LT1307B| Datasheet

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LT1307/LT1307B Single Cell Micropower 600kHz PWM DC/DC Converters

FEATURES
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DESCRIPTIO

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Uses Small Ceramic Capacitors 50uA Quiescent Current (LT1307) 1mA Quiescent Current (LT1307B) Operates with VIN as Low as 1V 600kHz Fixed Frequency Operation Starts into Full Load Low Shutdown Current: 3uA Low-Battery Detector 3.3V at 75mA from a Single Cell Automatic Burst Mode Operation at Light Load (LT1307) Continuous Switching at Light Load (LT1307B) Low VCESAT Switch: 295mV at 500mA

The LT 1307/LT1307B are micropower, fixed frequency DC/DC converters that operate from an input voltage as low as 1V. First in the industry to achieve true current mode PWM performance from a single cell supply, the LT1307 features automatic shifting to power saving Burst Mode operation at light loads. High efficiency is maintained over a broad 100uA to 100mA load range. The LT1307B does not shift into Burst Mode operation at light loads, eliminating low frequency output ripple at the expense of light load efficiency. The devices contain a lowbattery detector with a 200mV reference and shut down to less than 5uA. No load quiescent current of the LT1307 is 50uA and the internal NPN power switch handles a 500mA current with a voltage drop of just 295mV. Unlike competitive devices, large electrolytic capacitors are not required with the LT1307/LT1307B in single cell applications. The high frequency (600kHz) switching allows the use of tiny surface mount multilayer ceramic (MLC) capacitors along with small surf
ace mount inductors. The devices work with just 10uF of output capacitance and require only 1uF of input bypassing. The LT1307/LT1307B are available in 8-lead MSOP, PDIP and SO packages.
, LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a registered trademark of Linear Technology Corporation.

APPLICATIO S
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Pagers Cordless Telephones GPS Receivers Battery Backup Portable Electronic Equipment Glucose Meters Diagnostic Medical Instrumentation

TYPICAL APPLICATIO
L1 10uH

C1 1uF 1.5V CELL SHUTDOWN

VIN LBI

SW FB R1 1.02M 1% R2 604k 1%

EFFICIENCY (%)

LT1307 SHDN LBO GND VC 100k 680pF

C1: MURATA-ERIE GRM235Y5V105Z01 MARCON THCS50E1E105Z TOKIN 1E105ZY5U-C103-F 3.3V C2: MURATA-ERIE GRM235Y5V106Z01 75mA MARCON THCS50E1E105Z TOKIN 1E106ZY5U-C304-F D1: MOTOROLA MBR0520L C2 L1: COILCRAFT D01608C-103 10uF SUMIDA CD43-100 MURATA ERIE LQH3C100 FOR 5V OUTPUT: R1 = 1M, R2 = 329k
1307 F01

Figure 1. Single Cell to 3.3V Boost Converter

U
Single Cell to 3.3V Converter Efficiency
90 80 VIN = 1.5V VIN = 1V VIN = 1.25V 70 60 50 0.1 1 10 LOAD CURRENT (mA) 100
1307 TA01

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