LT1375CS8#PBF Analog Devices

LT1375/LT1376 1.5A, 500kHz Step-Down Switching Regulators FEATURES Constant 500kHz Switching Frequency is current mode for fast transient response and good loop Uses All Surface Mount Components stability. Both fixed output voltage and adjustable parts are Inductor Size Reduced to 5H available. Easily Synchronizable A special high speed bipolar process and new design Saturating Switch Design: 0.4 techniques achieve high efficiency at high switching fre- Effective Supply Current: 2.5mA quency. Efficiency is maintained over a wide output cur- Shutdown Current: 20A rent range by using the output to bias the circuitry and by Cycle-by-Cycle Current Limiting utilizing a supply boost capacitor to saturate the power U switch. A shutdown signal will reduce supply current to APPLICATIO S 20A on both parts. The LT1375 can be externally syn- chronized from 580kHz to 900kHz with logic level inputs. Portable Computers The LT1375/LT1376 fit into standard 8-pin PDIP and SO Battery-Powered Systems packages, as well as a fused lead 16-pin SO with much Battery Charger lower thermal resistance. Full cycle-by-cycle short-cir- Distributed Power cuit protection and thermal shutdown are provided. Standard surface mount external parts are used, includ- DESCRIPTIO ing the inductor and capacitors. The LT 1375/LT1376 are 500kHz monolithic buck mode For low input voltage applications with 3.3V output, see switching regulators. A 1.5A switch is included on the die LT1507. This is a functionally identical part that can along with all the necessary oscillator, control and logic operate with input voltages between 4.5V and 12V. circuitry. High switching frequency allows a considerable , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. reduction in the size of external components. The topology All other trademarks are the property of their respective owners. TYPICAL APPLICATIO 5V Buck Converter Efficiency vs Load Current D2 100 1N914 V = 5V OUT V = 10V IN C2 90 L = 10H 0.1F BOOST OUTPUT** INPUT V V SW IN 5V, 1.25A 6V TO 25V 80 L1** C3* + LT1376-5 BIAS 5H 10F TO DEFAULT 50F SHDN FB 70 = ON GND V C1 C + 100F, 10V D2 C SOLID C 1N5818 60 3.3nF TANTALUM 50 * RIPPLE CURRENT I /2 OUT 0 0.25 0.50 0.75 1.00 1.25 ** INCREASE L1 TO 10H FOR LOAD CURRENTS ABOVE 0.6A AND TO 20H ABOVE 1A LOAD CURRENT (A) FOR INPUT VOLTAGE BELOW 7.5V, SOME RESTRICTIONS MAY APPLY. 1375/76 TA01 SEE APPLICATIONS INFORMATION. 1375/76 TA02 13756fd 1 EFFICIENCY (%) U ULT1375/LT1376 ABSOLUTE MAXIMUM RATINGS (Note 1) FB Pin Current (Adjustable Part) ............................ 1mA Input Voltage Sense Voltage (Fixed 5V Part) .................................. 7V LT1375/LT1376 .................................................. 25V SYNC Pin Voltage ..................................................... 7V LT1375HV/LT1376HV ........................................ 30V Operating Junction Temperature Range BOOST Pin Voltage LT1375C/LT1376C ............................... 0C to 125 C LT1375/LT1376 .................................................. 35V LT1375I/LT1376I............................. 40C to 125C LT1375HV/LT1376HV ........................................ 40V Storage Temperature Range ................ 65C to 150C SHDN Pin Voltage ..................................................... 7V Lead Temperature (Soldering, 10 sec)................. 300C BIAS Pin Voltage ...................................................... 7V FB Pin Voltage (Adjustable Part) ............................ 3.5V PACKAGE/ORDER INFORMATION TOP VIEW TOP VIEW TOP VIEW BOOST 1 8 V BOOST 1 8 V C GND 1 16 GND C V 2 7 FB/SENSE V 2 7 FB/SENSE NC 2 15 NC IN IN V 3 6 GND V GND BOOST 3 14 V SW 3 6 C SW SHDN SYNC V 4 13 FB/SENSE 4 5 BIAS 4 5 SHDN IN V 5 12 GND SW S8 PACKAGE N8 PACKAGE N8 PACKAGE S8 PACKAGE 8-LEAD PLASTIC SO BIAS 6 11 SHDN 8-LEAD PDIP 8-LEAD PDIP 8-LEAD PLASTIC SO = 100C/ W (N8) = 100C/ W (N8) NC 7 10 NC JA JA = 120C/ W TO 150C/W DEPENDING ON = 120C/ W TO 150C/W DEPENDING ON JA JA GND 8 9 GND PC BOARD LAYOUT (S8) PC BOARD LAYOUT (S8) S PACKAGE ORDER PART S8 PART ORDER PART S8 PART 16-LEAD PLASTIC NARROW SO NUMBER MARKING NUMBER MARKING =50C/ W WITH FUSED CORNER PINS JA CONNECTED TO GROUND PLANE OR LARGE LANDS LT1375CN8 LT1376CN8 LT1375CN8-5 LT1376CN8-5 ORDER PART NUMBER LT1375IN8 LT1376IN8 LT1375IN8-5 LT1376IN8-5 LT1376CS LT1375CS8 1375 LT1376CS8 1376 LT1376IS LT1375CS8-5 13755 LT1376CS8-5 13765 LT1376HVCS LT1375HVCS8 1375HV LT1376HVCS8 1376HV LT1376HVIS LT1375IS8 1375I LT1376IS8 1376I LT1375IS8-5 1375I5 LT1376IS8-5 1376I5 LT1375HVIS8 375HVI LT1376HVIS8 376HVI Order Options Tape and Reel: Add TR Lead Free: Add PBF Lead Free Tape and Reel: Add TRPBF Lead Free Part Marking: