POWER LOSS (W) LTC3549 250mA Low V Buck IN Regulator in 2mm 3mm DFN FEATURES DESCRIPTIO 1.6V to 5.5V Input Voltage Range The LTC 3549 is a high ef ciency, monolithic synchronous Internal Soft-Start buck regulator using a constant-frequency, current mode Low Ripple Burst Mode Operation architecture. The output voltage is adjusted via an external Output Ripple: <20mV resistor divider. P-P I : 50A Q A xed switching frequency of 2.25MHz is supported. 2.25MHz Constant-Frequency Operation This switching frequency allows the use of small surface High Ef ciency: Up to 93% mount inductors and capacitors, including ceramics. 250mA Output Current (V = 1.8V, V = 1.2V) IN OUT Supply current during Burst Mode operation is only 50A 450mA Peak Inductor Current dropping to < 1A in shutdown. The 1.6V to 5.5V input No Schottky Diode Required voltage range makes the LTC3549 ideally suited for single Low Dropout Operation: 100% Duty Cycle cell Li-Ion, Li-Metal and 2-cell alkaline, NiCd or NiMH 0.611V Reference Voltage battery-powered applications. 100% duty cycle capabil- Stable with Ceramic Capacitors ity provides low dropout operation, extending battery Shutdown Mode Draws <1A Supply Current life in portable systems. Burst Mode operation can be Current Mode Operation for Excellent Line and Load user-enabled, increasing ef ciency at light loads, further Transient Response extending battery life. Overtemperature Protection Available in a Low Pro le (0.75mm) 6-Lead The internal synchronous switch increases ef ciency and (2mm x 3mm) DFN Package eliminates the need for an external Schottky diode. Internal soft-start offers controlled output voltage rise time at start- U up without the need for external components. APPLICATIO S , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. 2 AA-Cell Applications Burst Mode is a registered trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, Cellular Phones including 5481178, 6580258, 6304066, 6127815, 6498466, 6611131. Digital Cameras MP3 Players TYPICAL APPLICATIO Burst Mode Ef ciency, V = 1.5V OUT 100 1 High Ef ciency Step-Down Converter 90 80 0.1 3.3H* LTC3549 70 V OUT SW V IN 1.5V 22pF V 60 IN 1.8V TO 4.7F 4.7F 5.5V RUN 50 0.01 CER CER MODE V 40 FB 200k 137k 30 V = 1.8V IN 0.001 V = 2.5V GND IN 20 V = 3.1V IN POWER LOST 10 *TDK VLF3012AT-3R3MR87 3549 TA01 AT V = 2.5V IN 0 0.0001 0.1 1 10 100 1k LOAD CURRENT (mA) 3549 TA02 3549f 1 EFFICIENCY (%) U ULTC3549 UUW ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) TOP VIEW Input Supply Voltage ................................... 0.3V to 6V RUN, V , MODE Voltages .............0.3V to (V + 0.3V) FB IN 6 5 4 SW Voltage < 100ns Pulse .............0.3V to (V + 0.3V) IN Operating Temperature Range (Note 2) ... 40C to 85C Junction Temperature (Note 3) ........................... 125C 7 Storage Temperature Range .................. 65C to 125C 1 2 3 DCB PACKAGE 6-LEAD (2mm 3mm) PLASTIC DFN T = 125C, = 64C/W JMAX JA EXPOSED PAD (PIN 7) IS GND MUST BE SOLDERED TO PCB ORDER PART NUMBER DCB PART MARKING LTC3549EDCB LBZR Order Options Tape and Reel: Add TR Lead Free: Add PBF Lead Free Tape and Reel: Add TRPBF Lead Free Part Marking: