POWER LOSS (W) LTC3547B Dual Monolithic 300mA Synchronous Step-Down Regulator FEATURES DESCRIPTIO High Ef ciency (Up to 96%) Dual Step-Down The LTC 3547B is a dual, 2.25MHz, constant-frequency, Outputs synchronous step-down DC/DC converter in a tiny 3mm 300mA Output Current per Channel at V = 3V 2mm DFN package. 100% duty cycle provides low drop- IN 2.25MHz Constant-Frequency Operation out operation, extending battery life in portable systems. 2.5V to 5.5V Input Voltage Range Low output voltages are supported with the 0.6V feed- Low Dropout Operation: 100% Duty Cycle back reference voltage. Each regulator can supply 300mA No Schottky Diodes Required continuous output current. Internally Compensated for All Ceramic Capacitors The input voltage range is 2.5V to 5.5V, making it ideal Independent Internal Soft-Start for Each Channel for Li-Ion polymer and USB powered applications. Supply Available in Fixed Output Versions current is only 1A in shutdown. Current Mode Operation for Excellent Line and Load An internally set 2.25MHz switching frequency allows the Transient Response use of tiny surface mount inductors and capacitors. Inter- 0.6V Reference Allows Low Output Voltages nal soft-start reduces inrush current during start-up. All Short-Circuit Protected outputs are internally compensated to work with ceramic Ultralow Shutdown Current: I < 1A Q capacitors. The LTC3547B is available in a low pro le Low Pro le (0.75mm) 8-Lead 3mm 2mm (0.75mm) 3mm 2mm DFN package. The LTC3547B DFN Package is also available in a xed output voltage con guration U selected via internal resistor dividers (see Table 2). APPLICATIO S , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Burst Mode is a registered trademark of Linear Technology Corporation. All other Cellular Telephones trademarks are the property of their respective owners. Protected by U.S. Patents, including 6580258, 5481178, 6304066, 6127815, 6498466, 6611131. Digital Still Cameras Wireless and DSL Modems Portable Media Players PDAs/Palmtop PCs Ef ciency vs Output Current TYPICAL APPLICATIO for V = 2.5V OUT 100 1 Dual Monolithic Buck Regulator in 8-Lead 3mm 2mm DFN 90 V IN 80 2.5V TO 5.5V 70 4.7F 0.1 RUN2 V RUN1 IN 60 LTC3547B 50 4.7H 4.7H V V OUT2 OUT1 SW2 SW1 2.5V AT 1.8V AT 40 10pF 10pF 300mA 300mA 0.01 30 20 V = 2.7V IN V V FB1 FB2 V = 3.6V 10 IN GND 475k 475k 4.7F 4.7F 237k 150k V = 4.2V IN 0 0.001 1 10 100 1000 3547b TA01 OUTPUT CURRENT (mA) 3547b TA01b 3547bfb 1 EFFICIENCY (%) U ULTC3547B ABSOLUTE AXI U RATI GS PIN CONFIGURATION (Note 1) TOP VIEW V IN LTC3547BE .............................................. 0.3V to 6V V 1 8 V FB1 FB2 LTC3547BI ............................................... 0.3V to 7V RUN1 2 7 RUN2 9 V , V ......................................... 0.3V to V +0.3V V 3 6 SW2 IN FB1 FB2 IN SW1 4 5 GND RUN1, RUN2 ..................................... 0.3V to V +0.3V IN SW1, SW2 (DC) ................................ 0.3V to V +0.3V IN DDB PACKAGE P-Channel Switch Source Current (DC)................500mA 8-LEAD (3mm 2mm) PLASTIC DFN N-Channel Switch Sink Current (DC) ...................500mA T = 125C, = 76C/W JMAX JA EXPOSED PAD (PIN 9) IS GND Peak SW Sink and Source Current (Note 5) .........700mA MUST BE SOLDERED TO PCB Ambient Operating Temperature Range (Note 2) LTC3547BE .......................................... 40C to 85C LTC3547BI ......................................... 40C to 125C Maximum Junction Temperature........................... 125C Storage Temperature Range ................... 65C to 125C ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3547BEDDB PBF LTC3547BEDDB TRPBF LCPD 8-Lead (3mm 2mm) Plastic DFN 40C to 85C LTC3547BEDDB-1 PBF LTC3547BEDDB-1 TRPBF LCPF 8-Lead (3mm 2mm) Plastic DFN 40C to 85C LTC3547BIDDB PBF LTC3547BIDDB TRPBF LCPD 8-Lead (3mm 2mm) Plastic DFN 40C to 125C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. *Temperature grades are 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: