Final Electrical Specifications
LT1308
Single Cell High Current
Micropower 600kHz
Boost DC/DC Converter
January 1998
FEATURES
s
s
s
s
s
s
s
s
s
s
s
DESCRIPTION
The LT
®
1308 is a micropower, fixed frequency boost
DC/DC converter that operates from an input voltage as
low as 1V. Capable of delivering 5V at load current of 1A
from a single Li-Ion cell, the LT1308 also features power
saving Burst Mode operation at light loads. High efficiency
is maintained over a broad 1mA to 1A load range.
The device contains a low-battery detector with a 200mV
reference and shuts down to less than 5µA quiescent
current. No-load quiescent current is 100µA and the
internal NPN power switch handles a 2A current with a
voltage drop of just 300mV.
High frequency 600kHz switching allows the use of small,
surface mount components. The LT1308’s current mode
architecture provides fast response to load and line varia-
tions. The device is available in an 8-lead SO package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a trademark of Linear Technology Corporation.
5V at 1A from a Single Li-Ion Cell
3.3V at 300mA from a Single NiCd Cell
Low Quiescent Current: 100µA
Operates with V
IN
as Low as 1V
Fixed Frequency Operation: 600kHz
Current Mode PWM Delivers Low Output Ripple
Guaranteed Start-Up into Full Load
Low Shutdown Current: 3µA
Low-Battery Comparator
Automatic Burst Mode
TM
Operation at Light Load
Low V
CESAT
Switch: 300mV at 2A
APPLICATIONS
s
s
s
s
s
s
s
GSM Terminals
Digital Cameras
Answer-Back Pagers
Cordless Telephones
DECT Phones
GPS Receivers
Battery Backup Supplies
TYPICAL APPLICATION
4.2V TO 3V
Converter Efficiency
95
SHDN
LBI
LT1308
Li-Ion
CELL
C1
10µF
LBO
V
C
R
C
47k
C
C
22nF
C1: CERAMIC
C2: AVX TPS SERIES
D1: INTERNATIONAL RECTIFIER 10BQ015
L1: COILTRONICS CTX5-1
COILCRAFT DO3316-472
V
IN
SW
R1
301k
FB
GND
R2
100k
L1
4.7µH
EFFICIENCY (%)
90
85
80
D1
5V
1A
+
C2
100µF
75
70
1308F01
65
1
Figure 1. Single Li-Ion Cell to 5V/1A DC/DC Converter
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-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
U
U
U
V
IN
= 3.6V
V
IN
= 4.2V
V
IN
= 3V
10
100
LOAD CURRENT (mA)
1000
1308 F01a
1
LINER [ LINEAR TECHNOLOGY ]
