LT1111_15 Datasheet, PDF (1/16 Pages) Linear Technology – Micropower DC/DC Converter Adjustable and Fixed 5V, 12V

FEATURES
s _{Operates at Supply Voltages from 2V to 30V}
s _{Works with Surface Mount Inductors}
s _{72kHz Oscillator}
s _{Only Three External Components Required}
s _{Step-Up or Step-Down Mode}
s _{Low-Battery Detector Comparator On-Chip}
s _{User Adjustable Current Limit}
s _{Internal 1A Power Switch}
s _{Fixed or Adjustable Output Voltage Versions}
s _{Space Saving 8-Pin MiniDIP or SO-8 Package}
U
APPLICATIO S
s _{3V to 5V, 5V to 12V Converters}
s _{9V to 5V, 12V to 5V Converters}
s _{Remote Controls}
s _{Peripherals and Add-On Cards}
s _{Battery Backup Supplies}
s _{Uninterruptible Supplies}
s _{Laptop and Palmtop Computers}
s _{Cellular Telephones}
s _{Portable Instruments}
s _{Flash Memory VPP Generators}
LT1111
Micropower
DC/DC Converter
Adjustable and Fixed 5V, 12V
DESCRIPTIO
The LT^®1111 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 LT1111 functions equally well in step-up, step-
down, or inverting applications.
The LT1111 oscillator is set at 72kHz, optimizing the
device to work with off-the-shelf surface mount inductors.
The device can deliver 5V at 100mA from a 3V input in
step-up mode or 5V at 200mA from a 12V input in step-
down mode.
Switch current limit can be programmed with a single
resistor. An auxiliary open-collector gain block can be
configured as a low-battery detector, linear post regulator,
undervoltage lock-out circuit, or error amplifier.
For input sources of less than 2V use the LT1110.
, LTC and LT are registered trademarks of Linear Technology Corporation
TYPICAL APPLICATIO
All Surface Mount 3V to 5V Step-Up Converter
3V INPUT
SUMIDA
CD54-220M
22µH
MBRS120T3
5V
100mA
I_LIM
V _IN
+
SW1
10µF* LT1111CS8-5
SENSE
GND
SW2
+
33 µ F
*OPTIONAL
LT1111 • TA01
Typical Load Regulation
6
5
4
V_IN = 2V 2.2 2.4 2.6 2.8 3V
3
2
1
0
0 25
50 75 100 125 150 175 200
LOAD CURRENT (mA)
LT1111 • TA02
1111fd
1