
1
LT1107
1107fa
FEATURES
APPLICATIU
DESCRIPTIOU
The LT
1107 is a versatile micropower DC/DC converter.
The device requires only three external components to
deliver a fixed output of 5V or 12V. Supply voltage ranges
from 2V to 12V in step-up mode and to 30V in step-down
mode. The LT1107 functions equally well in step-up, step-
down, or inverting applications.
The LT1107 is pin-for-pin compatible with the
LT1111, but
has a duty cycle of 70%, resulting in increased output
current in many applications. The LT1107 can deliver
150mA at 5V from a 2AA cell input and 5V at 300mA from
24V in step-down mode. Quiescent current is just 320
μ
A,
making the LT1107 ideal for power-conscious battery-
operated systems. The 63kHz oscillator is optimized to
work with surface mount inductors and capacitors.
Switch current limit can be programmed with a single
resistor. An auxiliary gain block can be configured as a
low-battery detector, linear post regulator, undervoltage
lock-out circuit, or error amplifier.
TYPICAL APPLICATIOU
Micropower
DC/DC Converter
Adjustable and Fixed 5V, 12V
Efficiency
I
Operates at Supply Voltages from 2V to 30V
I
Consumes Only 320
μ
A Supply Current
I
Works in Step-Up or Step-Down Mode
I
Only Three External Components Required
I
Low-Battery Detector Comparator On-Chip
I
User Adjustable Current Limit
I
Internal 1A Power Switch
I
Fixed or Adjustable Output Voltage Versions
I
Space Saving 8-Pin MiniDIP or SO-8 Package
I
Palmtop Computers
I
3V to 5V, 5V to 12V Converters
I
24V to 5V, 12V to 5V Converters
I
LCD Bias Generators
I
Peripherals and Add-On Cards
I
Battery Backup Supplies
I
Cellular Telephones
I
Portable Instruments
LOAD CURRENT (mA)
1
E
82
80
78
76
74
72
70
68
66
64
10
100
400
1107 TA02
V
IN
= 3V
V
IN
= 2.5V
V
IN
= 2V
5V
150mA
MBRS120T3
L1*
33
μ
H
47
2
×
AA
ALKALINE
CELLS
100
μ
F
SUMIDA CD54-330K
COILCRAFT DT3316-473
*
I
LIM
V
IN
SENSE
SW2
SW1
GND
47
μ
F
LT1107-5
1107 TA01
+
+
Palmtop Computer Logic Supply
, LTC and LT are registered trademarks of Linear Technology Corporation