1V/DIV LTC3444 Micropower Synchronous Buck-Boost DC/DC Converter for WCDMA Applications FEATURES DESCRIPTIO Optimized Features for WCDMA Handsets The LTC 3444 is a highly efficient, fixed frequency, buck- Regulated Output with Input Voltages boost DC/DC converter, which operates from input volt- Above, Below, or Equal to the Output ages above, below, and equal to the output voltage. The 0.5V to 5V Output Range topology incorporated in the IC provides a continuous Up to 400mA Continuous Output Current From transfer function through all operating modes, making the a Single Lithium-Ion Cell product ideal for a single Lithium-Ion or multi-cell Minimal External Components applications where the output voltage can vary over a wide 1.5MHz Fixed Frequency Operation range. Internal Loop Compensation for Fast Response The LTC3444 has been optimized for use in 3G WCDMA <25 s Full Scale Output Slewing C 4.7F OUT applications. A unique design yields high efficiency at Output Disconnect in Shutdown very low output voltages while also eliminating external 2.75V to 5.5V Input components. The high speed error amplifier provides the <1A Shutdown Current fast transient response required to slew the RF power Internal Soft-Start amplifier from standby to transmit and transmit to stand Output Overvoltage Protection by power levels. Output overvoltage protection protects Single Inductor, No Schottky Diodes Required the RF power amplifier. Small, Thermally Enhanced 8-Lead (3mm 3mm) DFN Package Operating frequency is internally set to 1.5MHz to mini- mize external component size while maximizing efficiency. U Other features include <1A shutdown current, internal APPLICATIO S soft-start, peak current limit and thermal shutdown. The WCDMA Applications3G Handsets with High Speed LTC3444 is available in a small, thermally enhanced Data Rate Capability 8-lead (3mm 3mm) DFN package. MP3 Players , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Digital Cameras All other trademarks are the property of their respective owners. Protected by U.S. Patents including 6404251, 6166527. TYPICAL APPLICATIO 2.2 H V OUT LTC3444 Dynamic Response 0.8V TO 4.2V LTC3444 340k SW1 SW2 3.1V TO 4.2V V V 4.7 F IN OUT V OUT SHDN FB V CONTROL 4.7 F + GND V C 205k Li-Ion 267k 10s/DIV V = 3.6V, V = 0.8V TO 4.2V IN OUT V = 2.36V TO 0.28V, I = 100mA V CONTROL LOAD CONTROL DAC 3444 G16a 3444 TA01 3444fb 1 U ULTC3444 UUW ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) TOP VIEW V ,V Voltages .......................................... 0.3 to 6V ORDER PART IN OUT SW1,SW2 Voltages DC .................................. 0.3 to 6V NUMBER SHDN 1 8 FB Pulsed <100ns ............... 0.3 to 7V SW1 2 7 V C LTC3444EDD 9 SHDN Voltage ................................................ 0.3 to 6V GND 3 6 V IN Operating Temperature (Note 2) .............. 40C to 85C SW2 4 5 V OUT Maximum Junction Temperature (Note 4) ............ 125C DD PACKAGE Storage Temperature Range .................. 65C to 125C DD PART MARKING 8-LEAD (3mm 3mm) PLASTIC DFN T = 125C, = 43C/W, JMAX JA LBVZ 4-LAYER BOARD = 2.96C/W JC EXPOSED PAD IS GND (PIN 9) MUST BE SOLDERED TO PCB Order Options Tape and Reel: Add TR Lead Free: Add PBF Lead Free Tape and Reel: Add TRPBF Lead Free Part Marking: