Datasheet

1
LT1617/LT1617-1
TYPICAL APPLICATION
U
APPLICATIO S
U
DESCRIPTIO
U
FEATURES
Micropower Inverting
DC/DC Converters
in SOT-23
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.
■
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
■
LCD Bias
■
Handheld Computers
■
Battery Backup
■
Digital Cameras
, LTC and LT are registered trademarks of Linear Technology Corporation.
1-Cell Li-Ion to –15V Inverting Converter
Efficiency
V
IN
SW
NFB
LT1617
V
IN
2.5V TO 4.2V
L1
22µH
D1
SHDN
24.9k
267k
C2
4.7µF
–15V
12mA
1617/-1 TA01
GND
C1
4.7µF
C1: TAIYO YUDEN LMK316BJ475
C2: TAIYO YUDEN EMK316BJ475
C3: TAIYO YUDEN TMK316BJ224
L1, L2: MURATA LQH3C220K34
D1: MOTOROLA MBR0530
L2
22µH
43
2
15
C3
0.22µF
LOAD CURRENT (mA)
0.1 1 10 30
EFFICIENCY (%)
80
75
70
65
60
55
50
1617/-1 TA01a
V
IN
= 4.2V
V
IN
= 2.5V