LT1615/LT1615-1
Micropower Step-Up
DC/DC Converters
in SOT-23
FEATURES
s
DESCRIPTIO
s
s
s
s
s
Low Quiescent Current:
20
µ
A in Active Mode
<1
µ
A in Shutdown Mode
Operates with V
IN
as Low as 1V
Low V
CESAT
Switch: 250mV at 300mA
Tiny 5-Lead SOT-23 Package
Uses Small Surface Mount Components
High Output Voltage: Up to 34V
APPLICATIO S
s
s
s
s
LCD Bias
Handheld Computers
Battery Backup
Digital Cameras
The LT
®
1615/LT1615-1 are micropower step-up DC/DC
converters in a 5-lead SOT-23 package. The LT1615 is
designed for higher power systems with a 350mA current
limit and an input voltage range of 1.2V to 15V, whereas
the LT1615-1 is intended for lower power and single-cell
applications with a 100mA current limit and an extended
input voltage range of 1V to 15V. Otherwise, the two
devices are functionally equivalent. Both devices feature a
quiescent current of only 20µA at no load, which further
reduces to 0.5µA in shutdown. A current limited, fixed off-
time control scheme conserves operating current, result-
ing in high efficiency over a broad range of load current.
The 36V switch allows high voltage outputs up to 34V to
be easily generated in a simple boost topology without the
use of costly transformers. The LT1615’s low off-time of
400ns permits the use of tiny, low profile inductors and
capacitors to minimize footprint and cost in space-con-
scious portable applications.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
L1
10µH
1-Cell Li-Ion to 20V Converter for LCD Bias
85
D1
20V
12mA
SW
LT1615
SHDN
C1
4.7µF
GND
FB
R2
130k
1615/-1 TA01
V
IN
2.5V TO 4.2V
V
IN
80
V
IN
= 4.2V
75
EFFICIENCY (%)
R1
2M
C2
1µF
70
65
60
55
50
0.1
C1: TAIYO YUDEN LMK316BJ475
C2: TAIYO YUDEN TMK316BJ105
D1: MOTOROLA MBR0530
L1: MURATA LQH3C100K24
0.3
U
Efficiency
V
IN
= 2.5V
V
IN
= 3.3V
1
3
10
LOAD CURRENT (mA)
30
1615/-1 TA01a
U
U
1
LINER [ LINEAR TECHNOLOGY ]
