Fina l Ele c tric a l Sp e c ific a tio ns
LT1308A/ LT1308B
Hig h Curre nt, Mic ro p o we r
Sing le Ce ll, 600kHz
DC/ DC Co nve rte rs
Aug ust 1999
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FEATURES
DESCRIPTION
The LT®1308A/LT1308B are micropower, fixed frequency
step-up DC/DC converters that operate over a 1V to 10V
input voltage range. They are improved versions of the
LT1308andarerecommendedforuseinnewdesigns.The
LT1308A features automatic shifting to power saving
Burst Mode operation at light loads and consumes just
140µA at no load. The LT1308B features continuous
switchingatlightloads andoperates ataquiescentcurrent
of 2.5mA. Both devices consume less than 1µA in
shutdown.
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5V at 1A from a Single Li-Ion Cell
5V at 800mA in SEPIC Mode from Four NiCd Cells
Fixed Frequency Operation: 600kHz
Boost Converter Outputs up to 34V
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Starts into Heavy Loads
Automatic Burst ModeTM Operation at
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Light Load (LT1308A)
Continuous Switching at Light Loads (LT1308B)
Low VCESAT Switch: 300mV at 2A
Pin-for-Pin Upgrade Compatible with LT1308
Lower Quiescent Current in Shutdown: 1µA (Max)
Improved Accuracy Low-Battery Detector
Reference: 200mV ±2%
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Low-battery detector accuracy is significantly tighter than
the LT1308. The 200mV reference is specified at ±2% at
room and ±3% over temperature. The shutdown pin
enables the device when it is tied to a 1V or higher source
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APPLICATIONS
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and does not need to be tied to V as on the LT1308. An
IN
internal V clamp results in improved transient response
C
GSM/CDMA Phones
Digital Cameras
LCD Bias Supplies
Answer-Back Pagers
GPS Receivers
Battery Backup Supplies
Handheld Computers
and the switch voltage rating has been increased to 36V,
enabling higher output voltage applications.
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The LT1308A/LT1308B are available in the 8-lead SO and
14-lead TSSOP packages.
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, 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
L1
4.7µH
Converter Efficiency
D1
5V
1A
95
V
= 3.6V
V = 4.2V
IN
IN
90
85
80
75
70
65
60
55
50
V
SW
IN
+
C1
47µF
R1*
309k
LBO
LBI
LT1308B
+
Li-Ion
CELL
C2
220µF
V
IN
= 2.5V
SHUTDOWN
SHDN
V
C
FB
GND
V
IN
= 1.5V
R2
100k
47k
100pF
C1: AVX TAJC476M010
C2: AVX TPSD227M006
D1: IR 10BQ015
L1: MURATA LQH6N4R7
*R1: 169k FOR V
= 3.3V
= 12V
OUT
1308A/B F01
887k FOR V
OUT
1
10
100
1000
Figure 1. LT1308B Single Li-Ion Cell to 5V/1A DC/DC Converter
LOAD CURRENT (mA)
1308A/B F01a
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tationthattheinterconnectionofits circuits as describedhereinwillnotinfringeonexistingpatentrights.
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