LTC3440 Micropower Synchronous Buck-Boost DC/DC Converter Features Description n Single Inductor The LTC 3440 is a high efficiency, fixed frequency, Buck- n Fixed Frequency Operation with Battery Voltages Boost DC/DC converter that operates from input voltages Above, Below or Equal to the Output above, below or equal to the output voltage. The topology n incorporated in the IC provides a continuous transfer Synchronous Rectification: Up to 96% Efficiency n function through all operating modes, making the prod- 25A Quiescent Current in Burst Mode Operation n uct ideal for single lithium-ion, multicell alkaline or NiMH Up to 600mA Continuous Output Current n applications where the output voltage is within the battery No Schottky Diodes Required (V < 4.3V) OUT n voltage range. V Disconnected from V During Shutdown OUT IN n 2.5V to 5.5V Input and Output Range The device includes two 0.19 N-channel MOSFET n Programmable Oscillator Frequency switches and two 0.22 P-channel switches. Switch- from 300kHz to 2MHz ing frequencies up to 2MHz are programmed with an n Synchronizable Oscillator external resistor and the oscillator can be synchronized n Burst Mode Enable Control to an external clock. Quiescent current is only 25A in n <1A Shutdown Current Burst Mode operation, maximizing battery life in portable n Small Thermally Enhanced 10-Pin MSOP and applications. Burst Mode operation is user controlled and (3mm 3mm) DFN Packages can be enabled by driving the MODE/SYNC pin high. If the MODE/SYNC pin has either a clock or is driven low, then fixed frequency switching is enabled. a Other features include a 1A shutdown, soft-start con- n Palmtop Computers trol, thermal shutdown and current limit. The LTC3440 n Handheld Instruments is available in the 10-pin thermally enhanced MSOP and n MP3 Players (3mm 3mm) DFN packages. n Digital Cameras L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. t ypical a Li-Ion to 3.3V at 600mA Buck-Boost Converter Efficiency vs V IN 100 L1 V = 3.3V OUT 10H V OUT 98 I = 100mA OUT 3.3V f = 1MHz OSC 600mA 96 3 4 SW1 SW2 94 LTC3440 V = 2.7V TO 4.2V IN 6 7 R1 92 V V IN OUT 340k 90 8 9 SHDN/SS FB C2 C5 1.5nF 88 22F 2 10 + MODE/SYNC V * C 86 C1 Li-Ion R3 10F 1 5 15k 84 R2 R GND T 200k R 82 T 60.4k 80 2.5 3.0 4.0 4.5 5.0 5.5 3.5 *1 = Burst Mode OPERATION C1: TAIYO YUDEN JMK212BJ106MG 3440 TA01 V (V) IN 0 = FIXED FREQUENCY C2: TAIYO YUDEN JMK325BJ226MM L1: SUMIDA CDRH6D38-100 3440 TA02 3440fd 1 For more information www.linear.com/LTC3440 EFFICIENCY (%) pplication pplicationsLTC3440 a bsolute Maxi Mu M r (Note 1) V , V Voltage ....................................... 0.3V to 6V Operating Temperature Range (Note 2)....40C to 85C IN OUT SW1, SW2 Voltage ...................................... 0.3V to 6V Storage Temperature Range .................. 65C to 125C V , R , FB, SHDN/SS, Lead Temperature (Soldering, 10 sec) ...................300C C T MODE/SYNC Voltage .................................. 0.3V to 6V p in c F TOP VIEW TOP VIEW R 1 10 V T C R 1 10 V T C MODE/SYNC 2 9 FB MODE/SYNC 9 FB 2 SW1 3 8 SHDN/SS SW1 3 11 8 SHDN/SS SW2 4 7 V IN V GND 5 6 OUT SW2 4 7 V IN GND 5 6 V MS PACKAGE OUT 10-LEAD PLASTIC MSOP DD PACKAGE T = 125C, JMAX 10-LEAD (3mm 3mm) PLASTIC DFN = 130C/W 1 LAYER BOARD JA EXPOSED PAD (PIN 11) IS GND = 100C/W 4 LAYER BOARD JA MUST BE SOLDERED TO PCB = 45C/W JC T = 125C, = 43C/W, = 3C/W JMAX JA JC o r Der i n F M