100% DFN Packages duty cycle), and both channels draw a total quiescent cur- rent of only 40A. In shutdown, the device draws <1A. APPLICATIONS L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks PDAs/Palmtop PCs of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 5481178, 6127815, 6304066, 6498466, 6580258 Digital Cameras 6611131.. Cellular Phones Portable Media Players PC Cards Wireless and DSL Modems TYPICAL APPLICATION LTC3548 Ef ciency Curve V = 2.8V IN 100 1000 TO 5.5V 95 10F 100k RUN2 V RUN1 IN MODE/SYNC POR RESET 90 EFFICIENCY 100 LTC3548 4.7H 2.2H 85 V = 2.5V V = 1.8V OUT2 OUT1 SW2 SW1 AT 400mA AT 800mA 68pF 33pF 80 10 POWER LOSS 75 V V FB1 FB2 70 1 887k 604k 280k GND 301k 4.7F 10F V = 3.3V, V = 1.8V IN OUT 65 Burst Mode OPERATION 3548 TA01 CHANNEL 1, NO LOAD ON CHANNEL 2 60 0.1 1 10 100 1000 Figure 1. 2.5V/1.8V at 400mA/800mA Step-Down Regulators LOAD CURRENT (mA) 3548 TA02 3548fc 1 EFFICIENCY (%)LTC3548 ABSOLUTE MAXIMUM RATINGS (Note 1) V Voltages .................................................0.3V to 6V Operating Temperature Range (Note 2)....40C to 85C IN V , V Voltages ...........................0.3V to V +0.3V Junction Temperature (Note 5) ............................. 125C FB1 FB2 IN RUN1, RUN2 Voltages ................................ 0.3V to V Storage Temperature Range ................... 65C to 125C IN MODE/SYNC Voltage .......................0.3V to V + 0.3V Lead Temperature (Soldering, 10 sec) IN SW1, SW2 Voltage ...........................0.3V to V + 0.3V MSE Only .......................................................... 300C IN POR Voltage .................................................0.3V to 6V PIN CONFIGURATION TOP VIEW TOP VIEW V 10 V 1 FB1 FB2 V 1 10 V FB1 FB2 RUN1 2 9 RUN2 RUN1 2 9 RUN2 V IN V 3 11 8 POR 11 3 8 POR IN SW1 4 7 SW2 SW1 4 7 SW2 MODE/ GND 5 6 GND SYNC 5 6 MODE/ MSE PACKAGE SYNC 10-LEAD PLASTIC MSOP DD PACKAGE T = 125C, = 45C/W, = 10C/W 10-LEAD (3mm s 3mm) PLASTIC DFN JMAX JA JC EXPOSED PAD (PIN 11) IS PGND, MUST BE CONNECTED TO GND T = 125C, = 45C/W, = 3C/W JMAX JA JC (SOLDERED TO A 4-LAYER BOARD) EXPOSED PAD (PIN 11) IS PGND, MUST BE CONNECTED TO GND (SOLDERED TO A 4-LAYER BOARD) ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3548EDD PBF LTC3548EDD TRPBF LBNJ 40C to 85C 10-Lead (3mm 3mm) Plastic DFN LTC3548IDD PBF LTC3548IDD TRPBF LBNJ 40C to 85C 10-Lead (3mm 3mm) Plastic DFN LTC3548EMSE PBF LTC3548EMSE TRPBF LTBNH 10-Lead Plastic MSOP 40C to 85C LTC3548IMSE PBF LTC3548IMSE TRPBF LTBNH 10-Lead Plastic MSOP 40C to 85C 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: