LT1317/LT1317B
Micropower, 600kHz PWM
DC/DC Converters
FEATURES
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DESCRIPTION
The LT
®
1317/LT1317B are micropower, fixed frequency
step-up DC/DC converters that operate over a wide input
voltage range of 1.5V to 12V. The LT1317 features auto-
matic shifting to power saving Burst Mode
TM
operation at
light loads. High efficiency is maintained over a broad
300µA to 200mA load range. Peak switch current during
Burst Mode operation is kept below 250mA for most
operating conditions which results in low output ripple
voltage, even at high input voltages. The LT1317B does
not shift into Burst Mode operation at light loads, eliminat-
ing low frequency output ripple at the expense of light load
efficiency.
The LT1317/LT1317B contain an internal low-battery de-
tector with a 200mV reference that stays alive when the
device goes into shutdown.
No-load quiescent current of the LT1317 is 100µA and
shuts down to 30µA. The internal NPN power switch
handles a 500mA current with a voltage drop of just
300mV.
The LT1317/LT1317B are available in MS8 and SO-8
packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a trademark of Linear Technology Corporation.
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100µA Quiescent Current
Operates with V
IN
as Low as 1.5V
600kHz Fixed Frequency Operation
Starts into Full Load
Low-Battery Detector Active in Shutdown
Automatic Burst Mode Operation at
Light Load (LT1317)
Continuous Switching at Light Loads (LT1317B)
Low V
CESAT
Switch: 300mV at 500mA
Pin for Pin Compatible with the LT1307/LT1307B
APPLICATIONS
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Cellular Telephones
Cordless Telephones
Pagers
GPS Receivers
Battery Backup
Portable Electronic Equipment
Glucose Meters
Diagnostic Medical Instrumentation
TYPICAL APPLICATION
L1
10µH
2-Cell to 3.3V Converter Efficiency
D1
90
2.2V
IN
3V
IN
+
C1
47µF
V
IN
LBI
LT1317
SHDN
V
C
R
C
33k
C
C
3.3nF
SW
FB
LBO
GND
R1
1M
1%
R2*
604k
1%
3.3V
200mA
80
EFFICIENCY (%)
2
CELLS
SHUTDOWN
70
+
C2
47µF
60
50
1317 F01
D1: MBR0520
L1: SUMIDA CD43-100
* FOR 5V OUTPUT, R2 = 332k, 1%
40
0.3
1
Figure 1. 2-Cell to 3.3V Boost Converter
U
U
U
1.65V
IN
10
100
LOAD CURRENT (mA)
1000
1317 TA01
1
LINER [ LINEAR TECHNOLOGY ]
