LT1305 Micropower High Power DC/DC Converter with Low-Battery Detector DESCRIPTIO FEATURES n 5V at 400mA from 2V Input The LT 1305 is a micropower step-up DC/DC converter TM n Supply Voltage As Low As 1.8V that uses Burst Mode operation. Similar to the LT1303, n 120A Quiescent Current the LT1305 features a 2A internal low-loss switch and can n Low-Battery Detector deliver up to four times the output power of the LT1303. n Low V Switch: 310mV at 2A Typ CESAT Quiescent current is only 120A and the Shutdown pin n Uses Inexpensive Surface Mount Inductors further reduces current to 10A. A low-battery detector n 8-Lead SO Package provides an open-collector output that goes low when the input voltage drops below a preset level. The LT1305 is available in an 8-pin SO, easing board space requirements. APPLICATI S , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a trademark of Linear Technology Corporation n 2-Cell and 3-Cell to 5V Conversion n EL Panel Drivers n Portable Instruments TYPICAL APPLICATI 2-Cell and 3-Cell to 5V/400mA DC/DC Converter with Low-Battery Detect Efficiency 90 L1 D1 10H V = 4.00V IN LOW BATTERY 316k GOES LOW AT V = 3.00V 1% V SW IN 100k IN V = 2.2V BAT 80 LBI LBO 412k C1 2 TO 3 301k LT1305 1% 220F V = 2.00V V CELLS 1% OUT IN SHUTDOWN SHDN FB 5V V = 2.50V IN 400mA GND PGND C2 70 100k 220F 1% C1, C2: AVX TPSE227010R0100 LT1305 TA03 D1: MOTOROLA MBRS130LT3 60 L1: COILCRAFT D03316-103 1 10 100 1000 LOAD CURRENT (mA) LT1305 TA02 1 EFFICIENCY (%) + + UO UO ULT1305 ABSOLUTEXAI U RATI GS PACKAGE/ORDER I FOR ATIO V Voltage .............................................................. 10V IN ORDER PART TOP VIEW SW1 Voltage ............................................................ 25V NUMBER FB Voltage ............................................................... 10V GND 1 8 PGND Shutdown Voltage ................................................... 10V LBO 2 7 SW LT1305CS8 LBO Voltage ............................................................. 10V SHDN 3 6 V IN LBI Voltage .............................................................. 10V FB 4 5 LBI S8 PART MARKING Maximum Power Dissipation ............................. 500mW S8 PACKAGE 8-LEAD PLASTIC SO Operating Temperature Range ..................... 0C to 70C 1305 T = 100C, = 80C/ W Storage Temperature Range ................. 65C to 150C JMAX JA Lead Temperature (Soldering, 10 sec).................. 300C Consult factory for Industrial and Military grade parts. ELECTRICAL CHARACTERISTICS T = 25C, V = 2.0V, unless otherwise noted. A IN SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS I Quiescent Current V = 0.5V, V = 2V l 120 200 A Q SHDN FB V = 1.8V l 715 A SHDN V Input Voltage Range 1.8 1.55 V IN l 2.0 V Feedback Voltage l 1.22 1.24 1.26 V Comparator Hysteresis l 6 12.5 mV Feedback Pin Bias Current V = 1V l 720 nA FB Oscillator Frequency Current Limit Not Asserted 120 155 185 kHz Oscillator TC 0.2 %/C DC Maximum Duty Cycle l 75 86 95 % t Switch On Time Current Limit Not Asserted 5.6 s ON Output Line Regulation 1.8V < V < 6V l 0.06 0.15 %/V IN V Switch Saturation Voltage I = 1A l 140 280 mV CESAT SW Switch Leakage Current V = 5V, Switch Off l 0.1 10 A SW Peak Switch Current V = 2V 1.35 2 2.35 A IN l 1.20 2.50 A V = 5V 1.15 2.15 A IN LBI Trip Voltage (Note 2) l 1.21 1.24 1.27 V LBI Input Bias Current V = 1V l 720 nA LBI LBO Output Low I = 100A l 0.11 0.4 V LOAD LBO Leakage Current V = 1.3V, V = 5V l 0.1 5 A LBI LBO V Shutdown Pin High l 1.8 V SHDNH V Shutdown Pin Low 0.5 V SHDNL I Shutdown Pin Bias Current V = 5V l 8.0 20 A SHDN SHDN V = 2V l 3.0 A SHDN V = 0V l 0.1 1 A SHDN The l denotes specifications which apply over the 0C to 70C operating Note 2: Low-battery detector comparator is inoperative when device is in temperature range. shutdown. Note 1: Hysteresis specified is DC. Output ripple may be higher if output capacitance is insufficient or capacitor ESR is excessive. 2 U U W W W WU