LT1374 4.5A, 500kHz Step-Down Switching Regulator UFEATURESDESCRIPTIO ■ Constant 500kHz Switching Frequency The LT®1374 is a 500kHz monolithic buck mode switching ■ High Power 16-Pin TSSOP Package Available regulator. A 4.5A switch is included on the die along with ■ Uses All Surface Mount Components all the necessary oscillator, control and logic circuitry. High ■ Inductor Size Reduced to 1.8 µ H switching frequency allows a considerable reduction in the ■ Saturating Switch Design: 0.07Ω size of external components. The topology is current mode ■ Effective Supply Current: 2.5mA for fast transient response and good loop stability. Both ■ Shutdown Current: 20µA fixed output voltage and adjustable parts are available. ■ Cycle-by-Cycle Current Limiting A special high speed bipolar process and new design tech- ■ Easily Synchronizable niques achieve high efficiency at high switching frequency. Efficiency is maintained over a wide output current range U by using the output to bias the circuitry and by utilizing a APPLICATIO S supply boost capacitor to saturate the power switch. ■ Portable Computers The LT1374 is available in standard 7-pin DD, TO-220, fused ■ Battery-Powered Systems lead SO-8 and 16-pin exposed pad TSSOP packages. Full ■ Battery Chargers cycle-by-cycle short-circuit protection and thermal shut- ■ Distributed Power down are provided. Standard surface mount external parts may be used, including the inductor and capacitors. There is the optional function of shutdown or synchronization. A shutdown signal reduces supply current to 20µA. Synchro- nization allows an external logic level signal to increase the internal oscillator from 580kHz to 1MHz. , LTC and LT are registered trademarks of Linear Technology Corporation. Protected by U.S. Patents, Including 6111439, 5668493, 5656965 UTYPICAL APPLICATIO5V Buck ConverterEfficiency vs Load Current D2 100 CMDSH3 OR FMMD914 VOUT = 5V VIN = 10V 95 C2 L = 10µH 0.27µF L1** 90 5 BOOST µH INPUT OUTPUT** VIN V 6V TO 25V SW 5V, 4.25A C3* + 85 LT1374-5 BIAS 10µF TO 50µF DEFAULT SHDN SENSE EFFICIENCY (%) = ON 80 GND VC C1 + D1 C 100µF, 10V C MBRS330T3 75 1.5nF SOLID TANTALUM 70 * RIPPLE CURRENT RATING ≥ IOUT/2 1374 TA01 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 ** INCREASE L1 TO 10µH FOR LOAD CURRENTS ABOVE 3.5A AND TO 20µH ABOVE 4A SEE APPLICATIONS INFORMATION LOAD CURRENT (A) 1374 TA02 1374fd 1