LTC1779 250mA Current Mode Step-Down DC/DC Converter in ThinSOT Fea T Descrip T n High Efficiency: Up to 94% The LTC 1779 is a constant frequency current mode step- n 250mA Output Current down DC/DC converter in a 6-lead ThinSOT package. The n Wide V Range: 2.5V to 9.8V part operates with a 2.5V to 9.8V input and can provide IN n 550kHz Constant Frequency Operation up to 250mA of output current. Current mode control n Burst Mode Operation at Light Load provides excellent AC and DC load and line regulation. n Low Dropout: 100% Duty Cycle The device incorporates an accurate undervoltage lockout n 0.8V Reference Allows Low Output Voltages feature that shuts down the LTC1779 when the input volt- n 2.5% Reference Accuracy age falls below 2V. n Current Mode Operation for Excellent Line and Load The LTC1779 boasts a 2.5% output voltage accuracy Transient Response and consumes only 135A of quiescent current. For ap- n Low Quiescent Current: 135A plications where efficiency is a prime consideration, the n Shutdown Mode Draws Only 8A Supply Current LTC1779 is configured for Burst Mode operation, which n Low Profile (1mm) ThinSOT Package enhances efficiency at low output current. To further maximize the life of a battery source, the a T internal P-channel MOSFET is turned on continuously in dropout (100% duty cycle). In shutdown, the device draws n 1- or 2-Cell Lithium-Ion-Powered Applications a mere 8A. High constant operating frequency of 550kHz n Cellular Telephones allows the use of a small external inductor. n Wireless Modems n Portable Computers The LTC1779 is available in a low profile (1mm) ThinSOT n Distributed 3.3V, 2.5V or 1.8V Power Systems package. n Scanners L, LT, LTC, LTM, Burst Mode, Linear Technology 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. Typical a T V IN Efficiency vs Load Current 2.5V C1 TO 9.8V C3 100 10F 0.1F L1 16V 22H 90 V OUT 1 6 2.5V I /RUN SW V = 3.3V TH IN + C2 100mA 80 169k LTC1779 20k 47F D1 V = 6V IN 2 5 6V GND V IN 70 100pF R1 78.7k V = 9.8V IN 10 3 4 60 V SENSE FB 1779 F01a 50 C1: TAIYO YUDEN CERAMIC EMK325BJ106MNT C2: SANYO POSCAP 6TPA47M 40 D1: IR10BQ015 V = 2.5V OUT L1: COILTRONICS UP1B220 R = 10 SENSE 30 0.1 1 10 100 1000 Figure 1. LTC1779 High Efficiency 2.5V/100mA Step-Down Converter LOAD CURRENT (mA) 1779 F01b 1779fa 1 For more information www.linear.com/LTC1779 EFFICIENCY (%) ion pplica ions pplica ion uresLTC1779 a Te Maxi Mu M r a T p in c F T (Note 1) Input Supply Voltage (V ) ......................... 0.3V to 10V IN TOP VIEW SENSE , SW Voltages ................... 0.3V to (V + 0.3V) IN I /RUN 1 6 SW TH V , I /RUN Voltages .............................. 0.3V to 2.4V FB TH GND 2 5 V IN SW Peak Output Current (<10s) ........................... 0.5A V 3 4 SENSE FB Storage Ambient Temperature Range ....65C to 150C S6 PACKAGE Operating Temperature Range (Note 2)....40C to 85C 6-LEAD PLASTIC SOT-23 Junction Temperature (Note 3) ............................ 150C T = 150C, = 230C/W JMAX JA Lead Temperature (Soldering, 10 sec) ...................300C o r Der i n F Ma T LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC1779ES6 PBF LTC1779ES6 TRPBF LTLP 6-Lead Plastic SOT-23 40C to 85C Consult LTC Marketing for parts specified with wider operating temperature ranges. Consult LTC Marketing for information on nonstandard lead based finish parts. For more information on lead free part marking, go to: