LT1307/LT1307B Single Cell Micropower 600kHz PWM DC/DC Converters UFEATURESDESCRIPTIO ■ Uses Small Ceramic Capacitors The LT®1307/LT1307B are micropower, fixed frequency ■ 50 µ A Quiescent Current (LT1307) DC/DC converters that operate from an input voltage as ■ 1mA Quiescent Current (LT1307B) low as 1V. First in the industry to achieve true current ■ Operates with V mode PWM performance from a single cell supply, the IN as Low as 1V ■ 600kHz Fixed Frequency Operation LT1307 features automatic shifting to power saving Burst ■ Starts into Full Load Mode operation at light loads. High efficiency is main- ■ Low Shutdown Current: 3µA tained over a broad 100µA to 100mA load range. The ■ Low-Battery Detector LT1307B does not shift into Burst Mode operation at light ■ 3.3V at 75mA from a Single Cell loads, eliminating low frequency output ripple at the ■ Automatic Burst Mode® Operation at expense of light load efficiency. The devices contain a low- Light Load (LT1307) battery detector with a 200mV reference and shut down to ■ Continuous Switching at Light Load (LT1307B) less than 5µA. No load quiescent current of the LT1307 is ■ Low V 50 CESAT Switch: 295mV at 500mA µA and the internal NPN power switch handles a 500mA current with a voltage drop of just 295mV. U Unlike competitive devices, large electrolytic capacitors APPLICATIO S are not required with the LT1307/LT1307B in single cell ■ Pagers applications. The high frequency (600kHz) switching al- ■ Cordless Telephones lows the use of tiny surface mount multilayer ceramic ■ GPS Receivers (MLC) capacitors along with small surface mount induc- ■ Battery Backup tors. The devices work with just 10µF of output capaci- ■ Portable Electronic Equipment tance and require only 1µF of input bypassing. ■ Glucose Meters The LT1307/LT1307B are available in 8-lead MSOP, PDIP ■ Diagnostic Medical Instrumentation and SO packages. , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a registered trademark of Linear Technology Corporation. UTYPICAL APPLICATIOSingle Cell to 3.3V Converter Efficiency L1 10µH D1 90 C1: MURATA-ERIE GRM235Y5V105Z01 MARCON THCS50E1E105Z VIN SW TOKIN 1E105ZY5U-C103-F C1 3.3V LBI FB C2: MURATA-ERIE GRM235Y5V106Z01 80 1µF 75mA V R1 MARCON THCS50E1E105Z IN = 1.5V LT1307 1.5V SHUTDOWN SHDN LBO 1.02M TOKIN 1E106ZY5U-C304-F CELL 1% VIN = 1V VC GND D1: MOTOROLA MBR0520L C2 70 L1: COILCRAFT D01608C-103 R2 10µF VIN = 1.25V SUMIDA CD43-100 100k 604k MURATA ERIE LQH3C100 EFFICIENCY (%) 1% 680pF FOR 5V OUTPUT: R1 = 1M, R2 = 329k 60 1307 F01 50 Figure 1. Single Cell to 3.3V Boost Converter 0.1 1 10 100 LOAD CURRENT (mA) 1307 TA01 1307fa 1