LTC1877 High Ef ciency Monolithic Synchronous Step-Down Regulator FEATURES DESCRIPTION n High Ef ciency: Up to 95% The LTC 1877 s a high ef ciency monolithic synchronous n Very Low Quiescent Current: Only 10A buck regulator using a constant-frequency, current mode During Operation architecture. Supply current during operation is only 10A n 600mA Output Current at V = 5V and drops to < 1A in shutdown. The 2.65V to 10V input IN n 2.65V to 10V Input Voltage Range voltage range makes the LTC1877 ideally suited for both n 550kHz Constant-Frequency Operation single and dual Li-Ion battery-powered applications. 100% n No Schottky Diode Required duty cycle provides low dropout operation, extending bat- n Low Dropout Operation: 100% Duty Cycle tery life in portable systems. n Synchronizable from 400kHz to 700kHz Switching frequency is internally set at 550kHz, allowing n Selectable Burst Mode Operation or the use of small surface mount inductors and capacitors. Pulse-Skipping Mode For noise sensitive applications the LTC1877 can be exter- n 0.8V Reference Allows Low Output Voltages nally synchronized from 400kHz to 700kHz. Burst Mode n Shutdown Mode Draws < 1A Supply Current operation is inhibited during synchronization or when the n 2% Output Voltage Accuracy SYNC/MODE pin is pulled low, preventing low frequency n Current Mode Control for Excellent Line and Load ripple from interfering with audio circuitry. Transient Response n The internal synchronous switch increases ef ciency Overcurrent and Overtemperature Protected n and eliminates the need for an external Schottky diode. Available in 8-Lead MSOP Package Low output voltages are easily supported with the 0.8V APPLICATIONS feedback reference voltage. The LTC1877 is available in a space saving 8-lead MSOP package. Lower input voltage n Cellular Telephones applications (less than 7V abs max) should refer to the n Wireless Modems LTC1878 data sheet. n Personal Information Appliances L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks n Portable Instruments of Linear Technology Corporation. All other trademarks are the property of their respective n owners. Distributed Power Systems n Battery-Powered Equipment Ef ciency vs Output Current TYPICAL APPLICATION 100 High Ef ciency Step-Down Converter V = 3.6V IN 95 10H* 90 V IN 5 7 V OUT SW SYNC 2.65V V = 10V 85 IN 3.3V 20pF TO 10V 10F** 6 LTC1877 + V IN 80 V = 7.2V CER IN 47F*** 1 RUN 75 887k V = 5V IN 3 2 V I FB 70 TH GND 220pF 280k 65 4 60 V = 3.3V OUT L = 10H 55 *TOKO D62CB A920CY-100M Burst Mode OPERATION **TAIYO-YUDEN CERAMIC LMK325BJ106MN 50 ***SANYO POSCAP 6TPA47M 0.1 1.0 10 100 1000 V CONNECTED TO V FOR 2.65V < V < 3.3V OUT IN IN 1877 TA01 OUTPUT CURRENT (mA) 1877 TA02 1877fb 1 EFFICIENCY (%)LTC1877 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) Input Supply Voltage (V ) ..........................0.3V to 11V IN TOP VIEW I , PLL LPF Voltage ................................. 0.3V to 2.7V RUN 1 8 PLL LPF TH I 2 7 SYNC/MODE TH RUN, V Voltages ...................................... 0.3V to V FB IN V 3 6 V FB IN GND 5 SW 4 SYNC/MODE Voltage .................................. 0.3V to V IN MS8 PACKAGE SW Voltage ................................... 0.3V to (V + 0.3V) IN 8-LEAD PLASTIC MSOP P-Channel MOSFET Source Current (DC) ............ 800mA T = 125C, = 150C/W JMAX JA N-Channel MOSFET Sink Current (DC) ................ 800mA Peak SW Sink and Source Current ..........................1.5A Operating Temperature Range (Note 2) .....40C to 85C Junction Temperature (Note 3) ............................ 125C Storage Temperature Range .................. 65C to 150C Lead Temperature (Soldering, 10 sec) ...................300C ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC1877EMS8 PBF LTC1877EMS8 TRPBF LTLU 8-Lead Plastic MSOP 40C to 85C LTC1877IMS8 PBF LTC1877IMS8 TRPBF LTLV 8-Lead Plastic MSOP 40C to 85C 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: