LT1374 4.5A, 500kHz Step-Down Switching Regulator FEATURES DESCRIPTIO 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 1.8H switching frequency allows a considerable reduction in the Saturating Switch Design: 0.07 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: 20A 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 20A. 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 TYPICAL APPLICATIO 5V Buck Converter Efficiency vs Load Current D2 100 CMDSH3 OR FMMD914 V = 5V OUT V = 10V IN 95 C2 L = 10H 0.27F L1** 90 5H BOOST INPUT OUTPUT** V V IN SW 6V TO 25V 5V, 4.25A + 85 C3* LT1374-5 BIAS 10F TO DEFAULT 50F SHDN SENSE 80 = ON GND V C C1 + D1 100F, 10V C C MBRS330T3 75 SOLID 1.5nF TANTALUM 70 * RIPPLE CURRENT RATING I /2 1374 TA01 OUT 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 ** INCREASE L1 TO 10H FOR LOAD CURRENTS ABOVE 3.5A AND TO 20H ABOVE 4A SEE APPLICATIONS INFORMATION LOAD CURRENT (A) 1374 TA02 1374fd 1 EFFICIENCY (%) U ULT1374 (Note 1) ABSOLUTE AXI U RATI GS Input Voltage FB Pin Current (Adjustable Part) ............................ 1mA LT1374 ............................................................... 25V SENSE Voltage (Fixed 5V Part) ................................. 7V LT1374HV .......................................................... 32V SYNC Pin Voltage ..................................................... 7V BOOST Pin Voltage ................................................. 38V Operating Junction Temperature Range BOOST Pin Above Input Voltage ............................. 15V LT1374C ............................................... 0C to 125 C SHDN Pin Voltage ..................................................... 7V LT1374I ........................................... 40C to 125C BIAS Pin Voltage ...................................................... 7V Storage Temperature Range ................ 65C to 150C FB Pin Voltage (Adjustable Part) ............................ 3.5V Lead Temperature (Soldering, 10 sec)................. 300C UUW PACKAGE/ORDER I FOR ATIO ORDER ORDER PART NUMBER PART NUMBER FRONT VIEW 7 FB OR SENSE* 6 BOOST LT1374CR LT1374CS8 5 V TAB IN LT1374CR-5 IS 4 GND LT1374CS8-5 GND 3 V SW LT1374CR-SYNC LT1374CS8-SYNC 2 SYNC OR SHDN* TOP VIEW 1 V C LT1374CR-5 SYNC LT1374CS8-5 SYNC R PACKAGE V 1 8 V IN SW LT1374HVCR LT1374HVCS8 7-LEAD PLASTIC DD SYNC 2 7 BOOST OR SHDN* LT1374IR LT1374IS8 T = 125C, = 30C/ W FB OR JMAX JA 3 6 V C SENSE* WITH PACKAGE SOLDERED TO 0.5 SQUARE INCH LT1374IR-5 LT1374IS8-5 FGND 4 5 BIAS COPPER AREA OVER BACKSIDE GROUND PLANE LT1374IR-SYNC LT1374IS8-SYNC OR INTERNAL POWER PLANE. CAN VARY JA S8 PACKAGE FROM 20C/W TO > 40C/W DEPENDING ON LT1374IR-5 SYNC 8-LEAD PLASTIC SO LT1374IS8-5 SYNC MOUNTING TECHNIQUES LT1374HVIR LT1374HVIS8 =80C/ W WITH FUSED (FGND) JA GROUND PIN CONNECTED TO GROUND ORDER PLANE OR LARGE LANDS S8 PART MARKING PART NUMBER TOP VIEW 1374 1374I GND 1 16 GND 13745 1374I5 LT1374CFE NC 2 15 V SW 1374SN 374ISN LT1374IFE V 3 14 V IN SW 3745SN 74I5SN LT1374HVCFE V 4 13 SYNC IN 1374HV 374HVI LT1374HVIFE BOOST 5 12 SHDN FB/SENSE 6 11 V C TAB IS ORDER FRONT VIEW GND NC 7 10 BIAS PART NUMBER FB OR SENSE* 7 GND 8 9 GND FE PART MARKING BOOST 6 V 5 IN FE16 PACKAGE LT1374CT7 4 GND 1374CFE 16-LEAD PLASTIC TSSOP 3 V SW LT1374CT7-5 SHDN 1374IFE 2 = 40C/ W JA V 1 C LT1374IT7 EXPOSED PAD SOLDERED TO 1374HVCFE GROUND PLANE T7 PACKAGE LT1374IT7-5 1374HVIFE 7-LEAD PLASTIC TO-220 T = 125C, = 50C/ W, = 4C/ W JMAX JA JC *Default is the adjustable output voltage device with FB pin and shutdown function. Option -5 replaces FB with SENSE pin for fixed 5V output applications. -SYNC replaces SHDN with SYNC pin for applications requiring synchronization. Consult LTC Marketing for parts specified with wider operating temperature ranges. 1374fd 2 U WWW