Micropower
DC-DC Converter
a
ADP1173
FUNCTIONAL BLOCK DIAGRAMS
FEATURES
Operates From 2.0 V to 30 V Input Voltages
Only 110 A Supply Current (Typical)
Step-Up or Step-Down Mode Operation
Very Few External Components Required
Low Battery Detector On-Chip
User-Adjustable Current Limit
Internal 1 A Power Switch
SET
ADP1173
A2
AO
V
IN
GAIN BLOCK/
ERROR AMP
I
LIM
SW1
1.245V
REFERENCE
Fixed or Adjustable Output Voltage Versions
8-Pin DIP or SO-8 Package
A1
COMPARATOR
OSCILLATOR
DRIVER
APPLICATIONS
Notebook and Palmtop Computers
Cellular Telephones
SW2
GND
FB
Flash Memory Vpp Generators
3 V to 5 V, 5 V to 12 V Converters
9 V to 5 V, 12 V to 5 V Converters
Portable Instruments
SET
ADP1173-3.3
ADP1173-5
ADP1173-12
LCD Bias Generators
A2
AO
V
IN
GENERAL DESCRIPTION
GAIN BLOCK/
ERROR AMP
I
LIM
The ADP1173 is part of a family of step-up/step-down switching
regulators that operates from an input supply voltage of as little as
2 V to 12 V in step-up mode and to 30 V in step-down mode.
SW1
1.245V
REFERENCE
A1
COMPARATOR
OSCILLATOR
DRIVER
SW2
The ADP1173 consumes as little as 110 µA in standby mode,
making it ideal for applications that need low quiescent current.
An auxiliary gain amplifier can serve as a low battery detector,
linear regulator (under voltage lockout) or error amplifier.
R1
ADP1173-3.3: R1 = 456kΩ
ADP1173-5: R1 = 250kΩ
ADP1173-12: R1 = 87.4kΩ
R2
753kΩ
GND
SENSE
The ADP1173 can deliver 80 mA at 5 V from a 3 V input in
step-up configuration or 100 mA at 5 V from a 12 V input in
step-down configuration. For input voltages of less than 2 V use
the ADP1073.
REV. 0
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reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
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© Analog Devices, Inc., 1997