POWER LOSS (W) LTC3125 1.2A Synchronous Step-Up DC/DC Converter with Input Current Limit FEATURES DESCRIPTION n Programmable Average Input Current Limit The LTC 3125 is a high ef ciency, synchronous step-up n 5% Input Current Accuracy DC/DC converter with an accurate programmable average n 200mA to 1000mA Program Range input current limit. The resistor programmable average n V : 1.8V to 5.5V, V : 2V to 5.25V input current limit is 5% accurate at 500mA and is suitable IN OUT n Supports High Current GSM/GPRS Load Burst for a wide variety of applications. In mobile computing, n V > V Operation GSM and GPRS cards demand high current pulses well IN OUT n 1.6MHz Fixed Frequency Operation beyond the capability of the PC Card and CompactFlash n Internal Current Sense Resistor slots. The LTC3125 in concert with a reservoir capacitor, n 1.2A Peak Current Limit keeps the slot power safely within its capabilities providing n Up to 93% Ef ciency a high performance and simple solution. n Output Disconnect in Shutdown Synchronous recti cation produces high ef ciency while n Soft-Start the 1.6MHz switching frequency minimizes the solution n Low Quiescent Current Burst Mode Operation footprint. The current mode PWM design is internally com- n Available in 2mm 3mm 0.75mm DFN Package pensated. Output disconnect allows the load to discharge in shutdown, while also providing inrush current limiting. APPLICATIONS Other features include a <1A shutdown current, short- n GSM/GPRS PCMCIA/CompactFlash PC Card Modems circuit and thermal overload protection. The LTC3125 is n Wireless Emergency Locators offered in a low pro le 0.75mm 2mm 3mm package. n Portable Radios L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation. n Supercap Chargers All other trademarks are the property of their respective owners. TYPICAL APPLICATION PCMCIA/CompactFlash (3.3V/500mA Max), Ef ciency vs Load Current 4V GSM Pulsed Load 100 1 2.2H 90 80 SW CS V V IN OUT 70 3.3V 4V 0.1 V V IN OUT 500mA 2A PULSED LOAD 60 10F LTC3125 CER 50 1.24M OFF ON SHDN 2200F 40 s2 TANT 0.01 30 PROG FB GND 536k 44.2k 20 3125 TA01a V = 4V OUT V = 3.3V 10 IN V = 2.4V IN 0 0.001 0.001 0.01 0.1 1 LOAD CURRENT (A) 3125 TA01b 3125fa 1 EFFICIENCY (%)LTC3125 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) TOP VIEW V , V Voltage ......................................... 0.3V to 6V IN OUT SW Voltage .................................................. 0.3V to 6V GND 1 8 SW SW Voltage < 100ns .................................... 0.3V to 7V FB 2 7 V OUT 9 All Other Pins ............................................... 0.3V to 6V PROG 6 SHDN 3 V 5 CS Operating Junction Temperature Range 4 IN (Notes 2, 5) ............................................ 40C to 125C DCB PACKAGE 8-LEAD (2mm s 3mm) PLASTIC DFN Junction Temperature ........................................... 125C T = 125C, = 64C/W (NOTE 6) JMAX JA Storage Temperature Range ................... 65C to 125C EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3125EDCB PBF LTC3125EDCB TRPBF LDGY 8-Lead (2mm 3mm) Plastic DFN 40C to 125C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based nish parts. For more information on lead free part marking, go to: