LT1617/LT1617-1
Micropower Inverting
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
Uses Small Surface Mount Components
High Output Voltage: Up to – 34V
Tiny 5-Lead SOT-23 Package
APPLICATIO S
s
s
s
s
LCD Bias
Handheld Computers
Battery Backup
Digital Cameras
The LT
®
1617/LT1617-1 are micropower inverting DC/DC
converters in a 5-lead SOT-23 package. The LT1617 is
designed for higher power systems with a 350mA current
limit and an input voltage range of 1.2V to 15V, whereas
the LT1617-1 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 without the use of costly transformers.
The LT1617’s low off-time of 400ns permits the use of
tiny, low profile inductors and capacitors to minimize
footprint and cost in space-conscious portable applications.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATION
1-Cell Li-Ion to –15V Inverting Converter
L1
22µH
5
V
IN
LT1617
4
C1
4.7µF
SHDN
GND
2
NFB
3
24.9k
C3
0.22µF
1
SW
D1
267k
C2
4.7µF
L2
22µH
80
–15V
12mA
EFFICIENCY (%)
V
IN
2.5V TO 4.2V
75
70
65
60
55
C1: TAIYO YUDEN LMK316BJ475
C2: TAIYO YUDEN EMK316BJ475
C3: TAIYO YUDEN TMK316BJ224
L1, L2: MURATA LQH3C220K34
D1: MOTOROLA MBR0530
1617/-1 TA01
50
0.1
U
Efficiency
V
IN
= 4.2V
V
IN
= 2.5V
1
10
LOAD CURRENT (mA)
30
1617/-1 TA01a
U
U
1
LINER [ LINEAR TECHNOLOGY ]
