LT1307_15 Datasheet, PDF (1/20 Pages) Linear Technology – Single Cell Micropower 600kHz PWM DC/DC Converters

FEATURES
s _{Uses Small Ceramic Capacitors}
s _{50µA Quiescent Current (LT1307)}
s _{1mA Quiescent Current (LT1307B)}
s _{Operates with VIN as Low as 1V}
s _{600kHz Fixed Frequency Operation}
s _{Starts into Full Load}
s _{Low Shutdown Current: 3µA}
s _{Low-Battery Detector}
s _{3.3V at 75mA from a Single Cell}
s _{Automatic Burst Mode}^® _{Operation at}
Light Load (LT1307)
s _{Continuous Switching at Light Load (LT1307B)}
s _{Low VCESAT Switch: 295mV at 500mA}
U
APPLICATIO S
s _Pagers
s _{Cordless Telephones}
s _{GPS Receivers}
s _{Battery Backup}
s _{Portable Electronic Equipment}
s _{Glucose Meters}
s _{Diagnostic Medical Instrumentation}
LT1307/LT1307B
Single Cell Micropower
600kHz PWM DC/DC Converters
DESCRIPTIO
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 main-
tained over a broad 100µA 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 low-
battery detector with a 200mV reference and shut down to
less than 5µA. No load quiescent current of the LT1307 is
50µA 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 al-
lows the use of tiny surface mount multilayer ceramic
(MLC) capacitors along with small surface mount induc-
tors. The devices work with just 10µF of output capaci-
tance and require only 1µF 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.
TYPICAL APPLICATIO
L1
10µH
1.5V
CELL
C1
1µF
SHUTDOWN
V_IN
SW
LBI
FB
LT1307
SHDN
LBO
V_C
GND
100k
680pF
D1
R1
1.02M
1%
R2
604k
1%
C1: MURATA-ERIE GRM235Y5V105Z01
MARCON THCS50E1E105Z
3.3V
75mA
TOKIN 1E105ZY5U-C103-F
C2: MURATA-ERIE GRM235Y5V106Z01
MARCON THCS50E1E105Z
TOKIN 1E106ZY5U-C304-F
D1: MOTOROLA MBR0520L
C2 _{L1: COILCRAFT D01608C-103}
10µF
SUMIDA CD43-100
MURATA ERIE LQH3C100
FOR 5V OUTPUT: R1 = 1M, R2 = 329k
1307 F01
Figure 1. Single Cell to 3.3V Boost Converter
Single Cell to 3.3V Converter Efficiency
90
80
V_IN = 1.5V
V_IN = 1V
70
V_IN = 1.25V
60
50
0.1
1
10
LOAD CURRENT (mA)
100
1307 TA01
1307fa
1