LTC3127 1A Buck-Boost DC/DC Converter with Programmable Input Current Limit FEATURES DESCRIPTION n Programmable (0.2A to 1A) 4% Accurate Average The LTC 3127 is a wide V range, highly efficient, 1.35MHz IN Input Current Limit fixed frequency buck-boost DC/DC converter that operates n Regulated Output with Input Voltages Above, from input voltages above, below or equal to the output Below or Equal to the Output voltage. The LTC3127 features programmable average n 1.8V to 5.5V (Input) and 1.8V to 5.25V (Output) input current limit, making it ideal for power-limited input Voltage Range sources. The input current limit is programmed with a n 0.6A Continuous Output Current: V > 1.8V single resistor and is accurate from 0.2A to 1A of average IN n 1A Continuous Output Current: V > 3V input current. IN n Single Inductor The topology incorporated provides a continuous n Synchronous Rectification: Up to 96% Efficiency transfer function through all operating modes. Other n Burst Mode Operation: I = 35A (Pin Selectable) Q features include <1A shutdown current, pin-selectable n Output Disconnect in Shutdown Burst Mode operation and thermal overload protection. n <1A Shutdown Current The LTC3127 is housed in thermally enhanced 10-lead n Small, Thermally Enhanced 10-Lead (3mm 3mm (3mm 3mm 0.75mm) DFN packages and 12-lead 0.75mm) DFN and 12-Lead MSOP Packages MSOP packages. L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks APPLICATIONS and PowerPath and ThinSOT are trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. n USB Powered GSM Modems n Supercap Charger n Handheld Test Instruments n PC Card Modems n Wireless Terminals TYPICAL APPLICATION USB or Li-Ion (500mA Maximum Input Current) to 3.3V Efficiency vs V IN L1 100 4.7H 300mA LOAD 90 SW1 SW2 USB OR Li-Ion V V OUT V IN OUT 2.9V to 5.5V 3.3V MODE 320k 80 SHDN FB OFF ON 2.2mF 70 PROG V C 10F SGND PGND 182k 499k 32.4k 100pF 60 V = 3.3V OUT L = 4.7H 3127 TA01 F = 1.35MHz 50 3 3.5 4 4.5 5 5.5 L1: COILCRAFT XPL4020-472ML V (V) IN 3127 TA01a 3127fa 1 For more information www.linear.com/LTC3127 EFFICIENCY (%)LTC3127 (Note 1) ABSOLUTE MAXIMUM RATINGS V , V Voltage .......................................... 0.3 to 6V PROG Voltage ................................................ 0.3 to 6V IN OUT SW1, SW2 DC Voltage ................................... 0.3 to 6V Operating Junction Temperature Range SW1, SW2 Pulsed (<100ns) Voltage .............. 0.3 to 7V (Note 2) ....................................................40C to 85C MODE, FB, V Voltage .................................... 0.3 to 6V Maximum Junction Temperature (Note 5) ........... 125C C SHDN Voltage ............................................... 0.3 to 6V Storage Temperature Range .................. 65C to 125C PIN CONFIGURATION TOP VIEW TOP VIEW SW1 1 10 SW2 PGND 1 12 PGND SW1 2 11 SW2 V 2 9 V IN OUT 13 V 3 10 V 11 IN OUT 3 SHDN 8 V C PGND PGND SHDN 4 9 V C MODE 4 7 FB MODE 5 8 FB PROG 5 6 SGND PROG 6 7 SGND MSE PACKAGE DD PACKAGE 12-LEAD PLASTIC MSOP 10-LEAD (3mm 3mm) PLASTIC DFN T = 125C, = 40C/W (NOTE 6) JMAX JA T = 125C, = 43C/W (NOTE 6) JMAX JA EXPOSED PAD (PIN 11) IS PGND, MUST BE SOLDERED TO PCB EXPOSED PAD (PIN 11) IS PGND, MUST BE SOLDERED TO PCB