LTC3444EDD

LTC3444 Micropower Synchronous Buck-Boost DC/DC Converter for WCDMA Applications DESCRIPTIO The LTC®3444 is a highly efficient, fixed frequency, buckboost DC/DC converter, which operates from input voltages above, below, and equal to the output voltage. The topology incorporated in the IC provides a continuous transfer function through all operating modes, making the product ideal for a single Lithium-Ion or multi-cell applications where the output voltage can vary over a wide range. The LTC3444 has been optimized for use in 3G WCDMA applications. A unique design yields high efficiency at very low output voltages while also eliminating external components. The high speed error amplifier provides the fast transient response required to slew the RF power amplifier from standby to transmit and transmit to stand by power levels. Output overvoltage protection protects the RF power amplifier. Operating frequency is internally set to 1.5MHz to minimize external component size while maximizing efficiency. Other features include > C3, R1 >> R4. U C3 C2 R5 C1 R4 R1 8 VOUT FB 3444 F08 360 270 180 PHASE (DEG) 90 0 –90 –180 –270 –360 1e8 3444 G02 3444fb 17 LTC3444 TYPICAL APPLICATIO S Example of Internal Compensation Transient Response for a Command Voltage Change LTC3444 Dynamic Response VOUT 1V/DIV VOUT VCONTROL 10μs/DIV VIN = 3.6V, VOUT = 0.8V TO 4.2V VCONTROL = 2.36V TO 0.28V, ILOAD = 100mA 3444 G16a Internally Compensated WCDMA Application. Singe Cell, 2.7V to 4.2V Input, 0.8V to 4.2V at 400mA Output. 1.5μH L1 LTC3444 SW1 2.7V TO 4.2V VIN CIN 4.7μF SHDN GND VOUT FB VC R2 267k R3 205k SW2 + Li-Ion CIN = MURATA:GRM31CR61C475K COUT = MURATA:GRM31CR61C475K L1 = COOPER BUSSMAN SD12-2R2 18 U LTC3444 Dynamic Response 1V/DIV VCONTROL 10μs/DIV VIN = 3.6V, VOUT = 4.2V TO 0.8V VCONTROL = 0.28V TO 2.36V, ILOAD = 100mA !""" /% VOUT 0.8V TO 4.2V R1 340k COUT 4.7μF VCONTROL DAC 3444 TA02 3444fb LTC3444 TYPICAL APPLICATIO S Single Li-Ion, 3.1V to 4.2V Input, 3.3V at 400mA Output with Internal Compensation 2.2μH L1 LTC3444 SW1 3.1V TO 4.4V VIN CIN 4.7μF SHDN GND VOUT FB VC R2 200k SW2 + Li-Ion CIN = MURATA:GRM31CR61C475K COUT = MURATA:GRM31CR61C475K L1 = COOPER BUSSMAN SD12-2R2 PACKAGE DESCRIPTIO 3.5 ± 0.05 1.65 ± 0.05 2.15 ± 0.05 (2 SIDES) PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 2.38 ± 0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-1) 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE PIN 1 TOP MARK (NOTE 6) Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. U U VOUT 3.3V AT 400mA R1 340k COUT 4.7μF 3444 TA04 DD Package 8-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1698) R = 0.115 TYP 5 0.675 ± 0.05 0.38 ± 0.10 8 3.00 ± 0.10 (4 SIDES) 1.65 ± 0.10 (2 SIDES) (DD) DFN 1203 0.200 REF 0.75 ± 0.05 4 0.25 ± 0.05 2.38 ± 0.10 (2 SIDES) 1 0.50 BSC 0.00 – 0.05 BOTTOM VIEW—EXPOSED PAD 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON TOP AND BOTTOM OF PACKAGE 3444fb 19 LTC3444 TYPICAL APPLICATIO 3.1V TO 4.2V VIN CIN 4.7μF SHDN GND VOUT FB VC R5 47.5k + Li-Ion CIN = MURATA:GRM31CR61C475K COUT = MURATA:GRM31CR61C475K L1 = COOPER BUSSMAN SD12-3R3 RELATED PARTS PART NUMBER LTC3403 LTC3408 LTC3440 LTC3441 LTC3442 LTC3443 DESCRIPTION 1.5MHz, 600mA, Synchronous Step-Down Regulator with Bypass Transistor 1.5MHz, 600mA, Synchronous Step-Down Regulator with Bypass Transistor Up to 2MHz, 600μA, Synchronous Buck-Boost DC/DC Converter 1MHz, 1.2A, Synchronous Buck-Boost DC/DC Converter Up to 2MHz, 1.2A, Synchronous Buck-Boost DC/DC Converter 600MHz, 1.2A Synchronous Buck-Boost DC/DC Converter COMMENTS 96% Efficiency, VIN: 2.5V to 5V, VOUT: 0.3V to 3.5V, ISD