LT1317/LT1317B
Micropower, 600kHz PWM
DC/DC Converters
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DESCRIPTION
FEATURES
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 ModeTM 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
notshiftintoBurstModeoperationatlightloads, eliminat-
ing lowfrequency output rippleatthe expenseof light load
efficiency.
■
100µA Quiescent Current
■
Operates with VIN 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 VCESAT Switch: 300mV at 500mA
■
Pin for Pin Compatible with the LT1307/LT1307B
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APPLICATIONS
The LT1317/LT1317B contain an internal low-battery de-
tector with a 200mV reference that stays alive when the
device goes into shutdown.
■
Cellular Telephones
■
Cordless Telephones
■
Pagers
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.
■
GPS Receivers
■
Battery Backup
■
Portable Electronic Equipment
■
Glucose Meters
■
Diagnostic Medical Instrumentation
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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TYPICAL APPLICATION
2-Cell to 3.3V Converter Efficiency
L1
10µH
D1
90
2.2V
3V
IN
IN
+
C1
V
LBI
SW
FB
80
70
60
50
40
IN
47µF
3.3V
1.65V
IN
200mA
LT1317
R1
1M
1%
2
SHUTDOWN
SHDN
V
C
LBO
GND
CELLS
+
C2
47µF
R2*
604k
1%
R
C
33k
C
C
3.3nF
D1: MBR0520
L1: SUMIDA CD43-100
* FOR 5V OUTPUT, R2 = 332k, 1%
1317 F01
0.3
1
10
100
1000
LOAD CURRENT (mA)
Figure 1. 2-Cell to 3.3V Boost Converter
1317 TA01
1