LTC1474IS8-3.3#PBF Analog Devices

LTC1474/LTC1475 Low Quiescent Current High Efficiency Step-Down Converters FEATURES DESCRIPTION n High Efficiency: Over 92% Possible The LTC 1474/LTC1475 series are high efficiency step- n Very Low Standby Current: 10m A Typ down converters with internal P-channel MOSFET power n Available in Space Saving 8-Lead MSOP Package switches that draw only 10m A typical DC supply current at n Internal 1.4W Power Switch (V = 10V) no load while maintaining output voltage. The LTC1474 IN n Wide V Range: 3V to 18V Operation uses logic-controlled shutdown while the LTC1475 fea- IN n Very Low Dropout Operation: 100% Duty Cycle tures pushbutton on/off. n Low-Battery Detector Functional During Shutdown TM The low supply current coupled with Burst Mode opera- n Programmable Current Limit with Optional tion enables the LTC1474/LTC1475 to maintain high effi- Current Sense Resistor (10mA to 400mA Typ) ciency over a wide range of loads. These features, along n Short-Circuit Protection with their capability of 100% duty cycle for low dropout n Few External Components Required and wide input supply range, make the LTC1474/LTC1475 n Active Low Micropower Shutdown: I = 6m A Typ Q ideal for moderate current (up to 300mA) battery-powered n Pushbutton On/Off (LTC1475 Only) applications. n 3.3V, 5V and Adjustable Output Versions The peak switch current is user-programmable with an U optional sense resistor (defaults to 325mA minimum if not APPLICATIONS used) providing a simple means for optimizing the design for lower current applications. The peak current control n Cellular Telephones and Wireless Modems also provides short-circuit protection and excellent start- n 4mA to 20mA Current Loop Step-Down Converter up behavior. A low-battery detector that remains functional n Portable Instruments in shutdown is provided . n Battery-Operated Digital Devices n Battery Chargers The LTC1474/LTC1475 series availability in 8-lead MSOP n Inverting Converters and SO packages and need for few additional components n Intrinsic Safety Applications provide for a minimum area solution. , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a trademark of Linear Technology Corporation. TYPICAL APPLICATION LTC1474 Efficiency 100 V IN LOW BATTERY OUT 4V TO 18V V = 5V IN + 90 10F 0.1F V = 10V IN 7 25V V IN 6 1 V 80 OUT SENSE V V = 15V FB IN 3.3V AT 250mA LTC1474-3.3 3 2 L1 + LOW BATTERY IN LBI LBO 100F 100H 70 6.3V 100k 8 5 RUN SHDN RUN SW GND D1 60 L = 100H 4 MBR0530 V = 3.3V OUT 1474/75 F01 R = 0 L1 = SUMIDA CDRH74-101 SENSE 50 0.03 0.3 3 30 300 Figure 1. High Efficiency Step-Down Converter LOAD CURRENT (mA) 1474/75 TA01 1 EFFICIENCY (%) U ULTC1474/LTC1475 ABSOLUTE MAXIMUM RATINGS Input Supply Voltage (V ).........................0.3V to 20V Operating Ambient Temperature Range IN Switch Current (SW, SENSE).............................. 750mA Commercial ............................................ 0 C to 70 C Switch Voltage (SW) ............. (V 20V) to (V + 0.3V) Industrial ............................................ 40 C to 85 C IN IN V (Adjustable Versions) ..........................0.3V to 12V Junction Temperature (Note 1)............................ 125 C FB V (Fixed Versions) ................................ 0.3V to 20V Storage Temperature Range ................. 65 C to 150 C OUT LBI, LBO ....................................................0.3V to 20V Lead Temperature (Soldering, 10 sec).................. 300 C RUN, SENSE .................................. 0.3V to (V + 0.3V) IN PACKAGE/ORDER INFORMATION TOP VIEW TOP VIEW TOP VIEW TOP VIEW V /V 1 8 RUN V /V 1 8 ON OUT FB OUT FB V /V 1 8 RUN OUT FB V /V 1 8 ON OUT FB LBO 2 7 V LBO 2 7 V LBO 2 7 V IN IN IN LBO 2 7 V IN LBI 3 6 SENSE LBI/OFF 3 6 SENSE LBI 3 6 SENSE LBI/OFF 3 6 SENSE GND 4 5 SW GND 4 5 SW GND 4 5 SW GND 4 5 SW MS8 PACKAGE MS8 PACKAGE 8-LEAD PLASTIC MSOP 8-LEAD PLASTIC MSOP S8 PACKAGE S8 PACKAGE 8-LEAD PLASTIC SO 8-LEAD PLASTIC SO T = 125 C, q = 150 C/ W T = 125 C, q = 150 C/ W T = 125 C, q = 110 C/ W T = 125 C, q = 110 C/ W JMAX JA JMAX JA JMAX JA JMAX JA ORDER PART NUMBER ORDER PART NUMBER ORDER PART NUMBER ORDER PART NUMBER LTC1474CMS8 LTC1475CMS8 LTC1474CS8 LTC1475CS8 LTC1474CMS8-3.3 LTC1475CMS8-3.3 LTC1474IS8 LTC1475IS8 LTC1474CMS8-5 LTC1475CMS8-5 LTC1474CS8-3.3 LTC1475CS8-3.3 LTC1474CS8-5 LTC1475CS8-5 LTC1474IS8-3.3 LTC1474IS8-5 MS8 PART MARKING MS8 PART MARKING S8 PART MARKING S8 PART MARKING LTBW LTBK 1474 1475 LTCR LTCP 1474I 1475I LTCS LTCQ 147433 147533 14745 14755 474I33 1474I5 Consult factory for Military grade parts. 2 U W U W U WW