LT1107 Datasheet, PDF (1/12 Pages) Linear Technology – Micropower DC/DC Converter Adjustable and Fixed 5V, 12V

LT1107
Micropower
DC/DC Converter
Adjustable and Fixed 5V, 12V
FEATURES
s _{Operates at Supply Voltages from 2V to 30V}
s _{Consumes Only 320µA Supply Current}
s _{Works in Step-Up or Step-Down Mode}
s _{Only Three External Components Required}
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}
APPLICATI S
s _{Palmtop Computers}
s _{3V to 5V, 5V to 12V Converters}
s _{24V to 5V, 12V to 5V Converters}
s _{LCD Bias Generators}
s _{Peripherals and Add-On Cards}
s _{Battery Backup Supplies}
s _{Cellular Telephones}
s _{Portable Instruments}
DESCRIPTIO
The LT1107 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 320µA,
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 APPLICATI
Palmtop Computer Logic Supply
L1*
33µH ^MBRS120T3
2 × AA
ALKALINE CELLS
47Ω
I_LIM
V_IN
+
SW1
47µF
LT1107-5
SENSE
GND
SW2
5V
150mA
+
100µF
* SUMIDA CD54-330K
COILCRAFT DT3316-473
1107 TA01
Efficiency
82
80
V_IN = 3V
78
76
V_IN = 2V
V_IN = 2.5V
74
72
70
68
66
64
1
10
100
400
LOAD CURRENT (mA)
1107 TA02
1