LT1617-1_15 Datasheet, PDF (1/8 Pages) Linear Technology – Micropower Inverting DC/DC Converters in SOT-23

FEATURES
s _{Low Quiescent Current:}
20µA in Active Mode
<1µA in Shutdown Mode
s _{Operates with VIN as Low as 1V}
s _{Low VCESAT Switch: 250mV at 300mA}
s _{Uses Small Surface Mount Components}
s _{High Output Voltage: Up to – 34V}
s _{Tiny 5-Lead SOT-23 Package}
U
APPLICATIO S
s _{LCD Bias}
s _{Handheld Computers}
s _{Battery Backup}
s _{Digital Cameras}
LT1617/LT1617-1
Micropower Inverting
DC/DC Converters
in SOT-23
DESCRIPTIO
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
V_IN
2.5V TO 4.2V
1-Cell Li-Ion to –15V Inverting Converter
L1
22µH
C3
0.22µF
L2
22µH
5
1
V_IN
SW
D1
LT1617
4
SHDN
3
NFB
C1
GND
4.7µF
2
267k
24.9k
C1: TAIYO YUDEN LMK316BJ475
C2: TAIYO YUDEN EMK316BJ475
C3: TAIYO YUDEN TMK316BJ224
L1, L2: MURATA LQH3C220K34
D1: MOTOROLA MBR0530
–15V
12mA
C2
4.7µF
1617/-1 TA01
80
75
70
65
60
55
50
0.1
Efficiency
V_IN = 4.2V
V_IN = 2.5V
1
10
30
LOAD CURRENT (mA)
1617/-1 TA01a
1