Final Electrical Specifications LT1308 Single Cell High Current Micropower 600kHz Boost DC/DC Converter January 1998 DESCRIPTION FEATURES n 5V at 1A from a Single Li-Ion Cell The LT 1308 is a micropower, fixed frequency boost n 3.3V at 300mA from a Single NiCd Cell DC/DC converter that operates from an input voltage as n Low Quiescent Current: 100A low as 1V. Capable of delivering 5V at load current of 1A n Operates with V as Low as 1V from a single Li-Ion cell, the LT1308 also features power IN n Fixed Frequency Operation: 600kHz saving Burst Mode operation at light loads. High efficiency n Current Mode PWM Delivers Low Output Ripple is maintained over a broad 1mA to 1A load range. n Guaranteed Start-Up into Full Load The device contains a low-battery detector with a 200mV n Low Shutdown Current: 3A reference and shuts down to less than 5A quiescent n Low-Battery Comparator current. No-load quiescent current is 100A and the TM n Automatic Burst Mode Operation at Light Load internal NPN power switch handles a 2A current with a n Low V Switch: 300mV at 2A CESAT voltage drop of just 300mV. U High frequency 600kHz switching allows the use of small, APPLICATIONS surface mount components. The LT1308s current mode n GSM Terminals architecture provides fast response to load and line varia- n Digital Cameras tions. The device is available in an 8-lead SO package. n Answer-Back Pagers , LTC and LT are registered trademarks of Linear Technology Corporation. n Cordless Telephones Burst Mode is a trademark of Linear Technology Corporation. n DECT Phones n GPS Receivers n Battery Backup Supplies TYPICAL APPLICATION Converter Efficiency 4.2V TO 3V 95 L1 V = 3.6V IN 4.7H 90 V SHDN IN V = 4.2V IN LBI SW R1 85 LT1308 D1 301k Li-Ion 5V C1 LBO FB CELL 1A 10F 80 V GND C V = 3V IN + C2 R2 75 R C 100F 100k 47k C C 70 22nF 1308F01 C1: CERAMIC 65 1 10 100 1000 C2: AVX TPS SERIES D1: INTERNATIONAL RECTIFIER 10BQ015 LOAD CURRENT (mA) L1: COILTRONICS CTX5-1 1308 F01a COILCRAFT DO3316-472 Figure 1. Single Li-Ion Cell to 5V/1A DC/DC Converter Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 1 EFFICIENCY (%) U ULT1308 O ABS LUTEXAI U RATI GS PACKAGE/ORDER I FOR ATIO V , SHDN, LBO Voltage ......................................... 10V IN ORDER PART TOP VIEW SW Voltage ............................................................. 30V NUMBER V 1 8 LBO C FB Voltage ....................................................... V + 1V IN LT1308CS8 FB 2 7 LBI V Voltage ................................................................ 2V C LT1308IS8 SHDN 3 6 V IN LBI Voltage ............................................ 0V V 1V LBI GND SW 4 5 Current into FB Pin .............................................. 1mA S8 PART MARKING Junction Temperature...........................................125C S8 PACKAGE 8-LEAD PLASTIC SO Operating Temperature Range 1308 T = 125C, = 80C/W JMAX JA Commercial (Note 1) ......................... 20C to 70C 1308I Industrial ........................................... 40C to 85C Consult factory for Military grade parts. Storage Temperature Range ................ 65C to 150C Lead Temperature (Soldering, 10 sec)................. 300C ELECTRICAL CHARACTERISTICS Commercial Grade 0C to 70C. V = 1.1V, V = V , T = 25C, unless otherwise noted. IN SHDN IN A SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS I Quiescent Current Not Switching l 80 160 A Q V = 0V l 13 A SHDN V Feedback Voltage l 1.20 1.22 1.24 V FB I FB Pin Bias Current (Note 2) V = V l 27 80 nA B FB REF Reference Line Regulation 1.1V V 2V (25C, 0C) 0.6 1.1 %/V IN 2V (70C) 1.5 %/V 1.1V V IN 2V V 6V l 0.3 0.8 %/V IN Minimum Input Voltage 0.92 1 V Input Voltage Range l16V g Error Amp Transconductance I = 5A40mhos m A Error Amp Voltage Gain 25C, 0C 100 V/V V 70C 80 V/V f Switching Frequency l 500 600 700 kHz OSC Maximum Duty Cycle l 80 88 95 % Switch Current Limit (Note 3) DC = 40% l 2.0 2.5 A DC = 80% 1.6 2 A Switch V I = 2A (25C, 0C) 300 350 mV CESAT SW I = 2A (70C) 330 400 mV SW Burst Mode Operation Switch Current Limit L = 3.3H, V = 3.3V, V = 1.2V 200 mA OUT IN Shutdown Pin Current V = 1.1V l 2.5 4.0 A SHDN V = 6V 13 26 A SHDN V = 0V l 1.5 2.5 A SHDN LBI Threshold Voltage l 180 200 220 mV LBO Output Low I = 10A l 0.1 0.25 V SINK LBO Leakage Current V = 250mV, V = 5V l 0.01 0.1 A LBI LBO LBI Input Bias Current (Note 4) V = 150mV l 530 nA LBI 2 U WU U W W W